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WAFSOPSG/5-WP/19/
International Civil Aviation Organization
WORKING PAPER / WAFSOPSG/5-WP/19
23/6/09
WORLD AREA FORECAST SYSTEM OPERATIONS GROUP (WAFSOPSG)
FIFTH MEETING
Paris, France, 16 to 18 September 2009
Agenda Item / 6: / Development of the WAFS6.2: / Visualization of WAFS forecasts
PROPOSAL TO AMEND THE LEGEND BOX TEXT OF WAFS FORECASTS
(Presented by the WAFC Provider States)
SUMMARYThis working paper presents proposals to amend the legend box text of WAFS forecasts in response to a work programme task from the WAFSOPSG/3 Meeting.
1. INTRODUCTION
1.1 At the WAFSOPSG/3 Meeting, the group endorsed an amendment to the legend box text of WAFS SIGWX forecasts (Conclusion 3/3 refers). In the lead up to this conclusion, it had been suggested to the group that, in addition to the name of the WAFC issuing the forecast, the legend box should also indicate the name of the provider that made the forecast available to the user. In this context, it was, however, noted that the underlying Annex 3 provisions only called for the inclusion of the name of the WAFC and that the addition of the name of the provider would not therefore be appropriate at this stage. The group, however, agreed that it would be important that the desirability to include in the legend box the name of the provider of the WAFS forecast to the end user be assessed by the group to ensure the traceability of WAFS forecasts. This issue was included in the future work programme of the group under task number 8 at the WAFSOPSG/3 Meeting.
1.2 The matter was not discussed further at the WAFSOPSG/4 Meeting and the work programme task remained, re-numbered as Task 7b) as follows:
Work Programme Task 7: Improve the visualization of WAFS forecasts in flight documentation by:
a) studying ways and means to ensure that the most relevant WAFS forecasts be presented in terms of space and time, in particular to meet the needs for long-haul flights; and
b) assessing the need, in the legend box of flight documentation, for the name of the centre supplying the WAFS forecast to the end user, in view of ensuring traceability.
1.3 An ad-hoc group (with China as Rapporteur) had been formed at the WAFSOPSG/3 Meeting to respond to Task 7a), with initial findings presented to the WAFSOPSG/4 Meeting. Task 7b) had not been assigned to an ad-hoc group as such. Nevertheless, following consultation with the Secretary, the WAFC Provider States now present recommendations for the consideration of the group.
2. discussion
2.1 In determining the desirability of including in the legend box the name of the provider of the WAFS forecast to the end user, it is first worthwhile considering which products would be affected. These fall into two following categories:
a) products generated from GRIB code-form WAFS forecasts; and
b) products generated from BUFR code-form WAFS forecasts.
2.2 Products generated from GRIB data would typically be upper wind/temperature charts; whilst products generated from BUFR data would be significant weather (SIGWX) charts for high- or medium-level operations. Such products should be prepared on an end-users workstation in accordance with the model charts contained within Annex 3, Appendix 1.
2.3 The GRIB and BUFR data themselves (i.e. the encoded bulletins) do not contain all the necessary information relating to the legend box. Whilst a parameter number representing the originating WAFC is encoded in such bulletins, the actual name of the WAFC is not, nor is the name of the “provider” of that forecast to the end user. For example, an end-user workstation will be expected to convert a parameter number of “93” within a BUFR bulletin to represent ‘Issued by WAFC London’ in the legend box. It is the responsibility of the end-user and their workstation provider to ensure that the legend box text conforms to the Annex 3 standard.
2.4 SIGWX products in the Portable Network Graphics (PNG) chart form are provided as a backup to BUFR code-form forecasts. There is no way for an end-user workstation to modify the text within the legend box of these products, since the products are generated by the WAFCs as is.
2.5 In addition to traditional forecasts such as upper wind/temperature charts generated from GRIB data, it is important to realise that there is an entirely new range of WAFS products relating to icing, turbulence and CB clouds which are not currently shown within Annex 3, but which will require legend box considerations before they reach operational acceptance.
3. Current legend box terminology used on WAFS forecasts
3.1 The following examples depict legend box text on an upper wind/temperature chart and SIGWX chart based on GRIB and BUFR data respectively, as per Amendment 74 to Annex 3.
3.1.1 Legend box text of upper wind and temperature chart for standard isobaric surface, extracted from Model IS:
3.1.2 Legend box text of significant weather charts, extracted from Model SWH and Model SWM respectively:
4. terms used in annex 3
4.1 When considering the form of wording that may be suitable to indicate which organisation or unit provided the WAFS forecast to whom, it is worthwhile reviewing Annex 3 Chapter 1. Paragraph 1.2 of Appendix 1 gives terms used with limited meaning, as follows:
a) to avoid confusion in respect of the term “service” between the meteorological service considered as an administrative entity and the service which is provided, “meteorological authority” is used for the former and “service” for the latter;
b) “provide” is used solely in connection with the provision of service;
c) “issue” is used solely in connection with cases where the obligation specifically extends to sending out the information to a user;
d) “make available” is used solely in connection with cases where the obligation ends with making the information accessible to a user; and
e) “supply” is used solely in connection with cases where either c) or d) applies.
4.2 Chapter 3 of ICAO Annex 3, at paragraph 3.3.2 d), states that “An aerodrome meteorological office shall carry out all or some of the following functions as necessary to meet the needs of flight operations at the aerodrome … d) provide briefing, consultation and flight documentation to flight crew members and/or other flight operations personnel; …”. Thus, the group may wish to agree that only the term “Provided by” would be appropriate when considering the provision of WAFS forecasts generated from GRIB or BUFR data by a third party to an end-user.
4.3 Chapter 3 of Annex 3 also states at paragraph 3.2.1 that “A contracting State, having accepted the responsibility for providing a WAFC within the framework of the world area forecast system shall arrange for that centre: … c) to issue the forecasts referred to in a) and b) in digital form to meteorological authorities and other users, as approved by the Contracting State on advice from the meteorological authority;” Given that many WAFS users will tend to obtain their flight documentation in pictorial form from a flight briefing facility, rather than directly from the WAFCs, the group may wish to agree that it would be worthwhile including the term “Issued by WAFC…..” for charts visualised from GRIB or BUFR data. For example, “Issued by WAFC London, provided by XYZ Met Service”
5. Advisory information contained in legend box text
5.1 At the present time, a BUFR or PNG SIGWX chart is required to include the following text within the legend box: “CHECK SIGMET, ADVISORIES, ASHTAM AND NOTAM FOR VOLCANIC ASH”.
5.2 To overcome any ambiguity concerning whether the advisories (and SIGMET) pertain the phenomenon other than volcanic ash, the group may wish to agree that the following text would be less ambiguous (using ICAO abbreviations for volcanic ash and tropical cyclone): “CHECK SIGMET, ADVISORIES FOR TC AND VA, ASHTAM AND NOTAM FOR VA”.
6. proposed amendment to the legend box text of WAFS forecasts
6.1 In view of the above discussion, the group is invited to consider the following amendment proposal to the legend box of WAFS forecasts:
6.1.1 WAFS forecasts generated from GRIB data excluding icing, turbulence and CB forecasts:
Proposal:ISSUED BY WAFC [LONDON/WASHINGTON]
PROVIDED BY [COMPANY NAME]
[PRODUCT NAME]
FL[XXX]
FIXED TIME PROGNOSTIC CHART
VALID [XX] UTC ON [XX XXX XXXX]
BASED ON [XX] UTC DATA ON [XX XXX XXXX]
UNITS USED: [UNITS]
HEIGHTS IN FLIGHT LEVELS
TEMPERATURE NEGATIVE
UNLESS PREFIXED BY A + OR PS / Worked example:
ISSUED BY WAFC LONDON
PROVIDED BY XYZ MET SERVICE
WIND AND TEMPERATURE
FL100
FIXED TIME PROGNOSTIC CHART
VALID 12 UTC ON 30 MAR 2009
BASED ON 00 UTC DATA ON 30 MAR 2009
UNITS USED: KNOTS, DEGREES CELSIUS
HEIGHTS IN FLIGHT LEVELS
TEMPERATURE NEGATIVE
UNLESS PREFIXED BY A + OR PS
6.1.2 WAFS forecasts generated from GRIB data including icing, turbulence and/or CB forecasts:
Proposal:ISSUED BY WAFC [LONDON/WASHINGTON]
PROVIDED BY [COMPANY NAME]
[PRODUCT NAME]
FL[XXX]
FIXED TIME PROGNOSTIC CHART
VALID [XX] UTC ON [XX XXX XXXX]
BASED ON [XX] UTC DATA ON [XX XXX XXXX]
CB IMPLIES TS, GR
MOD OR SEV TURB AND ICE
UNITS USED: [UNITS]
HEIGHTS IN FLIGHT LEVELS
TEMPERATURE NEGATIVE
UNLESS PREFIXED BY A + OR PS
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA / Worked example:
ISSUED BY WAFC LONDON
PROVIDED BY XYZ MET SERVICE
WIND AND MEAN ICING
FL100
FIXED TIME PROGNOSTIC CHART
VALID 12 UTC ON 30 MAR 2009
BASED ON 00 UTC DATA ON 30 MAR 2009
CB IMPLIES TS, GR
MOD OR SEV TURB AND ICE
UNITS USED: KNOTS, ICING POTENTIAL INDEX
HEIGHTS IN FLIGHT LEVELS
TEMPERATURE NEGATIVE
UNLESS PREFIXED BY A + OR PS
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA
Note that [PRODUCT NAME], FL[XXX] and [UNITS] cannot be specified more categorically here due to the range of products that will be available in GRIB code-form – e.g. wind, temperature, icing, turbulence, CB etc. The end-user workstation may be capable of plotting two or more products, for differing levels, on any one chart.
6.1.3 WAFS forecasts generated from BUFR data
Proposal:ISSUED BY WAFC [LONDON/WASHINGTON]
PROVIDED BY [COMPANY NAME]
FIXED TIME PROGNOSTIC CHART
ICAO AREA [X] SIGWX
FL[XXX-XXX]
VALID [XX] UTC ON [XX XXX XXXX]
CB IMPLIES TS, GR MOD OR SEV TURB AND ICE
UNITS USED: HEIGHTS IN FLIGHT LEVELS
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA / Worked example:
ISSUED BY WAFC LONDON
PROVIDED BY XYZ MET SERVICE
FIXED TIME PROGNOSTIC CHART
ICAO AREA H SIGWX
FL250-630
VALID 12 UTC ON 30 MAR 2009
CB IMPLIES TS, GR MOD OR SEV TURB AND ICE
UNITS USED: HEIGHTS IN FLIGHT LEVELS
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA
7. CONCLUSIONS
7.1 By adopting the above recommendations, a revision to the model charts in Annex 3 will be required. In addition, once Annex 3 has adopted the change, minor software updates will be necessary on end-user workstation software to ensure that the correct legend box text is displayed when charts are generated from GRIB or BUFR data.
7.2 In view of the above discussion, the group is invited to formulate the following draft conclusion:
Conclusion 5/.. – Update to the legend box text of WAFS forecastsThat, the WAFC Provider States, in co-ordination with WMO,
a) adopt the following text in the legend box of WAFS charts. For charts:
1) based on GRIB data, adopt:
ISSUED BY WAFC [LONDON/WASHINGTON]
PROVIDED BY [COMPANY NAME]
[PRODUCT NAME]
FL[XXX]
FIXED TIME PROGNOSTIC CHART
VALID [XX] UTC ON [XX XXX XXXX]
BASED ON [XX] UTC DATA ON [XX XXX XXXX]
UNITS USED: [UNITS]
HEIGHTS IN FLIGHT LEVELS
TEMPERATURE NEGATIVE
UNLESS PREFIXED BY A + OR PS
Note. — Where icing, turbulence and/or CB clouds gridded forecast data is used, the following text shall also be included:
CB IMPLIES TS, GR, MOD OR SEV TURB AND ICE
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA
2) based on BUFR data, adopt:
ISSUED BY WAFC [LONDON/WASHINGTON]
PROVIDED BY [COMPANY NAME]
FIXED TIME PROGNOSTIC CHART
ICAO AREA [X] SIGWX
FL[XXX-XXX]
VALID [XX] UTC ON [XX XXX XXXX]
CB IMPLIES TS, GR MOD OR SEV TURB AND ICE
UNITS USED: HEIGHTS IN FLIGHT LEVELS
CHECK SIGMET, ADVISORIES FOR TC AND VA, AND ASHTAM AND NOTAM FOR VA
and,
b) provide revised GRIB and BUFR model charts, based on the above proposal, to the Secretary by 15 December 2009 for inclusion in draft Amendment 75 to Annex 3.
8. ACTION BY THE wafSOPSG
8.1 The WAFSOPSG is invited to:
a) note the information contained in this paper; and
b) decide on a draft conclusion for the groups consideration.
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