A Synoptic Analysis of Cyclonic Activities at Different Levels of Iran Atmosphere Case study: Year 1990

Document Type : Research Paper

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Abstract

The present research has studied the synoptic of cyclonic activities at different levels of Iran’s atmosphere. The cyclone-genesis zones and its movement paths can be identified by several algorithms. This research has performed to identify the temporal and spatial conditions of effective cyclones on  Iran climate on seasonal and monthly scales. To identify the Cyclones, 6hours data of geo potential heights (HGT) for 1000,925, 850, 700, and 500 hPa levels were extracted from NCEP/NCAR database for coordinates of  30◦west  up to 80◦ east  and 0◦ - 80◦ north for year 1990. The statistical analysis of cyclones in several levels of atmosphere showed that in 1990, maximum number of cyclones occurred in 500 hPa level and the least frequencies occurred in 850 hPa that have only 990 cyclones. Generally in 500 and 700 hPa, the peak of Mediterranean cyclones activities occurred in December to February. In cold period, a cyclone- genesis center has been  located in Italy. The second cyclone- genesis center is extended from Greece up to Cypress. In winter, Italian cyclone- genesis centers are transferred to eastern half of Mediterranean Sea, on Cypress, Syria and Turkey. These locations comprise the main cyclone- genesis centers in winter. Generally it seems that the expanding limit of dynamic cyclones are from 500 to 700 hp level. Only if the cyclone is very strong it can be seen at levels lower than 700 hPa.

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History

  • Receive Date: 17 June 2014
  • Accept Date: 17 June 2014

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