| dc.description.abstract | The surface radiation budget affects different components of Earth’s climate system. Accurate assessments of the surface radiation budget help improve climate forecasts, such as drought prediction. In addition, short-term diabatic heating and cooling influence convection, temperature, and wind. Surface observations are the most accurate way to measure surface radiative fluxes. However, many locations across the globe do not have access to precise surface radiation measurements. In addition, surface observations are point-based measurements and offer little spatial coverage. As a result, areas with little to no surface observations rely on top-of-the-atmosphere (TOA) satellite instruments to measure surface radiation. Accurate radiative flux measurements from space are much more complicated and prone to errors than surface observations as they are derived from TOA radiances. Thus, a thorough understanding of satellite-based surface flux data are needed.
The Clouds and the Earth’s Radiant Energy System (CERES) is an instrument currently deployed on four satellites. Surface radiative fluxes derived from CERES TOA measurements must account for atmospheric variables such as aerosol optical depth, zenith angle, aerosol and trace gas concentrations, cloud fraction, cloud optical thickness, and cloud albedo. The State of Oklahoma invested in a dense Mesonet network of 120 stations. A dense population of Mesonet stations with a high-resolution product makes it possible to effectively evaluate the CERES surface downward shortwave radiative fluxes based on a simple parameterized code.
This work compares the CERES-Aqua and CERES-Terra Single Scanner Footprint (SSF) Level 2 Edition 4A surface radiation product collocated with the Mesonet-derived observed downward shortwave radiative fluxes for the period 2019 to 2021. We explore clear-sky and all-sky environments by separating the dataset into three different bins using the Moderate Resolution Imaging Spectrometer (MODIS). We find a strong correlation (i.e., correlation coefficient greater than 0.9) between CERES-Aqua and CERES-Terra downward shortwave surface radiative fluxes with the collocated equivalent Mesonet irradiance observations for all three cloud fraction bins. The correlation coefficients of the all-sky bins slightly increased versus the clear-sky bins. During all three years, the CERES-Terra data had higher Mean Absolute Difference (MAD), Mean Bias Difference (MBD), and Root Mean Squared Difference (RMS) than the CERES-Aqua data. We also examine the seasonal dependence of the CERES-Mesonet differences, where the summer all-sky differences are larger than the other seasons. | en_US |
