Summer precipitation determinant factors of Iran's South-East
Indian Ocean is known as a source of moisture for southeast of Iran due to summer precipitation. In this study, in order to investigate the role of SST of Indian Ocean, and the convergence and divergence fields in the precipitation of southeast of Iran, precipitation data of five synoptic stations were used during 2000-2010, including Iranshahr, Khash, ChahBahar, Zabul, and Saravan. To investigate synoptic circumstances of precipitation, different atmospheric levels of data was obtained from National Oceanic and Atmospheric of United States (NOAA) website with the horizontal resolution of 5.2 degree. Afterward, maps of wind, heights, and moisture flux were prepared. The results show that these three important factors (including Indian Ocean surface temperature (SST), convergence and divergence fields, and monsoon returned east jet stream) have one important role in the summer rainfall event for the study region. In addition, summer precipitation is influenced by the wet and shallow summer monsoon, sea surface temperatures, and convergence and divergence in continental regions. East jet stream have also been effective in these regions. Summer rainfall patterns. have played roles in this region, including the convergence of the wind in southeast of Iran and the divergence of wind in the southeast of Arabian Peninsula in first pattern. The above circumstances as well as high temperatures of sea surface are considered in second pattern, and high sea surface temperature and the monsoon East jet stream in third pattern.
The summertime mei-yu–baiu rainband over East Asia displays considerable interannual variability. A singular value decomposition (SVD) analysis for interannual variability reveals that precipitation anomalies over the mei-yu–baiu region are accompanied by in situ anomalies of midtropospheric horizontal temperature advection. Anomalous warm (cool) advection causes increased (decreased) mei-yu–ba...متن کامل
The lack of a precisely-dated, unequivocal climate proxy from northern China, where precipitation variability is traditionally considered as an East Asian summer monsoon (EASM) indicator, impedes our understanding of the behaviour and dynamics of the EASM. Here we present a well-dated, pollen-based, ~20-yr-resolution quantitative precipitation reconstruction (derived using a transfer function) ...متن کامل
precipitation changes in the region on orbital timescales. 22 The Nordeste, a semi-arid region in northeastern Brazil, 23 is known for its severe and recurrent droughts, which cause 24 socioeconomic problems for millions of people. Observational and 25 modelling studies have convincingly linked below-normal rainfall 26 in the Nordeste during the rainy season (February, March and 27 April) to pe...متن کامل
The simulations of summertime diurnal cycle of precipitation and low-level winds by the Community Atmosphere Model, version 5, are evaluated over subtropical East Asia. The evaluation reveals the physical cause of the observed diurnal rainfall variation in East Asia and points to the source of model strengths and weaknesses. Two model versions with horizontal resolutions of 2.88 and 0.58 are us...متن کامل
In the present study, the main aim was the spatial evaluation summer rainfall of northwest of Iran based on30 stations in northwest of Iran during 30 years of statistical period (1985-2014). An attempt, using geo-statistical modeling by ordinary least squares (OLS) and geographically weighted regression (GWR) procedures, was also made. The results represented that the GWR model with higher S2, ...متن کامل
We use measurements of recent decades, 1500-yr proxy data, and millennium model simulations with a variety of climate facings to study the temporal and spatial variability of summer precipitation over eastern China. Spectral analysis of the proxy data using multi-taper method reveals three statistically significant bidecadal (15–35-yr), 5 pendadecadal (40–60-yr), and centennial (65–170-yr) osci...متن کامل
دوره 3 شماره 1
صفحات 59- 70
تاریخ انتشار 2017-01-01
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