DSJRA-55 Product Users’
Handbook
Climate Prediction Division
Global Environment and Marine Department
Japan Meteorological Agency
July 2017

DSJRA-55 Product Users’ Handbook

Change recordVersion
1.0

Date
13 July 2017

Remarks
First version

2

DSJRA-55 Product Users’ Handbook

Contents
1.

Introduction ............................................................................................................... 5

2.

Downscaling method ................................................................................................. 53.

File format ................................................................................................................. 64.

File names .................................................................................................................. 6

5.

Output parameters...................................................................................................... 7
5.1.

Land surface boundary conditions (bnd_land) ................................................. 7

5.2.

Surface boundary conditions (bnd_surf) .......................................................... 75.3.

Land surface forecast fields (fcst_land)............................................................ 85.4.

Isobaric forecast fields (fcst_p) ........................................................................ 85.5.

Two-dimensional average diagnostic fields (fcst_phy2m) ............................... 85.6.

Two-dimensional instantaneous diagnostic fields (fcst_surf) .......................... 9

5.7.

Land and sea surface conditions ..................................................................... 10

5.7.1. Land and sea surface conditions for instantaneous fields (kind) ................ 105.7.2. Land and sea surface conditions for average fields (kind_phy) ................. 106.

Invariant data ........................................................................................................... 116.1.

Topographical information (Lambert5km_land) ............................................ 11

6.2.

Latitude/longitude information (Lambert5km_latlon) ................................... 11

7.

Code table ................................................................................................................ 117.1.

Code table JMA4.10: Meso-Scale Model surface conditions (KIND) ........... 11

8.

Grid .......................................................................................................................... 129.

Vertical coordinates ................................................................................................. 129.1.

10.

Isobaric coordinates ........................................................................................ 12
Physical constants ............................................................................................... 12References ...................................................................................................................... 133

DSJRA-55 Product Users’ Handbook

List of figure
Figure 2-1 Timelines illustrating the flow of DSJRA-55 calculation ...................... 5

List of tables
Table 4-1 Naming convention .................................................................................. 6
Table 4-2 Sample file names (1st January 1981, 03 UTC) ....................................... 7
Table 5-1 Parameter of land surface boundary conditions (bnd_land) .................... 7
Table 5-2 Parameter of surface boundary conditions (bnd_surf) ............................. 7
Table 5-3 Parameter of land surface forecast fields (fcst_land) ............................... 8
Table 5-4 Parameters of isobaric forecast fields (fcst_p) ......................................... 8
Table 5-5 Parameters of two-dimensional average diagnostic fields (fcst_phy2m) 9
Table 5-6 Parameters of two-dimensional instantaneous diagnostic fields(fcst_surf) ......................................................................................................... 9
Table 5-7 Parameter of land and sea surface conditions for instantaneous fields(kind) .............................................................................................................. 10
Table 5-8 Parameter of land and sea surface conditions for average fields(kind_phy) ...................................................................................................... 11
Table 6-1 Parameters of topographical information (Lambert5km_land).............. 11
Table 6-2 Parameters of latitude/longitude information (Lambert5km_latlon) ..... 11
Table 7-1 Code table JMA4.10: Meso-Scale Model surface conditions (KIND) .. 11
Table 8-1 Grid ........................................................................................................ 12
Table 10-1 Physical constants ................................................................................ 134

DSJRA-55 Product Users’ Handbook

1. Introduction
To help clarify climatic characteristics (such as trends of extreme phenomena) andsupport case studies on extreme meteorological events in Japan, the Japan
Meteorological Agency (JMA) conducted DSJRA-55 (a regional downscaling based on
the Japanese 55-year Reanalysis (JRA-55, Kobayashi et al. 2015) for initial andboundary conditions) for the period from 1958 to 2012 to produce a climate dataset witha horizontal resolution of 5 km that appropriately represents phenomena associated withJapan’s uneven terrain (Kayaba et al. 2016). This handbook provides an overview of theproduct derived from DSJRA-55.

2. Downscaling method
The DSJRA-55 product is based on time integration from six-hourly JRA-55 analysis
fields as initial conditions with the JMA operational Meso-Scale Model (MSM) as ofNovember 2012 (JMA 2013).
These initial conditions do not incorporate cloud physics variables for the MSM. As
certain integration hours are needed for the MSM to produce appropriate precipitation
data from such initial conditions, there is a tendency for insufficient production of
precipitation data at the beginning of forecast integrations. One way to circumvent thisissue is to perform a spin-up run covering a period of three to six hours immediately

Figure 2-1 Timelines illustrating the flow of DSJRA-55 calculation
Grey dots: output hours for boundary conditions; red dots: starting hours of averaging periods for averagediagnostic fields; black circles: output hours for instantaneous fields. The first three hours immediately after thestart of forecasts are allotted to spin-up runs both for the 15-km resolution MSM (as per the 5-km resolution
MSM, except with a horizontal resolution of 15 km) and the 5-km resolution MSM.

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DSJRA-55 Product Users’ Handbook

after the start of forecasts. JRA-55 analysis fields, which have a horizontal resolution of55 km, are also too coarse for the initial and boundary conditions adopted for the 5-km
resolution MSM, and terrain differences would produce non-negligible noise in forecast
fields. Thus, boundary conditions with intermediate resolution are necessary for areas inbetween. Accordingly, in DSJRA-55, the 15-km resolution MSM (as per the 5-km
resolution MSM except with a horizontal resolution of 15 km) is first employed in theformulation of 12-hour forecasts from JRA-55 analysis fields. Next, 3- to 12-hour
forecast fields are used as initial and boundary conditions for 9-hour forecasts based onthe 5-km MSM. Data on the resulting 3- to 9-hour forecast fields are then provided in
the form of the DSJRA-55 product (Figure 2-1). It should be noted that DSJRA-55
consists of 6 – 12 h forecasts with respect to the JRA-55 analysis, and may therefore
contain forecast errors equivalent to those observed in 6 – 12 h forecasts of theoperational MSM (JMA 2013).

3. File format
The DSJRA-55 product is encoded in Gridded Binary (GRIB) Edition 2 format(WMO 2015) except for latitude/longitude information (Lambert5km_latlon) (Section
6.2). Output is category-based at hourly and six-hourly intervals.
Latitude/longitude information is saved in 4-byte big-endian floating-point format.

4. File names
DSJRA-55 product file names follow the convention shown in Table 4-1, and eachfile contains one time-step data point. Dates in file names are in UTC. Table 4-2 shows
sample file names (for 1st January 1981, 03 UTC).
Table 4-1 Naming convention
TypeFilename

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

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

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DSJRA-55 Product Users’ Handbook

Table 4-2 Sample file names (1st January 1981, 03 UTC)Type

2D fields

3D fields

Filename
bnd_land.1981010103
bnd_surf.1981010103
fcst_land.1981010103
fcst_phy2m.1981010103
fcst_surf.1981010103
kind.1981010103
kind_phy.1981010103
fcst_p_tmp.1981010103
fcst_p_depr.1981010103
fcst_p_totcon.1981010103
fcst_p_ugrd.1981010103
fcst_p_vgrd.1981010103
fcst_p_vvel.1981010103
fcst_p_dzdt.1981010103
fcst_p_relv.1981010103
fcst_p_hgt.1981010103
fcst_p_cdca.1981010103

5. Output parameters1
5.1. Land surface boundary conditions (bnd_land)
Land surface boundary conditions (Table 5-1) are output at the initial time of each
forecast (at 03, 09, 15 and 21 UTC as indicated by the gray dots in Figure 2-1) and kept
constant during each forecast (for nine hours).
Table 5-1 Parameter of land surface boundary conditions (bnd_land)

Codefigures
2,0,Parameter
1

Units

Surface roughnessm

5.2. Surface boundary conditions (bnd_surf)
Surface boundary conditions (Table 5-2) are output at the initial time of each forecast(at 03, 09, 15 and 21 UTC as indicated by the gray dots in Figure 2-1) and kept constantduring each forecast (for nine hours).
Table 5-2 Parameter of surface boundary conditions (bnd_surf)

Codefigures
0, 19,

1

Parameter
1

Units

Albedo%The code figures in the tables indicate discipline, parameter category and parameter number.

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DSJRA-55 Product Users’ Handbook

5.3. Land surface forecast fields (fcst_land)
Soil temperature to a depth of 0.04 m (Table 5-3) for land areas and sea surface
temperature for sea areas are output on an hourly basis.
Table 5-3 Parameter of land surface forecast fields (fcst_land)
Codefigures

2,Parameter

3, 18

Units

Soil temperature

Note
Soil temperature of thelayer within the depth of
0.04 m over land and sea
surface temperature oversea

K

5.4. Isobaric forecast fields (fcst_p)
The parameters listed in Table 5-4 are vertically interpolated onto the isobaric
surfaces listed in Section 9.1 except relative vorticity, which is interpolated onto the 850,
700 and 500 hPa isobaric surfaces only. These fields are output every hour.
Table 5-4 Parameters of isobaric forecast fields (fcst_p)
Codefigures

Parameter

Units

0,0,0

Temperature

K0,0,7

Dewpoint depression (or deficit)

K

Filename
fcst_p_tmp
fcst_p_depr-10,1, 80

Total condensate

kg kg

0,2,2

u-component of wind

m s

-1

fcst_p_ugrd

0,2,3

v-component of windm s-1

fcst_p_vgrd

0,

2,8

Vertical velocity (pressure)Pa sfcst_p_vvel

0,2,

9

Vertical velocity (geometric)

-1

m s

fcst_p_dzdt

0,2, 12

Relative vorticity-1

fcst_p_relv

0,3,5

Geopotential heightsgpm

0,6,7

Cloud amount%fcst_p_cdca-1

fcst_p_totcon

fcst_p_hgt

5.5. Two-dimensional average diagnostic fields (fcst_phy2m)
Two-dimensional average diagnostic fields (Table 5-5) are produced every hour.
Dates in file names indicate the beginning of the averaging period.

8DSJRA-55 Product Users’ Handbook

Table 5-5 Parameters of two-dimensional average diagnostic fields (fcst_phy2m)
Codefigures
0, 0, 10Latent heat net flux

0,Sensible heat net flux

0, 11Parameter

Units-2-2-2s-2s-2s

1, 52

Total precipitation rate

kg m

1, 65

Rain precipitation rate

kg m0,1, 66

Snow precipitation rate
Graupel (snow pellets) precipitation
rate
Downward short-wave radiation flux

kg m

1, 75

0,4,7-2kg m-1

Ground or water surface-1

Ground or water surface-1

Ground or water surface-1

Ground or water surface

s-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface-2

Ground or water surface
Nominal top of theatmosphere
Nominal top of theatmosphere
Nominal top of theatmosphereW m0,4,8Upward short-wave radiation flux

W m

0,5,3

Downward long-wave radiation flux

W m0,5,4

Upward long-wave radiation flux

W m-20,4,7

Downward short-wave radiation flux

W m

0,4,8

Upward short-wave radiation flux

W m

0,5,4

Upward long-wave radiation flux

W m

5.6. Two-dimensional(fcst_surf)

Ground or water surface

W m0,0,Ground or water surface

W m0,

Level

-2-2

instantaneous

diagnostic

fields

Two-dimensional instantaneous diagnostic fields (Table 5-6) are produced everyhour.
Table 5-6 Parameters of two-dimensional instantaneous diagnostic fields (fcst_surf)
Codefigures

Parameter

Units
-2

Level

0,2, 17

Momentum flux, u-component

N m0,2, 18

Momentum flux, v-component

0,3,Pressure

N mPa

Ground or water surface

0,

3, 18

Planetary boundary layer heightmGround or water surface

0,6,3

Low cloud cover%Surface to 0.85 * P s

0,

6,

4

Medium cloud cover

%

0,6,5

High cloud cover

%

0,1,

3

Precipitable water

kg m

0,1, 69

Total column integrated cloud water

0,6,1

Total cloud coverkg m%

Entire atmosphere

0,3,0PressurePa

Mean sea level

0,0,0Temperature

K

1.5 m

0,0,

7

Dewpoint depression (or deficit)

K

1.5 m

0,2,2u-component of windm s0,2,3v-component of windm s0-2Ground or water surface

0.85 * P s to min(500 hPa,-29

Ground or water surface-20.68 * P s)min(500 hPa, 0.68 * P s)
to 100 hPa
Entire atmosphere
Entire atmosphere

-1

10 m

-110 mDSJRA-55 Product Users’ Handbook

5.7. Land and sea surface conditions
Land and sea surface conditions are kept constant during each forecast (for ninehours). There are two types of land and sea surface conditions: one for instantaneousfields (land surface forecast fields, isobaric forecast fields and two-dimensional
instantaneous diagnostic fields) and the other for average fields (two-dimensional
average diagnostic fields). Both are stored as hourly data and, their content is identicalfor all hours except 00, 06, 12 and 18 UTC. The difference arises from the fact that theinitial time differs between the two at these hours, with instantaneous fields (blackcircles in Figure 2-1) being nine-hour forecasts started nine hours previously andaverage fields (red dots in Figure 2-1) being forecasts averaged over three to four hours
with a start time three hours before. At hours other than 00, 06, 12 and 18 UTC, surface
conditions for instantaneous and average fields are identical.

5.7.1. Land and sea surface conditions for instantaneous fields(kind)
The land and sea surface conditions for instantaneous fields (kind) (Table 5-7) can beused to check land and sea surface conditions for land surface forecast fields (fcst_land),isobaric forecast fields (fcst_p) and two-dimensional instantaneous diagnostic fields(fcst_surf).
Details of the Meso-Scale Model surface conditions (KIND) in Table 5-7 are given inSection 7.1.
Table 5-7 Parameter of land and sea surface conditions for instantaneous fields (kind)

Codefigures
2,192,Parameter0UnitsMeso-Scale Model surface condition(KIND)(Code table
JMA4.10)5.7.2. Land and sea surface conditions for average fields(kind_phy)
The land and sea surface conditions for average fields (kind_phy) (Table 5-8) can beused to check land and sea surface conditions for two-dimensional average diagnosticfields (fcst_phy2m).
Details of the Meso-Scale Model surface conditions (KIND) in Table 5-7 are given inSection 7.1.

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DSJRA-55 Product Users’ Handbook

Table 5-8 Parameter of land and sea surface conditions for average fields (kind_phy)

Codefigures
2,192,Parameter0UnitsMeso-Scale Model surface condition(KIND)(Code tableJMA4.10)

6. Invariant data
6.1. Topographical information (Lambert5km_land)
Table 6-1 shows the parameters of topographical information (Lambert5km_land).
Table 6-1 Parameters of topographical information (Lambert5km_land)
Codefigures

Parameter

Units

Level2,0,0Land cover (0 = sea, 1 = land)

Proportion Ground or water surface

2,0,

7

Model terrain heightmGround or water surface

6.2. Latitude/longitude information (Lambert5km_latlon)
Latitude/longitude information (Lambert5km_latlon) (Table 6-2) is saved in 4-byte
big-endian floating-point format. Details of the grid are given in Section 8.
Table 6-2 Parameters of latitude/longitude information (Lambert5km_latlon)
Byte No.
(1)～(ParameterUnits721*577)

LatitudeDegree(721*577+1)～(2*721*577)

LongituteDegree

7. Code table
7.1. Code table JMA4.10: Meso-Scale Model surface conditions(KIND)
The surface conditions listed in Table 7-1 are defined for DSJRA-55.
Table 7-1 Code table JMA4.10: Meso-Scale Model surface conditions (KIND)
Codefigure

Meaning0

Reserved

1

Land with no snow

2

Sea with no ice

3

Snow over land

4

Sea ice

5–254

Reserved255

Missing11DSJRA-55 Product Users’ Handbook

8. Grid
Table 8-1 describes the grid used for the MSM.
Table 8-1 Grid

Map projection

Lambert conformal conic
Earth assumed spherical withradius = 6371 km
721

Shape of the EarthNx – number of points along the x-axis
Ny – number of points along the y-axis
Longitude of meridian parallel to y-axis
along which latitude increases as the ycoordinate increases
Grid length577
140 °E
5 km
The first 721 words contain data
for the northernmost line,
starting from the west edge
toward the east at intervals of
5 km. The remaining lines follow
at intervals of 5 km toward thesouth.

Scanning modeFirst latitude from the pole at which thesecant cone cuts the sphere
Second latitude from the pole at which thesecant cone cuts the sphere
Reference grid point(position from the west edge on the x-axis,
position from the north edge on the y-axis)
Latitude/longitute of the reference gridpoint

60 °N
30 °N
(489, 409)
(140 °E, 30 °N)

9. Vertical coordinates
9.1. Isobaric coordinates
Isobaric fields are produced for 16 isobaric surfaces (1000, 975, 950, 925, 900, 850,800, 700, 600, 500, 400, 300, 250, 200, 150 and 100 hPa) except for relative vorticity,which is produced only for 850, 700 and 500 hPa.

10.

Physical constants

Table 10-1 shows the fundamental physical constants used in the MSM.

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DSJRA-55 Product Users’ Handbook

Table 10-1 Physical constants
Quantity

Value-8

Stefan-Boltzmann constant σ-25.67 x 10-4

W mK

6

Earth's radius

6.371 x 10 m

Angular speed of Earth's rotation

7.292 x 10-5

-1

rad s-2

Gravitational acceleration

9.80665 m sGas constant for dry air

287.05 J K-1-1kg-1

Specific heat of dry air at constant pressure c p1004.675 J KSpecific heat of water

4187.0 J K

-1

kg

-1

kg

-1-1

kg

-1

Specific heat of ice

2093.0 J K

Latent heat of vaporization

2.5 x 10 J kg

6-1

5-1

Latent heat of fusion

3.336 x 10 J kg

Solar constant1367 W m-2

References
JMA. (2013). Meso-Scale Model (JMA-MSM1206). Outline of the operational
numerical weather prediction at the Japan Meteorological Agency. JMA, Japan,
71-93.

Retrievedfrom

http://www.jma.go.jp/jma/jma-eng/jma-center/nwp/outline2013-nwp/index.htm
Kayaba, N., T. Yamada, S. Hayashi, K. Onogi, S. Kobayashi, K. Yoshimoto, K.
Kamiguchi, and K. Yamashita. (2016). Dynamical Regional Downscaling Using
theJRA-55

Reanalysis(DSJRA-55).

SOLA,

12,

1-5,

http://doi.org/10.2151/sola.2016-001.
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. http://doi.org/10.2151/jmsj.2015-001.
WMO.

(2015).

Manual

on

codes

I.2.

WMO-No.

306.

Retrievedfrom

http://www.wmo.int/pages/prog/www/WMOCodes/WMO306_vI2/VolumeI.2.ht
ml13