Recent Climatic Changes over Kazakhstan

We used a comprehensive archive of daily in situ meteorological information for Republic of Kazakhstan created by joint efforts of the Kazakh Scientific Research Institute of Ecology and Climate of the Ministry of Environment Protection of the Republic of Kazakhstan, All-Russian Research Institute for Hydrometeorological Information-World Data Center of the Federal Service for Hydrometeorology and Environmental Monitoring, Obninsk, Russian Federation, and the NOAA National Climatic Data Center, Asheville, North Carolina. Archive includes the data of 351 synoptic stations and spans the period of instrumental observations with the best data coverage during the 1936-2006 period. This period was used to assess climatology and the latest (since 1990) climatic changes in surface air temperature, precipitation, relative humidity, and the near surface wind speed and atmospheric pressure over Kazakhstan. We found that during the last two decades (1990-2006) compared to the previous three decades, surface air temperature, T, in Kazakhstan increased by 1 to 2 K in winter, spring, and autumn (with the maximum warming in the autumn) but not in summers where a cooling was observed in the central parts of the nation. Changes in relative humidity were symmetric and negatively correlated with T: reporting drier surface air conditions in winter, spring, and autumn and an increase in the mean summer relative humidity values. Countrywide, annual precipitation did not change substantially (it somewhat increased in winter and summer, but mostly decreased in the intermediate seasons). The largest change signal found is a substantial nationwide decrease of the wind speed at 10 m above the ground in all seasons.