Understanding the Uncertainty and Variability of Earth’s Radiation Budget Components Over the Past 3 Decades Using Radiative Fluxes from the NASA’s GEWEX Surface Radiation Budget Release 4 Integrated Product

Abstract:

The NASA/GEWEX Surface Radiation Budget (SRB) project produced a 30+ year time series of 3-hourly Top-of-Atmosphere (TOA) and surface radiative flux components at a 1x1 degree resolution. This SRB Release 4 Integrated Product (R4-IP) is derived using GEO/POES AVHRR imager data products from the cross-calibrated ISCCP (International Satellite Cloud Climatology Project) “H Series” radiance, cloud and surface property data products. SRB R4-IP relies upon other GEWEX global data products including the ISCCP nnHIRS atmospheric temperature and moisture dataset (used for ISCCP cloud retrievals), sea surface (SeaFlux v2.0) and land surface (LandFlux) products and the Max Planck Institute Aerosol Climatology aerosol history (MAC v1; consistent with ISCCP HX). Total solar irradiance is now variable and consistent with SORCE measurements. Trace gas variability O3 and CO2 over the 30 year time period is also consider. Numerous other improvements were made to the SW and LW algorithms including improved cloud optical property treatments and specification of surface spectral albedo and emissivity for various surface conditions.

Here we analyze the new SW and LW SRB datasets, comparing them to the previous Release 3, BSRN, GEBA and PMEL surface measurements, and ERBE and CERES satellite datasets. For the TOA fluxes, the anomalies of the fluxes in the early period are compared to the MEaSURES ERBE and the latter period to CERES datasets for a benchmark. For surface flux validation besides ensemble comparisons, we show the variability of SRB vs surface measurements from BSRN beginning in 1992 and GEBA SW from 1983 using an ensemble anomaly analysis for available site measurements. We assess the variability of the surface flux anomalies, particularly the net fluxes and the cloud radiative effects, over the entire time period and discuss relative to CERES surface fluxes. This includes a changepoint analysis that helps associate various changes in the ISCCP GEO/LEO configurations and other inputs to variations in the radiative budget components. Lastly, using the benchmark comparisons and information on inhomogeneities of the time series inputs, we assess the ability to determine long-term changes for the global and select regions over the past 30+ years.