Abstracts for the 6th International GAME Conf.
3-5 December 2004
Kyoto Japan
Indications of the influence of vegetation on the meteorological regime and snow in West Siberia
Lev Kitaev (1), Olaf Krueger (2), Boris Sherstyukov (3), Hendrik Hobe (2)
(1) Institute of Geography RAS, Russia
(2) Max Planck Institute of Meteorology, Germany
(3) All-Russian Research Institute of Hydrometeorology , Russia
Radiation balance is of major importance for the Earth’s climate. The surface albedo serves as one of the radiation balance indices. The most changeable factor of surface albedo variability is the area occupied with a snow cover. The structure of a snow cover varies during the winter period; it may vary even within day on dynamics of temperature of air. Thus, changes of features of a snow cover depend on a climate, changes of structure of a snow cover define to its albedo changes and changes of albedo of snow cover are the important factor of changes of a climate. Now there are no the data describing high-resolution existential variability of a snow cover and it albedo. However, quantitative acknowledgements of influence of a snow cover on air temperature through change of radiating balance of spreading surface are possible. The estimation of influence of a snow cover on meteorological conditions of the autumn and spring periods is the purpose of the given work.
The territory of the south of Western Siberia from 60oE 90oE and from 45oN up to 60oN, over area of merge of Tobol, Irtysh and Ob is investigated. In this territory various vegetative communities, from semidesertic up to taiga settle down. The data of daily observation of 24 meteorological stations for the period of 1966-1995 – air temperature, snow covering and snow depth, are used. The satellite data of albedo are used also (AVHRR, NASA 7, 9, 11).
Higher daily mean, maximal and minimal air temperatures of the winter period and greater long-term trend of their changes are characteristic for taiga. By it the least may be defined here a long-term gain of a snow cover. As a logical explanation of it may serve low àëüáåäî taiga sites. The increase of albedo from semidesertic and steppe sites to deciduous woods on a background of increase of snow depth and snow covering is received. At big snowinnes the albedo in taiga is least and it is defined of low albedo coniferous woods.
The analysis of spatial changes of snow depth, snow covering, and albedo is carried out . In latitude and longitudinal directions the increase albedo occurs according to increase of snow depth, snow covering within the limits of semideserts, steppe and deciduous woods. In taiga areas, despite of big snowinness, sharp fall albedo is observed. It is defined of same low albedo of coniferous woods also.
The original method for an estimation of features of changes of air temperature and precipitation is offered at transition of snow covering in 50 % in big (winter) or smaller (spring) side. The principle of this method is that a meteorological parameter average is calculated in that case if a certain event under analysis occurred. For comparison averages of the same parameter are calculated in the relevant days before and after the event. Two events were analyzed: a) the appearance of snow in autumn; b) the melting of snow in spring. Seasonal temperature drop by autumn at some moment results in appearance of a snow cover, which, in turn, promotes additional small downturn of temperature. Temperature drop at appearance of a snow cover on the average makes 1.5oÑ. Seasonal growth of temperature is a primary factor of snow melting in the spring, thus there is a return positive connection, after snow melt growth of temperature is accelerated. In the spring at gradual reduction of a snow cover, there is an accelerated growth of temperature. Full destruction of a snow cover causes sharp rise in temperature on 1.5oÑ. This process has special features in conditions of different vegetative communities.
Submittal Information
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Institute of Geography, Russian Academy of Sciences | |
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109017, Moscow, Staromonetniy per., 29 | |
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