GeoTIFF conversion of "Shikisai image" (SGLI Standard Data/JASMES format)
April 16, 2021

Introducing how to convert "Shikisai image" of JASMES format to GeoTIFF using GDAL
command and parameters.
The processing method differs in the following target areas.
・around Japan (250m)
・Global map(5km)【Case 1】around Japan(250m)
・Ocean / Chlorophyll a concentration (CHLA) image ------------------------------- p.2【Case 2】Global map(5km)・Ocean / Sea surface temperature (SST) image -------------------------------------- p.4
If you download JASMES SGLI data, please register on following site.
https://www.eorc.jaxa.jp/JASMES/registration.html

1【Case 1】around Japan(250m) Ocean / Chlorophyll a concentration (CHLA) image
Introducing an example of GeoTIFF conversion of around Japan (250m) / ocean / chlorophyll aconcentration (CHLA).

Acquisition of product information
１） Get SD array name
The following is an example using OSGeo4W Shell which is installed when
QGIS is installed on Windows.
Move to the directory where the image data is saved and enter the file name after
the gdalinfo command as shown below to get the SD array name.
On Linux, it can be used in terminal applications, but GDAL must be installed.

netCDF file name

Use the information in the red frame of SUBDATASET_1_NAME at the bottom ofthe displayed information.

2

【Case 1】around Japan(250m) Ocean / Chlorophyll a concentration (CHLA) image
GeoTIFF conversion / reprojection
２） GeoTIFF conversion
Using the information of SUBDATASET_1_NAME in the red frame of 1) asthe input file name, use the gdal_translate command to perform GeoTIFF
conversion as shown below.
Output file format

Input file name

Input file reference
coordinate system

Output file name< Output file display example in QGIS >3

【Case 2】 Global map(5km) Ocean / Sea surface temperature (SST) image
Introducing an example of GeoTIFF conversion of global map(250m) / ocean / sea surface temperature (SST).
Product information acquisition 1) SD sequence name acquisition is the same as image 1.

Acquisition of product information１） Get SD array name
The following is an example using OSGeo4W Shell which is installed when
QGIS is installed on Windows.
Move to the directory where the image data is saved and enter the file name afterthe gdalinfo command as shown below to get the SD array name.
On Linux, it can be used in terminal applications, but GDAL must be installed.

netCDF file name

Use the information in the red frame of SUBDATASET_1_NAME at the bottom ofthe displayed information.

4

【Case 2】 Global map(5km) Ocean / Sea surface temperature (SST) image
The image on the JASMES format(SGLI standard Data) is centered at 180 degrees longitude, but here
it is converted to an image centered at 0 degrees longitude.
In QGIS "Custom Projection" settings, 180 degrees longitude is displayed as the center of the image.
As a reference, we will introduce a conversion example with the center image at 180 degrees
longitude at the end.
GeoTIFF conversion / reprojection
２） GeoTIFF conversion
Using the information of SUBDATASET_1_NAME in the red frame of 1) as
the input file name, use the gdalwarp command to perform GeoTIFF
conversion as shown below.
Output file format

Output file nameOutput file reference coordinate
system and output range

Input file reference
coordinate system

Input file nameClarified that itstraddles 180 degrees< Output file display example in QGIS >※ It is necessary to recalculate the physical quantity.
Get add_offset and scale_factor from the gdalinfo
information of "SST_AVE" and calculate using the QGIS
raster calculator.

Input file name5【Case 2】 Global map(5km) Ocean / Sea surface temperature (SST) image
GeoTIFF conversion / reprojection３） Custom projection settings
Select "Custom Projection" from the toolbar on the QGIS screen.
Settings > Custom Projection
Click the "+" button in the red circle at the right end of the “Custom
Coordinate Reference System Definition" screen. Set the Name, Format
and Parameters as follows, and click the "OK" button at the bottom.
NameFormat
Parameters： JASMES [Give it any name]： Select “Proj String”： +proj=longlat +lon_wrap=180 +ellps=WGS84

Click inside the red circle at the bottom
right of the screen.

Select the coordinate system set in "UserDefined Coordinate Systems" in the redframe below.Here, select JASMES
above,Click Apply at the bottom.

< After changing the coordinate system >6

【Case 2】 Global map(5km) Ocean / Sea surface temperature (SST) image<Reference>
１） GeoTIFF conversion (Longitude center 180 degrees)
GeoTIFF conversion is performed with the gdal_translate command as
shown below, using the acquired SD array name SUBDATASET_1_NAME
information as the input file name.
Output file format

Input file reference
coordinate system

Input file nameClarified that it
straddles 180 degrees

Output file name* It may not be possible to read with other tools orsuperimpose with a map vector.
Longitude display in QGIS is 0-360 degrees.
< Output file display example in QGIS >7