Tropical Atmospheric ResearchTropical Atmospheric Researchin Singaporein Singapore

Asst. Prof. Tieh-Yong Koh Asst. Prof. Tieh-Yong Koh

许 智扬许 智扬Nanyang Technological University (NTU)Nanyang Technological University (NTU)

南洋理工大学南洋理工大学19 Mar 200719 Mar 2007

Acknowledgements:• Naval Research Laboratory, USA• Meteorological Service Division, National Environment Agency, Singapore• Centre for Remote Imaging, Sensing and Processing, National University of Singapore

SingaporeSingapore

Malay PeninsulaMalay Peninsula

SumatraSumatraIslandIsland BorneoBorneo

IslandIsland

Satellite picture taken by MODIS-TERRA at 11:33 am Satellite picture taken by MODIS-TERRA at 11:33 am

on 27 Dec 2001 Singapore Time.on 27 Dec 2001 Singapore Time. With courtesy from Centre for Remote Imaging, Sensing and Processing, With courtesy from Centre for Remote Imaging, Sensing and Processing, National University of Singapore (CRISP/NUS)National University of Singapore (CRISP/NUS)

Typhoon Vamei

Equator

Severe WeatherSevere Weathere.g. e.g. TyphoonTyphoon VameiVamei, , 27 Dec 200127 Dec 2001

• In In SingaporeSingapore, 28 flights were diverted , 28 flights were diverted and 22 flights were delayed at and 22 flights were delayed at Changi International Airport.Changi International Airport.

• In hardest hit In hardest hit Johor and southern Johor and southern Pahang in MalaysiaPahang in Malaysia, the storm took , the storm took away 5 lives and forced the away 5 lives and forced the evacuation of 7000 people.evacuation of 7000 people.

26 Oct 2002, 9:38 amPSI24h=64, low moderate15 Oct 2002, 9:25 amPSI24h=92, high moderate

•Smoke-hazeSmoke-haze pollution pollution from forest from forest fires fires

Atmospheric PollutionAtmospheric Pollution

~1.4km away

Merapi Volcano, Central Java, 24 Aug 2003

Channel NewsAsia InternationalOnline report on 15 May 2006

• Volcanic Volcanic eruptionseruptions

e.g. Merapi in e.g. Merapi in Aug 2003, Aug 2003, May 2005…May 2005…

Global warmingGlobal warming from increased CO from increased CO22 levels, leading to: levels, leading to: • increase in sea level;increase in sea level;• redistribution of temperature, humidity & rainfall;redistribution of temperature, humidity & rainfall;• changes in storm frequency, duration and intensity.changes in storm frequency, duration and intensity.

Climate ChangeClimate Change

Larsen B ice shelf and parts of Antarctic Peninsula

COAMPSCOAMPS Real-Time Forecast SystemReal-Time Forecast SystemA project of Tropical Weather Group, TL@NTU

Team MembersTieh-Yong KOHLan YIChee-Kiat TEO

COAMPS Real Time ForecastCOAMPS Real Time Forecast

• Model DescriptionModel Description• System FeaturesSystem Features• Process FlowProcess Flow• Web DisplayWeb Display• Verification: case studyVerification: case study

ObjectiveObjectiveTo create a automated system capable of To create a automated system capable of timely delivery of reliable 24h-forecasts for timely delivery of reliable 24h-forecasts for the SE Asia regionthe SE Asia region

• The The Tropical Weather groupTropical Weather group acquired the acquired the COAMPS model from COAMPS model from Naval Research Naval Research LaboratoryLaboratory, USA, for research purposes , USA, for research purposes from Feb 2002from Feb 2002 and has been running and and has been running and testing the model ever since. testing the model ever since. Development Development work is still on-goingwork is still on-going..

• A A trial versiontrial version of the automated of the automated Real Time Real Time Forecast SystemForecast System is currently run at is currently run at TL@NTU TL@NTU since July 2006since July 2006. This version is . This version is being presented to you now.being presented to you now.

Model DescriptionModel Description• COAMPS stands for COAMPS stands for Coupled Ocean/Atmosphere Coupled Ocean/Atmosphere

Mesoscale Prediction System.Mesoscale Prediction System.

• It is a It is a mesoscalemesoscale numerical weather prediction numerical weather prediction (NWP) model for (NWP) model for regionalregional weather forecast. weather forecast.

• The current version is implemented on a The current version is implemented on a 64-cpu64-cpu Linux PC cluster.Linux PC cluster.

• It has It has customizablecustomizable vertical and horizontal grid vertical and horizontal grid resolutions and is capable of resolutions and is capable of horizontal nestinghorizontal nesting..

• It uses It uses up-to-date numerical methodsup-to-date numerical methods and has a and has a suite of suite of complex physical parameterizationscomplex physical parameterizations..

• 3D non-hydrostatic compressible equations3D non-hydrostatic compressible equations• 11 prognostic variables: 11 prognostic variables:

u, v, w, u, v, w, θθ, , , q, q, q, qc, c, qqi, i, qqr, r, qqs s , e, e

• Terrain-following Terrain-following σσzz-coordinates-coordinates• Limited-area model with Limited-area model with grid-nestinggrid-nesting option option• MercatorMercator projection used for the tropics projection used for the tropics

• Initial and boundary conditions from Initial and boundary conditions from NOGAPSNOGAPS (Navy Operational Global Atmospheric Prediction System)(Navy Operational Global Atmospheric Prediction System)

• Data analysis by Data analysis by Multi-Variate Optimal InterpolationMulti-Variate Optimal Interpolation

•Physics modules:Physics modules:– radiative transfer radiative transfer (Harshvardhan et al., 1987)(Harshvardhan et al., 1987)– cumulus convection cumulus convection (Kain & Fritsch, 1993)(Kain & Fritsch, 1993)– cloud microphysics cloud microphysics (Rutledge & Hobbs, 1983)(Rutledge & Hobbs, 1983)– boundary-layer turbulence boundary-layer turbulence (Mellor & Yamada, (Mellor & Yamada,

1982)1982)– surface sub-layer physics surface sub-layer physics (Louis, 1979)(Louis, 1979)– simple land surface model simple land surface model (Deardorff, 1978)(Deardorff, 1978)– coupled ocean data assimilation schemecoupled ocean data assimilation scheme (CODA)(CODA)– time-dependent lateral boundariestime-dependent lateral boundaries (Davies, 1976) (Davies, 1976)

•Finite-difference method on Finite-difference method on staggered Arakawa C-grid staggered Arakawa C-grid

•Split-timeSplit-time integration integration

System FeaturesSystem FeaturesThe The COAMPS Real Time Forecast SystemCOAMPS Real Time Forecast System is developed is developed

in-house at TL@NTU, based on the model and post-in-house at TL@NTU, based on the model and post-processing source codes provided by NRL.processing source codes provided by NRL.

The following are the The following are the features of the systemfeatures of the system::

• Automated routine forecastsAutomated routine forecasts– DATA DOWNLOADDATA DOWNLOAD: wget from data server, convert GRIB : wget from data server, convert GRIB

format to IEEE flat files readable by COAMPS analysis format to IEEE flat files readable by COAMPS analysis modulemodule

– ASSIMILATION & FORECASTASSIMILATION & FORECAST: supply model date time group : supply model date time group and previous date time group with consistency and previous date time group with consistency

– GRAPHICAL INTERFACEGRAPHICAL INTERFACE: post processing forecast outputs : post processing forecast outputs and visualize the results using batch GrADS scriptsand visualize the results using batch GrADS scripts

– WEB DISPLAYWEB DISPLAY: sftp to web server, and update the time : sftp to web server, and update the time stamp on the webpagestamp on the webpage

• Smart troubleshootingSmart troubleshooting that detects and solve ad-hoc that detects and solve ad-hoc problems automatically:problems automatically:– when wget is interruptedwhen wget is interrupted, missing files are identified and , missing files are identified and

wget is attempted until the dataset is complete. wget is attempted until the dataset is complete. (*There are 852 NOGAPS files + 7 ADP & OCN files)(*There are 852 NOGAPS files + 7 ADP & OCN files)

– computer nodes that are downcomputer nodes that are down are detected and the model are detected and the model domain decomposition is adjusted for MPI-processing.domain decomposition is adjusted for MPI-processing.

– aborted forecast jobsaborted forecast jobs are detected and post-processing is are detected and post-processing is performed as long as >24 hr forecast has been accomplished.performed as long as >24 hr forecast has been accomplished.

• Twice dailyTwice daily data assimilation and forecast at 00Z and data assimilation and forecast at 00Z and 12Z. Forecast products are available by 12Z. Forecast products are available by 08Z08Z and and 20Z20Z..

(Future plans: 00Z, 06Z, 12Z and 18Z) (Future plans: 00Z, 06Z, 12Z and 18Z)

• 3-level nesting3-level nesting with with 9km-resolution9km-resolution in the innermost in the innermost domain for mesoscale predictions.domain for mesoscale predictions.

(Future plans: up to 5-level nesting with resolutions at 3km, (Future plans: up to 5-level nesting with resolutions at 3km, 1km) 1km)

Process Process FlowFlow Start WGET:

(1) NOGAPS forecast(2) APD data(3) OCN data

Preprocessing downloaded data:•Format change•Directory Change

Execute COAMPS(1) Analysis(2) Forecast(3) Post processing

SFTP results toWeb Server

Impr

ovem

ent

Investigation

Verification

20 min – 1 hr

10 min

1 – 2 hr

20 minWorld-wide Observations

Forecast resultsavailable on the

web by 4am & 4pm SGT(08 & 20 UTC)

SGT

Web DisplayWeb Display• The web display was developed in consultation The web display was developed in consultation

with with Meteorological Services Division, National Meteorological Services Division, National Environment Agency, SingaporeEnvironment Agency, Singapore to ensure its to ensure its utility and friendliness to operational forecasters.utility and friendliness to operational forecasters.

• Putting COAMPS forecast products Putting COAMPS forecast products onlineonline – ensuresensures easy accessibilityeasy accessibility of from anywhere with of from anywhere with

internet connectivity.internet connectivity.– facilitates communicationfacilitates communication with forecasters, model with forecasters, model

developers and research scientists.developers and research scientists.• Features of the web portal:Features of the web portal:

http://www1.spms.ntu.edu.sg/~sunshine/http://www1.spms.ntu.edu.sg/~sunshine/– Quick-look displaysQuick-look displays of a subset of meteorological of a subset of meteorological

variables of interest to forecasters;variables of interest to forecasters;– AnimatedAnimated, , frame-by-frameframe-by-frame and and all-at-onceall-at-once displays of displays of

time evolution of a particular variabletime evolution of a particular variable– LatestLatest and and next oldernext older forecasts are available. forecasts are available.

Thunderstorms in Singapore and Thunderstorms in Singapore and Southern Malay Peninsula Southern Malay Peninsula

1717thth-20-20thth Dec 2006 Dec 2006

* Start:* Start: Morning, Sunday 17 Dec Morning, Sunday 17 Dec* Peak:* Peak: Tuesday 19 Dec Tuesday 19 Dec* Movement* Movement northwardsnorthwards: Wednesday 20 : Wednesday 20 DecDec* Reduction:* Reduction: after 20 Dec after 20 Dec

Verification: case studyVerification: case study

Mudslide at Little Guilin

Tree uprooted at Hillview

Wall caved-in at Mohd Sultan

Johor-Singapore rail service disrupted

Floods in Thomson & Mandai

From the article “From the article “Singapore SwimmingSingapore Swimming” on ” on TODAYonlineTODAYonline• Rainfall recorded from 12am to 8pm,19 Dec 2006 was 345mm Rainfall recorded from 12am to 8pm,19 Dec 2006 was 345mm (cf. climatological average for the whole month of December is (cf. climatological average for the whole month of December is only 284mm);only 284mm);• Highest 24h-rainfall recorded in Singapore was 512mm in 1978; Highest 24h-rainfall recorded in Singapore was 512mm in 1978; • Second highest was 467mm in 1969.Second highest was 467mm in 1969.

SINGAPORESINGAPORE

“…what we saw in Johor was not even recorded in the last 100 years.”-- Director-general Datuk Keizrul Abdullah, Drainage and Irrigation Department (DID), Malaysia

104,000 people104,000 people evacuated!evacuated!

PENINSULA MALAYSIAPENINSULA MALAYSIA

Forecast of the Onset on 17 DecForecast of the Onset on 17 DecCOAMPS 48h-forecast initializedfrom 8 pm (00 UTC) 15 Dec 2006

Radar observations (courtesy of Malaysian Met Dept)

8 am (00 UTC)17 Dec 2006

8 pm (12 UTC)17 Dec 2006

Forecasted ONSET: 2-5am 17 DecForecasted ONSET: 2-5am 17 Dec?

Enhancement of Rain on 19 DecEnhancement of Rain on 19 Dec

Radar Observations at 8 pm 19 Dec 2006(Courtesy of Malaysian Met Dept)

COAMPS 36h-forecastvalid at 8 pm 19 Dec 2006

Northward Migration of Rain Centre on 20 Northward Migration of Rain Centre on 20 Dec Dec (a recess of rain in Singapore)(a recess of rain in Singapore)

Radar Observations at 8 am 20 Dec 2006(Courtesy of Malaysian Met Dept)

COAMPS 12h-forecastvalid at 8 am 20 Dec 2006

?

• COAMPS captured the beginning of the heavy rain COAMPS captured the beginning of the heavy rain episode. Forecast made on 8 pm Friday 15 Dec episode. Forecast made on 8 pm Friday 15 Dec predicted the predicted the onset of continuous precipitationonset of continuous precipitation in in Singapore Singapore from 2-5am Sunday 17 Dec 2006from 2-5am Sunday 17 Dec 2006 (i.e. > 1 (i.e. > 1 day in advance). day in advance).

• But the agreement on detailed rainfall distribution But the agreement on detailed rainfall distribution varies inconsistently from good to below average… varies inconsistently from good to below average… Expected from a 48h-forecast at mesoscales (~10km)?Expected from a 48h-forecast at mesoscales (~10km)?

• COAMPS captured the COAMPS captured the enhancement of rainfallenhancement of rainfall in in Singapore Singapore on Tuesday 19 Dec 2006on Tuesday 19 Dec 2006. .

• COAMPS captured the COAMPS captured the northward migrationnorthward migration of the of the heavy rain patch heavy rain patch from 19 Dec to 20 Dec 2006from 19 Dec to 20 Dec 2006 but but locations differlocations differ..

COAMPS PerformanceCOAMPS Performance

On-going workOn-going work

• 2-month statistical verification over 2-month statistical verification over SCSMEX period (May-June 1998)SCSMEX period (May-June 1998)

• Doppler Radar Data AssimilationDoppler Radar Data Assimilation

• Satellite Data RetrievalSatellite Data Retrieval