Arabian gulf

Indian ocean

Gulf CooperativeCouncil

G.C.C Countries - The Location

“Eye on U.A.E” SHAIKH ZAYED 1971PRESIDENT KHALIFA

Assimilation and simulation of Assimilation and simulation of Cyclone Gonu using WRF Cyclone Gonu using WRF

Forecast modelForecast model

--United Arab EmiratesUnited Arab Emirates--Meteorological DepartmentMeteorological Department

September 2007September 2007By:Rashed S. ALTanaiji

Presentation planPresentation planGeneralities about tropical storms and cyclones.

Description of cyclone Gonu: Genesis, Track and dissipation.

The Weather Research & Forecasting (WRF) model at Meteorological Department.

Assimilation of Cyclone Gonu by WRF 3D-Var objective analysis technique component.

Simulation of Cyclone Gonu with the massively nested WRF forecast component.

The Alert system regarding the severe weather phenomena.

Tropical storms & cyclonesTropical storms & cyclonesThey are intense tropical systems characterized by:

A well defined circulationIntense winds, Intense rainfall, High surgesA center of extremely low pressure with steep pressure gradient.An extension of 200-600 km horizontally and 15 km height.

Their formation and intensification is due mainly to:High Sea Surface Temperature (SST) over warm ocean waters.Coriolis force generated by the Earth rotationPresence of instability: Rapid cooling in the upper-air.

We can distinguish three categories of these circulations:Tropical depression: clouds and thunderstorms with sustained winds of less than 33 knotsTropical storm: organized system of strong thunderstorms with winds of 34 to 63 knotsCyclone: Very strong system with huge energy and sustained winds of more than 64 knots (they are called “Typhoons” in the western pacific, “Hurricanes” in the North Atlantic

Worldwide regions of concernWorldwide regions of concern

Hurricanes Typhoons

Tropical cyclones

Anatomy of a Tropical CycloneAnatomy of a Tropical Cyclone

Cloud shield - 500-600 km in diameterEye - 20-50 km in diameter

relatively warmlight windsclear/broken cloudslow surface pressureSinking vertical motion

Eye wallvery strong windsring of intense thunderstorms/rain surrounding the eyeRising vertical motion

Converging winds at the surface and divergent winds at the Tropopause.Spiral bands / rainbands

Super Cyclonic Storm GonuSuper Cyclonic Storm GonuGonu developed from a persistent area of convection in the western Indian Coasts on June 1st , 650 km to the west of Mumbai, India.

It rapidly intensified to attain peak winds of 130 knots on June 3rd , with an encouraging upper-level environment and warm sea surface temperatures.

It weakened since June 4th after encountering dry air and cooler waters to the north, but remained looming.

Late on June 5 it made landfall on the eastern-most tip of Oman (Al Hadd Tip) where it devastated large areas including Muscat.

Gonu final trackGonu final track

7 June 6 June 5 June 4 June 3 June 2 June 1 June

Categories 1 2 3 5 4 2 1

Presence of an upper-air trough on late 02 June

attracted the cyclone more than 300 km to the northeast

High Resolution Gonu Satellite ImagesHigh Resolution Gonu Satellite ImagesMonday 4 June Tuesday 5 June

Wednesday 6 June Thursday 7 June

Near-sea surface winds derived from

LEO satellites (Quick SCAT) on 4 June.

Speed ~ 130 knots

MODerate resolution Imaging Spectro-radiometer (MODIS) Satellite images

5 3

2 1

Monday 4 JuneClear and distinct eye

Ragged and Diffuse eye

Eye absent Eye Re-appearance Scattering and dissipation

Gonu Associated rainfallGonu Associated rainfall

Accumulated rainfall from May 31 through June 7, 2007, from the Multi-satellite Precipitation Analysis (MPA).

Although the center of Gonu never made landfall in Oman, it camevery close to the northeast coastline where it dumped upwards up250 millimeters of rain

The WRF model at AFAD The WRF model at AFAD Meteorological DepartmentMeteorological Department

Weather Research & Forecasting Modeling system is the result of international scientific contributions in weather simulations.

It uses all the available meteorological information (stations, aircrafts, Ships, Buoy, soundings, Radar, Satellite, old forecasts) and produces a short to medium term weather forecast using huge scientific (dynamics, physics, mathematics) packages.

Generally, numerical weather prediction models consume huge computing resources. They should be run on supercomputers.

WRF is implemented since August 2006 and showed good performance in predicting extreme weather phenomena like, large scale winter systems, summer convection cells, fog occurrences, dust storms, …etc)

WRF makes forecasts for ranges up to 5 days.

d01: Middle-Eastd02: Arabian Peninsulad03: U.A.E.WRF 3DVAR is used for data assimilationUAE/WRF became operational at UAE since August 2006

Brief overview about WRF Brief overview about WRF

d01

d02

d03

Dedicated HPC systemDedicated HPC systemHARDWARE SOFTWARE

Machine SUN Grid OS Linux SUSE Enterprise

CPU AMD OPTERON

2.8 GHz

Compilers PGI CDK 6.2

Interconnect INFINIBAND 10 Gb/s

Debuggers PGDEBUG, TOTALVIEW

Number of Processors

70 Scientific libraries

BLAS, LAPACK,

ESSL, NAGTotal Memory 300 GB Message

passingSCALI MPI Connect

Total online storage

5 TB Jobs scheduler

SUN GRID Engine

Archiving system

SUN L500 robotic system

File system Parallel SUN QFS

Total offline storage

10 TB Archiving software

NetBackup OpenVision

Aggregate performance 400 Giga FLOPS

SUN GRID AMD SUN GRID AMD OPTERONOPTERON

Observational coverage over Middle-East region

Observational coverage over Middle-East region

SYNOP

AMDAR GEOAMV GPSREF

METAR

SATEM

TEMP SHIP/BUOY

~1600~1600

~300~300 ~15000~15000 ~20~20

~80~80~70~70

~500~500

~1000~1000

Gonu Track as analyzed by WRF 3DGonu Track as analyzed by WRF 3D--Var on Var on early June 2007early June 2007

The WRF model used to analyze Gonu track is the one running over“d01” domain at 20 km horizontal resolution and 38 vertical levels

Despite the relatively poor resolution, WRF succeeded in localizing Gonu in an acceptable way. The minimum pressure depicted is 950 hPaand the maximum analyzed wind is 95 knots.

MSL Pressure & Wind Direction

Low level Vorticity & Wind Speed

Gonu Track forecast 3 days before issued from Gonu Track forecast 3 days before issued from analyses using analyses using only conventional dataonly conventional data

The subsequent 3 days forecast was deviating the Gonu track to U.A.E. The eye was tracking strait to Abu-Dhabi ! as it could be seen also on the next slide.

MSL Pressure & Wind Direction

Low level Vorticity & Wind Speed

Use of new informative observational data to Use of new informative observational data to enhance the model qualityenhance the model quality

The model was need to use new observation datavery useful for depicting weather phenomena over the ocean :

Near-sea high resolution winds (Quick SCAT)GPS RefractivityOccultation linked to temperature, humidity and pressure.

Quick SCAT

GPS RO

Quick SCAT and GPSRO in WRF 3DQuick SCAT and GPSRO in WRF 3D--VARVAR

About 150 soundings per day in our region

About 2500 wind data per day in our region

Quick SCATGPS RO

Gonu Analysis with all data types Gonu Analysis with all data types including the new dataincluding the new data

Gonu track is followed accurately by the model analyses, especially at the date of landfall (05/06 June 2007)

The minimum pressure and maximum winds depicted are respectively939 hPa and 126 knots (The actual values are 920 hPa and 130 knots).

MSL Pressure & Wind Direction

Low level Vorticity & Wind Speed

Gonu Track forecast 3 days before issued from Gonu Track forecast 3 days before issued from analyses using analyses using all data typesall data types

Gonu track is predicted accurately by the model forecasts, especially at the date of landfall (05/06 June 2007), despite a little mismatch at the end of validity.

The minimum pressure and maximum winds depicted are respectively941 hPa and 115 knots (The actual values are 920 hPa and 130 knots).

MSL Pressure & Wind Direction

Low level Vorticity & Wind Speed

Associated high surges as predicted by Associated high surges as predicted by wave model wave model

WRF wave model is based on a version of the ECMWF wave height forecast model, adapted to our region for a spatial resolution of 3 km

WRF wave model predicted accurately the surges occurrence associated with the cyclone (more than 20 feet in the Arabian Sea)

Surges as high as 20

feet

How the meteorological department dealt How the meteorological department dealt with the cyclone danger ?with the cyclone danger ?

Before Monday 4th June:the Cyclone behavior was followed closely since 01 June using numerical models and satellite imagery.

On Monday morning: WRF predicted the track of Gonu to hit United Arab EmiratesA crisis unit was established at 03:00 GMTAn emergency state was established and an alert was emitted on 05:00GMTReports were written and transmitted to the Head Quarter on a hourly basis.

After Monday :WRF corrected Gonu track and downgraded the danger.Reports continued to be transmitted until Thursday 07 June.

Immediately after Gonu dissipation different studies and research experiments were conducted in order to enhance the model quality.

ConclusionConclusion

Gonu Cyclone was a very important opportunity to:

Learn more about cyclones genesis and evolvement.Test our forecasting tools in a real crisis time.Test our ALARM systemTune the scientific aspects of our numerical weather prediction operational suite based of WRF model.

Slideshow illustration of Gonu Slideshow illustration of Gonu AftermathAftermath

Gonu Meteorological aspectsGonu Meteorological aspectsMay 31 Tropical disturbance developed about 645 km south of Mumbai, India with

cyclonic convection and a well-defined mid-level circulation

June 01 A low-level circulation (depression) formed. It tracked westward along the southwestern periphery of a mid-level ridge over southern India with increasing convection.

June 02 The storm steadily intensified despite encountering dry and cool air to the north. It was classified as tropical storm

June 03 I continued the westward track after ridging built to the north of the storm, accompanied by a solid area of intense convection combined with a local increase in ocean heat content

June 04 With low amounts of vertical wind shear and favorable upper-level outflow, Gonu strengthened further to attain peak 1-min sustained winds of 260 km/h and gusts to 315 km/h, while located about 285 km east-southeast of Masirah Island on the coast of Oman.

June 05 The eye became cloud-filled and ragged, and the cyclone gradually weakened as it continued tracking northwestward over cooler water temperatures and through drier air

June 06/07

After emerging into the Gulf of Oman, the cyclone intensified slightly. But, Increasing wind shear and entrainment of dry air from the Arabian Peninsula continued to remove deep convection from its eastern semicircle. On June 7 Gonu became a normal cyclonic storm hitting Iran.