Imaging procedure for GCOM-C(SHIKISAI) product by using QGISThis document shows how to read the GCOM-C (SHIKISAI) level-2 land surface temperature product byusing QGIS and visualize it as an image. For detail of QGIS, please refer to the link below.

https://gportal.jaxa.jp/gpr/information/tool?lang=enPlease refer to the "G-Portal User's Manual" below for how to search for and download products fromG-Portal.
https://gportal.jaxa.jp/gpr/assets/mng_upload/COMMON/upload/GPortalUserManual_en.pdf

JAXA/G-Portal Support Deskz-gportal-support@ml.jaxa.jp

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[STEP1] Prepare Land Surface Temperature productFirst, prepare land surface temperature product in "GeoTIFF" format to load into QGIS.
There are two ways to get it:
A. Using the processing request function of G-Portal, convert land surface temperature product toGeoTIFF format and download it.
B. Download land surface temperature product from G-Portal, convert the HDF5 format to GeoTIFF
format using “SGLI Map projection & GeoTIFF conversion Tool”.

2[STEP1-A](1/2) Get data in GeoTIFF format using G-Portal's processing
request function(1) Search land surface temperature data of GCOM-C (Shikisai) from G-Portal that you want todisplay as an image in QGIS.
(2) When the search results are displayed, click the "Processing" button in the row of the desired
data.

click the "Processing" button※ If you click the "Download" button, the data will be downloaded in HDF5 format.
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[STEP1-A](2/2) Get data in GeoTIFF format using G-Portal's processing
request function(3) Execute the processing request as follows, and download the GeoTIFF file after receiving emailof “[G-Portal] Notice of completion of product production”.

Check ”GeoTIFF”, andClick “Request prosessing” button.
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[STEP1-B](1/2) Convert HDF5 format to GeoTIFF format
Open command prompt and convert HDF5 product to GeoTIFF using SGLI Map projection & GeoTIFF conversion Tool.
Please refer to the following instruction manual for SGLI Map projection & GeoTIFF conversion Tool.
https://gportal.jaxa.jp/gpr/information/tool?lang=en#GCOM-C
C:¥xxxxx¥Desktop¥GCOM-C_L2-LST>SGLI_geo_map_win.exe GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000.h5 -d Image_data/LST========================== Input parameters ==========================
Input file= GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000.h5
Projection coordinates = Geodetic Latitude/Longitude[Example]
Pixel spacing= Default (7.5sec/15sec/30sec)
Resampling method= BL
we will use the tile data for Japan
Data selection= Image_data/LST
on August 10, 2022.
Output directory=.
======================================================================
product_type = L2/tile
tile = 0529
pid = GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000
hemi = 0
p=0, Image_data/LST
data rank = 2
data size = 4800/4800
data type = unsigned short
INFO: type of attr is int -> cast to unsigned short! function (H5_common_read2.c) line = 272
max_valid_DN = 65534
x range = 129.4125000000, 141.6000000000
y range = 30.0000000000, 38.8083333333
outsize = 5850, 4228
output = [.¥GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000_LST.tif]
output = [.¥GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000_LST.xml]
done...

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[STEP1-B](2/2) Convert HDF5 format to GeoTIFF format
Command options for SGLI Map projection & GeoTIFF conversion Tool
Set band offset/scaling(slope) values from HDF attributes to GDAL_METADATA Tag (42112) with an
option specified at METADATA.
If you specify the option, you can omit the calculation of the slope/offset value in the formula
described on page 18 of this document. However, please note that the temperature is in absolutetemperature (K).
[Example]>SGLI_geo_map_win.exe GC1SG1_20220810D01D_T0529_L2SG_LST_Q_3000.h5 -d Image_data/LST –a default

For details of options, refer to page 4 of the instruction manual mentioned in the previous section.
https://gportal.jaxa.jp/gpr/information/tool#GCOM-C6

[STEP2] Read GeoTIFF with the free tool QGIS (https://qgis.org/en/site/)and image it<Prepare - Download the land data input to QGIS ->Download the land data (used to color land when imaging data with QGIS) from the following sites.
https://tapiquen-sig.jimdofree.com/english-version/free-downloads/world/

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Click here, select "Save file" andpress "OK".
(Please note that the savelocation varies depending on thebrowser you are using.)

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Open the folder where you saved the file and double-click the file named "World_Countries.rar"
to unzip it, and you will see the file "World_Countries.shp“.
(The "World_Countries.shp“ will be used later.)・World_Countries.dbf
・World_Countries.prj・World_Countries.sbn
・World_Countries.sbx
・World_Countries.shp
・World_Countries.shp.xml
・World_Countries.shx
・World_Countries_README.txt

9[STEP3] Load GeoTIFF data into QGIS
１. Start QGIS.

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Double click to “New Empty Project”

11Drag and drop the following two files.
・GeoTIFF file・ "World_Countries.shp" (Refer to page 9)

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The data is displayed as an image.

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Select "Raster Calculator" on the menu "Raster".

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A screen like this will open.
On this screen, create a formula to convert thevalues contained in the data into the land surfacetemperature.

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①①Double-click the file name in the“Raster Bands" frame.
(Then, it will be displayed in the"Formula" box below.)16

②Click the "*" button. (Then, it will bedisplayed in the "Formula" box below.)②17

③Place the cursor on the right side of "*",
click once, and input "0.02".
※The value stored in the data can beconverted to temperature (℃) by thefollowing formula.
Temperature (℃) = [value stored in data] *[0.02 (slope value for LST)] + [0 (offsetvalue for LST)] - 273 (K)③

https://suzaku.eorc.jaxa.jp/GCOM_C/data/update/Algorithm_LST_en.html

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④ Click the "-" button.
⑤ When "-" is displayed in the"Expression" field, click the right side ofthe expression once to make it ready for
input.
⑥ Input “273".
④⑤⑥19

⑦⑦Click “...” at the right end of“Output layer” in the “Result layer”.

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⑧ Specify the directory (example:desktop) and give any name (example:“GCOM-C_L2_LST" etc.), click the savebutton.

GCOM-C_L2_LSTSaveCancel
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⑨ Click to ”OK”.

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When the calculation process is complete,
you will see a screen like this.

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The following explanation is how to create a colored image

Double-click the name of thefile saved on page 21.
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A window like this will open.

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「Select "Singleband pseudocolor" from"Render type".

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Enter the land surface temperature
range you want to display.
In this example, set the 20ﾟC as theminimum value (lowest temperature)and 60ﾟC as the maximum value(highest temperature).

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When you make image the land surface
temperature data with the default
settings, high temperatures are displayed
as blue and low temperatures aredisplayed as red. If you want to reverse it,press "▼" on the right side of the color
ramp, and then press "Invert color ramp"
in the displayed items.

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The color ramp will be reversed like this.

Put a check mark.
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You can also make fine adjustments to "Brightness","Saturation" and "Contrast" in this field.

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Click “Apply” and then “OK”.

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As a result, you will see an colored image like this.

Uncheck to hide data before conversion.
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Zoom inZoom out
Pan MapYou can zoom in/out or movethe area with these tools.

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To save the created land surface temperature data, select"Save As" on the "Project" menu, give it any name and saveit in any folder.

The next time you want to open the same image, doubleclick on the saved file and QGIS will automatically launchand open it.

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If you want to output the image file, select "Import/Export"
from "Project" in the menu and click "Export Map to Image".

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Give any name and click the “Save” button.

GCOM-C_L2_LST

Click the “Save” button.
CancelSave36

Select "Exit QGIS" from "Project" in the menu at last.

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