1. IHOP Radiosonde and Dropsonde Data: Highlights and Problems
Radiosonde data
Summary
Humidity sensors
Problems
Dropsonde data
Scientific Highlights
Junhong (June) Wang
Kate Beierle
NCAR/ATD
This talk is about IHOP dropsonde data. I will first give you an overview … Performances focus on the dry bias and the performance inside clouds
I would acknowledge my co-author, kate and other …

2. Summary of all radiosonde data from IHOP
Radiosonde Systems
Number of soundings
Radiosonde Types
Sites
Time (UTC)
NWS
1653 (410)
Vaisala RS80-H & VIZ 14
00 and 12 UTC every day, 11 IOPs at 15, UTC, and 4 IOPS at 18, 21, 03 UTC
ARM
862
Vaisala RS90
5 (C1, B1, B4, B5, B6)
02, 05, 08, 11, 14, 17, 20, 23 UTC
ISS
138
Vaisala RS80-H
Homestead
18 UTC every day, and various times for IOPs
Ref. Sonde 16
Ref/RS80H/VIZ
18 UTC and others
Mobile_CLASS 60
RS80-H
mobile
various
Mobile_GLASS1 74
Mobile_GLASS2 77
Total
2625
3 types 
mobile 
 Various
Check these number????
Here is a summary of all radiosonde data collected from IHOP. It includes soundings at 13 NWS radiosonde stations, 5 ARM stations, one ATD ISS at Homestead, and three mobile sounding systems. Total …

3. Reference sonde
Two NWS stations (DDC and Alb.) launch VIZ sondes, and others use Vaisala sondes.

4. Radiosondes Reference radiosonde VIZ B-2 Vaisala RS80-H
400MHz transmitter
GPS receiver
Swiss Radiosonde C34
SW chilled-mirror DP hygrometer
– reference humidity sensor
Carbon hygristor
Copper-constantan thermocouple
Hypsometer
Vaisala RS80
NWS VIZ B-2
Reference radiosonde
RS90 (~1993):
Smaller THERMOCAP
Heated twin F-HUMICAP
VIZ-B2:
Rod thermistor
Carbon hygristor
Vaisala RS80-H
VIZ B-2
RS80-H (~1990):
THERMOCAP
F-HUMICAP
Vaisala radiosondes are used in ~51% of global radiosonde stations, so it is necessary to say a little bit about it. RS80 still used in most of stations has two types ..
40s heating, then 100 s measuring

5. SnowWhite Chilled-mirror dewpoint hygrometer
Scattering light detector
Heated sensor housing
Reflecting light detector
Thermocouple
Mirror
Let me first explain how the SW measures humidity.
Here is the picture of SW, including electronics, batteries, sensor housing and electrical heat pump. Here is a schematic plot showing how SW measures humidity.
SW is based on physically well-known chilled-mirror principle. A mirror is mounted on the cold side of a Peltier. The system maintains a frost layer on the mirror all the time. The mirror T is DPT.
One of advantages with SW is that it can detect clouds and possibly total liquid/ice water content. I will show you some results latter. The sensor housing is heated. The air sample containing water or ice particles is warmed up by heated housing. All droplets are evaporated, causing a measurement of super-saturation.
Fast response
No influences of radiation, wind and others
Peltier
Accurate measurement of dew/frost point
Detects clouds and measures their liquid/solid water
Needs no individual calibration and recalibration after recovered

6. Data quality control for ATD Radiosonde Data
1. In-field data processing
2. ASPEN
3. Individual
Skew-T examination
SAH during IHOP is due to the fact that the aspirator used for collecting prelaunch data was not shaded from direct sunlight during IHoP and it draws the air from the surface.
SAH: s ( m) for RH, negligible for T
Pick up one sounding showing the SAH error??? (extreme??)
In-field data processing: (Ned’s software)
Outliner removing (mainly remove transmission error)
Low-pass filtering to remove balloon swinging
Interpolate all data to the same time scale: 1s
Filling small data gaps (< 30s)
Transmission errors: operator’s error (tuning frequency to keep tracking balloon, atmospheric noise, equipment failure)
ASPEN’s QC procedures include: limit check, satellite check (dropsonde), buddy check, outlier check, filter check, monotonic pressure check, vertical velocity check (dropsonde)
4. Comparisons of
prelaunch and surface data
5. Comparisons
with other data

7. Aspirator upgrade for ISS
New
Old
The new aspirator has much more air to the sensor and better air flow, draw the air horizontally, has a stable holder for the sonde for easy launch under strong wind condition and has a smaller and folding table for both fixed and mobile sounding system.

8. Summary of all dropsonde data from IHOP
PTU/W profiles
Validation for newer WV instruments
Missions
Falcon
Lear
Total
BLH 19 17 36
M LLJ 62 93
155 CI 7
169
176
E LLJ 53 88
332
420
The dropsonde was mainly used to provide PTU/W profiles and for validating other new WV instruments, such as DIAL.
Launched from Falcon and Lear for four types of missions, … and with different flight patterns for different missions, such as box flight patterns for MLLJ
Total 420 dropsondes were launched. Lear launched much more than Falcon. CI and MLLJ missions used most of dropsondes

9. NCAR GPS Dropsonde
Here is our GPS dropsonde (~400 g). The dropsonde is dropped from research aircrafts over remote areas such as the oceans, polar regions and sparsely inhabited land masses. It descends through the atmosphere on a parachute to measure PTU and wind profiles. Here is a detail picture of the sonde, including a 4-channel transmitter, so you can have four sondes in the air at the same time. Dropsonde data during hurricane flights have improved the accuracy of forecasts of hurricane landfall by about 20% over the decade of the 1990s.
Currently the system is installed …
We also completed our automatic dropsonde system about two years ago. It stores 16 dropsondes in a pot, which is installed below aircrafts. You don’t need operators in the aircraft. All pilots need to do is to push a button for starting releasing sondes.
Next I am going to give you a couple of dropsonde data highlights.

10. Large parachute Small parachute
Here are % of good points for all Lear dropsondes for T (black), RH (red) and winds (green).
On average, T and RH have ~90% good points, but 50% for winds.
You see smaller percentages before June 5. I think it is due to the small parachute used before June 5, but the large one afterwards, ask Terry??
Next I am going to use data from two missions to show you some scientific highlights.
Large parachute
Small parachute

11. MLLJ on June 9 (1200-1930 UTC) Box flight path (clockwise)
Clear sky in the domain
LLJ on the northern leg
Lear: 48 (took off from NW corner, ~50 km, two box flights)
Falcon: 21 (took off from SE corner, ~50 km)
Mapping moisture and intercomparison with DIAL, LASE, NAST
Here is a MLLJ mission on June 9
Both Lear and Falcon flied boxes. …
Let’s look at dropsonde winds along this line from E-W from both lear (red) and falcon (black). You see maximum speed reaching 30m/s
Next let’s look at T/RH variations along the box from lear dropsondes from two box flights

12. T/RH variations for two Lear box flights June 9
East-west Terrain change
T differences for two flights: T warmer up by several degrees from the first to the second flights
RH shows larger W-E (or longitudinal) variations: BL getting moister form W to E and topped by a shallow dry layer. Another moist layer is developed around 650 mb. Similar features shown in the second flights but with smaller magnitudes.
Next I am going to show you detail structure in this W-E leg.
RH variations within each box (stronger E-W variations)
RF9
RF10

13. MLLJ (East-West on the Northern Leg on June 9)
Inversion-capped moist layer
Two-layer moisture
Specific Humidity (g/kg)
DIAL on Falcon
The location of the dryline (dramatic increasing of surface Q by > 5g/kg)?
Inversion-capped moist layer, increasing in depth eastward
Two-layer moisture structure near NE corner

14. CI on June 12 ( UTC)
Plot color filling to see why there is a minimum for 2102 UTC??? Replot the plot to change 6/09 to 6/12 and put vertical line on CAPE/CIN fig.
Development of moist layer around 500 mb
High CAPEs and near-zero CINs in all soundings in the second flight (Development of convection)??

15. Performance in Clouds CI May 22 22:14-22:39 UT
Dry Line
Look at CAPE, CIN and LCL (cloud base?), how ARM CF lidar/radar data?
Here is a CI mission on May dropsondes were dropped along this line. Corresponding T/RH/Q profiles are shown here. Red lines are RH. Perpal lines show 90% RH lines
Satellite data show Wave clouds
>90% RH, strong T inversion above cloud top, Last four show very similar structures but RHs in moist layers can vary from 90% to 100%. Also notice the development of second moist layer from 3-4 km.
I show you this sounding before with comparison with RS90 data at CF. very good agreement
This is consistent with what we found from Dycoms-II data.

16. Data quality control for ATD Dropsonde Data
ASPEN
(limit, buddy, outlier, filter, etc.)
2. Individual Skew-T examination
3. Histograms of PTU and wind
4. Time series of PTU and wind
5. Comparisons with other data
Pick up one example

17. Geopotential height problems and solutions
Before
After
Integrate from
flight-level down
Unknown
surface
altitude
1. No flight-level PTU
data
2. Use flight-level height
but 1st available pressure
(~20s)
~ m overestimate of heights
1. Problems:
2. Corrections:
Good soundings
Integrate
from surface up
Surface
elevation
Soundings with
missing data
above surface
from FL down
Add PTU
to FL
Corrected heights

18. Geo-potential height data after corrections
Missing data before landing

19. Importance Notes for IHOP radiosonde/dropsonde data
Do not use reference sonde pressure and wind data:
The reference sonde (RS) uses a hypsometer to measure pressure. Unfortunately the hypsometer was not stable and has all kinds of problems.
We didn't correct balloon swing at all for winds and had quite big balloon swing because of bigger balloons used.
Sensor arm heating error in radiosonde data at Homestead:
The SAH error depends on a lot of factors
Different impacts for T and RH: s ( m) for RH, negligible for T.
Take precautious about dropsonde geopotential data:
The Geopotential height problems in IHOP dropsonde data are investigated and corrected. But there may be some un-identified problems in some individual soudnings.
Errors/Biases and Error variances in radiosonde and dropsonde data will show latter