Recorded presentation7B.6
Changes in cloudiness and related variables over Russia, 1950–2000
Garrett P. Marino, Massachusetts Institute of Technology, Cambridge, MA; and D. Kaiser
We use a newly-acquired update (through 2000) of Russian 3- and 6-hourly meteorological observations to investigate changes in total and low cloud amount, cloud type frequencies of occurrence, and several other related variables. The database was provided to the Department of Energy's Carbon Dioxide Information Analysis Center (CDIAC) under the auspices of a research agreement between CDIAC, NOAA, and the All-Russian Research Institute of Hydrometeorological Information (RIHMI) – World Data Centre in Obninsk, Russia. Past studies by several authors investigated variations and trends in several meteorological variables using an earlier version of the database extending from 1936–1990 that contained data from 223 stations distributed over all territories of the former Soviet Union (FSU). The current version contains only observations from Russia of the same 25 meteorological variables as the earlier FSU database and has been quality assured by both RIHMI and CDIAC. The 6-hourly observations extend from 1936 through 1965; 3-hourly observations extend from 1966 through 2000. We examine the period 1950–2000 because some station records do not begin in 1936, and because World War II caused numerous multi-year gaps during the 1940s. We settled on using a total of 125 station records that are nearly complete and produce broad coverage of the Russian territory with the exception of northern parts of Siberia. While characterizing climate behavior over a large area through simple averaging is often of limited value, we confirmed that FSU-averaged trends found by earlier investigators for several cloudiness variables through 1990 have essentially continued through 2000 for Russia alone. Given the vastness of the region, we found trend magnitudes and signs to often vary spatially, and we depict these regional differences. Total cloud cover has increased at a slight (but significant at the 95% level) 0.2%/decade over Russia despite a significant decrease in low cloud cover of 1.1%/decade. Meanwhile, the frequency of occurrence of low-level stratiform clouds significantly decreased at 1.6%/decade and cumulus clouds significantly increased by 1.4%/decade. We hypothesize that the decrease (increase) in stratus (cumulus) clouds may be associated with the large-scale warming observed over Russia in recent decades and an attendant decrease in static stability. Not all of our trends findings correspond to those of earlier studies, and we examine possible reasons; e.g., differences in both the start and end of the periods of record, and also data coverage differences. We emphasize significant changes observed over large parts of Russia, rather than simply drawing general conclusions from all-Russia averages that may not accurately characterize climate trends. Recorded presentation
Session 7B, Climate of 20th Century (C20C) Part I
Tuesday, 22 January 2008, 1:30 PM-3:00 PM, 217-218
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