aviation reports, forecasts and warnings ii aeronautical fixed telecommunication network ......

Aviation Reports, Forecasts and Warnings II

WMO VCP Training Course on Aviation Meteorological ServicesJuly 2005

Topics

Flight documentationAviation data processing system & communication infrastructureVerification of forecast accuracy & computer-based verification systemPresentation and dissemination of data and products

Flight documentation

According to ICAO Annex 3, met. info. shall be supplied to operators and flight crew membersMeteorological information supplied should cover the whole routeDestination and alternate aerodromes Flt. Doc. should comprise the following information

Current and forecast: upper winds, upper-air temperatures & humidityExisting & expected significant en-route weather phenomenaMETAR, SPECI (trend)TAFSIGMET & special air-reports


Met. offices should provide information received within the framework of the world area forecast systemNormal info. source for flight documents

Aeronautical Fixed Telecommunication network (AFTN)World Area Forecast System (WAFS)

Satellite DIStribution System (SADIS)International Satellite Communication System (ISCS)

WAFS FTP backup system


Upper-wind data WAFS T4 charts have been replaced by forecasts in digital GRIB format since Jul 2005Standard coverage

SADIS User GuideGRIB code

FM92-XI Ext. GRIB

Flight documentation – GRIB codes

File naming conventionH[HPRTUV][DIJKLMNOP][ACEGI][99|98|92|89|85|70|50|40|30|20|15|10 ]_yyyymmddzz ]Data Type:

H- height, P- pressure, R- relative humidityT-temp., U- E wind component, V- W wind component

Area: J- 60E-150E, 0-90N

Reference Time: A- analysis, E- 24 hour forecast, K- 72 hour forecast

Level99- 1000 hPa, 92- 925 hPa, 89- reduced to MSL85….10- standard levels

Flight documentation – GRIB codes

Each GRIB has 5 sectionsSection 0: Indicator sectionSection1: Product definition sectionSection 2: GRIB description sectionSection 3: Bit map sectionSection 4: Binary data section


Significant weather charts

High level, medium level and low levelHigh level – WAFS chartsMedium level – limited areas available from WAFSWAFS T4 charts SIGWX charts generated from BUFR data


HK SIGWX MediumFlight level between 100 and 250Significant weather such as thunderstorms, TC, severe squall lines, mod/sev turb/icing, widespread sandstormClouds associated with sig. wx.Frontal systemsLocation of volcanic ashLocation of radioactive materials


Software packages for generation of significant weather charts are available commerciallyWAFS Transition of T4 SIGWX charts to forecasts in BUFR data scheduled next year

Flight documentation – BUFR codes

WAFC London BUFR dataBUFR charts based on 0000 UTC model run – T+24 issued between 10:00 and 11:00BUFR charts based on 0600 UTC model run – T+24 issued between 16:00 and 17:006 –hourly thereafter


BUFR FEATURES COMMON NAME

WMO HEADER used by WAFC London

Jet -streams JETS JUWE96 EGRRClear Air Turbulence (C.A.T.)

CAT JUCE00 EGRR

Embedded Cumulo- nimbus

CLOUD JUBE99 EGRR

Tropopause height TROP JUTE97 EGRRFrontal systems FRONTS JUFE00 EGRRTropical Cyclone, Sandstorms & Volcanoes

V_T_S JUVE00 EGRR


BUFR FEATURES COMMON NAME WMO HEADER used by WAFC London

SWM Tropopause height

M-TROP JUOE00 EGRR

SWM jet-streams M-JETS JUTE00 EGRR

SWM fronts M-FRONTS JUJE00 EGRR

SWM cloud, in-cloud icing and turbulence

M-CLOUD JUNE00 EGRR

SWM Clear Air Turbulence

M-CAT JUME00 EGRR


TAF TAF for departure, destination and alternate aerodromesInform the flight operators of any amendmentsTAF included without modificationProvisional forecast to be prepared when TAF is not available after trying various sourcesThere should be an indication to the flight crew that the TAF is provisional


METARLatest reports for destination, take-off, en-route and alternate aerodromes (and Trend)

SIGMETSIGMETs and special air-reports relevant to whole route

Flight Document System

Flight Document Back-end system to compile flight documentsRuns on a web interfaceDisseminate to another web-based system for airlines to download the documents Related databases –OPMET database, image database, profile database


Inputs to Flight Doc SystemAFTN and WAFS OPMET messagesPrognostic wind/temp and SIGWX chartsFlight schedule Other wx charts and messages, including manually inserted charts

The system checks for the availability of charts for flights and alert the operator to take appropriate actions


Main functions Login to the system View or edit flights

Modify the parameters of the flight (type of charts and bulletins supplied)Delete a particular flight View flights sorted by departure time and flight number


Main functionsView TAF/METAR/SPECI bulletins and WAFS chartsDissemination of flight documents via facsimileInclusion of supplementary information in the flight documentsInput of provisional forecastView flight document log

Aviation Processing system and Communication Infrastructure

Aviation Processing Sys & Communication

A computer system for acquisition, processing and distribution of weather informationMeteorological Data Processing System (METPS) used in HK. Inputs include:

Synoptic wx reportsSatellite and radar imagesData from Automatic wx stations and rainguagesSIGWX and wind/temp charts from WAFSNWP products


METPS data collection and exchange

Integrates with a no. of systems to collect and exchange observational, analysis and forecast data

Aerodrome Meteorological Observing SystemWindshear and Turbulence Warning System


Hong Kong Observatory Main Computer System

GTS data are decoded and objective analysis produced. Routine charts are posted to HKO’s Intranet for use by forecasters. Graphical terminals are used by forecasters to analyse the weather situations

GTS Reception SystemWorld Area Forecast System


METPS interface with Civil Aviation Department (CAD) systems

Automatic Message Switching System OPMET data from AFTN is acquired through an interface with the Automatic Message Switching System

OPMET data exchanged with other centresRadar Data Processing and Display System

Grid-point wind & temp. data over South China Sea for 21 levels (airway winds) METAR/SPECI of adjacent aerodromesQNH of adjacent aerodromes

Aeronautical Information DatabaseSix pages of meteorological information such as METPage, aerodrome warnings, Local Routine Report, etc.


Interface with Airport Authority (AA)METPS obtains flight schedule from the Airport Operation Database (AODB) of AA in the compilation of flight documentsMETPS provides weather information of major cities around the world to AODB

AMIDS Sub-system for airlines to retrieve flight documents

AMO Staff

TDWR AMOS

WTWS

AMIDS

LIDAR

RadarSatellite

Wind profilerCAD

AA-AODB

Airlines / PLA /CAD ...(Clients)

HKO Computer

METPS



Tools to prepare aviation meteorological products for the AMO

Observatory’s AFTN Input SystemA PC-based client-server software to prepare observation reports, forecast and warnings Data/information input by AMO via user-interface on client PC, or automatically injected from other systemsProducts are disseminated to end users via the AFTN circuit


Requirements for and Use of Communication

Suitable telecommunication facilities shall be made available to permit met. offices and met. watch offices to supply the met. informationContent of D-VOLMET

METRA/SPECI, trend, TAF, SIGMET, special air-reports not covered by SIGMET

Content of VOLMET broadcasts

Digital VOLMET Printout in Cockpit

/HKGVOYA.TI2/VHHH ENR ATIS

HONG KONG VOLMETVHHK SIGMET A2 VALID 090530/090930 VHHH-HONG KONG CTA EMBD TS FCST S OF N19 E OF E114 TOP FL 350 STNR NC =METAR VHHH 090730Z 16011KT 130V190 9999 SCT028 BKN300 33/23 Q1007 NOSIG=

METAR ZGGG 090700Z 13004MPS 9999 FEW040TCU FEW040 34/23 Q1007 NOSIG=METAR ROAH 090730Z 19013KT 9999 FEW015 32/25 Q1010=METAR RCTP 090730Z 28012KT 9999 SCT012 FEW020CB BKN022 BKN050 30/27

Q1009 TEMPO 3000 -SHRA=METAR RCKH 090730Z 18017KT 9999 FEW020 SCT300 33/23 Q1007 NOSIG=METAR RPLL 090700Z 14008KT 9999 SCT025 SCT100 31/18 Q1008 TCU W=METAR RPVM 090700Z 24014KT 9999 FEW020 SCT300 31/26 Q1007 A2976=TAF VHHH 090530Z 090615 18010KT 9999

Forecast Verification and Computer-based Verification System

Products

Automatic and objective verification systemWeb-based user interfaceAccessible to authorized usersFlexible and easy to useGenerate routine and special reports of verification results

Records to be Processed

Forecasts

9-hour TAF

24-hour TAF

TREND

Forecasts for take-off

Observations

METAR

SPECI

Verification Methodologies

Standard verification based on ICAO’s accuracy requirements

Refer to ICAO Annex 3 Attachment B on Operationally Desirable Accuracy of Forecasts

Contingency table approachComparison with persistence and no-skill random forecastsPercentage of correct forecasts (POC)

Standard Verification

Elements to be verifiedVisibility Cloud amountPrecipitation Cloud heightWind directionWind speedTemperatureOccurrence of thunderstormsCloud base

Focus on conditions that have operational significance to aircraft

Thresholds for change groups or fcst amendment:

150m, 350m, 600m, 800m, 1500m, ...

Deviation from ICAO Requirement

Criteria for inclusion of change groups or amendment of forecast

E.g. VisibilityICAO req.:

within 30% for 700m or above

Operational considerations

Wind directionICAO desirable accuracy ± 30°Criteria adjusted to suite climate and terrain of Hong Kong –HK adopts a threshold of 60°Forecast direction not verified when wind speeds are light (<= 6kt)

Wind speed Follows ICAO requirement Speed forecast is correct if the difference between forecast and actual speed <10kt

% of correct wind dir/speed forecast will be used as representative % of correct wind dir/speed forecast


VisibilityFollows ICAO requirementVisibility forecast is correct if

the forecast visibility is within 200m up to 700mwithin 30% between 700m and 10 km of reported value

Forecast of CAVOK – taken to mean a forecast of 10 km % of correct visibility forecast based on above criteria used as the representative % of correct visibility forecast


PrecipitationOccurrence or non-occurrence of moderate or heavy ppt is correctly forecastOccurrence or non-occurrence of light ppt is not verified% of correct forecast for occurrence and non-occurrence of ppt. used as representative % of correct ppt forecast


Cloud amount and heightOnly clouds below 5000 ft are verified Total cloud amount – largest extent of all layers at or below 5000 ftCloud amount considered correct if it is within one category of the reported amountCloud height forecast considered correct if the difference between forecast & actual height is within the accuracy limit


Air temperature Considered correct if the reported value within +/-1°C of the forecast value

Max/Min temp Considered correct if forecast is within +/-1°C of the observed value

% of correct temp forecast used as the representative % of correct temp forecast

Handling of change groups

‘FM” indicatorUsed to describe a significant change in a weather elementThe forecast value takes effect at the time specified after the ‘FM’ indicator

BECMG’ indicatorDescribe changes where the conditions are expected to reach or pass through specified threshold Forecast value takes effect after the time period indicated by the time groupThe transition period is usually shortForecast considered correct if the reported value within the transition period is within the prescribed accuracy range of the forecast value before or after the change


e.g. visibility forecast to change from 5000 m to 3000 m andreported visibility during transition period indicated by “BECMG’ is 2000 mForecast considered incorrect as

Reported value is outside 30% accuracy range of both 5000 m and 3000 m

If reported visibility is 6000mForecast considered correct as reported vis is within 30% of 5000 m


‘TEMPO’ indicator

Use to denote temporary fluctuations No. of hours correctly forecast by a ‘TEMPO’ group should not exceed ½ of the time periodHowever, the other condition for “TEMPO” condition to last to last <1 hr in each instance is not considered:

in view of inherent limitations in observation time-resolutionA penalty is imposed if “TEMPO” condition is not observed:

The penalty for non-occurrence is that up to 1/3 of the forecast hours covered by the time period will be counted as incorrect


‘PROB30’ or ‘PROB40’ indicators

Describe probability of occurrence of an alternative value for a weather elementRarely used in Hong Kong and not verified at present

Construction of weather history

The ‘hour’ is taken as the basic unit in computing the percentage of cases of accurate forecastFor any period of verification

% of correct forecasts= total no. of correct forecast hour/totalno. of hours

To determine the total no. of correct forecast hours, a ‘history’ of weather conditions is built up

Each routine observation is valid for half an hour from the reporting time unless a SPECI is issuedEach SPECI is valid for the period from reporting time to the next routine observation

Computation of % of accurate forecasts

Computation of % of accurate forecastsCompare the weather history with the forecast to determine

Fraction of the hour in which the weather has been accurately forecast% of correct forecasts

Aviation Forecast Verification System

Example of the daily TAF Verification Result

Example of the monthly TAF Verification Result

Presentation and Dissemination of Data and Products

Different modes of delivery

AFTN –conventional method for exchange of OPMET dataMeteorological information supplied to air traffic services

HKIA TAFHK Airspace SIGMETAerodrome warningsTropical Cyclone and Strong Monsoon SignalsExtra weather observationOperational status of equipment/systems


Web-based information systemSecure web based information systemparticularly for flight documentsAviation Meteorological Information Dissemination System

Telephone consultationFacsimile

E.g. aerodrome warnings

Short Message Service

To provide timely update

aerodrome warnings on TS and hail local tropical cyclone warning signals


BroadcastVOLMET broadcast (including D-VOLMET)ATIS broadcast (including D-ATIS)Direct voice-to voice communication with pilots


Dedicated systemsExamples in Hong Kong

Meteorological Data Processing System – Aeronautical Information Database interfaceMeteorological Data Processing System – Automatic Message Switching System interfaceMeteorological Data Processing System – Radar Data Processing and Display System interface

Internet Latest TAF/METAR/SPECI/SIGMET and Local Aviation Forecast

IntranetClassified incoming messages from AFTN and GTS circuitForecast and warning messages issued by Central Forecasting OfficeAlert messages

Presentation of met. information

Aviation Meteorological Information Dissemination System (AMIDS)

Web-based, on-line information systemProvides aviation users with the latest weather information for flight operationsRemote access Now serving over 40 organisations in the aviation sector

Web-based aviation weather information system

Access methodsDial-up telephone lines

Speed of access limited Modem requiredUser-name and password required

Internet (Broadband)Broadband recommended for speedy accessDigital certificate required to be installedUser-name and password required for installation of digital certificate and to log onto the system

ISDNISDN link required for users to access the system


ContentHomepage of the AMIDSWarningsFlight documentsLocal meteorological informationSatellite, radar images and lightning location informationReference section

Thank you !

aviation reports, forecasts and warnings ii aeronautical fixed telecommunication network ......

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