ALBERT

Description: Effects of cloud diurnal cycle on top-of-atmosphere (TOA) and surface regional monthly mean irradiances, climatological mean, and anomalies are analyzed using CERES derived TOA irradiances and surface irradiances computed with MODIS derived cloud properties. Cloud properties derived from Terra and Aqua MODIS are sufficient to capture cloud diurnal cycle to compute regional monthly mean surface irradiances. While missing cloud diurnal cycle leads to a biased TOA and surface regional irradiances for regions with a strong cloud diurnal cycle, monthly regional TOA and surface anomalies derived from one sun-synchronous orbit agrees well with those derived from two sun-synchronous orbits. Based on these results, the algorithm to produce Edition 4.2 CERES EBAF product is developed. Regional TOA and surface climatological means derived from one sun-synchronous orbit are adjusted to match corresponding climatological means derived from Terra+Aqua observations. This climatological adjustment approach is used to merge the Terra only period to the Terra+Aqua period and to extend the Terra and Aqua record by merging NOAA20 observations. Two additional differences of Edition 4.2 EBAF algorithm to compute surface irradiances compared to the earlier version are: 1) no geostationary satellite derived cloud properties are used and 2) temperature and humidity from MERRA-2 instead of GEOIS-5.4.1 are used. Once surface monthly regional mean irradiances are compared with surface observations, the agreement is equivalent to the agreement with the earlier version. However, because surface irradiances are not affected by geostationary satellite artifacts, regional surface irradiance anomaly time series is significantly improved, especially for longwave irradiances.

Description: The NASA Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) product fluxes are used to monitor the Earth’s energy balance and validate climate models. The CERES EBAF product relies on Terra (10:30 MLT) and Aqua 1:30 MLT) CERES flux observations and the hourly geostationary (GEO) derived broadband fluxes to estimate the regional diurnal cycle. The CERES EBAF product migrated to a NOAA-20 and GEO based flux product during the April 2022 data month, due to the drifting Terra and Aqua orbits. The hourly GEO fluxes are now critical to resolve the regional diurnal cycle. A constellation containing CERES-like sensors would be able to monitor the regional diurnal flux variability more accurately as well as to further constrain the GEO derived fluxes, than a dataset based on a single CERES sensor. The Geostationary Earth Radiation Budget sensor provides 15-minute broadband fluxes that can be used to perform orbital sampling studies. The GERB (Meteosat 0° East) satellite domain encompasses all the systematic diurnal cycle regions including maritime stratus, afternoon convection, and desert land heating. The CERES temporal SW and LW interpolation and averaging algorithms will be applied to the hypothetical orbit sampled fluxes to estimate both the regional daily and monthly mean fluxes as well as hourly and monthly hourly fluxes, which will be compared to the GERB averaged regional fluxes. Combinations of sun-synchronous and precessionary orbit sampling will be evaluated to identify constellations that capture the daily diurnal TOA flux variability.