Large-scale modes of climate change and the consistency of changes in the spatio-temporal structure of the field of atmospheric precipitation in the Altai region

Today the regional response to the global changes in modern climate is a very urgent problem. In this article the impact of large-scale modes of modern climate change on a particular space-time structure of the fields in annual and seasonal precipitation amounts in the Altai region has been analyzed. A significant trend in the dynamics of annual precipitation on the background of increasing global temperatures in recent decades has not been fixed. The insignificant growth of the annual amounts was due to precipitation in the warm half of the year. The decrease of precipitation in the cold half of the year at most stations was revealed. The maximum increase in annual precipitation in all the considered periods was recorded in the steppe regions of the Altai region, at stations Kulunda and Klyuchi. Considerable spatial heterogeneity of changes in precipitation in the region is primarily due to the terrain relief. Relief, as it is known, is one of the basic climate factors. The study area has two parts. In the first part, global processes (the trend, annual variation) make a significant contribution to the changes in precipitation. In the second part, the periodic components and local conditions have a decisive influence. So, at the stations belonging to the first and third classes, from 70 to 95% of the variability of precipitation series is determined by deviations (frequency, remnants). The second part is the mountainous part of the region. These stations belong to the fourth class. Here, one would expect the maximum influence of local conditions on the precipitation regime. But the deviations almost everywhere here are up to 50%. Thus, in the more difficult terrain, the variability of precipitation is almost equally determined by both deviations and global factors. The consistency in changing the seasonal structures of these climatic characteristics is shown. The increase in the variability of precipitation during the cold period in the recent fifteen years in the Altai region on the background of the decreasing speed of global warming was found. The response was revealed in the precipitation regime in the region to the mechanism El Nino - Southern Oscillation. This response is contradictory. At this stage, we can conclude that the sharp decrease in the amount of precipitation at most stations of the Altai region is observed in the periods of very strong El Nino. At most of the stations six- and eight-year-old harmonics were leading, that is making the greatest contribution to the variability of precipitation series. On average, the events of El Nino repeat with such a period. The obtained results have shown that the global climate change now is not provoked by substantial transformations in the space-time mode of precipitation of the Altai region. Its oscillations are observed with typical periods showing the response of the precipitation regime in the Altai region to the external events of different scales.

Keywords

Authors

References