DSS Generated Documention for JRA-25

ALERT: Please note that in the fcst_phy2m, fcst_phy2m25, fcst_phy3m, and fcst_phy3m25 categories, the correct valid time appears to be 3 hours EARLIER than the encoded reference time for variables in which 6-hour averaging was applied. Keep this in mind if variables seem to be temporally out of phase with the encoded reference time and expected valid time. See surface solar radiation downwards diurnal cycle example.

JRA 6-Hour Average 2-Dimensional Diagnostics, 2.5°

fcst_phy2m25

JRA 6-Hour Average 3-Dimensional Diagnostics

fcst_phy3m

JRA 6-Hour Average 3-Dimensional Diagnostics, 2.5°

fcst_phy3m25

JRA Land Forecast

fcst_phyland

JRA Land Forecast, 2.5°

fcst_phyland25

JRA Model-Grid First Guess

ges_mdl

JRA Model-Grid First Guess Interpolated to Pressure Levels

ges_p

JRA Model-Grid First Guess Interpolated to Pressure Levels, 2.5°

ges_p25

Detailed Variable Metadata by Grid Type

Link to Metadata

Important Notes and Alerts

1.125° x ~1.125°, from 0E to 358.875E and 89.142N to 89.142S (320 x 160 Gaussian Longitude/Latitude)

320 x 160 Gaussian Longitude/Latitude

NOTE: Please note that JMA encoded incorrect 320 x 160 Gaussian longitude/latitude grid metadata in the Grid Definition Section of their GRIB 1 files. This has been duly corrected by the Data Support Section at NCAR, resulting in new files distinguished by a "subc60" embedded in the file name. (In addition, the subcenter, octet 26, is set to 60 in the Product Definition Section, in the corrected files.)

1.25° x 1.25°, from 0E to 358.75E and 90N to 90S (288 x 145 Longitude/Latitude)

288 x 145 Longitude/Latitude

2.5° x 2.5°, from 0E to 357.5E and 90N to 90S (144 x 73 Longitude/Latitude)

144 x 73 Longitude/Latitude

% x 1.25°, from 0E to 0E and 90N to 90S (1 x 145 Longitude/Latitude)

1 x 145 Longitude/Latitude

NOTE: These are zonal means.

% x 2.5°, from 0E to 0E and 90N to 90S (1 x 73 Longitude/Latitude)

1 x 73 Longitude/Latitude

NOTE: These are zonal means.

Additional Alerts and Notes

JMA encoding of year 2000 (see † at right).
JMA encoding of fcst_phy2m and fcst_phy2m25 level indicator (see ‡ at right).

† ALERT: In the Product Definition Section (PDS) for year 2000 GRIB 1 files, JMA encoded octets 13 and 25 resulting in decimal values of 0 and 21, respectively. Strictly speaking (following the GRIB 1 standard), for the year 2000, octets 13 and 25 should be encoded so that they yield decimal values of 100 and 20, respectively. In general, most GRIB 1 decoders (such as wgrib) will compute the year assuming dYYYY = (dO₂₅ - 1)100 + dO₁₃, where dYYYY is the decimal value of the year, and dO_i is the decimal value of the ith octet. But this may not always be the case. However, if the decoder employs the assumed formula for year 2000 JRA files, it will yield the correct result. The following table illustrates these points:

Reanalysis	Year	PDS		dYYYY = (dO₂₅ - 1)100 + dO₁₃
Reanalysis	Year	dO₁₃	dO₂₅	dYYYY = (dO₂₅ - 1)100 + dO₁₃
ERA-40	1999	99	20	1999
JRA-25	1999	99	20	1999
ERA-40	2000	100	20	2000
♦ JRA-25	2000	0	21	2000 ♦
ERA-40	2001	1	21	2001
JRA-25	2001	1	21	2001

‡ ALERT: Note that in the fcst_phy2m and fcst_phy2m25 categories, variables designated as 2 meter (2m) or 10 meter (10m) have been assigned a level indicator of 1 (ground water or surface) by JMA — strictly speaking these variables should have been assigned a level indicator of 105 (specified height level above ground). We retain the JMA encoding, relying on the long name as the ultimate arbiter.

Model Information

Model grid and numerical attributes for JRA-25

Model level conventions and hybrid coefficients for JRA-25

Model physical constants for JRA-25

Assimilation System

3D-Var data assimilation system used in JRA-25

Pressure and Isentropic (Theta) Levels (with Standard Atmosphere)

JRA pressure and isentropic (theta) levels

JRA Generalized Soil Depth for Soil Wetness and Soil Water Content
\s\s\s (SOILW_HBL in anl_land, anl_land25, fcst_phyland, and fcst_phyland25 categories)