Global distribution of Earth's surface shortwave radiation budget

Abstract

Abstract. The monthly mean shortwave (SW) radiation budget at the Earth's surface (SRB) was computed on 2.5-degree longitude-latitude resolution for the 17-year period from 1984 to 2000, using a radiative transfer model accounting for the key physical parameters that determine the surface SRB, and long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2). The model input data were supplemented by data from the National Centers for Environmental PredictionNational Center for Atmospheric Research (NCEP-NCAR) and European Center for Medium Range Weather Forecasts (ECMWF) Global Reanalysis projects, and other global data bases such as TIROS Operational Vertical Sounder (TOVS) and Global Aerosol Data Set (GADS). The model surface radiative fluxes were validated against surface measurements from 22 stations of the Baseline Surface Radiation Network (BSRN) covering the years 1992-2000, and from 700 stations of the Global Energy Balance Archive (GEBA), covering the period 1984-2000. The model is in good agreement with BSRN and GEBA, with a negative bias of 14 and 6.5 Wm −2 , respectively. The model is able to reproduce interesting features of the seasonal and geographical variation of the surface SW fluxes at global scale. Based on the 17-year average model results, the global mean SW downward surface radiation (DSR) is equal to 171.6 Wm −2 , whereas the net downward (or absorbed) surface SW radiation is equal to 149.4 Wm −2 , values that correspond to 50.2 and 43.7% of the incoming SW radiation at the top of the Earth's atmosphere. These values involve a long-term surface albedo equal to 12.9%. Significant increasing trends in DSR and net DSR fluxes were found, equal to 4.1 and 3.7 Wm −2 , respectively, over the 1984-2000 period (equivalent to 2.4 and Correspondence to: N. Hatzianastassiou (nhatzian@cc.uoi.gr) 2.2 Wm −2 per decade), indicating an increasing surface solar radiative heating. This surface SW radiative heating is primarily attributed to clouds, especially low-level, and secondarily to other parameters such as total precipitable water. The surface solar heating occurs mainly in the period starting from the early 1990s, in contrast to decreasing trend in DSR through the late 1980s. The computed global mean DSR and net DSR flux anomalies were found to range within ±8 and ±6 Wm −2 , respectively, with signals from El Niño and La Niña events, and the Pinatubo eruption, whereas significant positive anomalies have occurred in the period 1992-2000.

Potential evaporation trends over land between 1983–2008: driven by radiative fluxes or vapour-pressure deficit?

“…Also, we cannot preclude the existence of spurious trends in our radiation model inputs, such as the ones reported by Evan et al (2007) for ISCCP. However, radiation flux trends derived by our earlier works compare well with observations from ground stations and satellites Hatzianastassiou et al, 2005;Fotiadi et al, 2005). With these caveats in mind, we continue our analysis.…”

The Global Energy Balance Archive (GEBA) version 2017: a database for worldwide measured surface energy fluxes

“…The earliest investigations that used GEBA data to assess satellite-derived surface fluxes were made by Whitlock et al (1995), Rossow and Zhang (1995), and Li et al (1995b). Hatzianastassiou et al (2005), based on their global satellite-derived surface radiation product validated against GEBA data, provided additional evidence for a lower downward shortwave radiation than commonly assumed, in line with the findings of the GEBA-based global energy balance studies mentioned above. A detailed assessment of their radiation scheme compared to GEBA data over the Mediterranean area was performed by Papadimas et al (2012) and Pyrina et al (2015).…”

Aerosols in the convective boundary layer: Shortwave radiation effects on the coupled land‐atmosphere system

“…With respect to observations, by isolating the aerosol impacts on the SW radiation, Hatzianastassiou et al [2005] and Wang et al [2009] have shown that detailed aerosol temporal evolution and vertical profiles are needed to reproduce the observed direct/diffuse partitioning and global irradiance [see also Meywerk and Ramanathan, 1999;Singh et al, 2010]. The available observational campaigns studying the aerosol impacts on the troposphere [e.g., de Wekker et al, 2004;Johnson et al, 2008] focused mainly on instrument comparisons and data validation without discussing in detail how the aerosols influence the boundary-layer vertical structure and the CBL heat budget.…”