Doppler Radar The Doppler Effect The Doppler Dilemma

Doppler Radar The Doppler Effect The Doppler Dilemma
Etc – other topics Doppler Analysis and Diagnosis (Important New and Original Material linked to slide 80) The important part of this modules is how to use conventional radar data in the analysis and diagnosis of the current weather situation. This type of material is mirrored in both the Conventional and Dual Polarized PowerPoint's as well.

The Doppler effect Classically, the Doppler effect is a frequency shift The change in frequency of a signal returned from a target owing to its radial motion relative to an observer With radar, this is measured as a shift in phase between the transmitted pulse and the backscattered microwave radiation Average radial velocity of the target is calculated from this phase shift

The Radar Waveform

Velocity Spectrum Stationary GC WX WX Moves -VN VN

Phase Shift Ambiguity A shift of ¼ wavelength is ambiguous.
You don’t know if your are coming or going?

Velocity folding – Phase Shift Ambiguity
Target radial velocities producing phase shifts greater than one-half wavelength (or p radians) results in velocity folding Maximum unambiguous radial velocity Vmax (Nyquist velocity) = (PRF X Wavelength) / 4 This range is not adequate to describe all horizontal velocities Nyquist velocity=1200 X 5cm/4 = 1500cm/sec=15m/s=30knots Is a Nyquist velocity of 30knots enough?

The velocities with this storm are HUGE !!!!
Quick, increase the PRF and give me a sector scan on the storm cell ! Vmax (Nyquist velocity) = (PRF X Wavelength) / 4 By increasing the PRF, velocity foldng starts at a higher radial velocity

Folded Doppler quickly reaches the maximum colour range and cycles to opposite colours = noisy, complicated fields Interpretation is challenging! Helen was right! ? ? After PRF increased Before Helen’s Demand

Another Example

Maximum unambiguous range:
Doppler Dilemma Maximum unambiguous range: Rmax = c / 2PRF What is this for PRF = 1200 ? VmaxRmax = cl/8 Vmax and Rmax are inversely proportional to each other, but we want to maximize both That’s the Doppler dilemma 125 km

How can we increase Vmax ?

Velocity Unfolding Use two PRF’s and take the difference in the Doppler velocities ! The difference turns out to be a unique function of the actual velocity out to much higher velocities!! So DV and one of the velocity measurements can be used to unambiguously calculate the actual radial velocity, perhaps up to 48 m/s (almost 100 knots).

Whoa. Now that’s fast!!

Dual PRF Unfolding

Now we can see the whole storm, Bill !
That’s great, Jo. Now if only Dorothy and pigs would fly !

Example: Radial Velocity Product with Vr to 48 m/s
N-S Warm Front? Katabatic Cold Front? WLY upper level winds SELY low level winds

Doppler Patterns

Doppler wind interpretation
You can determine wind direction vs. height away from radar in two different directions Go out along zero line Draw line back to radar Wind is perpendicular to this line, towards the red echoes

Doppler wind interpretation
For any height you can attempt to determine the wind in 4 locations Determine the two zero line winds Look roughly 90° away for the max wind, which should be all directed along a radial In this way you can see areas of non-uniform flow confluence, diffluence

Doppler Uniform 30 m/s wind everywhere Uniform wind
The simplest case of all is that the wind is the same everywhere within radar coverage. In this case the radial velocity will varying only as a function of the antenna direction. If the antenna points directly into the wind then the observed radial velocity will be the wind speed (Towards) and if the antenna points downwind then the observed radial velocity will be the wind speed (Away). On the other hand if the antenna points directly across the wind, then the radial velocity will be zero. In between these extremes the wind varies sinusoidally. Figure 2. shows an example of how a uniform wind would appear on the King 95 display system.

Doppler Display - Uniform Wind Shear
Vertical Wind Shear of 13 knots per kilometre = Speed Shear only Vertically sheared wind and the PPI More typically, the wind will vary in height. In the simplest case the wind is uniform at any height and the radial velocity varies sinusoidally with antenna direction at each height. Typically radial velocity is viewed on a PPI surface, on which range corresponds to height, so the radial velocity can be interpreted as a sinusoid at each range. Directional shear: The simplest directional shear is that the direction changes linearly with height while the speed is constant. Velocity shear: The simplest case of velocity shear is one in which the radial velocity increases linearly from the surface. Figure 3. shows this situation as it would appear on a King 95 display.

Doppler with Directional Shear and Jet
Directional Shear and Wind Maximum 20 Jets: Frequently the velocity profile will involve a maximum in speed at some level. Figure 5. shows an example of a jet at 2km, with slight rotation of the wind with height.

Doppler with Wind Shear - Speed and Directional
Direction veering with height Speed increasing with height Directional and speed shear: Figure 4. shows an example of speed and direction increasing linearly with height.

The Doppler Vortex Rotating flows are not uncommon in the atmosphere, so it is useful to recognize how they may appear. At the smallest scale a vortex might be a mesocyclone associated with tornadic storm. At the larger scale a vortex might be the flow around a low pressure centre. Figure 6:Small embedded vortex. Figure 6. shows a 10km wide vortex rotating in solid body rotation added to a field with uniform motion of 5m/s.

Doppler Practice Westerly Winds with only Speed shear

Doppler Practice Westerly Winds with Low Level Jet

Doppler Practice Veering Winds with no Speed shear

Doppler Practice Backing Winds with no Speed shear

Changes in Stability? Doppler Practice
Low Level Veering under High Level Backing Winds - no Speed shear

Doppler Practice Wind shift line

Doppler Practice Large Scale Convergence

Doppler Practice Radar Site Divergence

Doppler Practice Radar Site Cyclonic Vortex

Doppler Practice SWLY NNELY LLJ QS Horizontal LLJ
Marginal winds Backing with Height - Cold Air Advection Maybe a Cold Conveyor Belt ahead of a synoptic system…

Doppler Displays

Velocity Azimuth Display - VAD
Doppler radial velocity data used to construct a wind profile in the vertical Direction, speed (m/s) and reflectivity (dBZ) displayed as a function of height (km) Note: Velocity scale is fixed in range 0-20 m/s ( i.e. most of the unfolded velocities are not used )

At a given height (h), then the radial velocity is: For a uniform flow field and assume Vw (Vertical Velocity) approximately = 0 then Best fit of a sine curve to the observations around the circle.

Accuracy of VAD decreases with elevation angle and height. The desired horizontal wind component becomes a smaller part of the radial wind component actually measure. Errors in the radial component has a bigger impact on the accuracy of the horizontal wind

VAD Example

A new Velocity Azimuth Display
LOLAA sees winds far from radar 3.5° scan sees winds closer in to radar – behaves most like a “profiler”

Doppler Spectra Width Rain Snow Spread of the Doppler Power Spectrum
the spread, range of terminal fall speeds of the scatterers (more pronounced for rain than for snow) spectra for rain spectra for snow turbulence of the air (upper levels in severe convection) vertical wind shear (e.g., along a gust front) antenna motion Rain Snow

Doppler Image Characteristics
Small Spectral Width Large Spectral Width

Spectral Width and “Doppler Display Texture”
Rain Texture Snow Texture

The Doppler Precipitation Spectral Width
Doppler Precipitation Texture Example As described, Doppler has texture that is the result of the spectral width of the radial velocity of the precipitation. Can we identify more things about this Doppler image. Where is the front? The front must lie at the top of the mixing layer. I sketched in a dashed white line, not worrying about being too exact – this is weather after all and not brain surgery. Close counts and the signals and signatures can be ambiguous. Is this the frontal surface with the mixing layer down below. If so the mixing layer winds appear to back below the dashed line which would be good since there should be cold air advection in the portion of the CCB that is mixing in this layer. Doesn’t there seem to be a counterclockwise twist in the colours like someone is twisting the top of a jar? I think that this analogy of twisting colours like the twisting of a lid is a good one. Below this dashed line (closer to the radar), the Doppler signal becomes noisy. Could this be the increased spectral width one would expect to observe as the snow melts into rain. I think so. Should we see a bright band on the conventional PPI to back this up. T Above this dashed line (further from the radar), the Doppler signal becomes smooth. Could this be the decreased spectral width one would expect to observe with pure snow (pure meaning it is all snow). I think so.

The Doppler Twist Signature - Example
The white dashed line separates different wind regimes in the vertical. It also separates regimes of differing Doppler texture. Above the dashed line the Doppler texture is uniform and characteristic of snow. Below the dashed line the texture is lumpy like oatmeal and characteristic of rain. This is also an example of the Virga Hole Signature The dashed line is likely the warm front. The layer immediately below is where the snow is melting into rain. I would have really liked the Dual Polarized imagery to go with this. I would also like a conventional radar PPI to show the bright band and to confirm this Doppler Texture analysis and diagnosis. Inherent in the Radar Palette and the Satellite Palette is the largely unspoken truism that the more evidence one can garner for a particular analysis or diagnosis, the more likely is that the analysis and diagnosis are correct.

Filtering using Doppler and Processing
Second trip echo to the northeast, urban multiple reflection spike, AP on the south shore of Lake Ontario, ground clutter. Highlighted in yellow are echoes due to second trip echoes. There are thunderstorms beyond Doppler range that are reflected by a previously transmitted pulse. Highlighted in white are reflections resulting from the radar beam being bent downwards. The beam is bent downwards (not the usual upward direction) due to an anomalous profile of the refractive index. See the beam height versus range diagram. This type of situation is most often observed in spring and fall conditions. The ground clutter (cyan highlighted) is present at all radar sites. There are reflections from the main beam but also from side lobes as well. The Niagara escarpment is to the west of the radar. The CAPPI (Constant Altitude Plan Position Indicator) product - see other examples - was developed to overcome the ground clutter problem. In green, an "urban" spike is highlighted. This is similar to the hail spike where mulitiple reflections from urban buildings in the city of Toronto cause a delay in returning the tranmitted pulse back to the radar and the echo appears at a longer range. Adaptive zero velocity filtering cleans up the image to show only weather echoes. There isvirtually no loss of weather echoes.. This has the big advantage of displaying the precipitation echo closest to the ground and best represents the precipitation that reaches the ground. The CAPPI indicates precipitation at 1.5 KM above the ground. Evaporation or growth of the precipitation and wind drift can cause discrepancies from the radar view and the surface view of the precipitation pattern.

Second Trip Echo – Extending the Range of the Doppler Scan
Random Phase Processing extends the Doppler Range Dual PRF’s extends the Nyquist Velocity

Second Trip Echoes

Second Trip Echo The velocity signatures of second trip echoes are very noisy. These still contribute to the reflectivity signal where they should not.

Second Trip Processing

Second Trip Processing
Doppler Reflectivity with Processed Second Trip Echoes Conventional CAPPI Doppler Reflectivity with Second Trip Echoes Doppler Reflectivity

Long Range Z The aim of these products is to extended the Doppler radar range to 220 km. Unfortunately, the governing radar equations imply that extending the Doppler range means sacrificing the maximum unambiguous Doppler velocity. There are two types of IRIS raw data files that can be accepted by KING95 for the creation of these products, they are the single PRF and the random phase - 2nd trip recovery modes. The straightforward approach is the use of the single PRF of 650. This mode is accompanied with a reduction of the maximum Doppler velocity to 8.7 m s-1.

Long Range Radial Velocity
To extend the Doppler velocity as well as radar range, a PRF mode of 1200 in conjunction with a technique called random phase processing (for the separation of 2nd trip echoes) is employed. In this mode, the maximum Doppler velocity is 16 m s-1. A side-effect of the 2nd trip recovery mode in the product display may be the appearance of a blanking ring at a radius just greater than 125 km. In the 2nd trip recovery algorithm, if the 1st trip's received power is more than 25 dB greater than the 2nd tip's power, the 2nd trip echo is swamped and thus unrecoverable. The IRIS configuration of the 2nd trip recovery mode places the beginning of the range of the 2nd trip echoes at 125 km, hence a power difference of greater than 25 dB at a distance of "x" km from the radar site will yield no information at the 2nd trip equivalent distance of "x+125" km. The pixel scale is 1 x 1 km for both these displays. The VAD table is not given in the long range radial velocity display, but otherwise, these displays may be interpreted identically as the previously described Doppler V and Z displays.

Doppler Wind Shifts B A The angle of viewing is very important and determines what one sees!

Operational Applications

Doppler Wind Shift

Doppler Wind Shift 30 minutes later
Velocity folding The most significant technological limitation occurs because the radar is pulsed. If the radial velocity is very high then the object can move more than one wavelength between pulses. But the radar processor is unable to distinguish phases that differ by an integer number of cycles. For example phases of 90°, 450° and -270° are all interpreted as 90°. The processing results in velocities that are all "folded" into a limited range of possible velocities. This range, known as the "Nyquist interval", depends on the radar's wavelength and the frequency with which pulses are emitted. Higher pulse repetition frequencies and longer wavelengths provide a larger Nyquist interval. Unfortunately high pulse repetition frequencies result in shorter maximum ranges, so a compromise needs to be made. Operational radars are configured so the vast majority of winds will be measured unambiguously, but every radar meteorologist will eventually encounter "folded velocities". Non-uniformity of the wind Non-uniformity of the wind at large scales was discussed above, but it also possible to have the wind changing within the sampling volume of the radar. For example at longer ranges the beam can have a vertical extent of several hundred metres, and winds can change radically through such depths. The radar system receives data that includes contributions from all the winds in the volume. Sometimes it will pick out some mean of the data, but often in such cases the system will recognize that it is faced with a confused situation and refuse to calculate any radial velocity. Dropouts in areas of high shear are not uncommon. Very very rarely the system will do something "crazy". Cold Front

Rain rate vs. Snow rate Radar equation for precipitation targets
K2 is 0.93 for water and for ice So for same Pr … Z for ice/snow is 5 times bigger than for rain (~ 6.5 dBZ greater) Since , you need lots of larger D snowflakes than raindrops to make the larger Z refractive index factor power returned reflectivity factor radar constant range

But these are not valid in all situations
Rain rate vs. Snow rate Reflectivity Z is empirically related to rain rate R in the form : Z = aRb In Canada we use Marshall-Palmer (stratiform rain) : Z = 200R1.6 U.S. NEXRAD : Z = 300R1.4 For snow we use : Z = 1780S2.21 But these are not valid in all situations

Rain Rate vs Snow Rate Snow being depicted using the Rain Z-R Relationship Snow depicted using the Snow Z-R Relationship Normal CAPPI height is 1.5 km - precipitation intensities are given in a mm/hr scale Cold season (snow expected) CAPPI height is lowered to 1.0 km better look at low level features that are significant in winter storms and may be missed at 1.5 km

Bird Migration and Radar
Birds are essentially big packets of water and thus return a lot of radar energy- they are huge rain drops. Radar studies estimate bird density and migration numbers. A vertical looking microphone has also been used to identify bird calls. A typical bird density during migration is only a bird or two in a volume roughly the size of a foot ball field. Non meteorological targets: birds and bugs Birds and insects in large numbers can make targets that look very much like weather to the radar processor. The human eye can usually distinguish them however because of their specked appearance in comparison to precipitation, which usually is much more uniform. The radar processor does attempt to remove isolated targets such as individual birds, insects or aircraft, so birds and insects are only seen if they are present in large numbers. Insects are widely believed to be the source of "clear air echos" that appear in summer at low levels. With the exception of insects that move in large groups (eg locust), insects usually have low mean speeds relative to the air and can be regarded as passive tracers. Thus the velocities from clear air echos due to insects can be regarded as due to winds. Birds on the other hand do migrate in large numbers in the spring and fall. Migrating birds can have large velocities relative to the air (10’s of m/s) and radial velocities due to birds cannot be related to winds. Most migrating birds fly on non-rainy nights in the lower few kilometres of the atmosphere. The bird "signature" usually starts slightly after sunset and continues until an hour or so before dawn. In southern Ontario, birds migrations can show up on radar from mid April to mid June and from early September to mid November. Times elsewhere should be similar. Migrating birds have enough reflectivity and uniformity of motion that the VAD routines will calculate winds from their motion.

Radar Detection of a Lake Breeze

“Clear” Air Radar Returns
The Clear Air return of radar energy is a result of scattering from bugs and dust. The air may be “clear” of precipitation but it is not clear of material that reflects radar energy. The lake breeze fronts are often identifiable on radar as the associated convergence concentrates targets in the atmosphere. In regions without precipitating clouds, i.e. clear air, it has been found that echoes are mostly due to insects or to strong gradients of refractive index in the atmosphere. The echoes are of very low intensity, and detected only by very sensitive radars. Equivalent Ze values for clear air phenomena appear in the range of -5 to -55 dBZ although these are not true Z parameters, the physical process generating the echoes being entirely different. For precipitation measurement, these echoes are a minor noise in the signal. Echoes due to refractive index fluctuations can usually be associated with some meteorological phenomenon such as a sea breeze, thunderstorm outflows or mixing in the boundary layer. Clear air echoes also can be associated with birds and insects in surprisingly low concentrations. Echo strengths of 5 to 35 dBZ are not unusual especially during migrations (see Table 3).

“Clear” Air Radar Returns and Lake Breeze
Blue Skies and Clear Air Echoes 16 Sep 98 There were clear blue skies in the Toronto area on the afternoon of Sept A beautiful fall day with moderate temperatures and little wind. BUT the radar showed good echo within 20 km of the radar. You can even see a lake breeze at the lake boundary. Index of refraction or bugs. It's been an El Nino summer this year and the bugs this week have been out in force at night. My guess - bugs.

“Clear” Air Thunderstorm Outflow Gust

Anomalous Propagation of the Radar Beam
Only Real Weather AP and Real Weather Anomalous propagation (AP) is the abnormal ducting of the radar beam back to the ground because of surface based inversions. The ground is highly reflective to the radar beam and thus returns a considerable amount of energy. In many AP examples, the outline of the Great Lakes is returned because of the ducting of the radar beam over the water and the resultant returns from the higher shorelines. In this example, AP and actual weather can be found in the same image. The AP is removed using the doppler radar filter. This recognizes that the ground does not move and thus has a zero doppler velocity while the weather is moving with the atmosphere. The zero motion “echoes” are removed to leave only actual weather. In this image, there is real weather echo and echo due to anomaloous propagation due to beam bending. Can you pick out which is which? Corresponding image taken in Doppler mode where ground echoes which don't move very much are filtered out. The echo to the southwest of the radar is now filtered out. To the untrained observer, it could have been interpreted as a stationary heavy rain storm potentially causing flash flooding but with the sophistication of the Doppler technology, this echo is removed. There is no flash flood situation present in this case. The Doppler Velocity View

Severe Weather Signatures on Radar

Radar Observation of Hail or Very Heavy Precipitation
The spikes signature is associated with hail or heavy rain. It results from the radar beam being reflected from the hail or rain in the thunderstorm, then reflecting from the surface then back to the thunderstorm and then back to the radar… a longer path...

Carvel Radar near Edmonton
An example of "hail spikes" from the Carvel Radar near Edmonton. The "spikes" are located in the storms to the south and southeast of the radar (centre of the picture). They are lined up radially from the radar. The hail spikes can be seen in the MAXR and Echo Top maps. The spike signature is associated with hail or heavy rain and is a result of the radar beam being reflected from the hail or rain in the thunderstorm, then reflecting from the surface then back to the thunderstorm and then back to the radar. The high amount of radar energy returning to the radar over a longer period of time, means that the “displayed return” is stretched along the radial from the radar. Multipath Occasionally the radar beam can be reflected off of buildings or even hail shafts and be sent in another direction other than along the radial away from the radar. If this deflected signal gets echoed back along the same path it will produce a Doppler shift that corresponds to a movement that is NOT the radial velocity. Usually the resulting velocity signature is recognized as "strange" but may not be recognized for what it is. ”Hail spikes" from the Carvel Radar near Edmonton

Hail Spikes & Side Lobe MAXR Echo Top

Hail Hazards Map The Hail Hazards Map
This map was generated by Paul Joe for the Hazards Poster project. The Canadian map is from the Canadian Climate Atlas and is repeated in several publications including Dave Phillips' Climates of Canada book. The US map is from Changnon and ?? as published in the AMS Met Monograph edited by Brant Foote and ??. The Mexican map is from ??? and is orignally from Frisby and Sansom, 1967.

The divergent signature is southeast of the radar and is too large (more than 4 km in diameter) to be classified as a microburst. The term is either a macroburst or downburst. Corresponding Radial Velocity Images. Note that at the higher elevation angles a rotation signature can be seen. Downbursts are often observed with rotation during its descent.

Rotating Downbursts on Descent
0.5 Doppler Velocity 1.5 Doppler Velocity 1.3km 4km 3.5 Doppler Velocity Rotating Downbursts on Descent 11km Cyclonic rotation

Downbursts The stages of s downburst. Note that the vector motion of the parent thunderstorm is added to the downburst winds.

A December Squall Line with Rear Inflow Jet
Rear Inflow Jet on a rare December Squall Line On Dec 1, 1996, radio reports indicated a possible tornado west of Guelph. This would be incredibly unusual to have a December tornado. The radar imagery shows a really nice bow echo. These can generate downbursts, microbursts and rear inflow jets. These things can do the same damage as tornadoes. The damage patterns would show different things.

Severe Thunderstorm Processes

3.5 Degree Doppler Close-up View
0.5 Degree PPI Reflectivity Display Mesocyclone on Reflectivity Display Automated Mesocyclone detection. This is a good example of a mesocyclone that was only detected on the 3.5 degree PPI. 0.5 Degree PPI Doppler Velocity 3.5 Degree PPI Doppler Velocity

0.5 and 3.5 Degree PPI Doppler

Doppler Analysis and Diagnosis Strategies
An operational guide to getting the most information from Doppler radar: Determining the actual wind direction Determining wind backing and veering Diagnosing spatial versus vertical wind variations The Screaming Eagle and Bird Patterns

Diagnosis of the Conveyor Belts
Wind direction and speed diagnosis should be completed independently in each conveyor belt Given the nature of isentropic flow, this is a prudent mode of diagnosis. Isentropic flows stay relatively separate and maintain their distinctive properties. The Doppler characteristics depicted in the CCB are separate from those in the WCB. When added, instructive patterns are revealed.

Range Ring versus Radial Zero Velocity Doppler Lines
B A B C A C Radial Zero Lines Range Ring Zero Lines A is the radar site Zero Doppler Velocity line that follows a radial from the radar like BC depicts velocity vectors that are: At ever increasing heights Depictions of vertical speed shear wind differences (no directional shear) Radial Zero Lines thus depict vertical wind difference/shear A is the radar site Zero Doppler Velocity line that follows a range ring like BC depicts velocity vectors that are: All at the same elevation Depictions of horizontal wind differences – primarily directional wind shear Range Ring Zero Lines thus depict spatial wind difference (primarily directional shear) These are important conceptual models in order to make the use of Doppler information. The characterisitcs of the Doppler Zero line reveals must about the wind shear. There are even many more signatures that reveal characteristics of the relative wind magnitude. The real Doppler data is a combination of these two patterns

Diagnosis of Wind Direction – Using the Zero Line
Draw a radial line from the radar site to the zero line The wind must be either zero or the wind direction must be exactly perpendicular to the radial line The wind direction can be determined as blowing from the toward colours (blue) to the away colours (red) perpendicular to the radial Click now Zero Line A B A is the radar site BC the zero line Everywhere along the zero line the radial component of the real wind detected by Doppler must be zero – meaning the total wind must be perpendicular to the radar radial – or actually zero which is unlikely. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection. In Doppler wind analysis always establish the layers where the zero line veers (turns clockwise with range/height) and layers where the zero line backs (turns counterclockwise with range/height. These are the thermal advection layers. The point of inflection between backing and veering separates these important analytical layers.

Diagnosis of Vertical Windshear – Using the Zero line
Determine the wind at B. Draw a radial line from the radar site to the zero line at B. Click Determine the wind at C. Click The wind backs from B to C Determine the wind at D. Click The wind veers from C to D B C D A Summary - Generalizations Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the thermal advections. The smaller the angle subtended by the arc, the weaker the advections. This angle is independent of range from the radar Thermal Advection Type If the arc rotates cyclonically with height (increasing range) the arc is associated with warm advection. If the arc rotates anticyclonically with height, the arc is associated with cold advection. Note that the directional wind shear increases with the angle subtended by the arc – This angle does not change with range from the radar (directional shear). The angle subtended by the zero line arc is the directional wind shear component of the velocity vector shear. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection. … and yes, I made this up – maybe even invented it for the first time. Who knows? Phil

Diagnosis of Vertical Windshear – Using the Zero line
B C D A B C D A The angle subtended by the counter-clockwise arc BC would be the same regardless of the exact location of C anywhere along the radial AC from the Doppler radar. The amount of backing with height is also independent of the location of C along the radial AC. The amount of wind shear (cold advection) is dependent only on the subtended angle and not the orientation of the arc. The angle subtended by the clockwise arc CD would be the same regardless of the exact location of D anywhere along the radial AD from the Doppler radar. The amount of veering with height is also independent of the location of D along the radial AD. The amount of wind shear (warm advection) is dependent only on the subtended angle and not the orientation of the arc. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection. … and yes, I made this up – maybe even invented it for the first time. Who knows? Phil The thermal VWS is thus the angle subtended by the arc divided by the elevation change that this thermal advection occurred over. The following slide illustrates these concepts.

Thermal Advections and Vertical Wind Shear
The angle subtended by the counter-clockwise arc BC is identical in 1, 2 and 3. In 1, the backing winds occur over a short radial range and thus a short height interval. The radial range difference increases for case 2 and is even more for case 3. The height interval for the Thermal VWS increases with the length of the radial AC from case 1 to case 3. The Thermal VWS determined by dividing the direction shear (subtended angle dependent) by the height interval (difference between AC and AB=AD) that it occurs over, is strongest for 1 and weakest for 3. As detailed, Thermal VWS is a combination of the size of the subtended angle and the radial range (AC-AB=AD) which when combined, is inversely proportional to the area CBD. This could feasibly be automatically calculated in URP. I sincerely doubt if it is. D C 1. A B A B C D 2. A B C D 3.

Thermal Advections and Vertical Wind Shear
Which has the strongest Thermal VWS? The smaller the area CBD, the more intense the Thermal VWS and thus the more intense the thermal advections. D C 1. A B For a given subtended angle: the strongest Thermal VWS occurs with a Doppler Zero Line closely following the range rings the weakest Thermal VWS occurs with a Doppler Zero Line closely following the radar radial lines C D 2. A B C Similarly for a given height interval CD radial: the strongest Thermal VWS occurs with the largest subtended angle the weakest Thermal VWS occurs with the smallest subtended angle D 3. A B

Diagnosis of Stability Trends
Stability increases with: Cold advection decreasing with height: Angle of Doppler arc backing counterclockwise decreasing (rate of cooling decreases) with height (range) increasing (Area CBD increasing), Warm advection increasing with height: Angle of Doppler arc veering clockwise increasing (rate of warming increases) with height (range) decreasing (Area CBD decreasing), Warm advection over cold advection: Doppler arc veering clockwise with height (range) over Doppler arc backing counterclockwise with height (range). Using the zero line to establish wind shear: For a fixed length of arc, if the wind shear is aligned along a range ring (spatial distribution of wind shear), then it is likely that the same wind shear is also experienced in the short vertical distance. Strong wind shear over a short vertical distance is associated with strong thermal advections. For a fixed length of arc, if the wind shear is aligned along a radar radial (vertical distribution of wind shear), then it is certain that the wind shear is also experienced in the larger vertical distance. Strong wind shear spread over a larger vertical distance is associated with weaker thermal advections. The conceptual model summary for this is that thermal advections should generally decrease as the angle between the range ring and the arc (zero line) increases. Of course, the exact about of wind shear can probably be determined by making the best estimate of the actual winds and wind shear from the colour display. This approach would take longer and not be used operationally.

Doppler Examples for Increasing Stability
Level D Weaker cold advection CD Level C Stabilization Stronger cold advection BC C Level B 1. A B Level D Stronger warm advection CD C Level C Stabilization B Weaker warm advection BC Level B 2. A D Level D (Strong) Warm advection CD C Level C Stabilization (Weak) Cold advection BC Level B 3. A D B Note: Angles kept constant. Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.

Diagnosis of Stability Trends
Stability decreases (Destabilization) with: Cold advection increasing with height: Angle of Doppler arc backing counterclockwise decreasing (rate of cooling increases) with height (range) Warm advection decreasing with height: Doppler arc veering clockwise with height (range) under Doppler arc backing counterclockwise with height (range). Angle of of Doppler zero arc veering clockwise increasing (rate of warming decreases) with height (range), Warm advection under cold advection: This needs to be checked more thoroughly… it might be a good idea but will take some study to be certain.

Doppler Examples for Increasing Instability
Level D Stronger cold advection CD Level C Destabilization C Weaker cold advection BC Level B 1. A B D Level D Weaker warm advection BC Level C Destabilization C Stronger warm advection BC Level B 2. A B D Level D (Weak) Cold advection CD B Level C Destabilization C (Strong) Warm advection BC Level B 3. A Note: Angles kept constant. Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.

Changing Stability by Changing the Angle of the Vertical Wind Shear
As the angle subtended by the zero line increases, the amount of directional wind shear also increases. The directional wind shear must be divided by the height over which this shear occurs in able to determine the magnitude of the thermal advections. Generally, as the angle increases, so does the thermal advections. The angle of the zero line relative to the range rings is essential to use this technique in an operational setting.

Doppler Examples for Increasing Stability
Level D Weaker cold advection CD C Level C Stabilization Stronger cold advection BC Level B 1. A B Level D Stronger warm advection CD C Stabilization B Level C Weaker warm advection BC Level B 2. A D Cold Advection Decreasing with Height Stabilization Warm Advection Increasing with Height Stabilization The angles that the zero line makes with the range rings is the operational approach to employ. o o CAA angle increasing with range/height. WAA angle decreasing with range/height. Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the enclosed area.

Doppler Examples for Increasing Instability
Level D Stronger cold advection CD Level C Destabilization Weaker cold advection BC C Level B 1. A B Level D Weaker warm advection CD Destabilization B Level C Stronger warm advection BC Level B 2. A C D Cold Advection Increasing with Height Destabilization Warm Advection Decreasing with Height Destabilization The angles that the zero line makes with the range rings is the operational approach to employ. o o CAA angle decreasing with range/height. WAA angle increasing with range/height. Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the enclosed area.

Example of Increasing Instability – Differential Warm Advection in the Vertical
Southeast of the radar Arc CD subtends a veering, clockwise angle with range/height. This is warm advection. As detailed the warm advection CE is stronger than that from ED. The air mass is strongly destabilizing southeast of the radar. Applying the same principles to AB, AF and FB, the air mass northwest of the radar is also destabilizing but not as much. B F A The Virga Hole C Note that the warm advection southeast of the radar from CD, is distinctly different that the warm advection described along the zero line from AB northwest of the radar. Northwest of the radar the AB warm advection occurs through roughly the same vertical depth as to the southeast vector CD. Within the CB layer, the height change is more or less equally distributed between the vectors AF and FB. As explained previously, the amount of the angle subtended by each arc gives the wind shear and thus the VWS associated with AF must be greater (greater angle for the same height differential) than that associated with FB (smaller angle for the same height differential) . Layer AB is destabilizing through differential warm advection in the vertical. The CD warm advection occurs through roughly the same vertical depth as AB but most of the angle is subtended by the arc CE with a minimal angle subtended by ED. The height change of vector CE is much smaller than that of ED. The combination of strong direction shear over a small height interval means that the thermal advection associated with CE is much greater than that associated with ED. Thus layer CD is becoming much more unstable. When the thermal advection of AB is compared with that of CD: Both are veering Both are warm advection AB are CD are both destabilizing CD is destabilizing faster than AB E D

Doppler Rate of Thermal Advections with Height
Consider the angle between the veering or backing arc and the radar range ring. If this angle increases (in time) from previous values then the rate of wind shear with height is decreasing, since height is a function of radial range. This must imply that for a given arc, the thermal advections have decreased. If this angle decreases (in space) along the arc then the rate of wind shear with height is increasing, since height is a function of radial range. This must imply that for a given arc, the thermal advections have increased. Track the angle the arc makes with the radar rings with both time (between scans) and in space along the trace of the arc… if the angle increases, then the associated thermal advections are decreasing. o

For example: A clockwise, veering arc associated with warm advection vertical wind shear: Indicates that the layer is becoming more stable if the angle with the range rings decreases with range. (warm advection increasing with height) Indicates that the layer is becoming more unstable if the angle with the range rings increases with range. (warm advection decreasing with height) To my knowledge, I invented this. I haven’t seen anyone else present this material.

For example: A counterclockwise, backing arc associated with cold advection vertical wind shear: Indicates that the layer is becoming more stable if the angle with the range rings increases with range. (cold advection decreasing with height) Indicates that the layer is becoming more unstable if the angle with the range rings decreases with range. (cold advection increasing with height) To my knowledge, I invented this. I haven’t seen anyone else present this material. This can get complicated.

The Doppler Twist Signature
The backing and veering of the zero line signature can be augmented by the Doppler Twist Signature. The Doppler Twist signature tends to be observed below the top of a layer. Different wind regimes from above the layer, mix/blend with the wind regime below the layer. Typically the top of a layer is a stable frontal zone with the mixing layer immediately beneath the frontal surface. As the name implies, the properties of the warm over-riding air aloft are blended with those of the cold air underneath in the mixing layer. Temperature, humidity and wind are the main air mass properties that are blended in this mixing layer. In the case of mixing the wind, the Doppler signature immediately under the frontal inversion resembles the pattern one would achieve if the Doppler colours are twisted like a lid until at the level (shortest radar range) where the winds are those of the unmixed colder air flow beneath. By matching colours from above and below the mixing layer, one can deduce the type and amount of wind shear between the to levels.

The Doppler Twist Signature - Example
The white vectors match the colours from below the mixing level to above the mixing level. The direction of rotation indicates the type of thermal advection associated with the Doppler Twist. The length of the vectors indicate the magnitude of the thermal advection. This is also an example of the Virga Hole Signature B F A The Virga Hole C Veering Lid Twist Signature E D

Conveyor Belt Conceptual Models
This information is repeated in links within the Conveyor Belt Conceptual Model

Doppler and the Conveyor Belt Conceptual Model
North of the Surface Warm Front Conceptual Models R = Right of the Col C = Centered on the Col L = Left of the Col

Vertical Deformation Zone Distribution and the CBM Simplified Summary
The WCB overrides the warm front CCB The CCB undercuts the warm front C The frontal surface overlies the mixing layer Wind shear in the CCB is variable Looking along the WCB flow: In WCB to the right of the Col expect veering winds with height – Katabatic warm front In WCB approach to the Col expect maximum divergence – the eagle pattern with ascent and increasing pcpn In WCB to the left of the Col expect backing winds with height – Anabatic warm front WCB DCB C C DCB Typical distributions of the conveyor belts and the associated deformation zones. Recall from the satellite palette that the deformation zone is actually a cross-section of the deformation sheath that encases an isentropic flow. Similarly, the vorticity centres depicted in the deformation zone conceptual model are actually vortex tubes that also slope in the vertical along with the deformation sheath. The Warm Conveyor Belt (WCB) typically rises isentropically with poleward (both northeasterly and northwesterly) motion and time. The WCB is shown with no vertical wind shift but typically it veers with height which is consistent with warm air advection. The Cold Conveyor Belt (CCB) typically sinks isentropically with equatorward (southwesterly) motion and time. The CCB typically backs with height which is consistent with cold air advection. The Dry Conveyor Belt (DCB) typically sinks isentropically with equatorward (southeasterly) motion and time. In the “dry slot” of the comma pattern, the DCB is typically rising isentropically with poleward (northeasterly) motion and time. The DCB typically veers with height with the approaching upper ridge. The flow ahead of the conveyor belt system has not been typically described but is the remains of the dry conveyor belt caught up in the upper ridge circulation. (Chadwick has described it in unpublished work.) This circulation is dry and subsiding with poleward (northwesterly) motion and time. The portion of the flow that turns southwesterly dry rises with equatorward (southwesterly) motion and time. This portion of the CCB typically veers with height which is consistent with warm air advection west of the upper ridge. The slope of the isentropic surfaces can be inferred from the overlap of the deformation zones. The slope of the isentropic surfaces can also be used to analyze instability. Isentropically speaking, sinking cold air and rising warm air converts thermal energy into kinetic energy. The vertical motions of dry air is not so simple isentropically speaking – have to ponder this! The introduction of isentropic thinking to NinJo will make the investigation of these concepts much easier.

CCB Doppler Diagnosis – CCB Conceptual Models
The CCB Conceptual Model is independent of that in the WCB. Like Mr. Potato Head, one can mix and match conceptual models in the distinctly different conveyor belts. B C C A A The Beaked Eagle The Headless Eagle A is the radar site AB is backing with height indicative of cold advection where really there should be veering as a result of the Ekman Spiral BC is veering with height indicative of warm advection B is the front with the mixing layer hidden in the cold advection This is a strong cold advection The warm front will be slow moving or stationary A is the radar site ABC is all veering with height indicative of warm advection. Layer AB is apt to be partially the result of the Ekman Spiral BC is veering with height indicative of warm advection Where is the front and the mixing layer? The cold advection is not apparent and the warm front will advance One must always attempt to identify the location of the boundaries between the conveyor belts. The methods to do this are: Consider the ever present Ekman Spiral which should cause veering with height. There will be an abrupt change in the wind direction and speed (gradient wind) at the top of the PBL and the Ekman Spiral. Know the expected characteristics of the conveyor belt one is diagnosing by placing the Doppler data into the conveyor belt pattern and employing situational awareness. Keep the mixing layer of any front within the cold air mass. The frontal surface is always higher than this mixing layer. To my knowledge, I invented this. I haven’t seen anyone else present this material.

Vertical Deformation Zone Distribution and the CBM Simplified Flows in the Vertical
CCB Above frontal surface: Winds back with Height and distance from Xl Above frontal surface: Winds veer with Height and distance from Xr Below frontal surface: Winds could veer or back but likely veer C Xc Xr Below frontal surface: Winds could veer or back Xl Warm Sector: Winds back with Height and distance from Xl Warm Sector: Winds veer with Height and distance from Xr No VWS DCB WCB C C DCB Typical distributions of the conveyor belts and the associated deformation zones. Recall from the satellite palette that the deformation zone is actually a cross-section of the deformation sheath that encases an isentropic flow. Similarly, the vorticity centres depicted in the deformation zone conceptual model are actually vortex tubes that also slope in the vertical along with the deformation sheath. The Warm Conveyor Belt (WCB) typically rises isentropically with poleward (both northeasterly and northwesterly) motion and time. The WCB is shown with no vertical wind shift but typically it veers with height which is consistent with warm air advection. The Cold Conveyor Belt (CCB) typically sinks isentropically with equatorward (southwesterly) motion and time. The CCB typically backs with height which is consistent with cold air advection. The Dry Conveyor Belt (DCB) typically sinks isentropically with equatorward (southeasterly) motion and time. In the “dry slot” of the comma pattern, the DCB is typically rising isentropically with poleward (northeasterly) motion and time. The DCB typically veers with height with the approaching upper ridge. The flow ahead of the conveyor belt system has not been typically described but is the remains of the dry conveyor belt caught up in the upper ridge circulation. (Chadwick has described it in unpublished work.) This circulation is dry and subsiding with poleward (northwesterly) motion and time. The portion of the flow that turns southwesterly dry rises with equatorward (southwesterly) motion and time. This portion of the CCB typically veers with height which is consistent with warm air advection west of the upper ridge. The slope of the isentropic surfaces can be inferred from the overlap of the deformation zones. The slope of the isentropic surfaces can also be used to analyze instability. Isentropically speaking, sinking cold air and rising warm air converts thermal energy into kinetic energy. The vertical motions of dry air is not so simple isentropically speaking – have to ponder this! The introduction of isentropic thinking to NinJo will make the investigation of these concepts much easier.

WCB to the Right of the Col
The Warm Right Wing Stoop CM The eagles right wing is folded in as if it is about to swoop down. The left wing is still fully extended to catch the lift of the WCB. C o Signature of Warm Frontal surface Warm advection Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Mixing layer Warm frontal surface Left Wing Right Wing Warm CB Within the WCB: East of radar veering, warm advection West of radar nil VWS

Inactive or Katabatic Warm Front
One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the warm frontal surface. If the wind veers above the frontal surface, then that wind is less than the forward speed of the warm front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a warm front with veering winds above the frontal surface must be katabatic.

WCB Approaching the Col
The Warm Screaming Eagle CM Both wings are fully extended to catch the lift of the WCB. This is a divergent signature. C Warm CB Warm frontal surface o Mixing layer Signature of Warm Frontal surface discontinuity Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Left Wing Right Wing Within the WCB: East of radar veering, warm advection – katabatic warm front. West of radar backing, cold advection – anabatic warm front.

The Warm Screaming Eagle Conceptual Model
Need to emphasize The PPI nature of the Doppler scan - The cone D A G C B E F This is the idea. I am contemplating: Leaving this material as is and letting COMET build it in Flash from the letters and the descriptive text Building this in HTML as the roll-overs area easier in HTML Note that this may also be done using links to text files. I will format the text box to be as small as possible and located where it does not obscure the image. This apporach works fairly well. Note that the animations in PPT obscure the lettering unless the presentation is in “play” mode. It makes it more difficult to work on. The animations highlight the best way to deduce winds vectors from the Doppler signal. The work below should highlight how the winds in the CCB are diagnosed separately from the winds in the WCB. The resultant diagnoses are then added together to create the mythical creature desired. A is at the radar site. The arc A to B represents the veering wind associated with the warm front as seen to the east of the radar. Is this the mixing zone or the warm air advection in the CCB? The warm frontal surface must be at the top of the mixing zone. The arc A to C is the same representation to the west. The difference in the height of B and C represents the slope of the warm front. The shape of the outbound reds in the arc A to B defines the eagles head. The stronger the low level CCB the “brighter” will be the “beak”. The more curved the A to B veering wind is the more prominent will be the beak. The best “beak” will be displayed by a backing wind in the lower part of the A to B layer. This backing wind is indicative of cold air advection within the CCB. This is suggestive that the cold layer underneath the warm frontal surface coninutes to cool with fresh reinforcements. The cold air is likely to become deeper and more entrenched thus preventing the northward progression of the warm front which is really the southward advance of the cold air. The smallest “beak” will be displayed by a veering wind in the lower part of the A to B layer. This veering wind is indicative of warm air advection within the CCB. This is suggestive that the cold layer underneath the warm frontal surface is warming and is likely to dissipate allowing the northward progression of the warm front which is really the northward retreat of the cold air. B and E are very close to being on the same radial which means that there is no change in wind direction and no thermal advection. From C to D there is a slight backing of the wind which becomes more pronounced at point F. This backing of the winds increases the height of the right wing. If we look at the radial from A to F and the winds are at right angles, then at point F our winds are from 160 degrees. Contrast this with what happens west of the radar. Between points E and G the winds back slightly and are about 180 degrees at point G. This backing of the winds increases the height of the right wing. Between points G and H the winds veer. At point H if we look at the A to H radial and go 90 degrees we define a wind direction of about 215 degrees. The 20 to 40 degree wind direction difference between D to F and G to H is what gives our eagle it’s wing shape. The 215 winds to the east of the radar and the 160 winds to the west indicate we are close to the col of the conveyor belt. As we move further west or as the warm conveyor belt moves over this radar the left wing of the eagle should maintain itself or become more curved and the right wing should straighten out. I think a simple streamline example will illustrate this. H The Warm Screaming Eagle Conceptual Model

Inactive or Katabatic Warm Front
Active or Anabatic Warm Front Approaching the Col the Warm Front should have characteristics intermediate between the Anabatic Warm Front to the Left of the Col and the Katabatic Warm Front to the Right of the Col Inactive or Katabatic Warm Front One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the warm frontal surface. If the wind veers above the frontal surface, then that wind is less than the forward speed of the warm front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a warm front with veering winds above the frontal surface must be katabatic.

WCB to the Left of the Col
The Warm Left Wing Stoop CM The eagles left wing is folded in as if it is about to swoop down. The right wing is still fully extended to catch the lift of the WCB. C o Signature of Warm Frontal surface … odd? Signature of Warm Frontal surface Warm advection Within the CCB: Probable Ekman spiral nearest surface Probable cold advection above Ekman spiral Cold CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Mixing layer Right Wing Warm frontal surface Left Wing Warm CB Within the WCB: West of radar backing, cold advection East of radar nil VWS

G D A C B F The Left Wing Stoop CM
On the west side of the warm conveyor belt the eagle has indeed lost it’s right wing. The left wing continues to show the 40 degrees of backing of the winds into the southeast. But now the right wing is also backing but by only about 10 or 15 degrees. The flow is still diffluent but not as much as in the middle of the arm conveyor belt.

Active or Anabatic Warm Front

WCB Doppler Diagnosis – Diagnosis of the Eagle Wing
The Left Eagle Wing The Right Eagle Wing A is the radar site BC is veering with height indicative of warm advection. CD is backing with height indicative of cold advection Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections A broad wing in the eagle is associated with strong advections A is the radar site BC is backing with height indicative of cold advection. CD is veering with height indicative of warm advection Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections A broad wing in the eagle is associated with strong advections The eagle wing analogy works – I am certain there are many more analogies that could be employed. Notice that the type and intensity of the thermal advections can be determined by the size of the angle that the arc subtends and the direction of the arc. Thermal Advection Intensity The larger the angle subtended by the arc, the stronger the advections. The smaller the angle subtended by the arc, the weaker the advections. Thermal Advection Type If the arc rotates cyclonically or clockwise with height, the arc is associated with warm thermal advection. If the arc rotates anticyclonically or counterclockwise with height, the arc is associated with cold thermal advection.

WCB Doppler Diagnosis – Diagnosis on the Gull Wing
The Gull Conceptual Model - weaker thermal advections C C A A D D B B The Left Eagle Wing The Right Eagle Wing A is the radar site BC is veering with height indicative of warm advection. CD is backing with height indicative of cold advection Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections A narrow wing in the gull is associated with weak advections A is the radar site BC is backing with height indicative of cold advection. CD is veering with height indicative of warm advection Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections A narrow wing in the gull is associated with weak advections The important concept is to realize that in Doppler radar data, the size of the backing or veering arc is directly related to the intensity of the thermal advections.

Within the Warm Sector Conceptual Models R = Right of the Col C = Centered on the Col L = Left of the Col

Radar Data and the Warm Sector Portion of the Warm Conveyor Belt
Precipitation returns will be limited in extent if they exist at all Radar data will be largely unavailable and unreliable This results in a very incomplete display of the Doppler wind field in particular Of course the information displayed on radar is dependent on the amount and extent of the precipitation. Along the warm conveyor belt, the radar information is bound to be limited if not non-existent. The examples and conceptual models illustrated optimistically and unrealistically assume that there is an abundance precipitation both in amount and extent. The cold conveyor belt will not be evident in these conceptual models since the warm front lies to the north of these conceptual models.

Within the Warm Sector Conceptual Models
These conceptual models will be virtually identical to those associated with the three locations north of the warm front with the exceptions that: There will be and cannot be any evidence of the cold conveyor belt The veering and backing with height signatures will be less pronounced The reduced extent of warm sector precipitation will be an issue Gulls are found in the warm sector, more so than eagles… I expect that these will be virtually identical to those associated with the three locations north of the warm front with the exceptions that: There will be and cannot be any evidence of the cold conveyor belt The veering and backing with height signatures will be less pronounced

Right of the WCB in the Warm Sector
The Headless Right Wing Stoop CM The headless gull’s right wing is folded in as if it is about to swoop down. The left wing is still fully extended to catch the lift of the WCB. o Signature of Ekman Spiral Within the PBL: Probable Ekman spiral near surface resulting in slight veering with range Note that this conceptual model was contructed without seeing actual Doppler Radar data from this area of the CBCM. A real image would help immensely. There is no hed in this conceptual model and I weakend the amount of veering to the right of the radar. Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Right Wing Left Wing Within the WCB: East of radar veering, warm advection West of radar nil VWS C

The Headless Right Wing Stoop CM
Left Wing This slide is reserved for an actual radar example.

Under the WCB in the Warm Sector
The Headless Gull CM Both wings are fully extended to catch the lift of the WCB. This is a straight line uniform wind field but could be a slightly divergent signature. Note that headless gulls can’t scream… The advections in the warm sector do not warrant this being called an eagle pattern. o Within the PBL: Probable Ekman spiral near surface resulting in slight veering with range Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Left Wing Right Wing Within the WCB: East of radar veering, weak warm advection – veering winds possible West of radar backing, cold advection – backing winds possible

The Headless Gull CM o The southwesterly WCB is essentially a straight flow but there are hints of the upper level divergence depicted in the conceptual model. Left Wing Right Wing

Left of the WCB in the Warm Sector
The Headless Left Wing Stoop CM The headless gull’s left wing is folded in as if it is about to swoop down. The right wing is still fully extended to catch the lift of the WCB. o Within the PBL: Probable Ekman spiral near surface resulting in slight veering with range Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Right Wing Left Wing Within the WCB: West of radar backing, cold advection East of radar nil VWS C

The Headless Left Wing Stoop CM
Right Wing Left Wing This slide is reserved for an actual radar example.

Behind the Cold Front Conceptual Models R = Right of the Col C = Centered on the Col L = Left of the Col

Radar Data and the Cold Front
Precipitation returns will be limited in extent Precipitation will tend to be very cellular This results in an incomplete display of the Doppler wind field in particular Of course the information displayed on radar is dependent on the amount and extent of the precipitation. Along the cold front, the radar information is bound to be limited due to the convective nature of the precipitation. The examples and conceptual models illustrated optimistically assume that there is an abundance of cold frontal precipitation both in amount and extent.

Behind the Cold Front Conceptual Models
Left of the Col looking along the flow. B Cold Frontal Cross-section along Poleward Branch of the Dry Conveyor Belt (DCB) A DCB Common area for deep instability WCB oriented for less frontal lift Mixing Zone CCB Surface Cold Front WCB A B Cold air in Cold Conveyor Belt (CCB) deep and moist Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Warm Conveyor Belt (WCB) is deep, warm and moist CCB backs with height consistent with cold advection WCB just ahead of cold front also typically veers with height Frontal slope is steeper than the typical 1:50 Backing winds above the frontal zone indicative of anabatic cold front The same backing winds make the warm front anabatic and active as well.

DCB to the Left of the Col
The Cold Left Wing Climb CM The eagles left wing is folded backward having just caught more air for a climb. This portion of the DCB in the dry slot is typically ascending. The right wing is still fully extended to catch the lift of the WCB. The steeper frontal slope of the cold front will be very evident. Notice that the frontal area outlined is an oval skewed to the cold side of the front. Mixing layer o Cold frontal surface Within the CCB – Cold Advection: Cold advection probably overpowers the Ekman spiral signature Dry CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Right Wing Within the DCB: West of radar backing, cold advection, Anabatic cold front East of radar nil VWS or possibly weaker backing Left Wing C

The Cold Left Wing Climb CM
Right Wing Left Wing o This cold front is oriented NE-SW.

Cross Section of Active Cold Front

Active or Anabatic Cold front
One only needs to apply the equation of continuity to explain the impact of a backing wind in the warm air above the cold frontal surface. If the wind backs above the cold frontal surface, then that wind is less than than the forward speed of the cold front. The air is convergent at this height and air must be ascending through continuity. Such a cold front with backing winds above the frontal surface must be anabatic.

Centered on the Col looking along the flow. Cold Frontal Cross-section along Poleward Branch of the Dry Conveyor Belt (DCB) A DCB Common area for deep instability B WCB oriented for less frontal lift Mixing Zone CCB Surface Cold Front WCB A B Cold air in Cold Conveyor Belt (CCB) becoming less deep and less moist compared to the left of the flow Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Warm Conveyor Belt (WCB) is still probably deep, warm and moist CCB nearly a straight flow with weakening cold advection WCB just ahead of cold front also typically veers with height Frontal slope is near the typical 1:50 Winds nearly straight above the frontal zone indicative of a cold front which is neither anabatic or katabatic

DCB Centred on the Col The Cold Screaming Eagle CM
Both of the eagle’s wings are fully extended. A B The steeper frontal slope of the cold front will be very evident. Notice that the frontal area outlined is an oval skewed to the cold side of the front. Mixing layer o Cold frontal surface Within the CCB – Cold Advection: Cold advection probably overpowers the Ekman spiral signature Dry CB C Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Left Wing Right Wing Within the DCB: Nil VWS

The Cold Screaming Eagle CM
Right Wing Left Wing This is a placeholder for a real example.

Right of the Col looking along the flow. Cold Frontal Cross-section along Equatorward Branch of the Dry Conveyor Belt (DCB) DCB Common area for deep instability A WCB oriented for less frontal lift B Mixing Zone CCB Surface Cold Front WCB A B Cold air in Cold Conveyor Belt (CCB) shallow and dry. Precipitation will be lacking for radar coverage. Notes: All descriptive terms are intended to be comparative between the various conveyor belts in the Conveyor Belt Conceptual Model. All quantities are intended to be the average or typical values Warm Conveyor Belt (WCB) is shallow, warm and moderately moist CCB probably veers backs with height consistent with warm advection … I know this seems odd. WCB just ahead of cold front also typically veers with height Frontal slope is more shallow than the typical 1:50 Veering winds above the frontal zone indicative of katabatic cold front

DCB Centred on the Col The Cold Left Wing Dive CM
The eagles left wing is folded forward as if it is about to turn to the right and swoop down. That is what this part of the DCB does. The right wing is still fully extended to catch the lift of the WCB. C The steeper frontal slope of the cold front will be very evident. Notice that the frontal area outlined is an oval skewed to the cold side of the front. A B Mixing layer o Cold frontal surface Within the CCB – Cold Advection: Cold advection probably overpowers the Ekman spiral signature Dry CB Stoop To bend or sag downward. To lower or debase oneself. To descend from a superior position; condescend. To yield; submit. To swoop down, as a bird in pursuing its prey. Left Wing Right Wing Within the DCB: Winds veer with range/height to the west Katabatic cold front

The Cold Left Wing Dive CM
Right Wing Left Wing This is a placeholder for a real example.

Cross Section of Inactive Cold Front

Inactive or Katabatic Cold Front
One only needs to apply the equation of continuity to explain the impact of a veering wind in the warm air above the cold frontal surface. If the wind veers above the cold frontal surface, then that wind is stronger than the forward speed of the cold front. The air is divergent at this height and air must be descending to fill the void through continuity. Such a cold front with veering winds above the frontal surface must be katabatic.

Preliminary Dry Conveyor Belt Conceptual Models R = Right of the Col C = Centered on the Col L = Left of the Col

Radar Data and the Preliminary Dry Conveyor Belt
Precipitation returns will be very limited in extent if they exist at all Radar data will be largely unavailable and unreliable This results in a very incomplete display of the Doppler wind field in particular Of course the information displayed on radar is dependent on the amount and extent of the precipitation. Along the preliminary dry conveyor belt, the radar information is bound to be limited if not non-existent. The examples and conceptual models illustrated optimistically and unrealistically assume that there is an abundance precipitation both in amount and extent.

Within the Preliminary Dry Conveyor Belt Conceptual Models
These conceptual models should be similar to those associated with the dry conveyor belt that trails the cold front. Typically, any frontal zone in this region of the conveyor belt conceptual model will be weak and ill defined and probably not worth finding. Further investigation especially using isentropic surfaces is required – very required! I expect that these will be virtually identical to those associated with the three locations north of the warm front with the exceptions that: There will be and cannot be any evidence of the cold conveyor belt The veering and backing with height signatures will be less pronounced

Illustrative Cross-section

Vertical Deformation Zone Distribution and the CBM Summary
CCB C WCB DCB C C C C DCB Typical distributions of the conveyor belts and the associated deformation zones. Recall from the satellite palette that the deformation zone is actually a cross-section of the deformation sheath that encases an isentropic flow. Similarly, the vorticity centres depicted in the deformation zone conceptual model are actually vortex tubes that also slope in the vertical along with the deformation sheath. The Warm Conveyor Belt (WCB) typically rises isentropically with poleward (both northeasterly and northwesterly) motion and time. The WCB is shown with no vertical wind shift but typically it veers with height which is consistent with warm air advection. The Cold Conveyor Belt (CCB) typically sinks isentropically with equatorward (southwesterly) motion and time. The CCB typically backs with height which is consistent with cold air advection. The Dry Conveyor Belt (DCB) typically sinks isentropically with equatorward (southeasterly) motion and time. In the “dry slot” of the comma pattern, the DCB is typically rising isentropically with poleward (northeasterly) motion and time. The DCB typically veers with height with the approaching upper ridge. The flow ahead of the conveyor belt system has not been typically described but is the remains of the dry conveyor belt caught up in the upper ridge circulation. (Chadwick has described it in unpublished work.) This circulation is dry and subsiding with poleward (northwesterly) motion and time. The portion of the flow that turns southwesterly dry rises with equatorward (southwesterly) motion and time. This portion of the CCB typically veers with height which is consistent with warm air advection west of the upper ridge. The slope of the isentropic surfaces can be inferred from the overlap of the deformation zones. The slope of the isentropic surfaces can also be used to analyze instability. Isentropically speaking, sinking cold air and rising warm air converts thermal energy into kinetic energy. The vertical motions of dry air is not so simple isentropically speaking – have to ponder this! The introduction of isentropic thinking to NinJo will make the investigation of these concepts much easier.

Note to Whom it May Concern
These conceptual models were constructed largely using the Conveyor Belt Conceptual Model to estimate what the Doppler radar should be seeing. This use of Doppler radar and in particular, the increased use of the 3.5 degree scan, are largely unprecedented. This is a first attempt at expanding the science and as a result, will likely require further refinements as we learn more.

Doppler Radar The Doppler Effect The Doppler Dilemma

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Doppler Radar The Doppler Effect The Doppler Dilemma

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