assess circulation pattern of drought periods using spi (case study: central iran)

نویسندگان

kamal omidvar

professor of climatology in yazd university, yazd, iran mehran fatemi

ph. d student of climatology in yazd university, yazd, iran mahdi narangifard

ph. d student of climatology in yazd university, yazd, iran khodakaram hatami bahman beiglou

ph. d student of climatology in isfahan university, isfahan, iran

چکیده

drought is a natural hazard that have in arid and semiarid areas more frequency. so the study and identify synoptic patterns affecting this phenomenon seems to be necessary. by using peripheral circulation approach, drought periods during the 30-year (2011-1982) in the six synoptic stations provinces of kerman, yazd and isfahan, which have a long-term cooperative period were calculated with using the standardized (spi). then use principal-component analysis (pca) method with the correlation matrix method and rotation that in the varimax method on 500 pressure level data to identify the basic elements of the atmospheric currents. then by using cluster analysis with ward method on component amounts, circulation patterns causing drought were identified. the study showed that more than 42% of the variance component analysis of 500 geo-potential height level by extending the sub-polar low in to the low latitudes that led to high flow like siberian high become southern and high pressure level on researched area is formed ,so domination of high pressure center on the region cause falling air cold, stable & no cloudiness weather that show there is not instability in the region, which climbed moisture in the atmosphere and cause little precipitation and drought events.

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عنوان ژورنال:
international journal of geo science and environmental planning

جلد ۱، شماره ۲، صفحات ۳۱-۴۳

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