Spectral unfiltering of ERBE WFOV nonscanner shortwave observations and revisiting its radiation dataset from 1985 to 1998

Abstract

Abstract. Wide-field-of-view (WFOV) nonscanner instruments were onboard NASA's Earth Radiation Budget Satellite (ERBS) and the NOAA-9 and NOAA-10 satellites, and provided broadband shortwave (SW) and longwave (LW) irradiances from 1984 to 1999. However, Lee et al. (2002) noted degradation in the WFOV SW dome transmissivity. To account for this degradation, these SW instruments were calibrated with the spectrally flat gray assumption. More recently, Loeb et al. (2012) showed higher degradation in the transmissivity of shorter wavelengths suggesting a need for both temporal and spectral dependent corrections for better calibration. Such an approach may also eliminate an additional adjustment that was applied to irradiances in the existing products to remove the observed trend of day-minusnight longwave irradiances (Wong et al. 2006). We plan to reprocess the ERBE WFOV nonscanner record by characterizing the spectral degradation of the SW dome transmissivity over time. Solar data observed by the WFOV SW nonscanner during calibration days are used to estimate a time and spectral dependent spectral response function (SRF). Coefficients derived from this SRF are then used to improve the irradiance estimate. In addition, since the spectrum of reflected irradiance depends on scene type, ISCCP-derived cloud properties and surface type are used. Preliminary results indicate that taking account of spectral degradation reduces the observed day-minus-night longwave irradiance trends in the tropics (20ON and 20OS) by ~34%, while almost all of the trend is removed in the region between 60ON and 60OS. This presentation explains the reprocessing approach and compares the existing and reprocessed ERBE dataset. Once ERBS measurements are calibrated against CERES instruments, this work allows for the generation of a long-term radiation datasets consistent with those provided by CERES.

Changes in atmospheric shortwave absorption as important driver of dimming and brightening

“…3 Rev.1[76] and ERBE WFOV Nonscanner data Ed. 4[80] (both WFOV Nonscanner data available from 1985 to 1999) are shown. The figure shows, that the DEEP-C data follows the same temporal evolution as the directly measured data and that no spurious inhomogeneities or trends are visible in the data record.…”

Preface to Monitoring the Earth Radiation Budget and Its Implication to Climate Simulations: Recent Advances and Discussions

“…The second approach is based on the differential measurement of the incoming and outgoing radiation at the ToA, that is, not the absolute values of each of them. This has been started in the 1980s with the Earth Radiation Budget Experiment (Shrestha et al., 2014, ERBE) onboard the Earth Radiation Budget Satellite (ERBS), which carried a scanner and nonscanner instrument. However, the goal could at the time not be achieved due to major technical problems (Wong et al., 2018).…”

Preface to Monitoring the Earth Radiation Budget and its Implication to Climate Simulations: Recent Advances and Discussions

“…First, there is the approach to measure the all components of the EEI at the ToA by scanning the globe and integrating the solar and thermal outgoing radiation along with the measurement of TSI. This has been started with the Earth Radiation Budget Experiment (Shrestha et al, 2014) onboard the Earth Radiation Budget Satellite (ERBS), and is currently undertaken with the Clouds and the Earth's Radiant Energy System (CERES) mission (Loeb et al, 2018). The second approach uses in-situ measurements of the ocean heat uptake, as it is currently done with the Argo float system (Argo, 2020;Riser et al, 2016), measuring the oceans heat uptake in absolute terms.…”