Synoptic-thermodynamic analysis and modeling of heavy spring rains in Lorestan province
Subject Areas :
Farzad Nourizadeh
1
,
Amir Gandomkar
2
,
Morteza Khodagholi
3
1 - Department of Geography, Najafabad Branch, Islamic Azad University, Najafabad, Iran
2 - Department of Geography, Najafabad Branch, Islamic Azad University, Najafabd, Iran
3 - Rangeland Research Department, Forests and Rangelands Research Institute, Agricultural Research, Education and Extension Organization, Tehran, Iran
Keywords: Lorestan, extreme precipitation, Synoptic, thermodynamic indices,
Abstract :
Heavy rains are one of the most important climatic hazards of Lorestan province, which has increased during recent decades in the context of climate change.In this research, the main goal is to reveal the synoptic-thermodynamic patterns that generate heavy spring rains in Lorestan province.In this regard, three categories of daily precipitation data from Lorestan stations, synoptic factors from NCEP/NCAR climate database, and upper atmosphere data from University of Wyoming database were used.First, using the 95th percentile method, the heavy rainfalls of the studied stations during the statistical period of 1995 to 2020 were determined in Lorestan province. Two cases of heavy spring rain (April 14, 2016, April 1, 2019) were extracted by applying the percentile method on the daily rainfall of Hamdid stations in Lorestan province. The results of synoptic analysis in the middle and upper level of the atmosphere, in the selected samples of the spring season, showed a deep trough over the eastern Mediterranean Sea and the western part of Iran, which has prepared the conditions for the ascent and entry of low pressure systems for the west of the country.At the surface of the earth, low pressure has prevailed in the west of Iran. The center of Wachrokhandi is formed over the Oman Sea and the Persian Gulf, which directs moisture from the Oman and Arabian Seas to the south and southwest of Iran. But the thermodynamic indicators did not reveal a significant difference in the atmospheric conditions of high spring rains.
