JRA-55 Product Users' Handbook
Model grid data
Climate Prediction Division
Global Environment and Marine Department
Japan Meteorological Agency
March 2014

JRA-55 Product Users' Handbook
Model grid data
Change record
Version

Date

Remarks

1.0

3 March 2014

First version

2.0

20 May 2014

Added latitudes and weights to the tables in Section 6.1
Corrected Table 11-1
Linguistic correction

3.0

22 May 2015

Added the comprehensive report on JRA-55 (Kobayashi etal. 2015) to References
Corrected Table 7-3

4.0

14 Oct 2015

Added notes on cloud work function and upward mass flux
at cloud base in Table 4-12 Parameters of model levelaverage diagnostic fields (fcst_phy3m).

5.0

11 Oct 2018

Added B005 and BR05 to Table 11-1

6.0

2 Jul 2021

Changed the climatological normal period to 1991-2020 in
Chapter 10.

2JRA-55 Product Users' Handbook
Model grid data

Contents
1.
2.
3.
4.

Introduction ............................................................................................................... 7File format ................................................................................................................. 7File names .................................................................................................................. 7
Output parameters...................................................................................................... 8
4.1.
Model grid data................................................................................................. 8
4.1.1. Constant fields (TL319) ............................................................................... 8
4.1.2. Total column analysis fields (anl_column) .................................................. 8
4.1.3. Isentropic analysis fields (anl_isentrop) ....................................................... 8
4.1.4. Land surface analysis fields (anl_land) ........................................................ 9
4.1.5. Model level analysis fields (anl_mdl) .......................................................... 9
4.1.6. Snow depth analysis fields (anl_snow) ...................................................... 10
4.1.7. Surface analysis fields (anl_surf) ............................................................... 10
4.1.8. Total column forecast fields (fcst_column) ................................................ 10
4.1.9. Land surface forecast fields (fcst_land)...................................................... 11
4.1.10. Model level forecast fields (fcst_mdl) .................................................... 11
4.1.11. Two-dimensional average diagnostic fields (fcst_phy2m) ..................... 12
4.1.12. Model level average diagnostic fields (fcst_phy3m).............................. 13
4.1.13. Land surface average diagnostic fields (fcst_phyland) .......................... 13
4.1.14. Two-dimensional instantaneous diagnostic fields (fcst_surf) ................ 14
4.1.15. Sea ice fields (ice)................................................................................... 14
4.1.16. Two-dimensional extreme fields (minmax_surf) ................................... 15
5. Type of vegetation ................................................................................................... 15
6. Grid .......................................................................................................................... 16
6.1.
Quasi-regular Gaussian latitude/longitude grid .............................................. 16
7. Vertical coordinates ................................................................................................. 21
7.1.
Hybrid coordinates ......................................................................................... 21
7.2.
Isentropic coordinates ..................................................................................... 23
7.3.
Soil layers of the land surface model ............................................................. 23
8. Physical constants .................................................................................................... 24
9. Monthly statistics..................................................................................................... 24
9.1.
Monthly statistics for fixed hours (Monthly_diurnal) .................................... 24
9.2.
Monthly statistics (Monthly) .......................................................................... 25
10.
Climatological normals ...................................................................................... 25
10.1.

Daily mean smooth climatological normals ................................................... 25

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JRA-55 Product Users' Handbook
Model grid data
10.2. Monthly mean climatological normals ........................................................... 26
11.
Production streams ............................................................................................. 26
12.
Differences from JRA-25 products..................................................................... 27
12.1. Parameter classification .................................................................................. 27
12.2. Dates in file names ......................................................................................... 28
12.3. Parameter additions and changes .................................................................... 28
12.4. Discontinued parameters ................................................................................ 29
12.5. Output interval ................................................................................................ 30
12.6. Vertical coordinates ........................................................................................ 30
12.6.1. Hybrid coordinates ................................................................................. 30
12.6.2. Isentropic coordinates ............................................................................. 30
12.7. Monthly statistics............................................................................................ 30
References ...................................................................................................................... 30

4

JRA-55 Product Users' Handbook
Model grid data
List of tables
Table 3-1 Naming convention for historical data. _____________________________________7
Table 3-2 Naming convention for climatological normals. _____________________________7
Table 4-1 Parameters of constant fields (TL319). _____________________________________8
Table 4-2 Parameters of total column analysis fields (anl_column)._____________________8
Table 4-3 Parameters of isentropic analysis fields (anl_isentrop). ______________________9
Table 4-4 Parameters of land surface analysis fields (anl_land). _______________________9
Table 4-5 Parameters of model level analysis fields (anl_mdl). _________________________9
Table 4-6 Parameter of snow depth analysis fields (anl_snow)._______________________ 10
Table 4-7 Parameters of surface analysis fields (anl_surf). __________________________ 10
Table 4-8 Parameters of total column forecast fields (fcst_column). ___________________ 10
Table 4-9 Parameters of land surface forecast fields (fcst_land). _____________________ 11
Table 4-10 Parameters of model level forecast fields (fcst_mdl). ______________________ 11
Table 4-11 Parameters of two-dimensional average diagnostic fields (fcst_phy2m). ____ 12
Table 4-12 Parameters of model level average diagnostic fields (fcst_phy3m). _________ 13
Table 4-13 Parameters of land surface average diagnostic fields (fcst_phyland). _______ 14
Table 4-14 Parameters of two-dimensional instantaneous diagnostic fields (fcst_surf). _ 14
Table 4-15 Parameter of sea ice fields (ice). ________________________________________ 14
Table 4-16 Parameters of two-dimensional extreme fields (minmax_surf). ____________ 15
Table 5-1 Types of vegetation (Code table JMA-252). _______________________________ 15
Table 6-1 Latitudes of the model grid and the number of grid points along each parallel(#1-40). __________________________________________________________________________ 17
Table 6-2 Latitudes of the model grid and the number of grid points along each parallel(#41-80). _________________________________________________________________________ 18
Table 6-3 Latitudes of the model grid and the number of grid points along each parallel(#81-120). _______________________________________________________________________ 19
Table 6-4 Latitudes of the model grid and the number of grid points along each parallel(#121-160). ______________________________________________________________________ 20
Table 7-1 Model levels from 1 to 39. _______________________________________________ 22
Table 7-2 Model levels from 40 to 60. ______________________________________________ 23
Table 7-3 Soil layers of the land surface model. ____________________________________ 24
Table 8-1 Physical constants. _____________________________________________________ 24
Table 9-1 Time range indicator for monthly statistics. ______________________________ 25
Table 11-1 Production streams of JRA-55. _________________________________________ 27
Table 12-1 Example of category change (for anl_mdl)._______________________________ 28

5JRA-55 Product Users' Handbook
Model grid data
Table 12-2 Example of category change (for fcst_phy2m). ___________________________ 28
Table 12-3 Example of file name date change (for fcst_phy2m.1981010100).___________ 28
Table 12-4 Discontinued parameter in isentropic analysis fields (anl_isentrop). _______ 29
Table 12-5 Discontinued parameter in model level forecast fields (fcst_mdl). __________ 29
Table 12-6 Discontinued parameters in two-dimensional diagnostic fields (fcst_phy2m). 29
Table 12-7 Discontinued parameters in three-dimensional diagnostic fields (fcst_phy3m).
_________________________________________________________________________________ 29
Table 12-8 Discontinued parameter in land surface diagnostic fields (fcst_phyland). ___ 30

6JRA-55 Product Users' Handbook
Model grid data

1. Introduction
This handbook gives an overview of products stemming from the Japanese 55-year
Reanalysis (JRA-55) project conducted by the Japan Meteorological Agency (JMA) forthe period from 1958 onward (Kobayashi et al. 2015), and also outlines how theseproducts differ from the corresponding JRA-25 versions (Onogi et al. 2007).

2. File format
Both daily and monthly data are encoded in Gridded binary (GRIB) Edition 1 format(WMO 2011). (Daily data include 3-, 6- and 24-hourly data, which vary by category).

3. File names
JRA-55 product file names follow the convention shown in Table 3-1 for historical
data and that shown in Table 3-2 for climatological normals.
Table 3-1

Naming convention for historical data.

Time range
Daily

M onthly_diurnal

M onthly

Table 3-2

Type

Filename

2D fields<category>.<year><month><day><hour>

3D fields<category>_<parameter>.<year><month><day><hour>

2D fields, average<category>.<year><month>_<hour>

2D fields, variance<category>_var.<year><month>_<hour>

3D fields, average<category>_<parameter>.<year><month>_<hour>

3D fields, variance<category>_<parameter>_var.<year><month>_<hour>

2D fields, average<category>.<year><month>2D fields, variance<category>_var.<year><month>

3D fields, average<category>_<parameter>.<year><month>

3D fields, variance<category>_<parameter>_var.<year><month>

Naming convention for climatological normals.

Time range
Daily
M onthly_diurnal
M onthlyType

Filename

2D fields<category>.clim<period>.day<month><day>

3D fields<category>_<parameter>.clim<period>.day<month><day>

2D fields, average<category>.clim<period>.mon<month>

3D fields, average<category>_<parameter>.clim<period>.mon<month>7

JRA-55 Product Users' Handbook
Model grid data

4. Output parameters4.1. Model grid data
4.1.1. Constant fields (TL319)
Table 4-1 shows the parameters of constant fields.
Table 4-1

Parameters of constant fields (TL319).

CodefigureField parameterUnit

6 Geopotential

m2 s-281 Land cover (1=land, 0=sea)

Proportion
Code Table
JM A-252

252 Type of vegetation

4.1.2. Total column analysis fields (anl_column)
Total column analysis fields (Table 4-2) are produced by integrating the corresponding
analyzed fields vertically from the bottom to the top of the atmosphere. These fields are
output every six hours at 00, 06, 12 and 18 UTC.
Table 4-2

Parameters of total column analysis fields (anl_column).

CodefigureField parameter

Unit

54 Precipitable waterkg m-2152 M eridional water vapour flux

kg m-1 s-1

157 Zonal water vapour flux

kg m-1 s-1

190 Zonal thermal energy flux+

W m-1

191 M eridional thermal energy flux+

W m-1+ See Section 12.3 “Parameter additions and changes”

Note: Precipitable water contains water vapour only.

4.1.3. Isentropic analysis fields (anl_isentrop)
The parameters shown in Table 4-3 are vertically interpolated to the isentropic
surfaces listed in Section 7.2 except specific humidity, which is interpolated to 14 levels
from 270 to 400 K only. These fields are output every six hours at 00, 06, 12 and 18 UTC.

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JRA-55 Product Users' Handbook
Model grid data
Table 4-3

Parameters of isentropic analysis fields (anl_isentrop).

CodefigureField parameter

Unit

1 Pressure+

FilenamePa

anl_isentrop_pres2-1

4 Potential vorticity

K m kg s

7 Geopotential heightgpm

33 u-component of wind
34 v-component of wind-1

anl_isentrop_pvor
anl_isentrop_hgt

ms-1

anl_isentrop_ugrd

ms-1

anl_isentrop_vgrd

2-2

anl_isentrop_mntsf

37 M ontgomery stream functionm s

39 Vertical velocity

Pa s-1

anl_isentrop_vvel

-1

kg kg

anl_isentrop_spfh-2

anl_isentrop_bvf2

51 Specific humidity
132 Square of Brunt-Vaisala frequencys+ See Section 12.3 “Parameter additions and changes”

4.1.4. Land surface analysis fields (anl_land)
The parameters shown in Table 4-4 are output from land surface analysis every six
hours at 00, 06, 12 and 18 UTC.
Table 4-4

Parameters of land surface analysis fields (anl_land).

CodefigureField parameter

Unit

Level

65 Water equivalent of accumulated snow depth

kg m-2Ground surface

144 Canopy temperature

K

Ground surface

145 Ground temperature

K

85 Soil temperature

K

225 Soil wetness

Proportion

Ground surface
Entire soil(considered as a single layer)
Underground layers

4.1.5. Model level analysis fields (anl_mdl)
The parameters shown in Table 4-5 are output to the model levels listed in Section 7.1
every six hours at 00, 06, 12 and 18 UTC.
Table 4-5

Parameters of model level analysis fields (anl_mdl).

CodefigureField parameter

Unit

Filename

7 Geopotential heightgpm

anl_mdl_hgt

11 TemperatureK

anl_mdl_tmp

33 u-component of wind
34 v-component of wind
39 Vertical velocityms-1

anl_mdl_ugrd

ms-1

anl_mdl_vgrd

Pa s

51 Specific humidity-1

anl_mdl_vvel-1

anl_mdl_spfh

kg kg

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JRA-55 Product Users' Handbook
Model grid data

4.1.6. Snow depth analysis fields (anl_snow)
The parameter shown in Table 4-6 is output from snow depth analysis at 18 UTC every
day.
Table 4-6

Parameter of snow depth analysis fields (anl_snow).

CodefigureField parameter

Unit

66 Snow depth

m

Level
Ground surface

4.1.7. Surface analysis fields (anl_surf)
Surface analysis fields (Table 4-7) are produced every six hours at 00, 06, 12 and 18
UTC.
Table 4-7

Parameters of surface analysis fields (anl_surf).

CodefigureField parameter

Unit

Level

1 Pressure

Pa

Ground or water surface

11 Temperature

K2m

13 Potential temperature

K

Ground or water surface-1

51 Specific humidity

kg kg

2m

52 Relative humidity%

2m

33 u-component of wind
34 v-component of wind

ms

-1

10m

ms

-1

10m

Note: The order of the parameters in monthly statistics and climatological normal files differs from that in daily files(Table 4-7), 1, 13, 11, 51, 52, 33 and 34.

4.1.8. Total column forecast fields (fcst_column)
Total column forecast fields (Table 4-8) are produced every three hours, integrating
vertically from the bottom to the top of the atmosphere three-hour forecast fields at 03,
09, 15 and 21 UTC, and six-hour forecast fields at 00, 06, 12 and 18 UTC.
Table 4-8

Parameters of total column forecast fields (fcst_column).

CodefigureField parameter

Unit

10 Total ozone

Dobson54 Precipitable waterkg m-258 Cloud ice+kg m-2152 M eridional water vapour flux*

kg m-1 s-1

157 Zonal water vapour flux*

kg m-1 s-1+

190 Zonal thermal energy flux

W m-1

191 M eridional thermal energy flux+

W m-1

227 Cloud liquid water+kg m-210

JRA-55 Product Users' Handbook
Model grid data+, * See Section 12.3 “Parameter additions and changes”

Note: Precipitable water contains water vapour only.

4.1.9. Land surface forecast fields (fcst_land)
Land surface forecast fields (Table 4-9) are produced every three hours at 00, 03, 06,
09, 12, 15, 18 and 21 UTC.
Table 4-9

Parameters of land surface forecast fields (fcst_land).

CodefigureField parameter

Unit

65 Water equivalent of accumulated snow depth+Level

kg m-2Ground surfacemGround surface

144 Canopy temperature

K

Ground surface

145 Ground temperature

K

Ground surface

223 M oisture storage on canopymGround surface

224 M oisture storage on ground/coverm

85 Soil temperature

K

225 Soil wetness+

Proportion

Ground surface
Entire soil(considered as a single layer)
Underground layers

226 M ass concentration of condensed water in soil+

kg m-3

Underground layers

66 Snow depth++ See Section 12.3 “Parameter additions and changes”

4.1.10. Model level forecast fields (fcst_mdl)
The parameters shown in Table 4-10 are output to the model levels listed in Section 7.1
every six hours at 00, 06, 12 and 18 UTC.
Table 4-10

Parameters of model level forecast fields (fcst_mdl).

CodefigureField parameter

Unit

Filename

7 Geopotential height

gpm

fcst_mdl_hgt

11 TemperatureKfcst_mdl_tmp

33 u-component of wind
34 v-component of wind
39 Vertical velocity

ms-1

fcst_mdl_ugrd

ms-1

fcst_mdl_vgrd-1

fcst_mdl_vvel

-1

kg kg

fcst_mdl_spfh%

fcst_mdl_tcdc

Pa s

51 Specific humidity*

71 Total cloud cover
221 Cloud water-1

fcst_mdl_cwat-1

fcst_mdl_clwc-1

fcst_mdl_ciwc-2 -1

kg m sfcst_mdl_mflxb-1

fcst_mdl_ozone

kg kg
+

228 Cloud liquid waterkg kg

229 Cloud ice+kg kg

230 Upward mass flux at cloud base237 Ozone mixing ratio

mg kg+, * See Section 12.3 “Parameter additions and changes”

11JRA-55 Product Users' Handbook
Model grid data

4.1.11. Two-dimensional average diagnostic fields (fcst_phy2m)
Two-dimensional average diagnostic fields are produced every three hours. The
parameters shown in Table 4-11 are averaged from the beginning of forecasts up to threehours for 00 - 03, 06 - 09, 12 - 15 and 18 - 21 UTC, and from three to six hours for 03 06, 09 - 12, 15 - 18 and 21 - 24 UTC.
Dates in file names indicate the beginning of the averaging period.
Table 4-11

Parameters of two-dimensional average diagnostic fields (fcst_phy2m).

CodefigureField parameter

Unit

1 Pressure
57 Evapolation

Pa++

61 Total precipitation

62 Large scale precipitation
63 Convective precipitation
64 Snowfall rate water equivalent

Level
Ground or water surface

mm day-1

Ground or water surface

mm day-1

Ground or water surface

mm day-1

Ground or water surface

mm day-1

Ground or water surface

mm day-1

Ground or water surface-2

Ground or water surface-2

Wm

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface

148 M eridional momemtum flux by long gravity wave

-2

Nm

Ground or water surface

154 M eridional momemtum flux by short gravity wave

N m-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Wm

Ground or water surface%

Ground or water surface%

Ground or water surface

121 Latent heat flux

Wm

122 Sensible heat flux
124 M omentum flux, u component

Nm

125 M omentum flux, v component

Nm

147 Zonal momemtum flux by long gravity wave

Nm

159 Zonal momemtum flux by short gravity wave

Nm

160 Clear sky upward solar radiation flux

Wm

161 Clear sky downward solar radiation flux

Wm

163 Clear sky downward long wave radiation flux
170 Frequency of deep convection+

171 Frequency of shallow convection+

172 Frequency of stratocumulus parameterisation+%

204 Downward solar radiation flux

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Nominal top of atmosphere-2Nominal top of atmosphere-2Nominal top of atmosphere-2Nominal top of atmosphere-2Nominal top of atmosphereWm

205 Downward long wave radiation flux

Wm

211 Upward solar radiation flux

Wm

212 Upward long wave radiation flux

Wm

160 Clear sky upward solar radiation flux

Wm

162 Clear sky upward long wave radiation flux

Wm

204 Downward solar radiation flux

Wm

211 Upward solar radiation flux

Wm

212 Upward long wave radiation flux

Wm

+ See Section 12.3 “Parameter additions and changes”

12JRA-55 Product Users' Handbook
Model grid data

4.1.12. Model level average diagnostic fields (fcst_phy3m)
Model level average diagnostic fields are produced every six hours. The parameters
shown in Table 4-12 are averaged from the beginning of forecasts up to six hours for 00 06, 06 - 12, 12 - 18 and 18 - 24 UTC, and output to the model levels listed in Section 7.1.
Dates in file names indicate the beginning of the averaging period.
Table 4-12
CodefigureParameters of model level average diagnostic fields (fcst_phy3m).
Field parameter

Unit

146 Cloud work function#

Filename

J kg-1151 Adiabatic zonal acceleration

fcst_phy3m_cwork-1

m s day-1

fcst_phy3m_adua-1-1fcst_phy3m_adva

165 Adiabatic meridional accelerationm s day

173 Gravity wave zonal acceleration

m s-1 day -1

fcst_phy3m_gwdua-1

fcst_phy3m_gwdva

174 Gravity wave meridional accelerationm s day

222 Adiabatic heating rate-1

fcst_phy3m_adhr-2 -1

fcst_phy3m_mflxb

K day
##

-1

230 Upward mass flux at cloud basekg m s231 Upward mass flux

kg m-2 s-1-1

236 Adiabatic moistening rate

kg kg day

239 Convective zonal accelerationm s day-1

fcst_phy3m_cnvua-1-1

fcst_phy3m_cnvva

m s day

241 Large scale condensation heating rate

K day -1
K day

fcst_phy3m_lrghr-1

fcst_phy3m_cnvhr-1

243 Convective moistening rate

kg kg day
K day

247 Vertical diffusion zonal acceleration

m s-1 day -1-1

m s day

fcst_phy3m_vdfva
-1

-1

K day

251 Longwave radiative heating rate

K day -1
-1

253 Large scale moistening rate

fcst_phy3m_vdfua-1

kg kg day

250 Solar radiative heating rate

fcst_phy3m_cnvmr
fcst_phy3m_vdfhr-1

249 Vertical diffusion moistening rate

-1

-1

246 Vertical diffusion heating rate
248 Vertical diffusion meridional acceleration

fcst_phy3m_admr-1

240 Convective meridional acceleration
242 Convective heating rate

fcst_phy3m_mflux-1kg kg dayfcst_phy3m_vdfmr
fcst_phy3m_swhr
fcst_phy3m_lwhr-1

fcst_phy3m_lrgmr# Cloud work functions at model levels from 1 to 10 are constant at 0 in the specifications of physical parameterization,

but model levels from 2 to 5 are used to output temporary variables of the cumulus convection scheme. Please discard
those data.
## Upward mass fluxes at cloud base at model levels from 1 to 10 are constant at 0 in the specifications of physicalparameterization, but model levels from 1 to 3 are used to output temporary variables of the cumulus convection
scheme. Please discard those data.

4.1.13. Land surface average diagnostic fields (fcst_phyland)
Land surface average diagnostic fields are produced every three hours. The parameters
shown in Table 4-13 are averaged from the beginning of forecasts up to three hours for 00- 03, 06 - 09, 12 - 15 and 18 - 21 UTC, and from three to six hours for 03 - 06, 09 - 12, 15- 18 and 21 - 24 UTC.
Dates in file names indicate the beginning of the averaging period.

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JRA-55 Product Users' Handbook
Model grid data
Table 4-13

Parameters of land surface average diagnostic fields (fcst_phyland).

CodefigureField parameter

Unit

Level

90 Water run-off

mm day -1

Ground surface

155 Ground heat flux

-2

Ground surface-2

Ground surface-2

Ground surface
The bottom of land surface
model

Wm

202 Evapotranspiration

Wm

203 Interception loss

Wm

90 Water run-off+mm day -1+ See Section 12.3 “Parameter additions and changes”

4.1.14. Two-dimensional instantaneous diagnostic fields (fcst_surf)Two-dimensional instantaneous diagnostic fields (Table 4-14) are produced every
three hours at 00, 03, 06, 09, 12, 15, 18 and 21 UTC.
Table 4-14

Parameters of two-dimensional instantaneous diagnostic fields (fcst_surf).

CodefigureField parameter

Unit

1 Pressure

Level

Pa

Ground or water surfacemGround or water surface

118 Brightness temperature

K

Ground or water surface

71 Total cloud cover*%

90 - 1100 hPa%

90 - 500 hPa%

500 - 850 hPa

83 Surface roughness+*

75 High cloud cover*

74 M edium cloud cover
73 Low cloud cover*%

850 - 1100 hPa

2 Pressure reduced to M SLPa

M ean sea level

11 Temperature

K

2m
-1

51 Specific humidity

kg kg

2m

52 Relative humidity%

2m

33 u-component of wind
34 v-component of wind

ms

-1

10m

ms

-1

10m

+, * See Section 12.3 “Parameter additions and changes”

4.1.15. Sea ice fields (ice)
Sea ice fields (Table 4-15) are output every three hours.
Table 4-15
CodefigureParameter of sea ice fields (ice).
Field parameter

Unit

91 Ice cover (1 = ice, 0 = no ice)

Proportion14JRA-55 Product Users' Handbook
Model grid data

4.1.16. Two-dimensional extreme fields (minmax_surf)Two-dimensional extreme fields (minmax_surf) are produced every three hours. The
parameters shown in Table 4-16 are computed from the beginning of forecasts up to
three hours for 00 - 03, 06 - 09, 12 - 15 and 18 - 21 UTC, and from three to six hours for
03 - 06, 09 - 12, 15 - 18 and 21 - 24 UTC.
Dates in file names indicate the end of the valid time.
Two-dimensional extreme fields (minmax_surf) are produced for daily data only;
they are not produced for monthly statistics.
Table 4-16

Parameters of two-dimensional extreme fields (minmax_surf).

CodefigureField parameter

Unit

15 M aximum temperatureK

16 M inumum temperature

K

219 M aximum wind speed

ms

2m
2m
-1

5. Type of vegetation
Types of vegetation defined for JRA-55 are as follows:
Table 5-1

Types of vegetation (Code table JMA-252).

CodefigureM eaning

0 Sea or inland water
1 Broadleaf-evergreen trees
2 Broadleaf-deciduous trees
3 Broadleaf and needleleaf trees
4 Needleleaf-evergreen trees
5 Needleleaf-deciduous trees
6 Broadleaf trees with groundcover
7 Groundcover
8 Broadleaf shrubs with groundcover
9 Broadleaf shrubs with bare soil
10 Dwarf trees and shrubs with groundcover (tundra)
11 No vegetation: bare soil
12 Broadleaf-deciduous trees with winter wheat
13 Perennial land ice

15

Level

10m

JRA-55 Product Users' Handbook
Model grid data

6. Grid6.1. Quasi-regular Gaussian latitude/longitude grid
Model grid data are output to the quasi-regular Gaussian latitude/longitude grid.
Latitudes of the model grid correspond to nodes for the 320-point Gauss-Legendre
formula. The number of grid points along each parallel varies with latitude (Table 6-1,
Table 6-2, Table 6-3 and Table 6-4). The grid points in each parallel are evenly spaced
and the first point is positioned at the standard meridian.
Table 6-1, Table 6-2, Table 6-3 and Table 6-4 also show weights for the 320-point
Gauss-Legendre formula.

16JRA-55 Product Users' Handbook
Model grid data
Table 6-1#

Latitudes of the model grid and the number of grid points along each parallel (#1-40).

(±) Latitude

WeightPoints18.95700895506066E+01

7.22417022893012E-05

48

28.90131761310220E+01

1.68158195616948E-04

643

8.84529738367130E+01

2.64200571979866E-04

80

48.78920284453444E+01

3.60229901103989E-0480

58.73308011797376E+01

4.56227095866134E-04

96

68.67694375145276E+01

5.52181197609065E-04

112

78.62079976214231E+01

6.48082526890580E-04

112

88.56465108479528E+01

7.43921712961107E-04128

98.50849932009119E+01

8.39689484512363E-04

128

10

8.45234541489144E+01

9.35376611415834E-04

144

11

8.39618996497181E+01

1.03097388562788E-03

144

12

8.34003336387369E+01

1.12647211435034E-03

160

13

8.28387588197095E+01

1.22186211760014E-03

160

14

8.22771771114337E+01

1.31713472754676E-03

192

15

8.17155899132664E+01

1.41228078862246E-03

192

16

8.11539982697129E+01

1.50729115799506E-03

192

17

8.05924029761777E+01

1.60215670622107E-03

192

18

8.00308046490314E+01

1.69686831799275E-03

224

19

7.94692037732916E+01

1.79141689293615E-03

224

20

7.89076007358379E+01

1.88579334643737E-03

224

21

7.83459958490356E+01

1.97998861048504E-03

224

22

7.77843893678486E+01

2.07399363452170E-03

240

23

7.72227815024451E+01

2.16779938630021E-03

240

24

7.66611724276204E+01

2.26139685274268E-03

256

25

7.60995622899381E+01

2.35477704080024E-03

256

26

7.55379512132081E+01

2.44793097831276E-03

288

27

7.49763393027374E+01

2.54084971486788E-03

288

28

7.44147266486620E+01

2.63352432265867E-03

288

29

7.38531133285838E+01

2.72594589733983E-03

288

30

7.32914994096763E+01

2.81810555888202E-03

288

31

7.27298849503795E+01

2.90999445242416E-03

320

32

7.21682700017747E+01

3.00160374912351E-03

320

33

7.16066546087075E+01

3.09292464700346E-03

320

34

7.10450388107113E+01

3.18394837179883E-03

320

35

7.04834226427713E+01

3.27466617779859E-03

320

36

6.99218061359604E+01

3.36506934868594E-03

336

37

6.93601893179717E+01

3.45514919837554E-03

336

38

6.87985722135654E+01

3.54489707184801E-03

384

39

6.82369548449477E+01

3.63430434598132E-03

384

40

6.76753372320917E+01

3.72336243037927E-03

384

17

JRA-55 Product Users' Handbook
Model grid data
Table 6-2

Latitudes of the model grid and the number of grid points along each parallel (#41-80).

#(±) Latitude

WeightPoints41

6.71137193930113E+01

3.81206276819674E-03

384

42

6.65521013439961E+01

3.90039683696182E-03

384

43

6.59904830998127E+01

3.98835614939459E-03

384

44

6.54288646738789E+01

4.07593225422256E-03

384

45

6.48672460784143E+01

4.16311673699262E-03

384

46

6.43056273245713E+01

4.24990122087953E-03

400

47

6.37440084225492E+01

4.33627736749070E-03

400

48

6.31823893816941E+01

4.42223687766737E-03

400

49

6.26207702105861E+01

4.50777149228198E-03

432

50

6.20591509171167E+01

4.59287299303171E-03

432

51

6.14975315085564E+01

4.67753320322809E-03

432

52

6.09359119916146E+01

4.76174398858260E-03

432

53

6.03742923724930E+01

4.84549725798827E-03

432

54

5.98126726569327E+01

4.92878496429701E-03

432

55

5.92510528502565E+01

5.01159910509285E-03

448

56

5.86894329574061E+01

5.09393172346077E-03

448

57

5.81278129829758E+01

5.17577490875123E-03

448

58

5.75661929312427E+01

5.25712079734024E-03

480

59

5.70045728061936E+01

5.33796157338490E-03

480

60

5.64429526115493E+01

5.41828946957433E-03

480

61

5.58813323507866E+01

5.49809676787602E-03

480

62

5.53197120271579E+01

5.57737580027733E-03

480

63

5.47580916437092E+01

5.65611894952227E-03

480

64

5.41964712032965E+01

5.73431864984338E-03

512

65

5.36348507085999E+01

5.81196738768865E-03

512

66

5.30732301621377E+01

5.88905770244343E-03

512

67

5.25116095662779E+01

5.96558218714727E-03

512

68

5.19499889232498E+01

6.04153348920559E-03

512

69

5.13883682351539E+01

6.11690431109609E-03

512

70

5.08267475039710E+01

6.19168741106998E-03

512

71

5.02651267315709E+01

6.26587560384770E-03

560

72

4.97035059197200E+01

6.33946176130936E-03

560

73

4.91418850700887E+01

6.41243881317955E-03

560

74

4.85802641842574E+01

6.48479974770674E-03

560

75

4.80186432637230E+01

6.55653761233693E-03

560

76

4.74570223099043E+01

6.62764551438165E-03

560

77

4.68954013241470E+01

6.69811662168028E-03

560

78

4.63337803077285E+01

6.76794416325643E-03

560

79

4.57721592618623E+01

6.83712142996855E-03

560

80

4.52105381877018E+01

6.90564177515453E-03

560

18

JRA-55 Product Users' Handbook
Model grid data
Table 6-3

Latitudes of the model grid and the number of grid points along each parallel (#81-120).

#(±) Latitude

WeightPoints81

4.46489170863444E+01

6.97349861527033E-03

560

82

4.40872959588346E+01

7.04068543052255E-03

576

83

4.35256748061674E+01

7.10719576549483E-03

576

84

4.29640536292911E+01

7.17302322976814E-03

576

85

4.24024324291106E+01

7.23816149853473E-03

576

86

4.18408112064890E+01

7.30260431320588E-03

576

87

4.12791899622508E+01

7.36634548201319E-03

640

88

4.07175686971841E+01

7.42937888060353E-03

640

89

4.01559474120422E+01

7.49169845262744E-03

640

90

3.95943261075457E+01

7.55329821032109E-03

640

91

3.90327047843849E+01

7.61417223508153E-03

640

92

3.84710834432205E+01

7.67431467803540E-03

640

93

3.79094620846860E+01

7.73371976060089E-03

640

94

3.73478407093888E+01

7.79238177504295E-03

640

95

3.67862193179117E+01

7.85029508502170E-03

640

96

3.62245979108143E+01

7.90745412613397E-03

640

97

3.56629764886338E+01

7.96385340644796E-03

640

98

3.51013550518869E+01

8.01948750703089E-03

640

99

3.45397336010700E+01

8.07435108246969E-03

640

100

3.39781121366611E+01

8.12843886138454E-03

640

101

3.34164906591199E+01

8.18174564693541E-03

640

102

3.28548691688896E+01

8.23426631732136E-03

640

103

3.22932476663967E+01

8.28599582627264E-03

640

104

3.17316261520529E+01

8.33692920353555E-03

640

105

3.11700046262550E+01

8.38706155535001E-03

640

106

3.06083830893861E+01

8.43638806491971E-03

640

107

3.00467615418160E+01

8.48490399287498E-03

640

108

2.94851399839021E+01

8.53260467772811E-03

640

109

2.89235184159896E+01

8.57948553632125E-03

640

110

2.83618968384127E+01

8.62554206426676E-03

640

111

2.78002752514945E+01

8.67076983638001E-03

640

112

2.72386536555477E+01

8.71516450710455E-03

640

113

2.66770320508754E+01

8.75872181092963E-03

640

114

2.61154104377713E+01

8.80143756280006E-03

640

115

2.55537888165200E+01

8.84330765851829E-03

640

116

2.49921671873976E+01

8.88432807513879E-03

640

117

2.44305455506723E+01

8.92449487135452E-03

640

118

2.38689239066043E+01

8.96380418787565E-03

640

119

2.33073022554465E+01

9.00225224780040E-03

640

120

2.27456805974447E+01

9.03983535697787E-03

640

19

JRA-55 Product Users' Handbook
Model grid data
Table 6-4

Latitudes of the model grid and the number of grid points along each parallel (#121-160).

#(±) Latitude

WeightPoints121

2.21840589328380E+01

9.07654990436300E-03

640

122

2.16224372618593E+01

9.11239236236356E-03

640

123

2.10608155847349E+01

9.14735928717903E-03

640

124

2.04991939016857E+01

9.18144731913153E-03

640

125

1.99375722129269E+01

9.21465318298861E-03

640

126

1.93759505186682E+01

9.24697368827792E-03

640

127

1.88143288191145E+01

9.27840572959380E-03

640

128

1.82527071144658E+01

9.30894628689559E-03

640

129

1.76910854049175E+01

9.33859242579788E-03

640

130

1.71294636906605E+01

9.36734129785236E-03

640

131

1.65678419718816E+01

9.39519014082157E-03

640

132

1.60062202487636E+01

9.42213627894429E-03

640

133

1.54445985214858E+01

9.44817712319260E-03

640

134

1.48829767902235E+01

9.47331017152068E-03

640

135

1.43213550551487E+01

9.49753300910516E-03

640

136

1.37597333164304E+01

9.52084330857721E-03

640

137

1.31981115742342E+01

9.54323883024608E-03

640

138

1.26364898287229E+01

9.56471742231435E-03

640

139

1.20748680800568E+01

9.58527702108464E-03

640

140

1.15132463283931E+01

9.60491565115794E-03

640

141

1.09516245738869E+01

9.62363142562335E-03

640

142

1.03900028166909E+01

9.64142254623943E-03

640

143

9.82838105695560E+00

9.65828730360694E-03

640

144

9.26675929482938E+00

9.67422407733312E-03

640

145

8.70513753045879E+00

9.68923133618732E-03

640

146

8.14351576398856E+00

9.70330763824821E-03

640

147

7.58189399556175E+00

9.71645163104223E-03

640

148

7.02027222531985E+00

9.72866205167360E-03

640

149

6.45865045340296E+00

9.73993772694564E-03

640

150

5.89702867994979E+00

9.75027757347349E-03

640

151

5.33540690509796E+00

9.75968059778822E-03

640

152

4.77378512898387E+00

9.76814589643226E-03

640

153

4.21216335174302E+00

9.77567265604622E-03

640

154

3.65054157350999E+00

9.78226015344704E-03

640

155

3.08891979441865E+00

9.78790775569746E-03

640

156

2.52729801460213E+00

9.79261492016686E-03

640

157

1.96567623419308E+00

9.79638119458336E-03

640

158

1.40405445332361E+00

9.79920621707733E-03

640

159

8.42432672125539E-01

9.80108971621609E-03

640

160

2.80810890730407E-01

9.80203151103004E-03

640

20

JRA-55 Product Users' Handbook
Model grid data

7. Vertical coordinates
7.1. Hybrid coordinates
Model level fields are produced for 60 hybrid levels. Each hybrid level is defined withhalf-levels p

k1
2

as the boundary;

p

k

A

1
2

k

B

1
2

1
2

k

ps ,

where ps is the surface pressure. Coefficients A and B are given in Table 7-1 and Table
7-2 for k = 0, 1, 2, …, 60. The following equation by Simmons and Burridge (1981)
gives full-levels, i.e. the pressures that represent each hybrid level except for theuppermost level (k = 60);
pk

exp

1
pk

p

k

1
2

ln p

k

1
2

p

k

1
2

ln p

k

1
2

C ,

where C = 1 and k = 1, 2, …, 59. The full-level pressure for the uppermost level (k = 60)
is given by
p60

1
p59.5 .
2

Table 7-1 and Table 7-2 also give half-level and full-level pressures with a surfacepressure of 1000 hPa.

21

JRA-55 Product Users' Handbook
Model grid data
Table 7-1

Model levels from 1 to 39.
Half level

Full level

A (Pa)

B

0.00000000000000E+00

1.00000000000000E+00

p (Pa)
1000000.5

100000.0 Surface

0.00000000000000E+00

9.97000000000000E-01

99700

1.5

99850.010.00000000000000E+00

9.94000000000000E-01

99400

2.5

99550.020.00000000000000E+00

9.89000000000000E-01

98900

3.5

99149.930.00000000000000E+00

9.82000000000000E-01

98200

4.5

98549.8

40.00000000000000E+00

9.72000000000000E-01

97200

5.5

97699.6

50.00000000000000E+00

9.60000000000000E-01

96000

6.5

96599.460.00000000000000E+00

9.46000000000000E-01

94600

7.5

95299.17

1.33051011276943E+02

9.26669489887231E-01

92800

8.5

93698.68

3.64904148871589E+02

9.04350958511284E-01

90800

9.5

91798.2

96.34602716447362E+02

8.79653972835526E-01

88600

10.5

89697.810

9.59797167291774E+02

8.51402028327082E-01

86100

11.5

87347.011

1.34768004165515E+03

8.19523199583449E-01

83300

12.5

84696.112

1.79090739595110E+03

7.85090926040489E-01

80300

13.5

81795.4

13

2.29484168994850E+03

7.48051583100515E-01

77100

14.5

78694.6

14

2.84748477771176E+03

7.09525152222882E-01

73800

15.5

75444.015

3.46887148811864E+03

6.68311285118814E-01

70300

16.5

72042.9

16

4.16295646296916E+03

6.24370435370308E-01

66600

17.5

68441.7

17

4.89188083250491E+03

5.80081191674951E-01

62900

18.5

64741.2

18

5.67182423980408E+03

5.34281757601959E-01

59100

19.5

60990.1

19

6.47671299638532E+03

4.88232870036147E-01

55300

20.5

57189.5

20

7.29746989472049E+03

4.42025301052795E-01

51500

21.5

53388.721

8.12215979124915E+03

3.95778402087509E-01

47700

22.5

49587.922

8.91408220106234E+03

3.50859177989377E-01

44000

23.5

45837.6

23

9.65618191050164E+03

3.07438180894984E-01

40400

24.5

42187.2

24

1.03294361777746E+04

2.65705638222254E-01

36900

25.5

38636.8

25

1.09126384442387E+04

2.25873615557613E-01

33500

26.5

35186.3

26

1.13696478308432E+04

1.89303521691568E-01

30300

27.5

31886.627

1.16953715974700E+04

1.55046284025300E-01

27200

28.5

28736.128

1.18612530873948E+04

1.24387469126052E-01

24300

29.5

25736.429

1.18554343163493E+04

9.64456568365075E-02

21500

30.5

22885.730

1.16633553655803E+04

7.23664463441966E-02

18900

31.5

20186.031

1.12854040644942E+04

5.21459593550578E-02

16500

32.5

17686.4

32

1.07299494055679E+04

3.57005059443214E-02

14300

33.5

15386.933

1.00146150535107E+04

2.28538494648935E-02

12300

34.5

13287.534

9.16724703583310E+03

1.33275296416689E-02

10500

35.5

11388.135

8.22624490770442E+03

6.73755092295582E-03

8900

36.5

9689.0367.20156898029828E+03

2.48431019701722E-03

7450

37.5

8164.337

6.08867300853392E+03

1.13269914660783E-04

6100

38.5

6763.838

4.95000000000000E+03

0.00000000000000E+00

4950

39.5

5515.039

22#p (Pa)#

JRA-55 Product Users' Handbook
Model grid data
Table 7-2

Model levels from 40 to 60.

Half level

Full level

A (Pa)B

p (Pa)#

p (Pa)#

4.00000000000000E+03

0.00000000000000E+00

4000

40.5

4466.640

3.23000000000000E+03

0.00000000000000E+00

3230

41.5

3608.141

2.61000000000000E+03

0.00000000000000E+00

2610

42.5

2914.542

2.10500000000000E+03

0.00000000000000E+00

2105

43.5

2353.0431.70000000000000E+03

0.00000000000000E+00

1700

44.5

1898.9441.37000000000000E+03

0.00000000000000E+00

1370

45.5

1532.045

1.10500000000000E+03

0.00000000000000E+00

1105

46.5

1235.146

8.93000000000000E+02

0.00000000000000E+00

893

47.5

997.1

47

7.20000000000000E+02

0.00000000000000E+00

720

48.5

804.9

48

5.81000000000000E+02

0.00000000000000E+00

581

49.5

649.3

49

4.69000000000000E+02

0.00000000000000E+00

469

50.5

524.0

50

3.77000000000000E+02

0.00000000000000E+00

377

51.5

422.2

51

3.01000000000000E+02

0.00000000000000E+00

301

52.5

338.3

52

2.37000000000000E+02

0.00000000000000E+00

237

53.5

268.4

53

1.82000000000000E+02

0.00000000000000E+00

182

54.5

208.9

54

1.36000000000000E+02

0.00000000000000E+00

136

55.5

158.4

55

9.70000000000000E+01

0.00000000000000E+00

97

56.5

116.0

56

6.50000000000000E+01

0.00000000000000E+00

65

57.5

80.5

57

3.90000000000000E+01

0.00000000000000E+00

39

58.5

51.5

58

2.00000000000000E+01

0.00000000000000E+00

20

59.5

29.0

59

0.00000000000000E+00

0.00000000000000E+00

0

60.5

10.0

60

7.2. Isentropic coordinates
Isentropic fields are produced for 21 isentropic surfaces (270, 280, 290, 300, 310, 320,
330, 340, 350, 360, 370, 380, 390, 400, 425, 450, 475, 550, 650, 750 and 850 K) except
specific humidity, which is produced for 14 levels from 270 to 400 K only.

7.3. Soil layers of the land surface model
Porosities and thicknesses of soil layers of the land surface model are defined foreach type of vegetation shown in Table 7-3 as follows:23

JRA-55 Product Users' Handbook
Model grid data
Table 7-3
CodefigureSoil layers of the land surface model.
Thickness (m)Porosity(m3 m-3)

Top (#1)

M iddle (#2)

Bottom (#3)

0

n/a

n/a

n/a

n/a

1

0.42

0.02

1.48

2

2

0.42

0.02

1.48

2

3

0.42

0.02

1.48

2

4

0.42

0.02

1.48

2

5

0.42

0.02

1.48

2

6

0.42

0.02

0.47

1

7

0.42

0.02

0.47

1

8

0.4352

0.02

0.47

1

9

0.4352

0.02

0.17

0.3

10

0.42

0.02

0.17

1

11

0.4352

0.02

0.17

0.3

12

0.4577

0.02

0.47

1

13

0.43521

1

1

8. Physical constants
The fundamental physical constants used in the forecast model are as follows:
Table 8-1

Physical constants.
Quantity

Value

Stefan-Boltzmann constant σ

5.67 x 10-8 W m-2 K-4

Earth's radius

6.371 x 106 m

Angular speed of Earth's rotation

7.29245 x 10-5 rad s -1

Gravitational acceleration

9.80665 m s -2

Gas constant for dry air

287.04 J K-1 kg-1

Specific heat of dry air at constant pressure c p1004.6 J K-1 kg-1

Latent heat of vaporization

2.507 x 106 J kg-1

Solar constant1365 W m-2

9. Monthly statistics
9.1. Monthly statistics for fixed hours (Monthly_diurnal)
Monthly averages and variances are produced for each of the output hours at 00, 06, 12
and 18 UTC (and 03, 09, 15 and 21 UTC when available), and are referred to as monthly
statistics for fixed hours (Monthly_diurnal).

24JRA-55 Product Users' Handbook
Model grid data
Table 9-1 shows the meanings of the time range indicator encoded in Octet 21 ofSection 1.

9.2. Monthly statistics (Monthly)
Averages and variances for the whole month are also produced using only six-hourly
data for analyzed and instantaneous forecast fields and averages from the beginning of
forecasts up to six hours for average diagnostic fields. These statistics are referred to as
monthly statistics (Monthly).
Table 9-1 shows the meanings of the time range indicator encoded in Octet 21 ofSection 1.
Table 9-1

Time range indicator for monthly statistics.

Code
M eaning
figure113 Average of N forecasts (or initialized analyses); each product has forecast period of P1 (P1 = 0
for initialized analyses); products have reference times at intervals of P2, beginning at the givenreference time
123 Average of N uninitialized analyses, starting at the reference time, at intervals of P2
128 Average of N forecast products with a valid time ranging between reference time + P1 andreference time + P2; products have reference times at Intervals of 24 hours, beginning at thegiven reference time
129 Temporal variance of N forecasts; each product has valid time ranging between reference time
+ P1 and reference time + P2; products have reference times at intervals of 24 hours, beginningat the given reference time; unit of measurement is square of that in Code Table 2
130 Average of N forecast products; each product has a forecast period from P1 to P2; products
have reference times at intervals of P2 - P1, beginning at the given reference time; thus the N
products cover a continuous time span.
131 Temporal variance of N forecasts; valid time of the first product ranges between R + P1 and R+ P2, where R is reference time given in octets 13 to 17, then subsequent products have valid
time range at interval of P2 – P1; thus all N products cover continuous time span; products
have reference times at intervals of P2 - P1, beginning at the given reference time; unit ofmeasurement is square of that in Code Table 2
132 Temporal variance of N uninitialized analyses (P1 = 0) or instantaneous forecasts (P1 > 0);each product has valid time at the reference time + P1; products have reference times atintervals of P2, beginning at the given reference time; unit of measurement is square of that in
Code Table 2

10.

Climatological normals

Climatological normals have been calculated for the period from 1991 to 2020 using
the methods described below.

10.1. Daily mean smooth climatological normals
This calculation involves two steps. In the first, daily values are computed using
six-hourly values for analysis and instantaneous forecast fields and averages from the25

JRA-55 Product Users' Handbook
Model grid data
beginning of forecasts up to six hours for average diagnostic fields, and a simple
average is then taken for the base period for each day of the year except leap days. In
the second, Lanzcos low-pass filtering (Duchon 1979) with 121-term weight factors anda 60-day cutoff is applied to the time sequence of daily values to treat thehigh-frequency variation remaining in the daily values calculated in the first step.
Climatological normals for leap days are derived by averaging the smoothclimatological normals for 28th February and 1st March.
The concept of this method is quite simple. It should be noted that monthly means
calculated from daily means do not coincide with those outlined above due to thedifference in treatment for leap days and with the presence or absence of filtering.

10.2. Monthly mean climatological normals
Monthly mean climatological normals are calculated by simply averaging historicalmonthly mean values.

11.

Production streams

The JRA-55 production was organized into several streams as shown in Table 11-1 inorder to shorten the time taken. Separate stream names are also assigned for cases inwhich data assimilation cycles were rerun or secondary products were recalculated.
These stream names are encoded in Octets 46 - 49 of Section 1.
There are three discontinuities among the streams in Table 11-1 at 00 UTC on 1 July
1958 (A003/A002), 00 UTC on 1 September 1980 (A004/B002) and 00 UTC on 1
October 1992 (B003/B002). For other stream changeovers, subsequent streams were
initiated from the last data of the preceding streams.

26

JRA-55 Product Users' Handbook
Model grid data
Table 11-1

Production streams of JRA-55.

StreamPeriodSection 1
Octets
46-49
AE03

A003

A002

A004

B002

B003

until
30 Jun 1958

AR03
A003

other parameters

A002

same as AE03
same as AR03, and
anl_isentrop (until 31 Dec 1972)
other parameters

1 Dec 1974
to
31 Aug 1980

AE04

same as AE03

AR04

same as AR03

A004

other parameters

1 Sep 1980
to31 M ay 1987

BE02

same as AE03

BR02

same as AR03, and anl_isentrop

B002

other parameters

BE03

same as AE03

BR03

same as AR03

B003

other parameters

BE02

same as AE03, but until 31 Dec 2012
same as AR03, but until 31 Dec 2012, and
anl_isentrop (until 31 Jan 2000)
other parameters

1 Jul 1958
to30 Nov 1974

1 Jun 1987
to30 Sep 1992

AR02

BR02

B004

1 Jan 2014
to3 Jun 2018
18UTC

B004

B005

3 Jun 2018
21UTC
onward12.

fcst_column125 (thermal energy fluxes)
fcst_p125 (cloud liquid water, cloud ice, ozone mixing ratio)
fcst_phy3m125
anl_isentrop125
fcst_column125 (other than thermal energy fluxes)
fcst_phy2m125
fcst_surf125 (surface roughness, brightness temperature)

AE02

1 Oct 1992
to
31 Dec 2013

B002

Note

B002

BR05

fcst_surf125 (from 4 Jun 2018 to 7 Oct 2018)

B005

other parameters

Differences from JRA-25 products

12.1. Parameter classification
JRA-25 products contained categories in which two- and three-dimensional fields were
put together. They are output into separate categories in JRA-55 products, and files ofthree-dimensional fields are divided into individual parameters except land surface fields.

27JRA-55 Product Users' Handbook
Model grid data
Table 12-1

Example of category change (for anl_mdl).

JRA-25JRA-55Model level analysis fields
anl_mdl_hgt (geopotential height)

anl_mdl

anl_mdl_tmp (temperature)…
Surface analysis fields
anl_surf

JRA-25 products contained categories in which instantaneous, average and extreme
fields were put together. These are output into separate categories in JRA-55 products.
Table 12-2

Example of category change (for fcst_phy2m).

JRA-25JRA-552-dimensional average diagnostic fields
fcst_phy2m

fcst_phy2m2-dimensional instantaneous diagnostic fields
fcst_surf
2-dimensional extreme fields 1
minmax_surf

1Extreme fields are produced for daily model grid data only; they are not produced for monthly statistics orlatitude/longitude grid data.

12.2. Dates in file names
In JRA-25 products, dates in file names indicated valid times for instantaneous fields
and the end of the averaging period for average diagnostic fields. In JRA-55 products,
dates in file names indicate the beginning of the averaging period.
Table 12-3

Example of file name date change (for fcst_phy2m.1981010100).
Valid timeJRA-25 from 18UTC on 31 Dec 1980 to 00UTC 1 Jan 1981
JRA-55 from 00 to 03UTC on 1 Jan 1981

12.3. Parameter additions and changes
Parameters added to JRA-55 products are indicated by a superscript + in the parameter
tables of Chapter 4.
Some parameters have been switched from average forecast fields to instantaneous
forecast fields in JRA-55 products. These are indicated by a superscript *.

28

JRA-55 Product Users' Handbook
Model grid data

12.4. Discontinued parameters
Table 12-4

Discontinued parameter in isentropic analysis fields (anl_isentrop).

CodefigureField parameter

Unit

11 Temperature

Table 12-5

K

Discontinued parameter in model level forecast fields (fcst_mdl).

CodefigureField parameter

Unit

52 Relative humidity

Table 12-6

Proportion

Discontinued parameters in two-dimensional diagnostic fields (fcst_phy2m).

Code
Field parameter
figure2 Pressure reduced to M SL (mean)

Unit
Pa

Level
M ean sea level

ms

-1

10m

137 v-component of wind (mean, surface)

ms

-1

10m

138 Temperature (mean, surface)K

136 u-component of wind (mean, surface)2m-1

139 Specific humidity (mean, surface)

kg kg

2m

80 Water temperature

K

Water surface

218 M oist process heating rate

W m-2

Entire atmosphere(considered as a single layer)

168 Frequency of precipitation%

Ground or water surface

169 Frequency of cumulus precipitation%

Ground or water surface

200 Zonal temperature flux

K Pa m s-1

201 M eridional temperature flux

K Pa m s-1

219 M aximum wind speed

m s-1

220 M aximum hourly precipitation

mm hour-1

76 Cloud waterkg m-2#

Entire atmosphere(considered as a single layer)
Entire atmosphere(considered as a single layer)
Lowermost hyblid level
Ground or water surface
Entire atmosphere(considered as a single layer)# In JRA-55 products, SST is output as brightness temperature in the Two-dimensional instantaneous diagnostic fields(fcst_surf).
Table 12-7

Discontinued parameters in three-dimensional diagnostic fields (fcst_phy3m).

Codefigure76 Cloud water

Field parameter

Unit
kg m-2175 Geopotential height (mean)gpm

176 u-component of wind (mean)m s-1

177 v-component of wind (mean)m s-1

178 Vertical velocity (mean)

Pa s-1179 Temperature (mean)K

180 Specific humidity (mean)

kg kg-1

29

JRA-55 Product Users' Handbook
Model grid data
Table 12-8

Discontinued parameter in land surface diagnostic fields (fcst_phyland).

CodefigureField parameter

86 Soil moisture content

Unit

Level

Proportion

Underground layers

12.5. Output interval
Most JRA-25 products were output at six-hourly intervals. In JRA-55 products, land
surface and two-dimensional forecast fields are output at three-hourly intervals.

12.6. Vertical coordinates
12.6.1. Hybrid coordinates
In JRA-25 products, model level fields were produced for 40 hybrid levels. In JRA-55
products, they are produced for the 60 hybrid levels listed in Section 7.1.

12.6.2. Isentropic coordinates
In JRA-25 products, isentropic fields were produced for 20 isentropic surfaces (270,280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 425, 450, 475, 550, 650
and 750 K). In JRA-55 products, they are produced for the 21 isentropic surfaces listed in
Section 7.2 (850 K has been added).

12.7. Monthly statistics
Monthly statistics for JRA-25 products were saved in 4-byte big-endian floating point
format. For JRA-55 products, they are saved in GRIB Edition 1 format (WMO 2011) inthe same way as daily data.
While only monthly averages were produced in JRA-25 products, variances are also
produced in JRA-55 products except for land surface and two-dimensional averagediagnostic fields. Variance files are indicated by “_var” at the end of file names (Table
3-1).

References
Duchon, C. E. (1979). Lanczos filtering in one and two dimensions. J. Appl. Meteor., 18,1016-1022.
Ebita, A., S. Kobayashi, Y. Ota, M. Moriya, R. Kumabe, K. Onogi, Y. Harada, S. Yasui,
K. Miyaoka, K. Takahashi, H. Kamahori, C. Kobayashi, H. Endo, M. Soma, Y.
Oikawa, and T. Ishimizu. (2011). The Japanese 55-year Reanalysis “JRA-55”: an30

JRA-55 Product Users' Handbook
Model grid datainterim report. SOLA, 7, 149-152. (This article is an interim report of JRA-55 asof 2011. Please refer Kobayashi et al. (2015) for the JRA-55 comprehensive
report.).
Kobayashi, S., Y. Ota, Y. Harada, A. Ebita, M. Moriya, H. Onoda, K. Onogi, H.
Kamahori, C. Kobayashi, H. Endo, K. Miyaoka, and K. Takahashi. (2015). The
JRA-55 reanalysis: General specifications and basic characteristics. J. Meteor.
Soc. Japan, 93, 5-48.
Onogi, K., J. Tsutsui, H. Koide, M. Sakamoto, S. Kobayashi, H. Hatsushika, T.
Matsumoto, N. Yamazaki, H. Kamahori, K. Takahashi, S. Kadokura, K. Wada, K.
Kato, R. Oyama, T. Ose, N. Mannoji, and R. Taira. (2007). The JRA-25 reanalysis.
J. Meteor. Soc. Japan, 85, 369−432.
Simmons, A. J., and D. M. Burridge. (1981). An energy and angular-momentum
conserving vertical finite-difference scheme and hybrid vertical coordinates. Mon.
Wea. Rev., 109, 758-766.
WMO.
(2011).
Manual
on
codes
I.2.
Retrievedfrom
http://www.wmo.int/pages/prog/www/WMOCodes/WMO306_vI2/VolumeI.2.ht
ml31