Terra and Aqua MODIS TEB intercomparison using Himawari-8/AHI as reference

Abstract

Intercomparison between the two MODIS instruments is very useful for both the instrument calibration and its uncertainty assessment. Terra and Aqua MODIS have almost identical relative spectral response, spatial resolution, and dynamic range for each band, so the sitedependent effect from spectral mismatch for their comparison is negligible. Major challenges in cross-sensor comparison of instruments on different satellites include differences in observation time and view angle over selected pseudoinvariant sites. The simultaneous nadir overpasses (SNO) between the two satellites are mostly applied for comparison and the scene under SNO varies. However, there is a dearth of SNO between the Terra and Aqua. This work focuses on an intercomparison method for MODIS thermal emissive bands using Himawari-8 Advanced Himawari Imager (AHI) as a reference. Eleven thermal emissive bands on MODIS are at least to some degree spectrally matched to the AHI bands. The sites selected for the comparison are an ocean area around the Himawari-8 suborbital point and the Strzelecki Desert located south of the Himawari-8 suborbital point. The time difference between the measurements from AHI and MODIS is <5 min. The comparison is performed using 2017 collection 6.1 L1B data for MODIS. The MODIS-AHI difference is corrected to remove the view angle dependence. The Terra-Aqua MODIS difference for the selected TEB is up to 0.6 K with the exception of band 30. Band 30 has the largest difference, which is site dependent, most likely due to a crosstalk effect. Over the ocean, the band 30 difference between the two MODIS instruments is around 1.75 K, while over the desert; the difference is around 0.68 K. The MODIS precision is also compared from the Gaussian regression of the double difference. Terra bands 27 to 30 have significant extra noise due to crosstalk effects on these bands. These Terra-Aqua comparison results are used for MODIS calibration assessments and are beneficial for future calibration algorithm improvement. The impact of daytime measurements and the scene dependence are also discussed.

GOES‐16/ABI Thermal Emissive Band Assessments Using GEO‐LEO‐GEO Double Difference

“…Our previous work on Terra-Aqua MODIS TEB comparison using Himawari-8/AHI as reference has demonstrated the LEO-GEO-LEO double difference method (Chang et al, 2019). This work extends and improves this method for the application to the comparison between GOES-16/ABI and Himawari-8/AHI.…”

“…The GOES sensors image the full disk of Earth and provide nearcontinuous observations, which is advantageous for intercomparison with other satellite sensors. The double difference has been demonstrated in the application to Terra-Aqua MODIS TEB comparison using Himawari-8/AHI as a bridge (Chang et al, 2019). A double difference method using a low earth orbit (LEO) satellite sensor can be applied to achieve their comparison.…”

“…In this work, measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board the Aqua satellite are used as a near-simultaneous reference over selected scenes Xiong et al, 2017). The double difference has been demonstrated in the application to Terra-Aqua MODIS TEB comparison using Himawari-8/AHI as a bridge (Chang et al, 2019). This method provides enormous number of samples that further enhance the comparison precision.…”

An Operational Split-Window Algorithm for Retrieving Land Surface Temperature from Geostationary Satellite Data: A Case Study on Himawari-8 AHI Data

“…Finally, we used MODTRAN 5.2 and Seebor V5.0 profiles to simulate the TOA BTs in two SW bands of MODIS and AHI. The results showed that the BT biases of the two sensors were very small at 11 µm (biases were less than 0.2 K) under the same conditions [95]. Therefore, we selected pixels with the absolute value of the BT difference at 11 µm within 2 K for validation.…”

Feasibility of cross-calibrating ocean-color sensors in polar orbit using an intermediary geostationary sensor of reference

“…This is facilitated by the frequent time and geometry coincidences, about daily, when the polarorbiting sensor crosses the field-of-view of the geostationary sensor around the Equator. In previous studies, AHI onboard Himawari has been utilized to cross-calibrate the solar reflective bands of VIIRS and MODIS (Yu and Wu, 2016;Qin et al, 2018) and the thermal emissive bands of MODIS-A and MODIS-T (Chang et al, 2019), although the calibrations are not ocean specific. Murakami et al (2019) did some preliminary work on cross-calibrating SGLI, MODIS-A, and VIIRS with AHI over global oceans using modeled bidirectional reflectance distribution function (BRDF) and aerosol signals.…”