ΆΓ Short Range Forecast Map -84 hours

Forecast Time 0 6 12 18 24 30 36 42
 MSLP & Precip.
 850 Temp, Wind & 700 P_Vel.
 500 Temp. & 700 T-Td
 500 GPH & 700 Rel. Vort.
 200 Stream & Wind
ALL
 
Forecast Time 48 54 60 66 72 78 84 ALL
 MSLP & Precip.
 850 Temp, Wind & 700 P_Vel.
 500 Temp. & 700 T-Td
 500 GPH & 700 Rel. Vort.
 200 Stream & Wind
ALL

ΆΓ COMMENTARY

- MSLP

Mean Sea Level Pressur [hPa]

- Precip

Precipitation for 12 hrs [mm/12hr]

- 850 Temp

850hPa Temperature [degree]

- 700 P_Vel

700hPa Pressure vertical Velocity [Pa/s]

- 700 T-Td

700hPa Dew Point Depression [degree]

- 500 Temp

500hPa Temperature [degree]

- 500 GPH

500hPa Geopotential Height [gpm]

- 500 Rel. Vort.

500hPa Relative Vorticity [/s]

Global Data Assimilation and Prediction System (GDAPS) at NWPD/KMA

Data assimilation, objective analysis and initialization
Everyday more than 5,000 synoptic observations, and various asynoptic observations, including satellite retrieval data, are used in the GDAPS. Table 1 presents the types and numbers of the observation that are available from the GTS. The pre-processing procedures such as data acquisition, quality control and decoding, are fully automated.

Table 1. The types and numbers of observations received through GTS, and the percentage of data used in global data assimilation for 24 hours in 2005.
Data type  
Number of data/day  
% used in assimilation  
1
SYNOP/ SHIP  
42,500  
49  
2
BUOY  
7,782  
84  
3
TEMP/ PILOT  
1,759  
91
4
AIREP/ AMDAR/ACARS
219,102  
8
5
SATEM  
29,289  
39  
6
SATOB  
20,341  
87  
7
ATOVS   
108,347  
18  
8
AWS  
5,518
57  
9
PAOB  
400
100  
10
Wind profiler  
332  
36  

The global analysis is performed with the 6-hour update cycle. A 6-hour forecast from the previous run provides a first guess for the next analysis. If a typhoon exists in the Western Pacific, a typhoon bogus profile is calculated and the profile is assimilated in 3dVar as an observation with observation error determined statistically. The best fits of analysis are made with the 3dVar system. The analysis resolution of global 3dVar is T426L40 for the outer loop and T106L40 for the inner loop. The analysis is performed up to 0.4 hPa.

A Non-linear Normal Mode Initialization (NNMI) with full physics is performed to suppress the amplitude of high-frequency gravity waves. The high frequency component is filtered out for each spherical harmonic component in the eight greatest vertical modes that exceed the critical frequency. Machenhauer's iterative scheme is used for determining the non-linear balanced solution.

Model Configuration
Dynamics  
Basic equation   Primitive equations in sigma- pressure hybrid vertical coordinate  
Numerics   Spectral representation of horizontal variables with triangular truncation of T426, corresponding to a Gaussian grid size of 0.28125 degrees or 30km  
Domain   Global  
Levels   40 vertical levels ranging from surface to 0.4 hPa  
Time integration   Eulerian semi-implicit scheme  
Physics  
Horizontal diffusion   Second order Laplacian, and Rayleigh friction  
Moist processes   Kuo scheme, large-scale condensation, and shallow convection scheme  
Radiation   Long wave radiation calculated every three hours
Short wave radiation calculated every hour  
Gravity wave drag   Long waves (wavelength>100km)
Short waves (wavelength 10km)  
PBL processes   Non-local diffusion scheme and similarity theory for surface layer  
Land surface   Simple biosphere model  
Surface state   NCEP daily SST anomaly added to monthly changing climatological SST
Climatological values are used for the soil moisture, snow depth, roughness length and albedo  

Operational aspects
GDAPS for 10-day projection runs at 00 UTC and 12 UTC with 2 hours and 20 minutes data cutoff. The 84-hour projection is used for short-range weather forecasts, and for the provision of lateral boundary condition for a regional model. The 10-day projection is used for weekly forecast. The wind fields predicted by GDAPS is used as an input for the trajectory model of yellow sand and the surface wind is also used as an input for the global wave model.

Recent changes
1st December 2005, GDAPS has improved its resolution from T213L30 to T426L40 owing to the complete installation of the new super computer Cray X1E at KMA. The analysis resolution of global 3dVar is increased in accordance with the improvement of model resolution. The outer loop increase its resolution from T213L30 to T426L40 and the inner loop is also improved from T63L30 to T106L40. The analysis top becomes higher from 10 to 0.4 hPa.