Comparing AGRI, AMI and AHI imagery with geo2grid version 1.1
As noted in this blog post, version 1.1 of geo2grid (available here!) includes support for reading AHI, AMI and AGRI data (in addition to ABI data) from JMA‘s Himawari-8 (and -9), KMA‘s GEOKOMPSAT-2 and CMA‘s FY4A (and FY4B), respectively. These multispectral imagers are similar — but not identical — as shown at the WMO OSCAR websites for AHI, AMI and AGRI. For example, both AHI and AMI detect energy at 510 nm (0.51 µm) that can be used to create true-color imagery. AGRI has detection at 0.47 µm and 0.65 µm only in the visible, so true color must be created using information from a near-infrared band, Band 3 on AGRI with a central wavelength at 0.825 µm (a slightly shorter wavelength than on NOAA’s GOES-R Satellites, where band 3 is at 0.86 µm). The true-color animation above, over Hainan Island and the Gulf of Tonkin, uses data from the three satellites. The ABI and AMI images look very similar; the AGRI image is a bit too brown, likely a result of atmospheric correction algorithms within geo2grid that remove the effects of scattering. The locations of clouds are somewhat different as well because of different parallax shifts from the satellites: Himawari-8 is over the Equator at 140.7o E, GEOKOMPSAT-2 is over the Equator at 128.2o E and FY4A is over the Equator at 104.7o E (Hainan Island is at 110oE).
Geo2grid can also create single channel imagery that can be color-enhanced as well. The cleanest window detection on AHI/AMI is near 10.4 µm, and near 10.8 µm on AGRI. AGRI has a nadir resolution of 4 km compared to the 2-km resolution on AMI and AHI, and that difference is stark!
The geo2grid code (and ImageMagick for annotation) is shown below. Note that the $GEO2GRID_HOME/bin/add_coastlines.sh command takes as an input a tif file, and outputs (by default) a png with a similar name.
$GEO2GRID_HOME/bin/geo2grid.sh -r agri_fy4a_l1 -w geotiff -p C13 --grids Haikou --grid-configs $GEO2GRID_HOME/Haikou.yaml -f /data-hdd/AGRI/*20221009*.HDF
$GEO2GRID_HOME/bin/geo2grid.sh -r ahi_hsd -w geotiff -p B13 --grids Haikou --grid-configs $GEO2GRID_HOME/Haikou.yaml -f /data-hdd/AHI/*
$GEO2GRID_HOME/bin/geo2grid.sh -r ami_l1b -w geotiff -p IR105 --grids Haikou --grid-configs $GEO2GRID_HOME/Haikou.yaml -f /data-hdd/AMI/*
$GEO2GRID_HOME/bin/add_colormap.sh ../../../enhancements/IR13_AWIPSAPPROX.txt FY-4A_AGRI_C13_20221009_050004_Haikou.tif
$GEO2GRID_HOME/bin/add_colormap.sh ../../../enhancements/IR13_AWIPSAPPROX.txt GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_Haikou.tif
$GEO2GRID_HOME/bin/add_colormap.sh ../../../enhancements/IR13_AWIPSAPPROX.txt HIMAWARI-8_AHI_B13_20221009_050000_Haikou.tif
$GEO2GRID_HOME/bin/add_coastlines.sh --add-coastlines --coastlines-resolution f --coastlines-level 5 --add-grid --grid-D 10.0 10.0 --grid-d 10.0 10.0 --grid-text-size 14 --add-colorbar --colorbar-text-color "black" --colorbar-title "FY4A Band 13 Clean Windown Brightness Temperature (K)" --colorbar-tick-marks 20 --colorbar-min 330 --colorbar-max 160 --colorbar-text-size 16 --colorbar-height 36 --colorbar-align bottom FY-4A_AGRI_C13_20221009_050004_Haikou.tif
$GEO2GRID_HOME/bin/add_coastlines.sh --add-coastlines --coastlines-resolution f --coastlines-level 5 --add-grid --grid-D 10.0 10.0 --grid-d 10.0 10.0 --grid-text-size 14 --add-colorbar --colorbar-text-color "black" --colorbar-title "AMI Band 13 Clean Windown Brightness Temperature (K)" --colorbar-tick-marks 20 --colorbar-min 330 --colorbar-max 160 --colorbar-text-size 16 --colorbar-height 36 --colorbar-align bottom GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_Haikou.tif
$GEO2GRID_HOME/bin/add_coastlines.sh --add-coastlines --coastlines-resolution f --coastlines-level 5 --add-grid --grid-D 10.0 10.0 --grid-d 10.0 10.0 --grid-text-size 14 --add-colorbar --colorbar-text-color "black" --colorbar-title "AHI Band 13 Clean Windown Brightness Temperature (K)" --colorbar-tick-marks 20 --colorbar-min 330 --colorbar-max 160 --colorbar-text-size 16 --colorbar-height 36 --colorbar-align bottom HIMAWARI-8_AHI_B13_20221009_050000_Haikou.tif
# The following commands are ImageMagick/Magick annotation commands
convert GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_Haikou.png -gravity Northwest -fill yellow -pointsize 16 -annotate +12+16 "GEOKOMPSAT-2A Clean Window (10.3 um) 0500 UTC 9 October 2022" GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_HaikouT.png
convert GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_HaikouT.png CIMSS_logo_web_multicolor_PNG_138x100.png -gravity northwest -geometry +30+30 -composite GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_HaikouTL.png
convert HIMAWARI-8_AHI_B13_20221009_050000_Haikou.png -gravity Northwest -fill yellow -pointsize 16 -annotate +12+16 "Himawari-8 Clean Window (10.3 um) 0500 UTC 9 October 2022" HIMAWARI-8_AHI_B13_20221009_050000_HaikouT.png
convert HIMAWARI-8_AHI_B13_20221009_050000_HaikouT.png CIMSS_logo_web_multicolor_PNG_138x100.png -gravity northwest -geometry +30+30 -composite HIMAWARI-8_AHI_B13_20221009_050000_HaikouTL.png
convert FY-4A_AGRI_C13_20221009_050004_Haikou.png -gravity Northwest -fill yellow -pointsize 16 -annotate +12+16 "FY4A Clean Window (10.8 um) 0500 UTC 9 October 2022" FY-4A_AGRI_C13_20221009_050004_HaikouT.png
convert FY-4A_AGRI_C13_20221009_050004_HaikouT.png CIMSS_logo_web_multicolor_PNG_138x100.png -gravity northwest -geometry +30+30 -composite FY-4A_AGRI_C13_20221009_050004_HaikouTL.png
convert -delay 200 -adjoin -loop 0 HIMAWARI-8_AHI_B13_20221009_050000_HaikouTL.png GEO-KOMPSAT-2A_AMI_IR105_20221009_050031_HaikouTL.png FY-4A_AGRI_C13_20221009_050004_HaikouTL.png AMI_AHI_AGRI_CleanWindow_20221009_050004_Haikouanim.gifNote: When I downloaded the FY4A data this time, I downloaded all FY4A data from 0500 UTC, including the 4-km data. When you do this, geo2grid is able to the atmospheric correction (as opposed to what occurred with this blog post). Also: there is a separate reader (agri_fy4b_l1) for AGRI data from FY4B!