WAFS Workshop on the Use and Visualization of Gridded SIGWX Forecasts September 2009

Overview  Introduction  Why interpolation?  Horizontal strip chart  Vertical cross-sectional chart  Monochrome presentation  Flight documentation  Great circle / “dog-leg” flight routes  User survey  Way forward

Introduction  WAFSOPSG/4 meeting agreed spatial and temporal linear interpolation could be used for generating a route-specific wind/temp chart for long-haul flights. study the applicability of interpolation on concatenated visualization of WAFS gridded forecasts of CB clouds, icing and turbulence.

Why interpolation?  Provide the MET information most relevant to the flight segment  Address problem with the large no. of gridded forecasts for each model run: Icing: 6 layers, max/mean CAT: 6 layers, max/mean In-cloud turbulence: 5 layers, max/mean CB cloud: horizontal extent, top and base heights Above forecasts for 11 time steps (T+6h, T+9h, …, T+36h)

Simple joining T+12h, T+18h and T+24h (from W to E)  Discontinuities are still observed at the grid points where two charts join (green lines), but such discontinuities are less obvious as compared to concatenated SIGWX chart considered previously.concatenated SIGWX chart T+24 hT+18 hT+12 h

Temporal linear interpolation  Consider temporal linear interpolation for a hypothetical flight route (on a Great Circle): Route: 0 o N 20 o E to 0 o N o E Flight time: 15 hr

flying from east to west flying from west to east Quality after interpolation: - main SIGWX features could be reproduced - smaller scale features smoothed out - intensity of features time-averaged  Linear interpolation for every consecutive hour Linear interpolation for every consecutive hour  Using T+6h, T+12h, T+18h, T+24h forecast data Using T+6h, T+12h, T+18h, T+24h forecast data  Route specific Strip Charts can be produced (width is configurable) Horizontal strip chart

Vertical cross-sectional chart  Similar concept Adopted by WMO CAeM-VI in 1976 Vertical forecast chart issued by JMA for airlines (JMA Chart) (Model Chart in 1976)

Simple joining T+12h, T+18h, T+24h (from W to E) Discontinuities could be present at chart boundaries (red lines) Icing In-cloud Turb CAT CB top + Horiz. Extent

Temporal interpolation Manages to capture SIGWX features and smooth out discontinuities Back

 Welcomed by IFALPA pilot  Suggest to use median/max value of surrounding grid points to reflect probable weather condition on the flight route  3×3 grid points of the same flight level are considered Vertical cross-sectional chart

Using median value within 3x3 grids: smooth out SIGWX features (c.f. previous)previous Using max value within 3x3 grids: tend to retain SIGWX features

Monochrome presentation  For operational use and suitable for ICAO Annex 3, monochrome charts are produced  Colour schemes are replaced by dotted / continuous / thick lines, grey shades or hatched areas  Simplified by presenting only two SIGWX “intensity” levels

Monochrome for flight document Two “intensity” levels

Further simplification by removing in-cloud turbulence and icing within CB Since CB implies in-cloud turb and icing, they may be seen as redundant & could be removed

Issues with CB top/base heights Zero/small CB top height? ?? Large CB base height?

Monochrome strip chart Other strip charts could be handled similarly

Route-specific flight doc (vertical)

Route- specific flight doc (horizontal) Width of strip is configurable Can be fitted into one page

Other High “at-a-glance” high/medium level horizontal SIGWX charts proposed by WAFCs Issues: SIGWX features like TC, VA, etc are not depicted Extensive CB area causes concerns to pilots Jetstream and icing info is limited (only for one FL) CAT info is limited (only for three FLs) Need users’ acceptance

Safety-related information needed 110.2E 2.8S 110.2E 2.8S FELICIA 3.1N 42.3E FELICIA 3.1N 42.3E Safety-related info (e.g. TC and VA) could be inserted when it is within certain distance from the flight route FELICIA 3.1N 42.3E

Great circle / dog-leg routes Example: flight route from Hong Kong to Vancouver with turning point at Anchorage - Hong Kong- Anchorage and Anchorage-Vancouver both lie on great circles

Great circle / dog-leg routes  The curved strip could be cut at the turning point - the duplicated area is indicated by the red dots.  Further straightening the strips requires different map projections, e.g. oblique Mercator / Stereographic projection and thus computer programming effort.oblique Mercator / Stereographic projection Anchorage TP1 ( See also route-specific chart presented in WAFSOPSG/4-WP/16 )route-specific chart

Great circle / dog-leg routes Vertical cross-section forecast chart for “dog-leg” flight route Turning point Anchorage TP1

User survey  HKO conducted a user survey on the WAFS trial gridded forecasts (15 returns)15 returns)  The survey results and our feedback regarding visualization issues are summarized below

Comments from users CommentsUser / Org  Strips are not good, they defeat situational awareness of the area to be flown. (HKO: The strips could be made wider, but there are also different views.)  Different scales should be available for particular regions. (HKO: Yes, only data relevant to the flight route concerned will be presented for operational use.)  There is now "tendency" information, e.g., fronts were depicted that pilot could have a better idea of the forecast. (HKO: Inclusion of SIGWX features, such as TC, VA and others required by the users, in future visualization of gridded forecasts is supported.) IFALPA Rep

Comments from users CommentsUser / Org  The improvement suggested by the HKO would help a lot, particularly if the horizontal "real time" strips can be developed. These would be very useful and very practical for the pilots.  “Potential” is meaningless! “Potential” is an unproven term that has appears to have no scientific definition or validity. It therefore of little or no assistance to a pilot. PROB on the other hand, gives the indication of the likelihood of the turbulence/icing/CAT being encountered.  The gridded forecasts cannot replace the SIGWX charts at this stage as the information is too general and some of the previous information to be omitted. (HKO: The above views are shared /supported.) IFALPA Pilot

Comments from users CommentsUser / Org  The strip should cover a corridor of 100 – 200 NM. (HKO: Narrowing the strip is feasible, but there are also suggestions to widen it.)  For route specific charts, cross section and strip charts should be shown on one page; instead of co-ordinates, using waypoint names is better. (HKO: Support to present the information in such a way to facilitate “at-a-glance” assimilation by users. Waypoint names would be used where possible.  For airlines not making their flight plans public, MET offices should provide concatenated or interpolated charts for fixed times. (HKO: Agreed.)  Interpolated charts are applicable to all flights (not only long-haul flight). (HKO: Agreed.) IATA Rep

Comments from users CommentsUser / Org  For severe delay departure, would pilot required to obtain updated flight documents? (HKO: In case of unusual delays, MET office should provide updated flight doc prior to departure.)  For strip charts, there may be visualization complexities for route other than equator – i.e. other great circles, “dog- leg” route, polar stereographic chart. (HKO: Addressed above.)  Could strips/ cross-section charts be in monochrome? (HKO: Addressed above.) WAFC Rep

Comments from users CommentsUser / Org  Linear time interpolation should not be processed until temporal resolution of WAFS forecasts increased to 3-hr. (HKO: Agreed. Interpolation aimed at helping users to assimilate the available information which would be done manually otherwise.)  Since CB top equal to zero means no CB cloud, spatial interpolation has no real sense for CB top field. (HKO: The CB top line may be removed when the height value drops below a certain altitude. However, there are also additional issues noted above with CB base height.) WAFS OPSG Member

Comments from users CommentsUser / Org  Route specific bands are too narrow for aircraft flying at 500kts.  Vertical cross sections are a nice snap shot of what might happen but of limited value unless it is real time. Pilots  Suitable only to color printer, not convenient.  Different colour schemes for different charts impair readability.  Need more charts to get necessary info.  Need more time to analyze the info when compared to the existing charts.  Existing charts are more comprehensive and informative.  We do prefer all information in one or two charts only.  Too specific, does not give a clear picture. (HKO: The above views are shared /supported.) Airlines Existing SIGWX chart

Way forward  Visualization models should be user- oriented and subject to user acceptance  Support inclusion of all SIGWX features required by users (esp safety-related)  Time to consider high “at-a-glance” route-specific charts for flight doc  Proposed models need refinement (e.g. address CB top/base height issues, no. of SIGWX levels, width of strips etc)

Thank you

Supplementary information

Consecutive gridded forecasts of max icing potential at FL180 T+6h T+12h T+18h T+24h Back

Concatenated SIGWX chart Back ( Extracted from WAFSOPSG/4-WP/16 )

Time-interpolation Forecast hour (UTC)Interpolated value 09(value at T+6 h)*3/6 + (value at T+12 h)*3/6 10(value at T+6 h)*2/6 + (value at T+12 h)*4/6 11(value at T+6 h)*1/6 + (value at T+12 h)*5/6 12 (value at T+12 h) – no interpolation 13(value at T+12 h)*5/6+(value at T+18 h)*1/6 14(value at T+12 h)*4/6+(value at T+18 h)*2/6 15(value at T+12 h)*3/6+(value at T+18 h)*3/6 16(value at T+12 h)*2/6+(value at T+18 h)*4/6 17(value at T+12 h)*1/6+(value at T+18 h)*5/6 18 (value at T+18 h) – no interpolation 19(value at T+18 h)*5/6+(value at T+24 h)*1/6 20(value at T+18 h)*4/6+(value at T+24 h)*2/6 21(value at T+18 h)*3/6+(value at T+24 h)*3/6 22(value at T+18 h)*2/6+(value at T+24 h)*4/6 23(value at T+18 h)*1/6+(value at T+24 h)*5/6 00 (next day) (value at T+24 h) – no interpolation Back

Time-interpolation of forecasts flying from east to west (interpolated) flying from west to east (interpolated) T+24 h forecast T+18 h forecast T+12 h forecast T+6 h forecast Back

Vertical cross-sections for T+6h, T+12h, T+18h, T+24h T+6h T+12h T+18h T+24h

Concatenated route-specific wind/temp chart Route-specific concatenated WAFC London wind forecast chart at FL390 based on UTC generated for the hypothetical flight route from VHHH to LIRF Back

Oblique map projection Oblique stereographic - Great circle which passing through the projection center become straight line (Figure courtesy of Wikipedia)Wikipedia Back Oblique Mercator - Great circle could be projected as an equator and thus a straight line (Figure courtesy of Swisstopo)Swisstopo

Existing SIGWX charts Back

List of Respondents to WAFS Survey IFALPA Rep (Captain Miguel Marin, Chairman of ATS Committee) IFALPA Pilot (Captain Brian Greeves, HKALPA) Pilots: The Guild of Air Pilots and Air Navigators (GAPAN) (Captain Brent Hawkins, Vice-Chairman, Hong Kong Region) Metrojet (Captain Peter Garraty) Airlines: Cathay Pacific Airways (Neil Phillips, Manager Line Operations) China Airlines (Lo Wai Lun Kevin, Dispatcher) Dragonair (Andy Jepps, FTU A320; Jim Ashby, Deputy Manager Line Operations) El Al Israel Airlines Limited (c/o Hammond Law, Team Manager) Fedex (Andy Yeung, Manager - Operations) Hong Kong Airport Services Limited (Gary Hor, Flight Dispatch Manager; Jackson Lam, Quality Assurance Manager) Japan Airlines (Stephen Chan, Manager of Flight Operation) Jardine Airport Services Limited (Hammond Law, Team Manager) South African Airways (Ringo Chui, Airport Manager & Vice-chairman of Airline Operators Committee)