Radiometric Inter-Calibration between Himawari-8 AHI and S-NPP VIIRS for the Solar Reflective Bands

Abstract

Abstract:The Advanced Himawari Imager (AHI) on-board Himawari-8, which was launched on 7 October 2014, is the first geostationary instrument housed with a solar diffuser to provide accurate onboard calibrated data for the visible and near-infrared (VNIR) bands. In this study, the Ray-matching and collocated Deep Convective Cloud (DCC) methods, both of which are based on incidently collocated homogeneous pairs between AHI and Suomi NPP (S-NPP) Visible Infrared Imaging Radiometer Suite (VIIRS), are used to evaluate the calibration difference between these two instruments. While the Ray-matching method is used to examine the reflectance difference over the all-sky collocations with similar viewing and illumination geometries, the near lambertian collocated DCC pxiels are used to examine the difference for the median or high reflectance scenes. Strong linear relationships between AHI and VIIRS can be found at all the paired AHI and VIIRS bands. Results of both methods indicate that AHI radiometric calibration accuracy agrees well with VIIRS data within 5% for B1-4 and B6 at mid and high reflectance scenes, while AHI B5 is generally brighter than VIIRS by~6%-8%. No apparent East-West viewing angle dependent calibration difference can be found at all the VNIR bands. Compared to the Ray-matching method, the collocated DCC method provides less uncertainty of inter-calibration results at near-infrared (NIR) bands. As AHI has similar optics and calibration designs to the GOES-R Advanced Baseline Imager (ABI), which is currently scheduled to launch in fall 2016, the on-orbit AHI data provides a unique opportunity to develop, test and examine the cal/val tools developed for ABI.

Calibration of the DSCOVR EPIC visible and NIR channels using MODIS Terra and Aqua data and EPIC lunar observations

“…The stray light correction was found to reduce the fit offsets and gains for all considered channel pairs. Yu and Wu (2016) investigated the intercalibration between Advanced Himawari Imager (AHI) in a geostationary orbit and VIIRS. They found strong linear relationship between the paired bands.…”

First Provisional Land Surface Reflectance Product from Geostationary Satellite Himawari-8 AHI

“…The Himawari-8 AHI and MODIS Terra/Aqua bias offset varied, with the green band showing −0.02 and the NIR (AHI B4, Terra/Aqua B2) band showing +0.03. A recent study by Yu and Wu also noted similar bias for TOA reflectance between Himawari-8 AHI and S-NPP VIIRS [6]. Diurnal cycles of meteorological variables and sun zenith/azimuth angle changes might be the main contributors to the bias between Himawari-8 AHI and MODIS SR. We used ray-matching screened pixels to remove the diurnal variability of aerosols and clouds in next section to further examine the possible discrepancy between Himawari-8 AHI and MODIS Terra/Aqua SR data.…”

“…We used the ray-matching method to select collocated pixel pairs from HM08_AHI12 and the reference MODIS data. The ray-matching method is a straightforward tool to match pixels from GEO and LEO sensors for comparison [6,29,30]. The method relies on precise spatially and view geometry collocated target pixels to reduce the atmosphere and BRDF impact.…”

“…These six solar reflective bands closely mimic the spectral characteristics of the NASA EOS flagship MODIS Terra/Aqua. Cross-calibration studies of the Himawari-8 AHI with LEO sensors show that the radiometric accuracy and stability of AHI is compatible with MODIS and VIIRS [5][6][7]. Abovementioned spectral and radiometric characteristics of AHI make producing high-frequency MODIS-like land products from Himawari-8 AHI possible.…”

Retrieval of Reflected Shortwave Radiation at the Top of the Atmosphere Using Himawari-8/AHI Data

“…Because of the varying spatial resolutions, they were averaged to a spatial distance of 2.0 km. Cao et al [27] reported that the absolute radiometric calibration accuracy of S-NPP/VIRS is less than 2% for CH1-CH6 and the calibration accuracy of this data and Himawari-8/AHI was reported to be within 6-8% of CH1-CH4 and CH6 except for CH5 (5%) [28]. …”