Distinctive spring shortwave cloud radiative effect and its inter‐annual variation over southeastern China

Abstract

AbstractThe shortwave cloud radiative effect (SWCRE) plays a critical role in the earth's radiation balance, and its global mean magnitude is much larger than the warming effect induced by greenhouse gases. This study investigates the SWCRE at the top of the atmosphere and its inter‐annual variation over southeastern China (SEC) using satellite retrievals and ERA‐Interim reanalysis data. The results show that in this region the largest SWCRE with the maximum intensity up to −120 W·m−2 occurs in spring and is also the strongest between 60°S and 60°N. The domain‐averaged intensity of SWCRE is much larger than the longwave cloud radiative effect (LWCRE), suggesting the dominant cooling role of SWCRE in the regional atmosphere–surface system. The spring SWCRE over SEC shows a weak increasing trend and its anomalies in most years exceed those of LWCRE during 2000–2017. This means that SWCRE also plays a dominant role in the inter‐annual variation of regional cloud radiative effects. Over SEC, low‐ to mid‐level ascending motion and water vapor convergence during spring favor the generation and maintenance of cloud water, leading to strong SWCRE. Statistical analysis shows that the spatial pattern and intensity of the spring SWCRE are well correlated with the low‐ to mid‐level ascending motion and water vapor convergence. The temporal correlation coefficient between domain‐averaged spring SWCRE and 850–500‐hPa vertical velocity is .76 during 2000–2017. The long‐term variation in spring SWCRE over SEC can be inferred to some extent from regional ascending motion and associated large‐scale circulations.