Variability of vegetation index NDVI during periods of drought in the Tomsk Regionстатья
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Дата последнего поиска статьи во внешних источниках: 4 мая 2020 г.
Аннотация:Current climate changes are characterized by an increase in the frequency of
occurrence of extreme natural phenomena, which include droughts and over moistening
periods of the territory. The main indicator of drought / over moistening periods is the state of
vegetation. Estimation of the interannual and intraseasonal variability of drought can be carried
out using vegetation indicators obtained from satellite image data. In article statistical
characteristics of NDVI for seven basic types of land cover, identified at the territory of the
Tomsk region were studied. NDVI is most stable during the summer in wetlands, changing on
average during the study period from 0.58 in May to 0.71 in July, then decreasing to September
to 0.64. The variability of NDVI in dark coniferous forests is slightly greater (0.64–0.81). The
greatest variability of NDVI was obtained for floodplain meadows (0.46-0.81) and croplands
(0.51-0.79). VCI is used to identify drought situations and determine the onset, especially in
areas where drought episodes are localized and ill defined. According to the analysis of the
VCI index, in May the greatest frequency of dry periods was observed in the Tomsk region.
Analysis of changes in frequency of extreme events occurrence have shown that the number of
droughts decreases, and number of excessive moisture periods increases since 2000 till 2017.