Cloud and aerosol contributions to variation in shortwave surface irradiance over East Asia in July during 2001 and 2007

Abstract

It is important to clarify the contributions of clouds and aerosols to the variation of surface shortwave irradiance (S) for climatological studies. This study examined the contributions of clouds and aerosols to the variation in S over East Asia (75°E-135°E, 20°N-55°N) in July during 2001 and 2007 using the index of potential radiative forcing (PRF) to characterize the temporal and geographical variation. After confirming the validity of PRF for multiyear analyses, we performed several temporal analyses of clouds and aerosols over the whole research domain. Changes in the geographical distribution, contribution histograms, and averaged values were studied. In agreement with previous studies that treated single-year cases, we confirmed that the magnitudes of the temporal changes in S variations due to clouds and aerosols were highly variable geographically. As for domain-averaged S variations, we did not observe defined trends for the research period. It was also found that the temporal variation between one parameter and its S variation was negatively correlated, from the point analyses at two locations. Based on these results, we concluded that PRF is a promising tool for research into long-term S variations. This kind of information will be quite valuable as basic data for use in climate modeling.

Quantifying the respective roles of aerosols and clouds in the strong brightening since the early 2000s over the Iberian Peninsula

“…Changes in the concentration of various atmospheric gases such as ozone and water vapor play a negligible role on the significant long‐term variations detected in the incoming SSR at the surface [e.g., Kvalevag and Myhre , ; Antón and Mateos , ; Mateos et al ., ]. Nevertheless, the relative contribution of clouds and aerosols to the temporal changes in SSR is not clear yet [e.g., Norris and Wild , ; Chiacchio and Vitolo , ; Kawamoto and Hayasaka , ]. On the one hand, the discussion of aerosol radiative effects is usually restricted to cloud‐free conditions.…”