4:45 PM - 5:00 PM
[MIS01-12] Freezing Precipitation and Freezing Events over Northern Eurasia and North America
Keywords:freezing precipitation, climatic change, northern extratropics
In our presentation using more than 1,500 long-term time series of synoptic observations for the past four decades, we present climatology and the empirical evidence about changes in occurrence, timing, and intensity of freezing rains and freezing drizzles over five countries of Northern Eurasia and two countries of North America.
The regions with the highest frequency of freezing rains (from 3 to 10 days per year) reside in the northeastern quadrant of the conterminous United States and adjacent areas of southeastern Canada south of 50°N, over the south and southwest parts of the Great East European Plain, and Central Europe. The frequency of freezing drizzle exceeds the frequency of freezing rain occurrence in all areas. During the past decade, the frequency of freezing rain events somewhat decreased over the southeastern U.S. In North America north of the Polar Circle, it increased by about 1 day yr-1. Over Norway, freezing rain occurrences increased substantially, especially in the Norwegian Arctic. In European Russia and western Siberia, the frequency of freezing rain generally increased (except the southernmost steppe regions) while freezing drizzle frequency decreased over entire Russia. The number of days with freezing events over Belarus did not change, however, the duration of these events (in hours) substantially increased. In the mountains of Central Asia (Kyrgyzstan) we documented increases in freezing rain and drizzle frequencies only at high elevations, while they decrease at elevations below 1 km (matching to a similar decrease over the steppe zone of southern Russia).
In the former Soviet Union, instrumental monitoring of ice load has been performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. Estimates of climatology and changes in ice load based on this monitoring at 958 Russian stations will be also presented.
This work is supported by the Ministry of Education and Science of the Russian Federation (grant 14.B25.31.0026) and the NASA LCLUC Program.