Cyclone tracking affecting precipitation in Iran
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ORIGINAL PAPER
Cyclone tracking affecting precipitation in Iran Atoosa Khojasteh 1 Received: 5 March 2020 / Accepted: 30 July 2020 # Saudi Society for Geosciences 2020
Abstract In recent years, fluctuations in precipitation have caused many environmental problems in Iran; understanding the reasons of these changes is essential for sustainable development planning. Mid-latitude cyclones play a significant role in providing precipitation over Iran. In the current research, cyclone centers were defined based on two features; on the investigation point, the geopotential height is minimum compared with the eight neighbors and the weighted average of the geopotential heights on the investigation point and the eight neighbors is at least 100 geopotential meter per 1000 km. Geopotential heights and the sea level pressure data during the period of 1986–2013 for spatial dimensions, 10 to 60 degrees of north latitude and − 40 to 80 degrees of east longitude, were taken from the American National Center for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR). Data review revealed that there is a northward shift in cyclone routes associated with precipitation for the country. Moreover, the cyclones entering from the eastern Mediterranean have been reduced. Global warming and changes in the path of storm tracks can be regarded as possible reasons behind the observed changes in precipitation in Iran. In response to the shifts in cyclonic routes entering Iran, changes in precipitation have also occurred. These reductions in precipitation may continue, at least, over foreseeable future. Keywords Cyclone . Mediterranean low pressure . Precipitation . Iran . Geopotential height
Introduction The general circulation of atmosphere determines the average atmospheric conditions in the long term which means the weather of every place changes every day. This suggests that the atmospheric conditions of each region are controlled by synoptic systems which may emerge as cyclone and anticyclone (Kaviani et al. 2012). Cyclones are the most important weather systems in mid-latitudes which are known as atmospheric disturbances (Masoudian 2012). Cyclone is a lowpressure center which depends on one or more isobar curves. Extratropical cyclones are the dominant phenomena for the mid-latitude climate. On the one hand, cyclones are responsible in transferring the important part of the water vapors needed for precipitation, while they are associated with many natural hazards of mid- and high-latitudes, such as land and sea Responsible Editor: Zhihua Zhang * Atoosa Khojasteh [email protected] 1
Department of geography, University of Zanjan, Zanjan, Iran
storms and extreme precipitation (Bayat et al. 2017). The Mediterranean region is one of the most active parts of the northern hemisphere, with the maximum cyclogenesis activity. Among many Mediterranean cyclone routes, there are two main routes: one belongs to the island of Iceland toward the north of Siberia and the other toward the Gulf of Genoa along the
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