Atmospheric impacts on climatic variability of surface incident solar radiation

Abstract

Abstract. The Earth's climate is driven by surface incident solar radiation (R s ). Direct measurements have shown that R s has undergone significant decadal variations. However, a large fraction of the global land surface is not covered by these observations. Satellite-derived R s has a good global coverage but is of low accuracy in its depiction of decadal variability. This paper shows that daily to decadal variations of R s , from both aerosols and cloud properties, can be accurately estimated using globally available measurements of Sunshine Duration (SunDu). In particular, SunDu shows that since the late 1980's R s has brightened over Europe due to decreases in aerosols but dimmed over China due to their increases. We found that variation of cloud cover determines R s at a monthly scale but that aerosols determine the variability of R s at a decadal time scale, in particular, over Europe and China. Because of its global availability and long-term history, SunDu can provide an accurate and continuous proxy record of R s , filling in values for the blank areas that are not covered by direct measurements. Compared to its direct measurement, R s from SunDu appears to be less sensitive to instrument replacement and calibration, and shows that the widely reported sharp increase in R s during the early 1990s in China was a result of instrument replacement. By merging direct measurements collected by Global Energy Budget Archive with those derived from SunDu, we obtained a good coverage of R s over the Northern Hemisphere. From this data, the average increase of R s from 1982 to 2008 is estimated to be 0.87 W m −2 per decade.

Contribution of solar radiation to decadal temperature variability over land

“…In Asia, DTR substantially decreased from the 1950s to the 1980s, was stable until 2000, and then decreased again, consistent with R s derived from sunshine duration (25) and the dimming of directly measured R s between 1960 and 1990 in China (11,31). As already mentioned, after the 1990s, direct observations of R s became inconsistent with those of DTR and sunshine (31), a result of the urban bias of R s observations.…”

“…However, R s in China increased suddenly during the early 1990s but not DTR and sunshine duration (25). The introduction of new pyranometers from 1990 to 1993 introduced this inhomogeneity into the R s observations (25,26). Fig.…”

Solar Energy Potential in Nepal and Global Context

“…Solar radiation, one of the major fuel sources, occurs abundantly everywhere and also in Nepal. Surface incident solar radiation governs/drives the atmospheric circulations, Earth's climate [17], and Earth's biosphere naturally. It is also the originator of all other sources of energy that exists on the face of this earth.…”

Estimation of atmospheric mixing layer height from radiosonde data

“…Then turbulence and the atmospheric boundary layer develop (Stull, 1988). Turbulence is much more efficient than molecular conduction at transporting momentum, mass and heat (Wang et al, 2012). Among the turbulent fluxes, the sensible heat flux transfers the surface-absorbed heat, including solar short-wave (Wang et al, 2012) and long-wave radiation (Wang and Dickinson, 2013), to the atmosphere; the latent heat flux moistens the atmosphere.…”

“…Turbulence is much more efficient than molecular conduction at transporting momentum, mass and heat (Wang et al, 2012). Among the turbulent fluxes, the sensible heat flux transfers the surface-absorbed heat, including solar short-wave (Wang et al, 2012) and long-wave radiation (Wang and Dickinson, 2013), to the atmosphere; the latent heat flux moistens the atmosphere. The unstable boundary layer that occurs during the daytime is also referred to as the "convective boundary layer" or "the mixing layer" because it is characterised by strong turbulent motions.…”