Andrew Mirza Aviation Weather Products UK Met Office · · 2007-01-31Andrew Mirza. Aviation Weather Products. ... WAFCs provide international forecasting services to meet Annexe

© Crown copyright 2006 Page 1Making our forecasts essential to everyone, everyday

Andrew Mirza

Aviation Weather Products

UK Met Office

Presentation to the XIIIth

Session of the WMO Commission for Aeronautical Meteorology

Geneva, Switzerland, 23 November 2006


Introduction

World Area Forecast Services & ProductsProducts & ServicesDevelopments

UK Met Office Products & ServicesDevelopmentsResearch


WAFS Aviation Weather Products http://www.metoffice.gov.uk/aviation/index.htm

•

World Area Forecast Products & Services•

WAFC -

London is operated and managed by the Met Office and is one of only two World Area Forecast Centres–

the other is WAFC –

Washington

•

WAFCs provide international forecasting services to meet Annexe 3 of the ICAO Convention on Civil Aviation.

•

Global upper-wind and temperature data twice daily

•

Significant Weather Data every six hours upto FL250

•

for international flights operating over Europe, the Middle East, Asia, Australasia, Africa and the Atlantic

•

Met Office Products and Services•

Provision of OPMET, TAFs, METARs and SIGMETs

•

VAAC, ASHTAMs, NOTAMs


Upper wind forecast with emphasis on jet streams

WAFS Aviation Weather Products (Graphical)

Graphic shows a forecast of volcanic ash concentration valid at 06Z on 2/11/2004 following the eruption of Grimsvotn on Iceland (non WAFS Product)

Significant Weather Charts (available in PNG format)


WAFS Aviation Weather Products

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WAFS Products & Services•

Main dissemination is by broadcast via Satellite Distribution (SADIS) that delivers ICAO products to customers’

desktop systems in more than 90

states•

Customers are kept informed about developments via the SADIS message board (http://www.icao.int/anb/wafsopsg/

or http://www.metoffice.gov.uk/sadis/news/)

•

Upgrade from SADIS to SADIS-2G expected to be completed by Dec 2008, providing greater resilience and cost effectiveness:

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Industry standard protocols•

Commercial Off-the-Shelf solutions to display digitally encoded products (BUFR & GRIB) in addition to coded text messages and SADIS administration messages (http://www.metoffice.gov.uk/sadis/software/index.html)

•

Availability 24 hour x 365 day support


WAFS Aviation Weather Products (Validation)

Winds and TemperatureForecasts are compared against the model's analysis for the same time. For wind, the computed errors are Root Mean Square Vector errors - this takes into account errors in the wind direction as well as the wind speed. For temperature the errors are Root Mean Square errors

Area 2 is a Met Office defined area, covering the north Atlantic

and parts of western Europe and north America. We have a long time series of data for this area which shows a steadily improving performance over the years.

http://www.metoffice.gov.uk/icao/index.html


WAFS Aviation Weather Products (New Products and Services)

Thinned GRIBThe Met Office Global Model has been downscaled to provide a 1.25 degree resolution product in latitude and longitude and covers the globe in eight sections, such that each section contains the same number (3447) of points.

New gridded products available on Thinned GRIB

ThunderstormsHeights of Cb tops

Icing Mean and Max Icing Potential

TurbulenceProbability of CATIn-layer Cloud Turbulance



• Various fields available:-

CB horizontal extent (%)-

Pressure/height of CB top-

Pressure/height of CB base-

Pressure/height of embedded CB top

-

Pressure/height of embedded CB base

• Produced using convective cloud forecast fields, where the cloud top is colder than -

30˚C

• Embedded CB fields produced where CBs occur adjacent to layer cloud

• A weakness of the product arises when downscaling from 40km to 140km (thinned GRIB) where isolated CB cells are kept whereas the spatial extent of larger CB cells maybe reduced due to the loss of these cells. This could be overcome by using a cluster algorithm.



• Mean & max icing potential fields available

• Gives a measure of icing potential

• Validation of icing forecasts has been done using, for example, TAMDAR (Tropospheric

Aircraft Meteorological Data Relay) data

• Supercooled

Liquid Water Content directly from the Unified Model was considered as a predictor

• Fractional layer cloud cover where temperature is -20 to 0˚C proved to better predictor and therefore is being used

• Units = fractional layer cloud cover where temperature is -20 to 0˚C

• Produced for 5 levels:

– 700 hPa (~FL100)

– 600 hPa (~FL140)

– 500 hPa (~FL180)

– 400 hPa (~FL240)

– 300 hPa (~FL300)



• Gives probability (as %) of encountering mountain wave or wind shear turbulence per 100km of flight

• Values ≥

4% indicate moderate or severe turbulence

• Qualitative validation against Significant Weather Charts

• Quantitative validation against GADS (Global Aircraft Data Sets) data

• Produced for 5 levels:

-

400 hPa (~FL240)

-

300 hPa (~FL300)

-

250 hPa (~FL340)

-

200 hPa (~FL390)

-

150 hPa (~FL445)



• Theory of CAT well advanced –

for shear induced CAT it is acknowledged that Lagrangian

rate of change of Richardson Number should be a good predictor

– Richardson number depends on ratio of vertical wind shear to static stability– Lagrangian

Rate of change is rate of change following the motion of a fluid particle– This gives highly non-linear, highly differentiated product – Errors in wind and temperature field can be amplified

• CAT predictions are verified by comparison with reports of turbulence (manual or automatic)• There are simpler algorithms than Lagrangian

rate of change of Richardson Number• Dutton[1] algorithm uses vertical and horizontal wind shear and was derived empirically• Elrod [2] TI1 algorithm uses vertical wind shear and horizontal wind deformation• Turner [3] algorithm uses a 3-D gravity wave stress field computed from 200hPa wind field• In the GRIB products we provide a CAT Index based on the maximum

probability value from the set of values computed from Elrod TI1 algorithm and the Turner Mountain Wave algorithm

[1] Dutton, M.J.O. 1980: ‘Probability forecasts of clear-air turbulence based on numerical model output’. Meteorological magazine, vol

109, pp293-310.[2] Ellrod, G. P. and Knapp, D. I. 1992: ‘An Objective Clear Air Turbulence Forecasting Technique: Verification and Operational Use’. Weather

Forecasting, vol. 7, pp 150-165.[3] Turner, J. 1999: ‘Development of a mountain wave turbulence prediction scheme for civil aviation’. Met Office Forecasting Research Technical

Report No. 265.



• Gives a measure of likelihood of turbulence within layer cloud

• Positive values indicate a risk of encountering in-cloud turbulence

• Typical values 0 to 0.001, the larger the value the larger the probability of turbulence

• There are no specific observations nor literature about this phenomenon

• Verification of results has proven to be difficult, although TAMDAR data could be a suitable source

• Within the cloud, the equivalent potential temperature gradient with height is computed; a negative value is used as an indicator for instability

• Produced for 5 levels: -

700 hPa (~FL100)-

600 hPa (~FL140)-

500 hPa (~FL180)-

400 hPa (~FL240)-

300 hPa (~FL300)


Met Office Aviation Weather Products (New Products and Services)

Advanced Weather Service –web based service development in partnership with SITA

SITA is a commercial organisation that has evolved from its original forum as the 'Société Internationale de Télécommunications Aéronautiques‘

Interactive service allowing the customer to overlay current and planned flight routes with weather information, e.g., forecasts of upper air winds, current rainfall radar and satellite imagery (compare with Geographic / Geospatial Information Systems)



For the projected position of the aviation user

Relevant Significant Weather Charts is displayed

TAFs and METARS along the route are updated every minute

Satellite imagery, rainfall radar imagery and sferics

Volcanic ash advisories are indicated



“GrafTAF”

This is not a graphical version of the coded TAF, but a working title for this product.

These are produced from the Met Office current model for site specific processing for airports worldwide.

The five-day forecast includes surface winds, cloud, visibility, mean sea-level pressure, freezing level, surface temperature and precipitation

Surface winds are resolved into components along the runway.


Aircraft - De-icing forecast serviceForecasts 24-hours ahead at one hourly intervals from single site forecast model; five-day outlook based on ensemble forecastsWhere observations exist, ensemble forecasts have been modified using a Kalman Filter (a statistical method)Forecast accuracy sensitive to precision of the observations and siteingof observation stationProvides holdover times based on FAA guidelines for de-icing fluidsBMI Case Study http://www.metoffice.gov.uk/aviation/Met-Office-bmi.pdf

Airports - Open RunwayForecasts of rain, frost, snow, ground icing, frost and freezing fog24-hours ahead at one hourly intervals and five-day outlookUses surface-type, screen and dew-point temperatures, estimates of surface-type temperature from the Met Office Road Surface Temperature Model – models surface heat balance to 20 levels (spaced non-linearly ~ 1centimetre to 150 centimetres) below ground Some airports have temperature sensors installed in the runway that provide observations at 20 minute intervals

Air Traffic Management - Optimum RoutesThe Met Office supplies five-day forecasts of optimum routes across the North Atlantic to NATS at Swanwick. Optimum route is computed using winds at 250 hPa, grid resolution 40km

Met Office Aviation Weather Services

http://www.metoffice.gov.uk/aviation/Met-Office-bmi.pdf



Met Office Development Programme 2006 - 2010Automation of Services

TAFsEnhance automation of production of SIGWX charts

improve algorithms to identify embedded thunderstorms, location of the jet stream and height of the tropopause

Upgrades to Environment Monitoring and Response CentreImplementation of latest version of Numerical Atmospheric dispersion Model – NAME – III, incorporates,

Training of forecasters to provide advice for Volcanic Ash DispersionNAME – III validation: maintain an archive of modelled events for any large eruptions



Met Office Development Programme 2005 – 2009A major component of our development work is within the FLYSAFE project

For an overview, see presentation by Joseph Huysseune: “FLYSAFE”For comparison, recall presentation by David Pace: “NGATS”

Met Office contribution to FLYSAFE To forecast at the Global and Continental Scales

Clear Air TurbulenceThunderstormsWave VortexIcing

To develop a weather data exchange model between ground-based systems and the aviation user, using XML/GML



Met Office Research Programme 2006 – 2010

Aims areTo provide better resolution of high impact weather in convective scale modelsTo enable our customers to utilise better the weather information we provide

ImprovementsTo implement higher resolution grid lengths for the UK forecast fields (4 km to 1.5 km) and Global forecast fields (40 km to 25 km)

To implement by 2010 a suite of tools, updated hourly between T+00 and T+06 hours, to forecast high impact weather up to 24 hours ahead

To provide estimates of confidence in the short-range forecast (T+00 to T+72) estimated from the 24-member Met Office Global and Regional Ensemble Prediction System (MOGREPS)



Examples from MOGREPSForecast Lead time of 6 hours for probability that Visibility < 1000m, Areas of 10m Wind speed > 22 knots, Cloud base < 500m with more than 4.5 oktas, Areas of Level 6 wind speed > 40 knots, surface pressure > 1020 hPa, and Areas where precipitation is > 5 mm/hr



Met Office Research Programme 2006 – 2010“integrated post-processing system”

To implement by 2010 an improved infrastructure that will provide automated and value-added products and servicesTo develop an integrated logical data store that is updated more frequently than the main production suite, providing nowcast forecasts (1 – 6 hours) that incorporate the latest observational, satellite and numerical data; and to provide enhanced products on a finer grid resolutions (< 1 km), where single-site forecasts take into account the effects of local orography, coastal effects, surface processes and land useSingle site forecasts will use an “intelligent” grid point selection algorithm near the selected site.

Observations

NWP

“ipp”

LDS

Automated Product A

Value-AddedProduct B

AutomatedService C

Resolution < 1kmUpdate Frequency < 6 hours

Mesoscale

/ Site Specific

Resolution > 1kmUpdate Frequency ~ 6 hours

Global & Regional ScaleLogical Data Store

(Weather Information Management)

General and Customised Products

and Services

SurfaceSatellite

Vertical Profiles



Met Office Research Programme 2006 – 2010

For the underlying core capability of the Met Office (selected high lights):Development of a new convective scale NWP model and data assimilation with a grid length of about 1kmReformulation of the Unified Model dynamical coreUtilise more satellite dataImplement operationally the trial version of MOGREPSResearch into perturbations to resolve more effectively storm scale convection within ensemblesDevelop forecaster tools for risk assessment of high impact weatherDevelop the Unified Model to represent atmospheric dispersion and chemistry processSupport development of Weather Information Management Systems for predicting CAT, thunderstorms, icing and wake vortex movement and dissipation.


Thank you for your attention.

Acknowledgements:Bob Lunnon, Manager, Aviation, Met Research & DevelopmentDebi

Turp, Thinned GRIB productsPhil Ellis, SITA Advanced Weather ServiceClare Bysouth

& Mark Burgoyne, GrafTAFIan Pearman, Paul Maisey

& Alisdair

Skea

Site Specific Processing

Contact Details:Andrew Mirza, Aviation, Met Research & [email protected]

Andrew Mirza Aviation Weather Products UK Met Office · · 2007-01-31Andrew Mirza. Aviation Weather Products. ... WAFCs provide international forecasting services to meet Annexe

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