Homogenized Water Vapor Absorption Band Radiances From International Geostationary Satellites

Abstract

In the past 20+ years, GEO Imagers with infrared 6.5‐μm bands have been observing the Earth's atmosphere, providing useful information of upper tropospheric moisture. Due to the instrumental differences and local viewing angles in GEO satellites, these observations are not consistent for generating climate data records (CDRs). In this study, a methodology has been developed to homogenize the 6.5‐μm radiances from the international GEO satellites, to generate a consistent CDR. Validations with Infrared Atmospheric Sounding Interferometer radiances from Metops for 2015–2017 for seven GEO Imager sensors show that the GEO radiances are homogenized well with small standard deviation and biases of the differences (smaller for newer sensors), temporally stable radiometric accuracy, and weak angle dependency (even weaker for sensors with two water vapor bands). The homogenized 20+ years of consistent 6.5‐μm radiance CDR can be used to evaluate reanalysis and climate models, especially the diurnal variation of the model simulation.

Evaluation of Environmental Moisture from NWP Models with Measurements from Advanced Geostationary Satellite Imager—A Case Study

“…For evaluation of global NWP models (GFS, UM, etc. ), ideally, homogenized global WV absorption band radiances from international geostationary satellites are needed [41].…”

Assessment of Upper Tropospheric Water Vapor Monthly Variation in Reanalyses With Near‐Global Homogenized 6.5‐μm Radiances From Geostationary Satellites

“…It covers the years from 2015 to 2017 at the temporal resolution of 3 hr over the latitudes of 45°N to 45°S and all longitudes. Only a few essential facts about this homogenized WV radiances data set are given here for completeness; the reader is referred to Li et al (2019) for detailed technical approaches. This data set was generated by homogenizing all other GEO Imager WV radiances to the nadir view radiances of GOES‐15 Imager 6.5‐μm WV band.…”

“…The reference data used in this study are homogenized clear‐sky IR radiances (expressed as equivalent brightness temperatures [BTs]) in the 6.5‐μm WV absorption band from seven imagers onboard international GEO weather satellites, including GOES‐13 Imager (G13I), G15I, ABI16, AHI8, MTSAT‐2, and Meteosat‐8/Meteosat‐10 SEVIRI (SEVIRI08 and SEVIRI10) (see Table 1 in Li et al, 2019). It covers the years from 2015 to 2017 at the temporal resolution of 3 hr over the latitudes of 45°N to 45°S and all longitudes.…”

“…They are caused by different levels of residual bias from different sensors in the homogenized WV data set. For example, from Figure 3 of Li et al (2019), the seven GEO imagers have overall biases ranging from −0.149 to −0.365 K. Also, the bias magnitudes increase with local zenith angle. So the discontinuities are most visible along the full disk edge because that's where one of the sensors has the largest bias.…”

“…In a recent study, a new data set (Li et al, 2019) providing consistent IR 6.5-μm WV absorption band radiances from international GEO satellites (referred to as homogenized WV radiances data in this paper) has been successfully generated and validated with hyperspectral sounder (Menzel et al, 2018) Infrared Atmospheric Sounding Interferometer (IASI) radiances. This data set incorporates multiple GEO imagers from international agencies (such as NOAA, EUMETSAT, and JMA).…”