Model:

Updated:

1 times per day, from 00:00 UTC

Greenwich Mean Time:

12:00 UTC = 07:00 EST

Resolution:

0.125° x 0.125° (India, South Asia)

Parameter:

Maximum wind velocity of convective wind gusts

Description:

The method of Ivens (1987) is used by the forecasters at KNMI to predict the
maximum wind velocity associated with heavy showers or thunderstorms. The
method of Ivens is based on two multiple regression equations that were
derived using about 120 summertime cases (April to September) between 1980 and 1983.
The upper-air data were derived from the soundings at De Bilt, and
observations of
thunder by synop stations were used as an indicator of the presence of
convection.
The regression equations for the maximum wind velocity (w_{max} ) in m/s
according
to Ivens (1987) are:

where

- if T
_{x}- θ_{w850}< 9°C- w
_{max}= 7.66 + 0.653⋅(θ_{w850}- θ_{w500}) + 0.976⋅U_{850}

- w
- if T
_{x}- θ_{w850}≥ 9° C - w
_{max}= 8.17 + 0.473⋅(θ_{w850}- θ_{w500}) + (0.174⋅U_{850}+ 0.057⋅U_{250})⋅√(T_{x}- θ_{w850})

where

- T
_{x}is the maximum day-time temperature at 2 m in K - θ
_{wxxx}the potential wet-bulb temperature at xxx hPa in K - U
_{xxx}the wind velocity at xxx hPa in m/s.

NCMRWF:

NCMRWF

This modeling system is an up-graded version of NCEP GFS (as per 28 July 2010). A general description of the modeling system can be found in the following link:

http://www.ncmrwf.gov.in/t254-model/t254_des.pdf

An brief overview of GFS is given below.

------------------------------------------------------

Dynamics: Spectral, Hybrid sigma-p, Reduced Gaussian grids

Time integration: Leapfrog/Semi-implicit

Time filter: Asselin

Horizontal diffusion: 8th

order wavenumber dependent

Orography: Mean orography

Surface fluxes: Monin-obhukov Similarity

Turbulent fluxes: Non-local closure

SW Radiation; RRTM

LW Radiation: RRTM

Deep Convection: SAS

Shallow convection: Mass-flux based

Grid-scale condensation: Zhao Microphysics

Land Surface Processes: NOAH LSM

Cloud generation: Xu and Randal

Rainfall evaporation: Kessler

Air-sea interaction: Roughness length by Charnock

Gravity Wave Drag and mountain blocking: Based on Alpert

Sea-Ice model: Based on Winton

-----------------------------------------------

This modeling system is an up-graded version of NCEP GFS (as per 28 July 2010). A general description of the modeling system can be found in the following link:

http://www.ncmrwf.gov.in/t254-model/t254_des.pdf

An brief overview of GFS is given below.

------------------------------------------------------

Dynamics: Spectral, Hybrid sigma-p, Reduced Gaussian grids

Time integration: Leapfrog/Semi-implicit

Time filter: Asselin

Horizontal diffusion: 8th

order wavenumber dependent

Orography: Mean orography

Surface fluxes: Monin-obhukov Similarity

Turbulent fluxes: Non-local closure

SW Radiation; RRTM

LW Radiation: RRTM

Deep Convection: SAS

Shallow convection: Mass-flux based

Grid-scale condensation: Zhao Microphysics

Land Surface Processes: NOAH LSM

Cloud generation: Xu and Randal

Rainfall evaporation: Kessler

Air-sea interaction: Roughness length by Charnock

Gravity Wave Drag and mountain blocking: Based on Alpert

Sea-Ice model: Based on Winton

-----------------------------------------------

NWP:

Numerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. Although the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer and computer simulation that it was feasible to do in real-time. Manipulating the huge datasets and performing the complex calculations necessary to do this on a resolution fine enough to make the results useful requires the use of some of the most powerful supercomputers in the world. A number of forecast models, both global and regional in scale, are run to help create forecasts for nations worldwide. Use of model ensemble forecasts helps to define the forecast uncertainty and extend weather forecasting farther into the future than would otherwise be possible.

Wikipedia, Numerical weather prediction, http://en.wikipedia.org/wiki/Numerical_weather_prediction(as of Feb. 9, 2010, 20:50 UTC).

Wikipedia, Numerical weather prediction, http://en.wikipedia.org/wiki/Numerical_weather_prediction(as of Feb. 9, 2010, 20:50 UTC).