Recent variations of cloudiness over Russia from surface daytime observations

Abstract

Changes of total and low cloud fraction and the occurrence of different cloud types over Russia were assessed. The analysis was based on visual observations from more than 1600 meteorological stations. Differences between the 2001-10 and 1991-2000 year ranges were evaluated. In general, cloud fraction has tended to increase during recent years. A major increase of total cloud fraction and a decrease of the number of days without clouds are revealed in spring and autumn mostly due to an increase of the occurrence of convective and non-precipitating stratiform clouds. In contrast, the occurrence of nimbostratus clouds has tended to decrease. In general, the ratio between the occurrence of cumulonimbus and nimbostratus clouds has increased for the period 2001-10 relative to 1991-2000. Over particular regions, a decrease of total cloud fraction and an increase of the number of days without clouds are noted.

Diurnal asymmetry to the observed global warming

“…This asymmetric change in cloud cover is compatible with the observed SAT asymmetries, as has been found by Dai et al (, ). Furthermore, the strongest increase in the convective cloud types was found in the Eurasian mid‐latitudes in summertime (Chernokulsky et al, ; Eastman and Warren, ) with the correlations between the CC and the SAT of −0.72 (Europe) and −0.56 (Northern Asia and China) as obtained by Tang and Leng () from the analysis of satellite cloud cover data over 1982–2009.…”

Climatology and changes in cloud cover in the area of the Black, Caspian, and Aral seas (1991–2010): a comparison of surface observations with satellite and reanalysis products

“…It should be pointed out that a longer period (1971–2009) was studied by these authors. Chernokulsky et al () analysed the same period as us (1991–2010), albeit only Russian stations, and found, as we did, an increase in TCC in the northeast of the Black Sea and the north of the Caucasus, particularly in autumn‐winter. This is not surprising because the ground observations of cloudiness are likely the same or very similar.…”

“…This latter paper, however, shows that the increase in TCC is not as evident in our study area; specifically, for the 1995–2009 subperiod, a decrease in TCC (from −2 to over −6 %TCC decade −1 ) affects the northern regions of the area. A more detailed study of clouds based upon visual observations at Russian meteorological stations over a 20‐year (1991–2010) period (Chernokulsky et al , ) shows that in the north of the Caucasus, between the Black and the Caspian Sea, daytime TCC tends to increase, particularly in autumn and winter (approximately 1 %TCC decade −1 ), and much less remarkably in summer and spring.…”

Comparison of NCEP/NCAR and ERA-40 total cloud cover with surface observations over the Tibetan Plateau

“…It is appropriate to investigate the inter-annual variations and trends of clouds, and several studies have analysed clouds at the regional and global scales. Total cloud cover (TCC) shows an increasing trend in the United States during 1976-2004(Dai et al, 2006, Australia during 1957Australia during -2007 (Jovanovic et al, 2011), the former Soviet Union during 1936-1990(Sun and Groisman, 2000 and Russia during 1991-2010 (Chernokulsky et al, 2011). In other regions and countries, the TCC has decreased including China during 1951-1994 (Kaiser, 1998(Kaiser, , 2000, India during 1961(Jaswal, 2010, most of South Africa during 1960(Kruger, 2007), and Italy during 1951-1996(Maugeri et al, 2001.…”