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OUTLINE NWP March 2006

Outline of the Operational Forecast and Analysis System of the Japan Meteorological Agency (March 2006)
Numerical Prediction Division
Forecast Department
Japan Meteorological Agency
1-3-4 Otemachi, Chiyoda-ku, Tokyo 100-8122, Japan

The following information is valid as of March 1, 2006. Information on the future update to the operational forecast and analysis system will be given whenever it is available.

1. General summary of the operational forecast and analysis system

JMA operationally performs three kinds of objective atmospheric analyses for global, regional and mesoscale forecast models. All of them employ a four-dimensional variational (4D-Var) scheme on model coordinates for the analysis of surface pressure, temperature, vector winds and relative humidity. The specifications of the atmospheric analysis schemes are listed in Table 1. Global snow depth analysis is performed every day, and described in Tables 2a.

JMA runs Global Spectral Model (GSM) four times a day (36 hour forecast from 06 UTC and 18 UTC, 90-hour forecast from 00 UTC and 216-hour forecast from 12 UTC), Regional Spectral Model (RSM) twice a day (51-hour forecasts from 00 and 12 UTC) and Mesoscale Model (MSM) eight times a day (15-hour forecasts from 00, 03, 06, 09, 12, 15, 18 and 21 UTC). Typhoon Model (TYM) is run four times a day (84-hour forecasts from 00, 06, 12 and 18 UTC) whenever a typhoon exists or is expected to be formed in the responsible area of RSMC Tokyo-Typhoon center. A medium-range ensemble forecast and a one-month ensemble forecast models run everyday and once a week, respectively. The basic features of the operational forecast models of JMA are summarized in Tables 3a and b and Tables 4a, b and c, respectively.

2. Analysis systems

Table 1. Specifications of Operational Objective Analyses

Cut-off time
  (global) 2:20 hours for early run analyses at 00, 06, 12 and 18 UTC map time,
11:35 hours for cycle run analyses at 00 and 12 UTC map time,
5:35 hours for cycle run analyses at 06 and 18 UTC map time
(regional) 2:45 hours for analyses at 00 and 12 UTC map time,
8:45 hours for analyses at 06 and 18 UTC map time
(mesoscale) 50 minutes for analyses at 00, 03, 06, 09, 12, 15, 18 and 21 UTC map time
Initial Guess
 (global)6-hour forecast by GSM
(regional)6-hour forecast by RSM
(mesoscale)3-hour forecast by MSM
Grid form, resolution and number of grids
  (global) Gaussian grid, 0.5625 degree, 640 x 320 for outer model
Gaussian grid, 1.1250 degrees, 320 x 160 for inner model
(regional) Lambert projection, 20 km at 60 N and 30 N, 325 x 257 for outer model
grid point (1, 1) at north-west corner and (200, 185) at (140 E, 30 N)
Lambert projection, 40 km at 60 N and 30 N, 163 x 129 for inner model
(mesoscale) Lambert projection, 10 km at 60 N and 30 N, 361 x 289 for outer model
grid point (1, 1) at north-west corner and (245, 205) at (140 E, 30 N)
Lambert projection, 20 km at 60 N and 30 N, 181 x 145 for inner model
Levels
  (global)40 forecast model levels up to 0.4 hPa + surface
(regional)40 forecast model levels up to 10 hPa + surface
(mesoscale)40 forecast model levels up to 10 hPa + surface
Analysis variables Surface pressure, temperature, wind and specific humidity
Methodology Four-dimensional variational (4D-Var) scheme on model levels
Data Used SYNOP, SHIP, BUOY, TEMP, PILOT, Wind Profiler, AIREP, SATEM, ATOVS, SATOB, Australian PAOB, surface wind data from the scatterometer on the QuikSCAT satellite and MODIS wind data from Terra and Aqua;
The Radar-AMeDAS (dense network of surface observations including precipitation) composite precipitation data for the regional and mesoscale models; Doppler radar radial wind and precipitable water and rain rate derived from microwave radiometer on SSM/I, TMI and Aqua for the mesoscale model; Typhoon bogussing applied for all analyses
Initialization
  (global) Incremental non-linear normal mode initialization and a vertical mode initialization
(regional and mesoscale) Non-linear normal mode initialization with full physical processes for the first five vertical modes>

Table 2a. Specifications of snow depth analysis

MethodologyTwo-dimensional Optimal Interpolation scheme
Domain and GridsGlobal, 1 x 1 degree regular lat-lon grids
First guessCombination of USAF/ETAC Global Snow Depth monthly climatology (Foster and Davy, 1988) with previous analyzed snow depth anomaly
Data usedSYNOP and METER snow depth data observed in past one day
FrequencyDaily

3. Forecast models

Table 3a. Specifications of Global Spectral Model (GSM0507)

Basic equationPrimitive equations
Independent variablesLatitude, longitude and sigma-pressure hybrid coordinates and time
Dependent variablesWinds (zonal, meridional), temperature, specific humidity, surface pressure
Numerical techniqueSpectral (spherical harmonics basis functions) in horizontal, finite differences in vertical Leapfrog, semi-Lagrangian, semi-implicit time integration scheme. Hydrostatic approximation
Integration domainGlobal in horizontal, surface to 0.4 hPa in vertical
Horizontal resolutionSpectral triangular 319 (TL319) roughly equivalent to 0.5625 x 0.5625 degrees lat-lon Gaussian grid, 640 x 320
Vertical resolution40 unevenly spaced hybrid levels
Time step15 minutes
OrographyGTOPO30 data set spectrally truncated and smoothed
Gravity wave dragLongwave scheme (wavelengths > 100 km) mainly for stratosphere
Shortwave scheme (wavelengths approximately 10 km) only for troposphere
Horizontal diffusionLinear, fourth-order
Vertical diffusionStability (Richardson number) dependent, local formulation
Planetary boundary layerMellor and Yamada level-2 turbulence closure scheme
Similarity theory in bulk formulae for surface layer
Treatment of sea surfaceClimatological sea surface temperature with daily analyzed anomaly
Climatological sea ice concentration
Land surface and soilSimple Biosphere (SiB) model
RadiationTwo-stream with delta-Eddington approximation for shortwave (hourly)
Table look-up and k-distribution methods for longwave (every three hours)
ConvectionPrognostic Arakawa-Schubert cumulus parameterization
CloudPrognostic cloud water, cloud cover diagnosed from moisture and cloud water
Forecast time90 hours from 00 UTC, 216 hours from 12 UTC and 36 hours from 06 and 18 UTC.

Table 3b. Specifications of GSM for medium-range ensemble forecasts

The model specifications are the same as those of the high resolution GSM (Table. 3a) except for the following ones.

Horizontal resolutionSpectral triangular 159 (TL159) roughly equivalent to 1.125 x 1.125 degrees
lat-lon Gaussian grid, 320 x 160
Time step20 minutes
Number of members51 members
Initial state perturbationBreeding of Growing Modes (BGM) method (25 independent breeding cycles in 12-hour periods)
Perturbed areaNorthern hemisphere and tropics (20S-90N)
InitializationNon-linear normal mode initialization with full physical processes for the first five vertical modes
Forecast time216 hours from 12 UTC

Table 4a. Specifications of Regional Spectral Model (RSM0404)

Basic equationPrimitive equations
Independent variablesx-y coordinate on a Lambert projection plane and sigma-p hybrid coordinate
Dependent variablesWind components of x-y direction, virtual temperature, natural log of surface pressure and specific humidity
Numerical techniqueEuler semi-implicit time integration, double Fourier for horizontal representation and finite difference in the vertical representation
Projection and grid sizeLambert projection, 20km at 60N and 30N
Integration domainEast Asia centering on Japan, 325 x 257 transform grid points
Vertical levels40 (surface to 10hPa)
Lateral boundary0-51 hours forecast by GSM runs
OrographyEnvelope orography, GTOPO30 data set is smoothed and spectrally truncated
Horizontal diffusionLinear, second-order Laplacian with targeted moisture diffusion
Moist processesLarge scale condensation + Prognostic Arakawa-Schubert convection scheme + middle level convection + shallow convection
Radiation (short-wave)
(long-wave)
Every hour
Every hour
CloudinessDiagnosed from relative humidity, maximum overlap
Gravity wave dragShort-wave scheme for lower troposphere
PBLMellor-Yamada level-2 closure scheme for stable PBL, non-local scheme for unstable PBL, and similarity theory for surface boundary layer
Land surfaceGround temperature predicted with the use of four levels in the ground
Evaporability dependent on location and season
Surface stateObserved SST (fixed during time integration) and sea ice distribution
Climatological values for evaporability, roughness length and albedo
Snow cover over Japan analyzed every initial time
Forecast time51 hours from 00 and 12UTC

Table 4b. Specifications of Mesoscale Model (MSM0603)

Basic equationsFully compressible non-hydrostatic equations
Independent variablesx-y coordinate on a Lambert projection plane and terrain-following height coordinates and time
Dependent variablesMomentum components in three dimensions, potential temperature, pressure, mixing ratios of water vapor, cloud water, cloud ice, rain, snow and graupel
Numerical techniqueFinite discretization onto the Arakawa-C type staggered coordinates, horizontally explicit and vertically implicit time integration scheme, fourth order horizontal finite differencing in flux form with modified advection treatment for monotonicity
Projection and grid sizeLambert projection, 5km at 60N and 30N
Integration domainJapan, 721 x 577 grid points
Vertical levels50 (surface to 21800m)
Time step24 seconds
Initial fields4D-VAR analysis with mixing ratios of cloud water, cloud ice, rain, snow, and graupel derived from preceding forecasts considering consistency with the analysis field of relative humidity
Lateral boundary 03-18 hours forecast by RSM runs for MSM runs from 03 and 15UTC
06-21 hours forecast by RSM runs for MSM runs from 06 and 18UTC
09-24 hours forecast by RSM runs for MSM runs from 09 and 21UTC
12-27 hours forecast by RSM runs for MSM runs from 12 and 00UTC
OrographyMean orography smoothed to eliminate the shortest-wave components
Horizontal diffusionLinear, fourth order Laplacian + nonlinear damper
Targeted moisture diffusion applied to the grid points where excessive updrafts appear
Moist processesThree-ice bulk cloud microphysics + Kain-Fritsch convection scheme
Lagrangean treatment for the fall of rain and graupel
Radiation (short-wave)Every 15 minutes
Radiation (long-wave)Every 15 minutes
CloudinessDiagnosed from relative humidity with maximum overlap assumed
Gravity wave dragNo parameterization scheme included
PBLDiffusion processes based on diagnosed turbulent kinetic energy, considering non-local effect by adjusting mixing length
Similarity theory adopted for the surface boundary layer
Land surfaceGround temperature predicted using a four-layer ground model
Evaporability prediction scheme included
Surface stateObserved SST (fixed during time integration) and sea ice distribution
Climatological values of evaporability, roughness length and albedo
Snow cover over Japan analyzed every 6 hours
Forecast time15hours from 00, 03, 06, 09, 12, 15, 18 and 21 UTC

Table 4c. Specifications of Typhoon Forecast Model (TYM0306)

The model specifications are the same as those of the RSM (Table. 4a) except for the followings:

Independent variablesx-y coordinate on a Lambert (Mercator) projection plane for target typhoon north (south) of 20 N and sigma-p hybrid coordinate
Integration domainCenter of domain is set at the median of expected typhoon track in the Western North Pacific, 271 x 271 grids, surface to 17.5 hPa
Projection and grid sizeLambert (Mercator) projection, 24 km at the typhoon center when the center of target typhoon is north (south) of 20 N
Vertical levels25
Forecast phenomenaTyphoon track and intensity
Lateral boundary0-84 hour forecast by early GSM runs (00 and 12 UTC)
6-90 hour forecast by early GSM runs (06 and 18 UTC)
OrographyMean orography, GTOPO30 data set (30" x 30") spectrally truncated and smoothed
Planetary boundary layerMellor-Yamada level-2 closure scheme and similarity theory for surface boundary layer
Typhoon bogussingSymmetric vortex generated using manually analyzed central pressure and radius of 30 kt winds with gradient-wind balance assumed in the free atmosphere, Ekman-frictional inflow and compensating outflow added in PBL and in upper levels, respectively (The vortex is blended with the global analysis in combination with asymmetric components taken from previous TYM forecasts, when available)
Forecast time84 hours from 00, 06, 12 and 18 UTC, maximum two runs

4. Reference

Foster, D. J. and R. D. Davy, 1988: Global Snow Depth Climatology, USAF-ETAC/TN-88/006, Scott Air Force Base, 48pp.