JRA-3Q Data Format
1.25-degree latitude/longitude grid data

December 2022
Information Infrastructure Department
Japan Meteorological Agency

Contents
JRA-3Q Data Format 1.25-degree latitude/longitude grid data .................................................... 1
1.

Introduction ........................................................................................................................... 4

2.

Product overview................................................................................................................... 4

3.

GRIB2 format ........................................................................................................................ 4
Section 0 – Indicator section ..................................................................................................... 4
Section 1 – Identification section .............................................................................................. 5
Section 2 – Local use section .................................................................................................... 5
Section 3 – Grid definition section ............................................................................................ 6
Section 4 – Product definition section....................................................................................... 6
Product definition template 4.0 – analysis or forecast at a horizontal level or in a horizontal
layer at a point in time ........................................................................................................... 7
Product definition template 4.8 – average, accumulation and/or extreme values or otherstatistically processed values at a horizontal level or in a horizontal layer in a continuous or
non–continuous time interval ................................................................................................ 7
Section 5 – Data representation section .................................................................................... 8
Data representation template 5.0 – Grid point data – simple packing................................... 9
Data representation template 5.3 – Grid point data – complex packing and spatialdifferencing ........................................................................................................................... 9
Section 6 – Bit-map section ...................................................................................................... 9
Section 7 – Data section ............................................................................................................ 9
Data template 7.0 – Grid point data – simple packing ........................................................ 10
Data template 7.3 – Grid point data – complex packing and spatial differencing............... 10
Section 8 – End section ........................................................................................................... 10

4.

Output parameters ............................................................................................................... 11
4.1.

Surface analysis fields (anl_surf125) ........................................................................... 11

4.2.

Snow depth analysis fields (anl_snow125) .................................................................. 11

4.3.

Isobaric analysis fields (anl_p125) .............................................................................. 11

4.4.

Isentropic analysis fields (anl_isentrop125) ................................................................ 12

4.5.

Land surface analysis fields (anl_land125) .................................................................. 12

4.6.

Two-dimensional instantaneous diagnostic fields (fcst_surf125) ................................ 14

4.7.

Isobaric forecast fields (fcst_p125) .............................................................................. 15

4.8.

Land surface forecast fields (fcst_land125) ................................................................. 15

4.9.

Ocean surface boundary conditions (bnd_ocean125) .................................................. 16

4.10.

Two-dimensional average diagnostic fields (fcst_phy2m125) ................................. 17
2

5.

4.11.

Isobaric average diagnostic fields (fcst_phyp125) ................................................... 18

4.12.

Land surface average diagnostic fields (fcst_phyland125) ...................................... 18

Invariant data ....................................................................................................................... 19
5.1.

Surface geopotential (LL125_surf) .............................................................................. 19

5.2.

Land surface information (LL125_land)...................................................................... 19

6.

Physical constants ............................................................................................................... 19

7.

Climatological normals ....................................................................................................... 19
7.1.

Daily mean smooth climatological normals................................................................. 19

7.2.

Monthly mean climatological normals......................................................................... 20

References ................................................................................................................................... 20

3

1.

Introduction
This document provides an overview of products (1.25-degree latitude/longitude grid data)

stemming from the Japanese Reanalysis for Three Quarters of a Century (JRA-3Q) conducted by
the Japan Meteorological Agency for the period from the late 1940s onward (Kobayashi et al.
2021).

2.

Product overview
1. Latitude/longitude grids
2. Data points: 288 × 145
3. Grid spacing: 1.25 × 1.25 degree
4. Time interval: every 6 hours (hourly or daily for some types), monthly statistics
5. Data volume: approx. 200 GB/year
6. Data format: Gridded Binary Edition 2 (GRIB2)

3.

GRIB2 format
The JRA-3Q product is encoded with GRIB2 as outlined below.
See the Manual on Codes I.2 (WMO 2022) for the information quoted in the tables here.

Section 0 – Indicator section
Octet No.
1-4
5-6
7
8
9-16

Contents
GRIB (coded according to the International Alphabet No.
5)
Reserved
Discipline - GRIB Master table number (see Code table
0.0)
GRIB edition number
Total length of GRIB message in octets (including
Section 0)

4

Value

Notes

GRIB

******
2******

Section 1 – Identification section
Octet No.

Contents

Value

Notes

1-4

Length of section in octets

21

5

Number of section
Identification of originating/generating centre (seeCommon Code table C-11)
Identification of originating/generating subcentre(allocated by originating/ generating centre)
GRIB master table version number (see Common Code table
C-0)
Version number of GRIB Local tables used to augment
Master tables (see Code table 1.1)
Significance of reference time (see Code table 1.2)

1******

Year (4 digits)******

15

Month******

16

Day******

17

Hour******

18

Minute019SecondProduction status of processed data in this GRIB message(see Code table 1.3)
Type of processed data in this GRIB message (see Codetable 1.4)

0

6-7
8-9
10
11
12
13-14

20
21

34

Tokyo (RSMC), Japan
Meteorological Agency

241 Reanalysis project
21

Version implemented on 2
May 2018

1

3 Re-analysis products******

Section 2 – Local use section
Octet No.

Contents

Value

Notes

1-4

Length of section in octets

17
2

5

Number of section

6-7

Local use

8-9

Local use

10-11

Local use

12-13

Local use

14-17

Stream******

5

Section 3 – Grid definition section
Octet No.

Contents

Value

Notes

1-4

Length of section in octets

72

5

Number of section

3

6

Source of grid definition (see Code table 3.0)

0

7-10

Number of data points

11

Number of octets for optional list of numbers

012Interpretation of list of numbers (see Code table 3.11)

0

13-14

41760
There is no appended
list
0 Latitude/longitude

Grid definition template number (see Code table 3.1)

Earth assumed spherical
6 with radius of 6 371
229.0 m15

Shape of the Earth (see Code table 3.2)

16

Scale factor of radius of spherical Earth

17-20

Scaled value of radius of spherical Earth21

Scale factor of major axis of oblate spheroid Earth

22-25

Scaled value of major axis of oblate spheroid Earth26

Scale factor of minor axis of oblate spheroid Earth

27-30

Scaled value of minor axis of oblate spheroid Earth

31-34

Ni - number of points along a parallel

288

35-38

Nj - number of points along a meridian

145

39-42

47-50

Basic angle of the initial production domain
Subdivisions of basic angle used to define extreme
longitudes and latitudes, and direction increments
La1 - latitude of first grid point

51-54

Lo1 - longitude of first grid point

43-46

Specified in Code table
3.1

090000000
056-59

La2 - latitude of last grid point

i direction increments
given
j direction increments
given
0x30 Resolved u- and vcomponents of vector
quantities relative toeasterly and northerly
directions-90000000

60-63

Lo2 - longitude of last grid point

358750000

64-67

Di - i direction increment

1250000

68-71

Dj - j direction increment

1250000

55

72

Resolution and component flags (see Flag table 3.3)

Points of first row orcolumn scan in the +i(+x) direction
Points of first row or
0 column scan in the –j (–y) direction
Adjacent points in i (x)direction areconsecutive

Scanning mode (see Flag table 3.4)

Section 4 – Product definition section
Octet No.

Contents

1-4

Length of section in octets

5

Number of section

6-7
8-9

Value

Notes

******
4

Number of coordinate values after template or number of
information according to 3D vertical coordinate GRIB2
message
Product definition template number (see Code table 4.0)

Product definition template (see template 4.X, where X
10-xx
is the product definition template number given in
octets 8-9)
Optional list of coordinate values or vertical grid[xx+1]-nn
information

60******

From the tenth octet onward, product definition template 4.8 is used for two-dimensional
average diagnostic fields (fcst_phy2m125), isobaric average diagnostic fields (fcst_phyp125),
land surface average diagnostic fields (fcst_phyland125) and monthly statistics (all types), and
4.0 is used elsewhere.
Product definition template 4.0 – analysis or forecast at a horizontal level or in a horizontal
layer at a point in time
Octet No.

Contents

Value

Notes

10

Parameter category (see Code table 4.1)******

11

Parameter number (see Code table 4.2)******

12

Type of generating process (see Code table 4.3)******

13

Background generating process identifier (defined byoriginating centre)

14
15-16
17
18
19-22

Analysis or forecast generating process identifier(defined by originating centre)
Hours of observational data cut-off after reference time
Minutes of observational data cut-off after referencetime
Indicator of unit of time range (see Code table 4.4)

Japanese Reanalysis for
141 Three Quarters of a
Century (JRA-3Q)

65534
0
1 Hour

Forecast time in units defined by octet 18******

23

Type of first fixed surface (see Code table 4.5)******

24

Scale factor of first fixed surface******

25-28

Scaled value of first fixed surface******

29

Type of second fixed surface (see Code table 4.5)******

30

Scale factor of second fixed surface******

31-34

Scaled value of second fixed surface******

Product definition template 4.8 – average, accumulation and/or extreme values or otherstatistically processed values at a horizontal level or in a horizontal layer in a continuous or7non–continuous time interval
Octet No.

Contents

Value

Notes

10

Parameter category (see Code table 4.1)******

11

Parameter number (see Code table 4.2)******

12

Type of generating process (see Code table 4.3)******

13

Background generating process identifier (defined byoriginating centre)

14
15-16

Analysis or forecast generating process identifier(defined by originating centre)
Hours after reference time of data cut-off

17

Minutes after reference time of data cut-off

18

Indicator of unit of time range (see Code table 4.4)

19-22

Japanese Reanalysis for
141 Three Quarters of a
Century (JRA-3Q)

65534
0
1 Hour

Forecast time in units defined by octet 18******

23

Type of first fixed surface (see Code table 4.5)******

24

Scale factor of first fixed surface******

25-28

Scaled value of first fixed surface******

29

Type of second fixed surface (see Code table 4.5)******

30

Scale factor of second fixed surface******

31-34

Scaled value of second fixed surface******

35-36

Year

******

37

Month******

38

Day******

39

Hour******

40

Minute041Secondn - number of time range specifications describing thetime intervals used to calculate the statisticallyprocessed field
Total number of data values missing in statisticalprocess

0

42
43-46

******
047-58 Specification of the outermost (or only) time range over which statistical processing
is done
47
48
49
50-53
54
55-58

Statistical process used to calculate the processed
field from the field at each time increment during thetime range (see Code table 4.10)
Type of time increment between successive fields used in
the statistical processing (see Code table 4.11)
Indicator of unit of time for time range over which
statistical processing is done (see Code table 4.4)
Length of the time range over which statisticalprocessing is done, in units defined by the previous
octet
Indicator of unit of time for the increment between the
successive fields used (see Code table 4.4)
Time increment between successive fields, in units
defined by the previous octet (see Notes 3 and 4)************
1 Hour******
1 Hour******

59-nn These octets are included only if n > 1, where nn = 46 + 12 x n
59-70
71-nn

As octets 47 to 58, next innermost step of processing
Additional time range specifications, included inaccordance with the value of n. Contents as octets 47 to
58, repeated as necessary

Section 5 – Data representation section
Octet No.

Contents

1-4

Length of section in octets

5

Number of section

6-9
10-11
12-nn

Value

Notes

******
5

Number of data points where one or more values are
specified in Section 7 when a bit map is present, total
number of data points when a bit map is absent.
Data representation template number (see Code table 5.0)
Data representation template (see template 5.X, where X
is the data representation template number given in
octets 10-11)8************

From the tenth octet onward, data representation template 5.3 is used for six-hourly, hourly anddaily data, and 5.0 is used for monthly statistics and climatological normals.
Data representation template 5.0 – Grid point data – simple packing
Octet No.

Contents

Value

Notes

12-15

Reference value (R) (IEEE 32-bit floating-point value)******

16-17

Binary scale factor (E)******

18-19

Decimal scale factor (D)Number of bits used for each packed value for simple
packing, or for each group reference value for complex
packing or spatial differencing
Type of original field values (see Code table 5.1)******

20
21******
0 Floating point

Data representation template 5.3 – Grid point data – complex packing and spatial differencing
Octet No.
12-21

Contents

Value

Notes

Same as data representation template 5.0

22Group splitting method used (see Code table 5.4)******

23

Missing value management used (see Code table 5.5)******

24-27

Primary missing value substitute******

28-31

Secondary missing value substituteNG - number of groups of data values into which field is
split
Reference for group widths
Number of bits used for the group widths (after thereference value in octet 36 has been removed)
Reference for group lengths******

Length increment for the group lengths******

True length of last group
Number of bits used for the scaled group lengths (after
subtraction of the reference value given in octets 38-41
and division by the length increment given in octet 42)
Order of spatial differencing (see Code table 5.6)
Number of octets required in the data section to specify
extra descriptors needed for spatial differencing(octets 6-ww in data template 7.3)******

32-35
36
37
38-41
42
43-46
47
48
49

******************************************

Section 6 – Bit-map section
Octet No.

Contents

Value

1-4

Length of section in octets

5

Number of section

6

Bit-map indicator (see Code table 6.0)
Bit-map - Contiguous bits with a bit to data point
correspondence, ordered as defined in Section 3. A bit
set to 1 implies the presence of a data value at thecorresponding data point, whereas a value of 0 implies
the absence of such a value.

7-nn

Notes

******
6************

Section 7 – Data section
Octet No.

Contents

1-4

Length of section in octets

5

Number of section

6-nn

Value

Notes

******
7

Data in a format described by data template 7.X, where X
is the data representation template number given in
octets 10-11 of Section 5.

From the sixth octet onward, data representation template 7.3 is used for six-hourly, hourly and9daily data, and 7.0 is used for monthly statistics and climatological normals.
Data template 7.0 – Grid point data – simple packing
Octet No.
6-nn

Contents
Binary data values - binary string, with each (scaled)data value

Value

Notes

******

Data template 7.3 – Grid point data – complex packing and spatial differencing
Octet No.

Contents
First value(s) of original (undifferenced) scaled data
values, followed by the overall minimum of thedifferences. The number of values stored is 1 greater
6-ww
than the order of differentiation, and the field widthis described at octet 49 of data representation template
5.3
NG group reference values (X1 in the decoding formula),each of which is encoded using the number of bits
specified in octet 20 of data representation template[ww+1]-xx
5.0. Bits set to zero shall be appended where necessary
to ensure this sequence of numbers ends on an octet
boundary
NG group widths, each of which is encoded using thenumber of bits specified in octet 37 of data
[xx+1]-yy representation template 5.2. Bits set to zero shall beappended as necessary to ensure this sequence of numbers
ends on an octet boundary
NG scaled group lengths, each of which is encoded using
the number of bits specified in octet 47 of data[yy+1]-zz representation template 5.2. Bits set to zero shall beappended as necessary to ensure this sequence of numbers
ends on an octet boundary
Packed values (X2 in the decoding formula), where each[zz+1]-nn value is a deviation from its respective group reference
value

Value

Notes

******************************

Section 8 – End section
Octet No.
1-4

Contents“7777” (coded according to the International Alphabet
No. 5)

10

Value
7777

Notes

4.

Output parameters1

4.1.

Surface analysis fields (anl_surf125)

CodefiguresParameter

0,

1, 64

0,

0,

0,

1, 13

0,

3,

Units

Total column integrated
water vapour

kg m

2 Potential temperature-2

K

Water equivalent ofaccumulated snow depth

kg m-20 PressurePa

0,194,

6 Energy stored in light snow J m-2

0,194,

7 Amount of light snow

kg m-20,

3,

1 Pressure reduced to MSL

Pa

0,

0,

0 Temperature

K

0,

0,

7

0,

1,

0 Specific humidity

kg kg

0,

1,

1 Relative humidity

%

0,

2,

2 u-component of wind

m s

-1

0,

2,

3 v-component of wind

m s

-1

Dewpoint depression (ordeficit)

K
-1

Level
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)101 (Mean sea level)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground10m)
103 (Specified heightlevel above ground10m)

Note: The saturated vapor pressure used to calculate dewpoint depression (or deficit) andrelative humidity from specific humidity is the value from over liquid water at a temperature of273.15K or higher, over ice at a temperature of 258.15K or lower, and the weighted average ofthe two with proportions linearly dependent on temperatures between 258.15 and 273.15K.
4.2.

Snow depth analysis fields (anl_snow125)

Codefigures0,

4.3.

ParameterUnits

1, 11 Snow depth

m

Level
1 (Ground or water
surface)

Isobaric analysis fields (anl_p125)

There are 45 isobaric surfaces (1,000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 700,
650, 600, 550, 500, 450, 400, 350, 300, 250, 225, 200, 175, 150, 125, 100, 85, 70, 60, 50, 40, 30,
20, 10, 7, 5, 3, 2, 1, 0.7, 0.3, 0.1, 0.03 and 0.01 hPa).

The code figures in the tables indicate discipline, parameter category and parameter number.
Parameter names conform to the notation of the Manual on Codes I.2 (WMO 2022).
1

11

Code
figures
0,

0,

0,

0,

0,
0,

Parameter

Units

FilenameK

anl_p125_tmp

K

anl_p125_depr

1,0 TemperatureDewpoint depression (or7deficit)0 Specific humidity

1,

1 Relative humidity

%

kg kg

-1

anl_p125_spfh
anl_p125_rh

0,

2,

2 u-component of wind

m s

-1

0,

2,

3 v-component of wind

m s

-1

anl_p125_vgrd

m

2

s

-1

anl_p125_strm

m

2

s

-1

anl_p125_vpot

Pa s-1

anl_p125_vvel

0,2,

4 Stream function

0,2,

5 Velocity potential

0,0,Vertical velocity
2, 8(pressure)2, 12 Relative vorticitys-1

anl_p125_relv-1

anl_p125_reld
anl_p125_hgt

0,2, 13 Relative divergence

s

0,

3,

gpm

5 Geopotential height

anl_p125_ugrd

Note: The saturated vapor pressure used to calculate dewpoint depression (or deficit) andrelative humidity from specific humidity is the value from over liquid water at a temperature of273.15K or higher, over ice at a temperature of 258.15K or lower, and the weighted average ofthe two with proportions linearly dependent on temperatures between 258.15 and 273.15K.
4.4.

Isentropic analysis fields (anl_isentrop125)

There are 36 isentropic surfaces (270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380,
390, 400, 425, 450, 475, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1,000, 1,250, 1,500,
1,750, 2,000, 2,500, 3,000, 3,500 and 4,000K).
Code
figuresParameter

Units

Filename

0,1,

0 Specific humidity

kg kg-1

anl_isentrop125_spfh

0,

2,

2 u-component of wind

m s

-1

anl_isentrop125_ugrd-1

anl_isentrop125_vgrd

0,

2,

3 v-component of wind

m s

0,

2,

6 Montgomery stream function

m2 s-2

anl_isentrop125_mntsf

Pa s-10,

Vertical velocity
2, 8(pressure)2, 14 Potential vorticity

0,

3,

Pa

anl_isentrop125_pres

0,

3,

gpm

anl_isentrop125_hgt

s-2

anl_isentrop125_bvf2

0,

K m

0 Pressure

5 Geopotential height
Square of Brunt-Vaisala
0,194, 38
frequency

4.5.

2

kg

anl_isentrop125_vvel
-1

s

-1

anl_isentrop125_pvort

Land surface analysis fields (anl_land125)

There are seven soil layers (2, 5, 12, 30, 50, 100 and 150 cm from the top).

12

Code
figures2,

ParameterUnits

3,192 Ground temperatureK

2,193,

1 Canopy temperatureK

2,193,

2

2,193,

3 Ice storage on canopy

2,193,

4

Liquid water storage on
groundcoverkg m

2,193,

5 Ice storage on groundcoverkg m-2Liquid water storage on
canopykg m-2kg m-2
-2

2,

0, 38

Soil volumetric ice content 3 -3m m(water equivalent)

2,

3, 10

Liquid volumetric soil
moisture (non-frozen)

2,3, 18 Soil temperature

m3 m-3

K

13

Level
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)106 (Depth below land
surface):106 (Depth
below land surface)
106 (Depth below land
surface):106 (Depth
below land surface)
106 (Depth below land
surface):106 (Depth
below land surface)4.6.

Two-dimensional instantaneous diagnostic fields (fcst_surf125)

CodefiguresParameter

Units

0,

1, 64

Total column integrated
water vapour

kg m

-2

0,

1, 69

Total column integrated
cloud water

kg m

-2

0,

1, 70

Total column integrated
cloud icekg m-20, 14,

0 Total ozone

DU0,1, 11 Snow depth

m

0,

1, 13

0,

2, 30 Frictional velocity

m s-1

0,

3,

Pa

Water equivalent ofaccumulated snow depth

kg m

0 Pressure-20,194,

6 Energy stored in light snow J m-2

0,194,

7 Amount of light snow

kg m

0,

6,

1 Total cloud cover

%

0,

6,

3 Low cloud cover

%

0,

6,

4 Medium cloud cover

%

0,

6,

5 High cloud cover

%

0,

3,

1 Pressure reduced to MSL

Pa

0,

0,

0 Temperature

K

0,

0,

7

0,

1,

0 Specific humidity

kg kg-1

0,

1,

1 Relative humidity

%

0,

2,

2 u-component of wind

m s-1

0,

2,

3 v-component of windm s

Dewpoint depression (ordeficit)

-2

K

-1

Level
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)100 (Isobaric
surface):100 (Isobaric
surface)100 (Isobaric
surface):100 (Isobaric
surface)100 (Isobaric
surface):100 (Isobaric
surface)100 (Isobaric
surface):100 (Isobaric
surface)101 (Mean sea level)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground 2m)
103 (Specified heightlevel above ground10m)
103 (Specified heightlevel above ground10m)

Note: The saturated vapor pressure used to calculate dewpoint depression (or deficit) andrelative humidity from specific humidity is the value from over liquid water at a temperature of273.15K or higher, over ice at a temperature of 258.15K or lower, and the weighted average of14

the two with proportions linearly dependent on temperatures between 258.15 and 273.15K.
4.7.

Isobaric forecast fields (fcst_p125)

There are 45 isobaric surfaces (1,000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 700,
650, 600, 550, 500, 450, 400, 350, 300, 250, 225, 200, 175, 150, 125, 100, 85, 70, 60, 50, 40, 30,
20, 10, 7, 5, 3, 2, 1, 0.7, 0.3, 0.1, 0.03 and 0.01 hPa).
Codefigures
0,

0,

0,

0,

0,
0,

Parameter

UnitsK

fcst_p125_tmp

K

fcst_p125_depr

1,0 TemperatureDewpoint depression (or7deficit)0 Specific humidity

1,

1 Relative humidity

%

kg kg

fcst_p125_ugrd
fcst_p125_vgrd

2,

2 u-component of wind

m s

2,

3 v-component of wind

m s-1

2,

0,

2,

0,

4 Stream function-1

fcst_p125_strm

m2 s-1

fcst_p125_vpot-1

fcst_p125_vvelm5 Velocity potential
Vertical velocity
2, 8(pressure)2, 12 Relative vorticity

fcst_p125_spfh
fcst_p125_rh

0,
0,

-1

-1

0,

0,

Filename

2

s

Pa s
s

-1

fcst_p125_relv-1

fcst_p125_reld
fcst_p125_hgt

0,2, 13 Relative divergence

s

0,

3,

5 Geopotential height

gpm

0,

6,

7 Cloud amount%1 Ozone mixing ratio

kg kg

-1

fcst_p125_o3mr

kg kg

-1

fcst_p125_cwat

0, 14,

0,194, 41 Cloud water

fcst_p125_cdca

Note: The saturated vapor pressure used to calculate dewpoint depression (or deficit) andrelative humidity from specific humidity is the value from over liquid water at a temperature of273.15K or higher, over ice at a temperature of 258.15K or lower, and the weighted average ofthe two with proportions linearly dependent on temperatures between 258.15 and 273.15K.
4.8.

Land surface forecast fields (fcst_land125)

There are seven soil layers (2, 5, 12, 30, 50, 100 and 150 cm from the top).

15

Code
figuresParameter

Units

2,

0,

1 Surface roughnessm2,

3,192 Ground temperatureK

2,193,

1 Canopy temperatureK

2,193,

2

2,193,

3 Ice storage on canopy

2,193,

4

Liquid water storage on
groundcoverkg m-2

2,193,

5 Ice storage on groundcoverkg m-2Liquid water storage on
canopykg m-2kg m-22,

0, 38

Soil volumetric ice content 3 -3m m(water equivalent)

2,

3, 10

Liquid volumetric soil
moisture (non-frozen)

2,3, 18 Soil Temperature

4.9.

m3 m-3K

Level
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)106 (Depth below land
surface):106 (Depth
below land surface)
106 (Depth below land
surface):106 (Depth
below land surface)
106 (Depth below land
surface):106 (Depth
below land surface)

Ocean surface boundary conditions (bnd_ocean125)

There are four layers of sea ice (7, 14, 51 and 78 cm from the top).
CodefiguresParameter

Units

10,

2,

0 Ice cover

Proportion

10,

2,

8 Ice temperature

K

10,

3,

0 Water temperature

K

10,

2,

8 Ice temperature

K

Level
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)160 (Depth below sea
level):160 (Depth
below sea level)

Note: Water temperatures in sea ice areas are estimated from sea ice concentrations.

16

4.10. Two-dimensional average diagnostic fields (fcst_phy2m125)
CodefiguresParameter

Units

Vertically integrated zonal
kg m-1 s-1
water vapour flux
Vertically integrated
0,194, 9 meridional water vapour
kg m-1 s-1
flux
0, 0, 10 Latent heat net flux
W m-2
0,194,8Level
1 (Ground or water
surface): 8 (Nominal
top of the atmosphere)

W m-2

0,

0, 11 Sensible heat net flux

0,

1, 37

0,

1, 52

0,

1, 53

0,

1, 54

0,

1, 79

0,

2, 17 Momentum flux, u-component

N m-2

0,

2, 18 Momentum flux, v-component

N m-2

0,

3,

Convective precipitation
rate
Total precipitation rate
Total snowfall rate waterequivalent
Large scale precipitation
rate
Evaporation rate

kg m-2 s-1
kg m

-2

-1

kg m-2 s-1
kg m-2 s-1
kg m-2 s-1

0 Pressure
Pa
Downward short-wave
0, 4, 7
W m-2
radiation flux
Upward short-wave radiation
0, 4, 8W m-2
flux
Downward short-wave
0, 4, 52
W m-2
radiation flux, clear sky
Upward short-wave radiation-20, 4, 53
W mflux, clear sky
Downward long-wave
0, 5, 3
W m-2
radiation flux
Upward long-wave radiation
0, 5, 4
W m-2
flux
Downward long-wave
0, 5, 8
W m-2
radiation flux, clear sky
Zonal momemtum flux by
0,194, 28
N m-2
short gravity wave
Meridional momemtum flux by
0,194, 29
N m-2
short gravity wave
Zonal momemtum flux by long
0,194, 30
N m-2
gravity wave
Meridional momemtum flux by
0,194, 31
N m-2
long gravity wave
Downward short-wave-20, 4, 7W m
radiation flux
Upward short-wave radiation
0, 4, 8W m-2
flux
Upward short-wave radiation-20, 4, 53
W mflux, clear sky
Upward long-wave radiation
0, 5, 4
W m-2
flux
Net long-wave radiation
0, 5, 6
W m-2
flux, clear sky

17s

1 (Ground or water
surface)

8 (Nominal top of
the atmosphere)4.11. Isobaric average diagnostic fields (fcst_phyp125)
Codefigures0,0,0,Parameter

Units

Temperature tendency due toK s-1
short-wave radiation
Temperature tendency due to
0, 23
K s-1
long-wave radiation-2-1
3, 27 Updraught mass flux
kg m s0, 220,194,

1 Adiabatic heating rate

K s

Large scale condensation
heating rate
0,194, 3 Convective heating rate
Vertical diffusion heating
0,194, 4
rate
0,194, 12 Adiabatic moistening rate
0,194,

2-1

fcst_phyp125_lrghr

K sfcst_phyp125_cnvhr

K s

-1

fcst_phyp125_vdfhr

0,194, 13 Large scale moistening rate kg kg
0,194, 14 Convective moistening rate

-10,194, 20
0,194, 21
0,194, 22
0,194, 23
0,194, 24
0,194, 25
0,194, 26
0,194, 27

fcst_phyp125_umflx-1-1

0,194, 19

fcst_phyp125_ttlwr

K s-1

kg kg

0,194, 18

fcst_phyp125_ttswr

fcst_phyp125_adhr-10,194, 15Filename

kg kg

s

-1

fcst_phyp125_admr

s-1

fcst_phyp125_lrgmrs-1

fcst_phyp125_cnvmr

Vertical diffusion-1-1
kg kg smoistening rate
Adiabatic zonal
-1
-1
m s s
acceleration
Adiabatic meridionalm s-1 s-1
acceleration
Convective zonalm s-1 s-1
acceleration
Convective meridionalm s-1 s-1
acceleration
Vertical diffusion zonalm s-1 s-1
acceleration
Vertical diffusion
m s-1 s-1
meridional acceleration
Orographic gravity wave
m s-1 s-1
zonal acceleration
Orographic gravity wave
-1
-1
m s s
meridional acceleration
Non-orographic gravity wave
-1
-1
m s s
zonal acceleration
Non-orographic gravity wave
-1
-1
m s s
meridional acceleration

fcst_phyp125_vdfmr
fcst_phyp125_aduafcst_phyp125_adva
fcst_phyp125_cnvua
fcst_phyp125_cnvva
fcst_phyp125_vdfua
fcst_phyp125_vdfva
fcst_phyp125_gwdoua
fcst_phyp125_gwdova
fcst_phyp125_gwdnua
fcst_phyp125_gwdnva

4.12. Land surface average diagnostic fields (fcst_phyland125)
CodefiguresParameterUnits2,193,

6 Interception loss

W m-2

2,193,

8 Transpiration

W m-2

2,193,

9 Water runoff

kg m-2 s-1

2,193,

9 Water runoff

kg m-2 s-1

18

Level
1 (Ground or water
surface)1 (Ground or water
surface)1 (Ground or water
surface)106 (Depth below land
surface 349cm)

5.

Invariant data

5.1.

Surface geopotential (LL125_surf)Codefigures0,3,

ParameterUnitsm2 s-2

4 Geopotential

Level
1 (Ground or water
surface)Land surface information (LL125_land)

5.2.

Code
figures2,0,Parameter
0

Units

Land cover (0 = sea, 1 =land)

ProportionLevel
1 (Ground or water
surface)Physical constants

6.

Quantity

Value
-8

W m

6

m

-2

Stefan-Boltzmann constant σ

5.67 x 10

Earth's radius

6.371 x 10

Angular speed of Earth's rotation

7.29245 x 10

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 10

Solar constant1365 W m

6

-5

K

-4

rad s

J kg

-1

-1

-2

Climatological normals

7.

Climatological normals have been calculated for the period from 1991 to 2020 using themethods described below.
7.1.

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 the 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 (Duchon1979) with 121-term weight factors and a 60-day cutoff is applied to the time sequence of daily
values to treat the high-frequency variation remaining in the daily values calculated in the firststep. Climatological normals for leap days are derived by averaging the smooth climatologicalnormals 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 the difference in treatment forleap days and with the presence or absence of filtering.
19

7.2.

Monthly mean climatological normals

Monthly mean climatological normals are calculated by simply averaging historical monthly
mean values.

References
Duchon, C. E., 1979: Lanczos filtering in one and two dimensions. J. Appl. Meteor., 18, 1016–
1022, doi:10.1175/1520-0450(1979)018<1016:LFIOAT>2.0.CO;2.
Kobayashi, S., Y. Kosaka, J. Chiba, T. Tokuhiro, Y. Harada, C. Kobayashi, and H. Naoe, 2021:
JRA-3Q: Japanese Reanalysis for Three Quarters of a Century. Joint WCRP-WWRP Symposium
on Data Assimilation and Reanalysis/ECMWF Annual Seminar 2021, online, 13-17 September
2021, O4-2, https://symp-bonn2021.sciencesconf.org/data/355900.pdf.
WMO, 2022: Manual on Codes I.2. World Meteorological Organization, Geneva, Switzerland,20