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Bridging the thermal band comparison between LEO-LEO sensors and between GEO-GEO sensors

TitleBridging the thermal band comparison between LEO-LEO sensors and between GEO-GEO sensors
Publication TypePresentation
Year of Publication2017
AuthorsChang, T., G. Keller, and X. Xiong
ProceedingsProc. SPIE - Earth Observing Systems XXII
MCST ConferenceSPIE - Earth Observing Systems XXII
KeywordsGOES-16; Himawari-8; Inter-comparison; MODIS; Radiometric calibration

MODIS onboard the Terra and Aqua satellites have operated since 1999 and 2002, respectively. The inter-comparison
between their thermal emissive bands is a useful tool in assessing their calibration consistency and enhancing their
product quality. Terra and Aqua MODIS has the same spectral bands and calibration algorithm. The comparison
between them will be beneficial for instrument calibration. However, the comparison is hindered by the time difference
of their measurements, since Terra is in the morning orbit and Aqua is in the afternoon orbit.
GOES-16 was launched on November 19, 2016 and Himawari-8 was launched on October 7, 2014. The Advanced
Baseline Imager (ABI) onboard GOES-16 and the Advanced Himawari Imager (AHI) onboard Himawari-8 are in the
same class and have almost identical thermal spectral bands. Their comparison will be very useful for sensor calibration
assessment. However, the comparison is challenged by the fact that they image different regions of the Earth.
The sensors on GEO satellite and the sensors on LEO satellite may have matching bands with close spectral coverage.
This work focuses on bridging the thermal band comparison between LEO-LEO sensors and between GEO-GEO
sensors. The double difference method is applied to assess the BT measurements between the two MODIS instruments
using the GOES imager as a bridge. The comparison between ABI and AHI can also be performed with bridging by
either MODIS or VIIRS measurements. GOES-16 and Himawari-8 are both positioned over tropical ocean regions.
Thus, the comparison with simultaneous nadir overpass can provide assessments for brightness temperature (BT)
measurements over the ocean surface type. The comparison can also be extended to simultaneous off-nadir
measurement over other types of targets that cover different BT range.