More frequent cloud‐free sky and less surface solar radiation in China from 1955 to 2000

Abstract

[1] Newly available data from extended weather stations and time period reveal that much of China has experienced significant decreases in cloud cover over the last half of the Twentieth century. This conclusion is supported by the analysis of the more reliably observed frequency of cloudfree sky and overcast sky. The total cloud cover and low cloud cover have decreased 0.88% and 0.33% per decade, respectively, and cloud-free days have increased 0.60% and overcast days decreased 0.78% per decade in China from 1954 -2001. Meanwhile, both solar radiation and pan evaporation have decreased in China, with solar radiation decreasing 3.1 W/m 2 and pan evaporation decreasing 39 mm per decade. Combining these results with findings of previous studies, we speculated that increased air pollution may have produced a fog-like haze that reflected/absorbed radiation from the sun and resulted in less solar radiation reaching the surface, despite concurrent increasing trends in cloud-free sky over China.

Inter-Annual Variations of Cloud and Precipitation and their Possible Relationships with Surface Aerosols in Shanghai

“…The vapor pressure presents a gradual increase trend before 1998 and a steady decline trend afterwards. The sunshine duration shows a decreasing trend during 1980-2010, which agrees with the previous finding in China (Qian et al, 2007). The changes of cloud fraction is reported as a crucial factor to impact sunshine duration in many studies (Cutforth and Judiesch, 2007;Li et al, 2011).…”

Is global dimming and brightening in Japan limited to urban areas?

“…The use of population alone as a proxy to infer the air pollution level is under debate (Alpert et al, 2005;Ramanathan et al, 2007;Alpert and Kishcha, 2008;Stanhill and Cohen, 2009;Imamovic et al, 2016). Related are issues associated with the use of population-based proxies to infer CO 2 emissions (for an overview, see Andres et al, 2012), even though CO 2 emissions are not necessar- Around 1955-1960Around 1975-1980Around 1995-2000 Akita Fukuoka Kagoshima 1957 (1) 1977 (1) 1996 (1) 1957 (2) 1977 (2) 1999 (1) 1954 (2) 1977 ( 13979 Around 1955-1960Around 1975-1980Around 1995-2000 Matsumoto Naha Sapporo 1959 (1) 1976 (1) 1995 (1) 1962 (2) 1977 (2) 1997 (1) 1958 (1) 1977 ( Figure 5. Chronological changes in land use surrounding the current and previous sites for the 14 observatories under study (length of the scale bar is 1 km).…”

“…In earlier studies, Ohmura and Lang (1989) proposed cloud changes as the cause of global dimming, while a few studies (Stanhill and Moreshet, 1992;Liepert et al, 1994) attributed the radiation changes to aerosols. Previous studies until now generally pointed to the dominant role of aerosols in bringing about global dimming and brightening in China and Japan (Kaiser and Qian, 2002;Hayasaka et al, 2006;Qian et al, 2006;Norris and Wild, 2009;Kudo et al, 2012;Wang et al, 2012;Wang and Yang, 2014), in Europe (Norris and Wild, 2007;Ruckstuhl et al, 2008;Wang et al, 2012), and globally (Wild et al, 2005) based on a variety of approaches to estimating or inferring clear-sky (or cloud-free) SSR. Streets et al (2006) showed that the temporal trends of global mean aerosol optical depth (AOD) derived from emission inventories for sulfate dioxide (SO 2 ) and black carbon (BC) have a resemblance to the global brightening and dimming phenomenon.…”

Resistance and Resilience of A Stream Salamander To Supraseasonal Drought

“…Pan evaporation Decreasing trends during recent decades are found in sparse records of pan evaporation (measured evaporation from an open water surface in a pan, a proxy for potential evapotranspiration) over the USA (Peterson et al, 1995;Golubev et al, 2001;Hobbins et al, 2004), India (Chattopadhyay and Hulme, 1997), Australia (Roderick and Farquhar, 2004), New Zealand (Roderick and Farquhar, 2005), China (Liu et al, 2004;Qian et al, 2006b) and Thailand (Tebakari et al, 2005). Pan measurements do not represent actual evaporation (Brutsaert and Parlange, 1998), and trends may be caused by decreasing surface solar radiation (over the USA and parts of Europe and Russia) and decreased sunshine duration over China that may be related to increases in air pollution and atmospheric aerosols and increases in cloud cover.…”