The drought and excessive moisture indices in a historical perspective in the principal grain-producing regions of the former Soviet Union
1997
The paper deals with catalogs (two listing by years) of droughts and conditions of excessive moisture in May-July in the basic cereals-producing area of the former Soviet Union (FSU) for 1891-1995. To calculate catalogs, data on precipitation averaged over the area of administrative regions and temperature at meteorological stations were used. The problem of the inhomogeneity of precipitation series at stations in the warm period of year is discussed, related to the introduction of corrections for moistening rain gauge bucket. The suggested catalogs of droughts and excessive moisture (index DM) explicitly include the area of distribution of certain precipitation and temperature combinations. This is their principle difference from other authors' catalogs. The paper studies the relationship between the index DM in the European (EP) and Asian (AP) parts of the territory under consideration with other drought indices and with the anomalies of cereals yield. Linear trends of the DM index series are presented, as are series of precipitation and temperature in May-July for 105 yr. It is shown that the DM time series for the European part is practically stationary. In the AP territory in May-July, the aridity grows (the positive trends of the DM index are statistically significant). The aridity growth in the AP of the basic cereals-producing area of the FSU is mainly determined by temperature rise; the negative, but statistically insignificant, trend of precipitation intensifies this process.
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