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11.
B. Alijani 《Theoretical and Applied Climatology》2002,72(1-2):41-54
Summary In order to explore the spatial and temporal variations of 500 hPa flow patterns and their relationship with the climate
of Iran, monthly mean geopotential heights for the region 0° E to 70° E and 20° N to 50° N, at 5 degree resolution, were analysed.
The study period covered the winter months October to March during the period 1961–90. The monthly height of the 500 hPa level
was averaged along each meridian from 25° N to 45° N. The height of the mean monthly pressure pattern was mapped against the
study years. The results showed that the characteristics of the 500 hPa flow pattern varied over monthly and annual time scales.
Principal Component Analysis, with S-mode and Varimax rotation, was also used to reduce the gridded data to 5 (6 in October)
significant factors. The factor scores for each month were then correlated with monthly Z-scores of precipitation and temperature
anomalies over Iran. The results showed that troughs and ridges located close to Iran had more influence on the climate of
Iran. Two troughs were identified and named the Caspian and Syrian troughs.
Received April 12, 2001 Revised July 24, 2001 相似文献
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Natural Resources Research - In this study, ZnO nanoparticles were modified with rice bran. Synthesis and production of ZnO nano-particles is highly important due to the use of rice bran. In... 相似文献
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Mesbahzadeh Tayyebeh Salajeghe Ali Sardoo Farshad Soleimani Zehtabian Gholamreza Ranjbar Abbas Krakauer Nir Y. Miglietta Mario Marcello Mirakbari Maryam 《Natural Hazards》2020,104(2):1801-1817
Natural Hazards - Dust storms are a major natural hazard to human health. Severe erosive storms in parts of the Central Plateau of Iran have made the situation very difficult for the inhabitants,... 相似文献
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Farshad Ahmadi Feridon Radmaneh Mohammad Reza Sharifi Rasoul Mirabbasi 《Environmental Earth Sciences》2018,77(18):643
Accurate estimation of low flow as a criterion for different objectives in water resource management, including drought is of crucial importance. Despite the complex nature of water deficits, univariate methods have often been used to analyze the frequency of low flows. In this study, low flows of Dez River basin were examined during period of 1956–2012 using copula functions at the upstream of headbranches’ junction. For this purpose, at first 7-day series of low flow was extracted at the studied stations, then their homogeneity was examined by Mann–Kendall test. The results indicated that 7-day low flow series of Dez basin were homogenous. In the next stage, 12 different distribution functions were fitted onto the low flow data. Finally, for Sepid Dasht Sezar (SDS), Sepid Dasht Zaz (SDZ), and Tang Panj Bakhtiyari (TPB) stations, logistic distribution had the best fit, while for Tang Panj Sezar (TPS) station, GEV distribution enjoyed the best fit. After specifying the best fitted marginal distributions, seven different copula functions including Ali–Mikhail–Haq (AMH), Frank, Clayton, Galambos, Farlie–Gumbel–Morgenstern (FGM), Gumbel–Hougaard (GH), and Plackett were used for bivariate frequency analysis of the 7-day low flow series. The results revealed that the GH copula had the best fitness on paired data of SDS and SDZ stations. For TPS and TPB stations, Frank copula has had the best correspondence with empirical copula values. Next, joint and conditional return periods were calculated for the low flow series at the upstream of branches’ junction. The results of this study indicated that the risk of incidence of severe drought is higher in upstream stations (SDZ and SDS) when compared with downstream stations (TPB and TPS) in Dez basin. Generally, application of multivariate analysis allows researchers to investigate hydrological events with a more comprehensive view by considering the simultaneous effect of the influencing factors on the phenomenon of interest. It also enables them to evaluate different combinations of required scenarios for integrated management of basin and planning to cope with the damages caused by natural phenomena. 相似文献
16.
Fathian Farshad Ghadami Mohammad Dehghan Zohreh 《Theoretical and Applied Climatology》2022,149(1-2):569-592
Theoretical and Applied Climatology - Due to increasing greenhouse gases, Iran is experiencing changes in patterns and trends of extreme climate events. Future climate extremes are one of the... 相似文献
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Investigation of spatial and temporal variability of precipitation in Iran over the last half century 总被引：4，自引：1，他引：3
Keivan Khalili Mohammad Nazeri Tahoudi Rasoul Mirabbasi Farshad Ahmadi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(4):1205-1221
Investigation of the precipitation phenomenon as one of the most important meteorological factors directly affecting access to water resources is of paramount importance. In this study, the precipitation concentration index (PCI) was calculated using annual precipitation data from 34 synoptic stations of Iran over a 50-year period (1961–2010). The trend of precipitation and the PCI index were analyzed using the Mann–Kendall test after removing the effect of autocorrelation coefficients in annual and seasonal time scales. The results of zoning the studied index at annual time scale revealed that precipitation concentration follows a similar trend within two 25-year subscales. Furthermore, the PCI index in central and southern regions of the country, including the stations of Kerman, Bandarabbas, Yazd, Zahedan, Shahrekord, Birjand, Bushehr, Ahwaz, and Esfahan indicates a strong irregularity and high concentration in atmospheric precipitations. In annual time scale, none of the studied stations, had shown regular concentration (PCI < 10). Analyzing the trend of PCI index during the period of 1961–2010 witnessed an insignificant increasing (decreasing) trend in 16 (15) stations for winter season, respectively, while it faced a significant negative trend in Dezful, Saghez, and Hamedan stations. Similarly, in spring, Kerman and Ramsar stations exhibited a significant increasing trend in the PCI index, implying significant development of precipitation concentration irregularities in these two stations. In summer, Gorgan station showed a strong and significant irregularity for the PCI index and in autumn, Tabriz and Zahedan (Babolsar) stations experienced a significant increasing (decreasing) trend in the PCI index. At the annual time scale, 50 % of stations experienced an increasing trend in the PCI index. Investigating the changes in the precipitation trend also revealed that in annual time scale, about 58 % of the stations had a decreasing trend. In winter, which is the rainiest season in Iran, about 64 % of stations experienced a decreasing trend in precipitation that caused an increasing trend in PCI index. Comparing the spatial distribution of PCI index within two 25 years sub-periods indicated that the PCI index of the second sub-period increased in the spring time scale that means irregularity of precipitation distribution has been increased. But in the other seasons any significant variations were not observed. Also in the annual time scale the PCI index increased in the second sub-period because of the increasing trend of precipitation. 相似文献
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Journal of Geographical Systems - Despite all distortions and incompleteness present in Sketch maps, they can be used for different purposes such as collecting and searching spatial data and... 相似文献
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Application of fuzzy multi-attribute decision-making to select and to rank the post-mining land-use 总被引：1，自引：1，他引：0
Isa Masoumi Saeed Naraghi Farshad Rashidi-nejad Shiba Masoumi 《Environmental Earth Sciences》2014,72(1):221-231
The selection of an optimal reclamation method is one of the most important portions of the surface mining design. There are many factors in this problem which seriously influence decision-making. The fuzzy set theory was applied due to the effect of uncertain parameters involved in the decision-making process. Therefore, the fuzzy multi-attribute decision-making method was proposed. The aim of this study is to use the fuzzy technique for order preference by similarity to ideal solution method for ranking the optimal post-mining land-use and the fuzzy analytic hierarchy process method in order to determine the weights of each criterion. This approach is applied to the surface coal mine by employing 28 criteria which influence the decision-making procedure. The TOPSIS and AHP methods have been the most used methods of mining decision-making and demonstrated their ability to make critical decisions. By evaluating the alternatives and considering effective criteria with proposed methods, agriculture is the optimal post-mining land-use. 相似文献