An Evaluation of Satellite-Based and Re-Analysis Radiation Budget Datasets Using CERES EBAF Products

Surface and top-of-atmosphere (TOA) radiative fluxes from CERES Energy Balanced and Filled (EBAF; Loeb et al., 2009) products were used to assess the performance of four long-term radiation budget datasets, two derived from satellite observations and the other two from re-analysis products. Satellite-derived datasets were the NASA/GEWEX Surface and TOA Radiation Budget Dataset Release-3 (Stackhouse et al., 2014) and the ISCCP-FD Dataset (Zhang et al., 2004). The re-analysis datasets were taken from the MERRA and the ERA-Interim products. Some of these datasets were also undergoing quality assessment under the GEWEX Radiative Flux Assessment (RFA) project. For the purposes of the present study, we treated EBAF dataset as the reference and compared the other datasets with it.

A 7-year period (2001-2007) that is common to all datasets is chosen for comparisons of global and zonal averages, monthly and annual average timeseries, and their anomalies. These comparisons showed significant differences between EBAF and the other datasets. Certain anomalies and trends observed in the satellite-derived datasets were attributable to corresponding features in satellite datasets used as input, especially ISCCP cloud properties. Comparisons of zonal averages showed significant differences especially over higher latitudes even when those differences were not obvious in the 7-year global averages. Special emphasis was placed on the analysis of the correspondence between spatial patterns of the geographical distribution of the above fluxes on a 7-year average as well as on a month-by-month basis using the Taylor (2001) methodology. Results showed that for 7-year average fields correlation coefficients between spatial patterns exceeded 0.95 for all fluxes with only one exception.

References: Loeb et al. (2009): J. Climate, Vol. 22, 748-766, (DOI: 10.1175/2008JCLI2637.1). Stackhouse et al. (2014): J. Clim. Appl. Meterol., Vol. 53 (submitted). Taylor (2001): J. Geophys. Res., Vol. 106, 7183-7192. Zhang et al. (2004): J. Geophys. Res., Vol. 109, (DOI: 10.1029/2003JD004457).