DOI: 10.20783/dias.670
title: Historical Gridded Meteorological Dataset in Japan
title: HGMD_Japan

description: The Historical Gridded Meteorological Dataset in Japan (HGMD-Japan) is a grided high-resolution (1km x 1km, approximately) daily (and in some cases hourly or yearly) meteorological datasets, intended for use in agricultural climate change analysis, created from 1978 to the latest year continuously.
The daily data were created by overlaying the spatially interpolated differences between observed and climate normal at the meteorological observation stations onto the 1km resolution gridded climate data. In this process, in order to maintain time-series homogeneity in each variable, possible source of time-series heterogeneities unrelated to climate change, such as changes in statistical methods and instrument types, were corrected as much as possible.

The details of this dataset are described as follows.

■ Common items
 Projection: Geographic
 Geodetic system: Tokyo Datum

◆ Daily data
Directory structure:
 HGMDJ_NARO(YYYY)daily[file]
File name:
 (YYYY)_d_(element).bin
Element name (element):
 Mean temperatures (tmp) [0.1 °C] 
 Maximum temperatures (hourly) (tmx) [0.1 °C] 
 Minimum temperatures (hourly) (tmn) [0.1 °C] 
 Precipitation (pre) [0.1 mm] 
 Solar radiation (srd) [0.1 MJ/m2/d] 
 Sunshine duration (sdr) [0.1 hour] 
 Relative humidity (rhu) [0.1 %] 
 Wind speed at 2.5m height (wsd) [0.1 m/s] 
 Downward long wave radiation (lrd) [0.1 MJ/ m2/d] 
 Potential evapotranspiration (pet) [0.1 mm] 
 FAO reference evapotranspiration (eto) [0.1 mm] 
 Paddy water temperature (LAI=0) (tw0) [0.1 °C] 
 Paddy water temperature (LAI=∞) (twi) [0.1 °C]
Error value:
 -999
Record format:
 Data format: Binary format (little endian) 
 Data size: 278,237,440 bytes 
 Record length: 736 bytes (4+366*2: see below) 
 Number of rows (meshes): 378040
Structure:
 1) 3rd mesh code (4 byte long), data (2 byte short) x 366 days 
 2) 3rd mesh code (4 byte long), data (2 byte short) x 366 days 
・・・ 
378040) 3rd mesh code (4 byte long), data (2 byte short) x 366 days 
* Dummy (-999) for the 366th day in no-leap years

◆ Hourly data
Directory structure:
 HGMDJ_NARO(YYYY)hourly[element][file]
File name:
 (YYYYMMDD)_h_(element).bin
Element name (element):
Rice panicle temperatures (tp) [0.1 °C] 
Air temperatures (ta) [0.1 °C]
Error value:
 -999
Record format:
Data format: Binary format (little endian) 
Data size: 19,658,080 bytes 
Record length: 52 bytes (4+24*2: see below) 
Number of rows (meshes): 378040
Structure:
 1) 3rd mesh code (4 byte long), data (2 byte short) x 24 hours 
 2) 3rd mesh code (4 byte long), data (2 byte short) x 24 hours 
・・・ 
378040) 3rd mesh code (4 byte long), data (2 byte short) x 24 hours 

◆ Yearly data
Directory structure:
HGMDJ_NARO(YYYY)yearly[file]
File name:
 (YYYY)_y_(element).bin
Element name (element):
 Heat-dose of daily maximum temperature above 35 ℃ (HD_x35) (hdx35) [0.1 °C day] 
 Heat-dose of daily minimum temperature above 25 ℃ (HD_n25) (hdn25) [0.1 °C day] 
 Heat-dose of daily mean temperature above 26 ℃ (HD_m26) (hdm26) [0.1 °C day] 
 Mean air temperature during 20 days after heading date (hed20atm) [0.1 °C]
 HD_m26 during 20 days after heading date (hed20hdm26) [0.1 °C day] 
 Mean panicle temperature during daytime within 5 days around heading date (ptm5dc) [0.1 °C] 
 Mean panicle temperature during daytime within 7 days around heading date (ptm7dc) [0.1 °C] 
Error value:
 -999
Record format:
 Data format: Binary format (little endian) 
 Data size: 2,268,240 bytes 
 Record length: 6 bytes (4+2: see below) 
 Number of rows (meshes): 378040
Structure:
 1) 3rd mesh code (4 byte long), data (2 byte short)
 2) 3rd mesh code (4 byte long), data (2 byte short)
・・・ 
378040) 3rd mesh code (4 byte long), data (2 byte short)