Readme document for APHRO_JP_V1207@update

                                                                                                 

 24 July 2017                  

 

1. Introduction

 

  APHRO_JP is a gridded (0.05x0.05 degree) surface precipitation data over the land in Japan. As Kamiguchi et al. (2010, 2011) described, we released daily grid precipitation data and extreme precipitation indices till 2011 (see http://www.chikyu.ac.jp/precip/data/AphroJP_V1207_readme.txt). It was one of the outcomes by the research project titled Asian Precipitation - Highly-Resolved Observational Data Integration Towards Evaluation of Water Resources (APHRODITE). We could launch APHRODITE-2 project during 2016-2019 (http://www.st.hirosaki-u.ac.jp/~aphrodite2/).

 As a first batch of products of APHRODITE-2, we release update of APHRO_JP. We used the same algorithm to make a 0.05 degree daily precipitation with that of above mentioned product. However there are two differences of the current set of products (2009 – 2015) from that of previously released ones; namely

1) We do not contain extreme indices, and

2) We release two different g24-hr accumulation timeh products.

 

 

2. Abstract of each data

 

2.1 Daily precipitation of Japanese local time (AphroJP_JST_DPREC).

 

  AphroJP_JST_DPREC takes the same g24-hrh accumulation time with that of the previous products (Kamiguchi et al.,2010).The daily station precipitation data are extracted from  Automated Meteorological Data Acquisition System (AMeDAS) network observed by the Japan Meteorological Agency (JMA) and spatial interpolation method is developed by Meteorological Research Institute (MRI).

Owing to the interpolation method considering of precipitation climatology and topographical effect.Details of data processing and characteristics are explained in the paper by Kamiguchi et al. (2010).

  Japanese local time is GMT+9, that means, we are 9 hrs ahead of the universal time. So, a Japanese day starts from 15 UTC of the previous day and ends at 15 UTC of the stamped date. Hence, we define as

  Start of the Day (SOD) = -9,  and

  End of the Day (EOD) = 15,

Since the 24 hour accumulation of this product is taken as Japanese local time.

 

2.2 Daily precipitation data of Universal Time (AphroJP_UTC_DPREC).

 

To make this version, we extracted hourly precipitation data from the AMeDAS network observed by JMA. Then we summed up them from 9 JST (= 00 UTC) of the day to 9 JST of next day (= 24 UTC of the day = 00 UTC of next day). So the 24-hr accumulation time of the daily precipitation of this product is as follows.

Start of the Day (SOD) = 0, and

End of the Day (EOD) = 24, according to the gstampedh date.

 

This 24-hr slot is the same with that of Radar AMeDAS daily precipitation (RAP) which is another widely used product from JMA.

 

 

3. Specification

 

3.1 Name of the files

 

   As described above, we released two kinds of data for 2009-2015. The Japanese 24-hr accumulation files are named as Aphro_JST_DPREC.YYYY  (YYYY means year in 4-digits), and

The universal time 24-hr accumulation files are named as

Aphro_UTC_DPREC.YYYY  (YYYY means year in 4-digits).

We attached control file of handling these files with GrADS software.

(AphroJP_JST_DPREC.ctl and AphroJP_UTC_DPREC.ctl).  All these files are gipped.

 

3.2 Parameters

 

   Each data file contains three parameters, namely,

1) Daily precipitation (-99.9 for missing, over ocean)

2) Number of stations used in each 0.05 degree grid box

   (whether 1, 2, or -99.9).

3) End of the Day (EOD)

   (If there is a station data, then the value is 15 for JST version, and 24 for UTC version).

 

For GrADS users, the control files are below.

[AphroJP_JST_DPREC.ctl]

DSET        ^AphroJP_JST_DPREC.%y4

UNDEF       -99.9

OPTIONS     little_endian template

TITLE       APHRO_JP V1207 daily precipitation

XDEF   460  LINEAR   123.025 0.05

YDEF   440  LINEAR    24.025 0.05

ZDEF    01  LEVELS   1

TDEF 42000  LINEAR   01JAN2009 1dy

VARS     3

precip      1 00 daily precipitation (mm/day)

nobs        1 00 Number of stations in each grid [1 or 2]

eod         1 00 End of the day (UTC) = 15 UTC

ENDVARS

 

[AphroJP_UTC_DPREC.ctl]

DSET        ^AphroJP_UTC_DPREC.%y4

UNDEF       -99.9

OPTIONS     little_endian template

TITLE       APHRO_JP V1207 daily precipitation

XDEF   460  LINEAR   123.025 0.05

YDEF   440  LINEAR    24.025 0.05

ZDEF    01  LEVELS   1

TDEF 42000  LINEAR   01JAN2009 1dy

VARS     3

precip      1 00 Daily precipitation (mm/day)

nobs        1 00 Number of stations in each grid [1 or 2]

eod         1 00 End of the day (UTC) = 24 UTC

ENDVARS

 

3.3  Area and horizontal resolution

 The data area is rectangle (lat. 123.0E-146.0E; lon. 24.0N-46.0N) surrounding Japan with 0.05x0.05 degree grid (approx. 5x5 km) in Cartesian coordinate. The number of horizontal grid is 460/440 in lon/lat, respectively. Available value is assigned in the land grid except some small islands.

 

3.4 File structure of one day/one parameter

 

 Value in each grid is stored with 4-byte real binary of little endian order. No record length headers are embedded. FORTRAN user can read the file by "direct access". The file consists of 4-dimensions: time, variable, latitude and longitude, and the sequence goes in the following order starting from the fastest varying dimension to the slowest varying dimension: longitude, latitude, variable, and time. The order of longitude is from west to east and that of latitude is from south to north.

 

The order of horizontal plane

(123.0E, 46.0N)          N         (146.0E, 46.0N)

        -----------------------------------

        |...........................|193200|

        -----------------------------------

        |.   .                             |

        |.   .                             |

   W    -----------------------------------   E

        |921|922|..........................|

        -----------------------------------

        |461|462|......................|920|

        -----------------------------------

        | 1 | 2 | 3 | 4 |..............|460|

        -----------------------------------

(123.0E, 24.0N)          S          (146.0E, 24.0N)

 

 The first grid (centered at 123.025E, 24.025N) is located on the left-bottom corner and the second grid is located on the east of the first one. As shown in the above figure, 460th grid is located at the east end of the line and the 461st grid moves to the north of westernmost grid.

 

 

4. Acknowledgment

 

 We thank Mr.Kenji Kamiguchi and Mr. Osamu Arakawa who permits to use APHRO_JP program.

 

 

5. Contact information

 

If you have any inquiries, please contact the following by email.

 

    Dr. Akiyo Yatagai

    Global Environment and Disaster Prevention Sciences

    Faculty/Graduate School of Science and Technology,

    Hirosaki University

    URL: http://www.st.hirosaki-u.ac.jp/~yatagai/

    Tel: +81-172-39-3685  Fax: +81-172-39-3543

    Email:

     APHRODITE-2 project technical team

     aphrodite.precinfogathgmail.com (change gath to @)

 

 

6. References

 

  So far, please refer the following paper. We will inform registered users when the reference paper of the current version is ready.

 

    Kamiguchi, K., O. Arakawa, A. Kitoh, A. Yatagai, A. Hamada, and N. Yasutomi, 2010: Development of APHRO_JP, the first Japanese high-resolution daily precipitation product for more than 100 years, Hydrological Research Letters, 4, 60-64, doi:10.3178/HRL.4.60.