Tropical Atmospheric Research in Singapore Asst Prof TiehYong

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Tropical Atmospheric Research in Singapore Asst. Prof. Tieh-Yong Koh 许 智扬 Nanyang Technological University

Tropical Atmospheric Research in Singapore Asst. Prof. Tieh-Yong Koh 许 智扬 Nanyang Technological University (NTU) 南洋理 大学 19 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

Malay Peninsula Typhoon Vamei Sumatra Island Borneo Island Singapore Equator Satellite picture taken by

Malay Peninsula Typhoon Vamei Sumatra Island Borneo Island Singapore Equator Satellite picture taken by MODIS-TERRA at 11: 33 am on 27 Dec 2001 Singapore Time. With courtesy from Centre for Remote Imaging, Sensing and Processing, National University of Singapore (CRISP/NUS)

Severe Weather e. g. Typhoon Vamei, 27 Dec 2001 • In Singapore, 28 flights

Severe Weather e. g. Typhoon Vamei, 27 Dec 2001 • In Singapore, 28 flights were diverted and 22 flights were delayed at Changi International Airport. • In hardest hit Johor and southern Pahang in Malaysia, the storm took away 5 lives and forced the evacuation of 7000 people.

Atmospheric Pollution ~1. 4 km away • Smoke-haze pollution from forest fires 15 26

Atmospheric Pollution ~1. 4 km away • Smoke-haze pollution from forest fires 15 26 Oct 2002, 9: 25 9: 38 am PSI 24 h=92, =64, high low moderate

Channel News. Asia International Online report on 15 May 2006 • Volcanic eruptions e.

Channel News. Asia International Online report on 15 May 2006 • Volcanic eruptions e. g. Merapi in Aug 2003, May 2005… Merapi Volcano, Central Java, 24 Aug 2003

Climate Change Larsen B ice shelf and parts of Antarctic Peninsula Global warming from

Climate Change Larsen B ice shelf and parts of Antarctic Peninsula Global warming from increased CO 2 levels, leading to: • increase in sea level; • redistribution of temperature, humidity & rainfall; • changes in storm frequency, duration and intensity.

COAMPS Real-Time Forecast System A project of Tropical Weather Group, TL@NTU Team Members Tieh-Yong

COAMPS Real-Time Forecast System A project of Tropical Weather Group, [email protected] Team Members Tieh-Yong KOH Lan YI Chee-Kiat TEO

COAMPS Real Time Forecast • Model Description • System Features • Process Flow •

COAMPS Real Time Forecast • Model Description • System Features • Process Flow • Web Display • Verification: case study

Objective To create a automated system capable of timely delivery of reliable 24 h-forecasts

Objective To create a automated system capable of timely delivery of reliable 24 h-forecasts for the SE Asia region • The Tropical Weather group acquired the • COAMPS model from Naval Research Laboratory, USA, for research purposes from Feb 2002 and has been running and testing the model ever since. Development work is still on-going. A trial version of the automated Real Time Forecast System is currently run at [email protected] since July 2006. This version is being presented to you now.

Model Description • COAMPS stands for Coupled Ocean/Atmosphere • • Mesoscale Prediction System. It

Model Description • COAMPS stands for Coupled Ocean/Atmosphere • • Mesoscale Prediction System. It is a mesoscale numerical weather prediction (NWP) model for regional weather forecast. The current version is implemented on a 64 -cpu Linux PC cluster. It has customizable vertical and horizontal grid resolutions and is capable of horizontal nesting. It uses up-to-date numerical methods and has a suite of complex physical parameterizations.

 • 3 D non-hydrostatic compressible equations • 11 prognostic variables: u, v, w,

• 3 D non-hydrostatic compressible equations • 11 prognostic variables: u, v, w, θ, , q, qc, qi, qr, qs , e • • • Terrain-following σz-coordinates Limited-area model with grid-nesting option Mercator projection used for the tropics • Initial and boundary conditions from NOGAPS (Navy Operational Global Atmospheric Prediction System) • Data analysis by Multi-Variate Optimal Interpolation

 • Physics modules: – radiative transfer (Harshvardhan et al. , 1987) – cumulus

• Physics modules: – radiative transfer (Harshvardhan et al. , 1987) – cumulus convection (Kain & Fritsch, 1993) – cloud microphysics (Rutledge & Hobbs, 1983) – boundary-layer turbulence (Mellor & Yamada, 1982) – surface sub-layer physics (Louis, 1979) – simple land surface model (Deardorff, 1978) – coupled ocean data assimilation scheme (CODA) – time-dependent lateral boundaries (Davies, 1976) • Finite-difference method on staggered Arakawa C-grid • Split-time integration

System Features The COAMPS Real Time Forecast System is developed inhouse at TL@NTU, based

System Features The COAMPS Real Time Forecast System is developed inhouse at [email protected], based on the model and postprocessing source codes provided by NRL. The following are the features of the system: • Automated routine forecasts – DATA DOWNLOAD: wget from data server, convert GRIB format to IEEE flat files readable by COAMPS analysis module – ASSIMILATION & FORECAST: supply model date time group and previous date time group with consistency – GRAPHICAL INTERFACE: post processing forecast outputs and visualize the results using batch Gr. ADS scripts – WEB DISPLAY: sftp to web server, and update the time stamp on the webpage

 • Smart troubleshooting that detects and solve ad-hoc problems automatically: – when wget

• Smart troubleshooting that detects and solve ad-hoc problems automatically: – when wget is interrupted, missing files are identified and wget is attempted until the dataset is complete. (*There are 852 NOGAPS files + 7 ADP & OCN files) – computer nodes that are down are detected and the model domain decomposition is adjusted for MPI-processing. – aborted forecast jobs are detected and post-processing is performed as long as >24 hr forecast has been accomplished. • Twice daily data assimilation and forecast at 00 Z and 12 Z. Forecast products are available by 08 Z and 20 Z. (Future plans: 00 Z, 06 Z, 12 Z and 18 Z) • 3 -level nesting with 9 km-resolution in the innermost domain for mesoscale predictions. (Future plans: up to 5 -level nesting with resolutions at 3 km, 1 km)

Start WGET: (1) NOGAPS forecast (2) APD data (3) OCN data 10 min Preprocessing

Start WGET: (1) NOGAPS forecast (2) APD data (3) OCN data 10 min Preprocessing downloaded data: • Format change • Directory Change 1 – 2 hr Execute COAMPS (1) Analysis (2) Forecast (3) Post processing Im pro ve me nt Process Flow 20 min – 1 hr SGT on ati ific r Ve World-wide Observations Investigation 20 min SFTP results to Web Server Forecast results available on the web by 4 am & 4 pm SGT (08 & 20 UTC)

Web Display • The web display was developed in consultation with • Meteorological Services

Web Display • The web display was developed in consultation with • Meteorological Services Division, National Environment Agency, Singapore to ensure its utility and friendliness to operational forecasters. Putting COAMPS forecast products online – ensures easy accessibility of from anywhere with internet connectivity. – facilitates communication with forecasters, model developers and research scientists. • Features of the web portal: – – – http: //www 1. spms. ntu. edu. sg/~sunshine/ Quick-look displays of a subset of meteorological variables of interest to forecasters; Animated, frame-by-frame and all-at-once displays of time evolution of a particular variable Latest and next older forecasts are available.

Verification: case study Thunderstorms in Singapore and Southern Malay Peninsula 17 th-20 th Dec

Verification: case study Thunderstorms in Singapore and Southern Malay Peninsula 17 th-20 th Dec 2006 * Start: Morning, Sunday 17 Dec * Peak: Tuesday 19 Dec * Movement northwards: Wednesday 20 Dec * Reduction: after 20 Dec

SINGAPORE From the article “Singapore Swimming” on TODAYonline • Rainfall recorded from 12 am

SINGAPORE From the article “Singapore Swimming” on TODAYonline • Rainfall recorded from 12 am to 8 pm, 19 Dec 2006 was 345 mm (cf. climatological average for the whole month of December is only 284 mm); • Highest 24 h-rainfall recorded in Singapore was 512 mm in 1978; • Second highest was 467 mm in 1969. Mudslide at Little Guilin Tree uprooted at Hillview Wall caved-in at Mohd Sultan Johor-Singapore rail service disrupted Floods in Thomson & Mandai

PENINSULA MALAYSIA “…what we saw in Johor was not even recorded in the last

PENINSULA MALAYSIA “…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 people evacuated!

Forecast of the Onset on 17 Dec COAMPS 48 h-forecast initialized from 8 pm

Forecast of the Onset on 17 Dec COAMPS 48 h-forecast initialized from 8 pm (00 UTC) 15 Dec 2006 Radar observations (courtesy of Malaysian Met Dept) 8 am (00 UTC) 17 Dec 2006 Forecasted ONSET: 2 -5 am 17 Dec ? 8 pm (12 UTC) 17 Dec 2006

Enhancement of Rain on 19 Dec COAMPS 36 h-forecast valid at 8 pm 19

Enhancement of Rain on 19 Dec COAMPS 36 h-forecast valid at 8 pm 19 Dec 2006 Radar Observations at 8 pm 19 Dec 2006 (Courtesy of Malaysian Met Dept)

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

Northward Migration of Rain Centre on 20 Dec (a recess of rain in Singapore) COAMPS 12 h-forecast valid at 8 am 20 Dec 2006 ? Radar Observations at 8 am 20 Dec 2006 (Courtesy of Malaysian Met Dept)

COAMPS Performance • COAMPS captured the beginning of the heavy rain episode. • Forecast

COAMPS Performance • COAMPS captured the beginning of the heavy rain episode. • Forecast made on 8 pm Friday 15 Dec predicted the onset of continuous precipitation in Singapore from 2 -5 am Sunday 17 Dec 2006 (i. e. > 1 day in advance). But the agreement on detailed rainfall distribution varies inconsistently from good to below average… Expected from a 48 h-forecast at mesoscales (~10 km)? • COAMPS captured the enhancement of rainfall in Singapore on Tuesday 19 Dec 2006. • COAMPS captured the northward migration of the heavy rain patch from 19 Dec to 20 Dec 2006 but locations differ.

On-going work • 2 -month statistical verification over SCSMEX period (May-June 1998) • Doppler

On-going work • 2 -month statistical verification over SCSMEX period (May-June 1998) • Doppler Radar Data Assimilation • Satellite Data Retrieval