15 Years of Aqua MODIS on-orbit operation, calibration, and performance

Earth and Space Science

2019

Geostationary satellite (GOES)-16/Advanced Baseline Imager (ABI) and Himawari-8/ Advanced Himawari Imager (AHI) represent a significant improvement over the imagers on board previous GOES. Their bands 7-16 are infrared channels covering the 3.9-to 13.3-μm spectral range and with a subpoint spatial resolution of 2 km. Their spectral coverage of the thermal emissive bands (TEBs) is almost identical, and both instruments employ similar calibration strategies using an on-board blackbody and a space look. The intercomparison between the two instruments will be very helpful for their calibration assessments and their product quality enhancements. GOES-16 was launched on 19 November 2016, initially to a test position at 89.5°west and reached its operational position (longitude of 75.2°west) on 11 December 2017. The Himawari-8 spacecraft was launched on 7 October 2014 and the observation focuses on Asia-Pacific region. In this work, an intercomparison of their TEB measurement is performed using double difference with Aqua Moderate Resolution Imaging Spectroradiometer (MODIS). The same type of scenes are selected for the two instruments, and their measurements with the closest observation times are compared with Aqua MODIS matching bands. The view angle effect is corrected and their spectral mismatching effect is estimated. The dependence on the scene uniformity is analyzed. The ABI-AHI differences are within 0.3K for bands 10 (7.35 μm), 11 (8.44 μm), 12 (9.64 μm), and 14 (11.24 μm), and up to 0.8K difference for bands 15 (12.38 μm) and 16 (13.28 μm). The ABI precision is better than AHI for all TEB and their image navigation and registration precisions are comparable. In general, the ABI performances before and after relocation are consistent.Key Points:• Application of double difference method to GEO-GEO sensor using LEO sensor as a bridge • GOES-16/ABI thermal emissive band assessment with comparison with Himawari-8/AHI and overall the ABI and AHI IR bands compare well. • GOES-16/ABI thermal emissive bands consistent assessment before and after spacecraft re-location.

Section: Abi-modis and Ahi-modis Spectral Matching Bandsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Chang

Earth and Space Science

2019

“…The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on-board the Terra and Aqua satellites have successfully operated since their launch in 1999 and in 2002, providing more than 18 and 16 years of continuous global observations, respectively. 1,2 Over a decade of continuous global observations have produced an unprecedented amount of science data products monitoring land surface temperature, sea surface temperature, cloud top altitude and temperature, and water vapor content. [3][4][5][6][7][8][9][10][11] The two MODIS instruments use similar on-board calibrators and on-orbit calibration algorithms.…”

Section: Introductionmentioning

confidence: 99%

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

Chang

Angal

2019

J. Appl. Rem. Sens.

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.

“…The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellite have successfully operated since their launch in 1999 and in 2002, providing more than 18 and 16 years of continuous global observations, respectively [1,2]. These global observations have resulted in generation of an unprecedented amount of science data products [3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Terra and Aqua MODIS inter-comparison using LEO-GEO double difference method

Chang¹,

Sensors, Systems, and Next-Generation Satellites XXII

Angal

2018

The Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites have successfully operated since their launch in 1999 and in 2002, providing more than 18 and 16 years of continuous global observations, respectively. The inter-comparison between the two MODIS instruments can be very supportive for the instrument calibration and uncertainty assessment. Aqua and Terra MODIS have almost identical relative spectral response, spatial resolution, and dynamic range for each band. Therefore, a site dependent correction for a sensor spectral band pair is not necessary for their comparison. However, Terra is in the morning orbit with an equator crossing time of 10:30 am, and Aqua is in the afternoon orbit with equator crossing time of 1:30 pm. Consequently, there is a dearth of simultaneous nadir overpasses (SNOs) between the two satellites. Major challenges in cross-sensor comparison of instruments on different satellites include differences in observation time, solar angle, and view angle over selected pseudo-invariant sites. In this work, the inter-comparisons of thermal emissive bands are performed over a pseudo-invariant target, using the observations from a sensor onboard a geostationary satellite as a bridge. Himawari8 was launched on October 7, 2014. The Advanced Himawari Imager (AHI) onboard Himawari8 can be used as a reference to bridge the comparison between Terra and Aqua MODIS. AHI has 16 channels; with spatial resolutions from 0.5 km to 2 km at nadir and produces a full disk observations every 10 minutes. The band spectral coverage matchup, comparable spatial resolution and near-simultaneous observation between MODIS and AHI provide feasibility to implement a double difference method. This comparison method minimizes the impact of the difference in observation time and solar angle. The comparison results will be used as an assessment for MODIS instrument calibration and will be helpful for future enhancement of the L1B product.