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Numerical Weather Prediction

Numerical Weather Prediction (NWP)

The numerical weather prediction (NWP) is a series of processes to predict future atmospheric conditions by solving dynamics and physics equations that explain the movements and changes of the atmosphere. The NWP equations are too complicate. So, the supercomputer needs to be used to solve them. The set of computer programs which are operated in supercomputer to solve the NWP equations is called the NWP model.

In the NWP model the atmosphere is assumed to be composed of a number of lumps in which corner points are called as the grid points. The more number of lumps indicates the more elaborate simulation. Simulation by the model generates the future state of the model atmosphere at all grid points from its initial state.

The products of numerical models are serviced to forecasters as well as public through the the dedicated delivery network. The forecasters analyse products and guidance from the NWP model with their expertise and experiences to issue everyday weather forecast. Besides atmospheric model, many other application models such as statistical model, ocean wave/surge model, and Asian dust model, etc. are operated to produce the outputs which ha ve various purposes.

KMA started to run numerical weather forecast model from 1999 with the introduction of 1st supercomputer(NEC/SX-5). The performance of KMA model has been significantly improved since KMA introduced Unified Model (UM) from UK Met Office in 2010. In addition, KMA’s next generation global model, named KIM (Korean Integrated Model), was developed by KMA/KIAPS (Korea Institute of Atmospheric Prediction System) for 9 years since 2011 and operationally launched on April 2020.
KMA is currently operating the global models, the local models and the ensemble models as weather prediction models, and the ocean wave/surge models, the Asian dust model and the statistical models, as the application models. The current status of numerical prediction models operated by KMA is shown in the following table.

Model Horizontal
(Vertical Layers)
Simulation/day Prediction Period Remarks
Global Prediction Model(GDAPS / KIM) 12 km (91) 2(00,12UTC) 12 days Global domain
2(06,18UTC) 3.5 days
Global Prediction Model(GDAPS / UM) 10 km (70) 2(00,12UTC) 12 days Global domain
2(06,18UTC) 3.5 days
Global Ensemble Model(EPSG / UM) 32 km(70) 2(00,12UTC) 12 days Global domain
Climate Prediction
60 km(85) 1 8 weeks
6 months
Local Prediction Model
1.5km(70) 4 48 hours East Asia
Very Short Range
Forecast Model
1.5km(70) 24 12 hours Korean Peninsula
Very Short Range
Forecast Model (KLAPS)
5km(40) 144 12 hours Korean Peninsula
Local Ensemble Model
2.2km(70) 2 72 hours Korean Peninsula
(13 members)
Global Wave Model
50 km 2 12 days Global domain
Regional Wave Model
8 km 2 5 days Asia domain
Regional Wave Model
8 km 2 5 days Asia domain
(24 ensemble members)
Coastal Wave Model
1 km 2 3 days 5 Coastal domains along Korean peninsula
Regional Tide/Surge
Model (RTSM)
8 km 2 5 days Asia domain
Local Tide/Surge
Model (LTSM)
1 km 2 3 days Korean Peninsula
Asian Dust Aerosol
Model 3 (ADAM3)
25 km(49) 4 7 days Asia domain
Statistical Model
5km, About 700points 2 12 days 11 element
(digital forecast element)