Fatemrh Dargahian; Azadeh Gohardoust; Sakineh Lotfinasabasl; Sara Teimouri
Volume 31, Issue 1 , June 2024, , Pages 74-92
Abstract
Background and ObjectivesNumerous studies have individually examined the influence of neighboring countries on dust generation in southwestern Iran (Khuzestan). However, the specific countries and regions within those countries with the most significant impact on dust events in the southwest still need ...
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Background and ObjectivesNumerous studies have individually examined the influence of neighboring countries on dust generation in southwestern Iran (Khuzestan). However, the specific countries and regions within those countries with the most significant impact on dust events in the southwest still need to be clarified. This study aimed to identify the primary sources of dust emissions affecting Khuzestan using the Aerosol Optical Depth (AOD) index for dust detection and the HYSPLIT model for tracing dust pathways.MethodologyDust events in Khuzestan province from 2003 to 2017 were identified using MODIS imagery and a suitable dust detection algorithm. Three criteria were applied to each event: spatial extent exceeding 50% of synoptic stations, horizontal field of view less than 5 km, and detection in at least three consecutive synoptic reports. Considering typical dust ingress into Iran at lower and middle atmospheric layers, dust pathways were investigated at 500, 1000, and 1500 meters above ground level. HYSPLIT model outputs for dust event days were combined with AOD images from each year's day before the event in Khuzestan. Areas with the highest dust emissions towards Khuzestan were identified by analyzing AOD concentrations in the days preceding dust events. Regions exceeding a threshold of 30 times the AOD concentration were designated as dust sources or intensification zones. This analysis was performed for each year and the entire period, allowing for prioritization of the most significant dust source areas.ResultsOur analysis of dust events revealed that different regions dominated dust emissions toward Khuzestan across the study period. In 2003, northern and eastern Arabia contributed the most dust. Subsequent years exhibited varying source regions, including the Iraq-Syria border (2004), Saudi Arabia (2005), southern Iraq (2006), southern and southeastern Iraq (2007-2008), southwestern Iraq and northern Iraq alongside northern and eastern Arabia (2009), southern and southwestern Iraq (2010), western, southern, and northern/eastern Iraq alongside Arabia (2011), and again southern and southwestern Iraq (2012-2013). In 2014 and 2015, northern and eastern Arabia re-emerged as the primary source. Finally, the Iraq-Syria border, western Iraq, and southern Iraq were identified as dominant sources in 2016 and 2017, respectively. Across the entire study period (2003-2017), eastern Iraq, the Iraq-Syria border, southern Iraq, and northern and eastern Arabia emerged as the most significant dust source regions impacting Khuzestan.ConclusionOur analysis revealed that Iraq contributes the highest proportion of dust emissions impacting Khuzestan province (68.8%), followed by Saudi Arabia, Syria, and Kuwait. Considering anticipated climate change and intensified dam construction activities in upstream countries, particularly Iraq, dust generation will likely worsen. The dust originating from these regions, situated along the path of synoptic systems towards Iran, has significantly impacted the environment, especially the Zagros forests. Identifying the primary dust source areas empowers policymakers to develop tailored and effective diplomatic strategies for controlling and mitigating the effects of regional fine dust.
Fatemrh Dargahian; Somayeh Heidarnejad; Samaneh Razavizadeh
Volume 28, Issue 3 , October 2021, , Pages 564-577
Abstract
Today, global warming and climate change are considered to be the greatest challenge of human life that has overshadowed other environmental challenges. In this study, it has been attempted to detect climate change phenomena in Yazd by monitoring the trend of heat wave changes and its relation to temperature ...
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Today, global warming and climate change are considered to be the greatest challenge of human life that has overshadowed other environmental challenges. In this study, it has been attempted to detect climate change phenomena in Yazd by monitoring the trend of heat wave changes and its relation to temperature anomaly. For this purpose, daily temperature data for the time period (1960– 2017) were used. Finally, the characteristics of heat waves such as the number of occurrences of heat waves, frequency of days with heat waves, heat wave continuity, magnitude and intensity of heat waves and average heat wave (hottest day of heat wave) using ClimPACT software in programming environment R 2.10 were calculated. Heat waves are the result of incremental temperature changes. Therefore, temperature anomaly of Yazd station was extracted and compared with the temperature anomaly of the Land's surface. The relationship between heat wave indices and temperature anomalies was investigated. The results showed that the highest number of heat wave events occurred in 2010 and 2016. The number of days associated with the hot wave has increased significantly, with 47 and 42 days in 2010 and 2016, respectively. An increasing trend in the continuity and intensity of heat waves was also observed. The longest continuation for 2013 was estimated to be 13 days. The findings also show that in the last two decades the magnitude of the heat wave has reached more than 31 ° C. Investigation of the relationship between all indices related to heat wave and Yazd temperature anomaly showed good correlation and coefficient of explanation of temperature anomaly and frequency of days with heat wave was higher than other indices and its R2 was approximately 0.6108. In general, the results indicate the intensification, continuity and intensity of heat waves in Yazd city, which can indicate the occurrence of climate change, especially in the last two decades in this region of the country as a representative of the arid regions. Due to the increasing temperature in the coming years on the frequency, intensity and continuity of these waves will increase, knowing how heat waves are processed can help managers and planners make risk management decisions about energy efficiency.
Fatemrh Dargahian; sakineh lotfinasabasl
Volume 27, Issue 2 , June 2020, , Pages 300-320
Abstract
This study investigates and analyzes the decades of change in climatic zones in Karkheh, Karoun, and Zohreh - Jarahi watersheds. For this purpose, the database of temperatures and precipitation networks during the period 1976-2015, with a spatial resolution of 15 x 15 km, formatted in the conical Lambert ...
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This study investigates and analyzes the decades of change in climatic zones in Karkheh, Karoun, and Zohreh - Jarahi watersheds. For this purpose, the database of temperatures and precipitation networks during the period 1976-2015, with a spatial resolution of 15 x 15 km, formatted in the conical Lambert image system, was used. In fact, because these two elements are the most important climatic drivers in the study area and the changes of other elements in these two elements are more visible, they have been used to study and analyze the climate change zone. After establishing the database, cluster analysis was used to identify climatic regions, and the audit analysis was used to validate it. Cluster analysis was performed on 52 indices of temperature and precipitation (monthly and annual average, coefficient of variation of temperature, and precipitation monthly and annual changes) during different periods, and climatic zones and their changes were analyzed. Based on the results, three climatic zones including humid and moderate zone, hot and dry zone, and very hot and dry zone were identified in the study area. The results showed that in recent periods, the humid area, in addition to having spatial displacement, its area reduced so that in the fifth period, the area reached less than five percent. Also, the hot and dry zone, stretched as a strip from the northwest to the southwest of the study area, had less spatial displacement, unlike the humid area, while its area increased in recent periods. On the other hand, the area of the very hot and dry zone has increased towards recent periods. Spatial and temporal increase of hot and dry climates and very hot and dry climates and decrease of the humid zone has been able to lead to the development and intensification of dust source, especially downstream of the studied watersheds.
Sakineh Lotfinasabasl; Mohammad Khosroshahi; Zahra Saeedifar; Fatemeh Dargahian
Volume 25, Issue 4 , February 2019, , Pages 923-943
Abstract
Precipitation temporal trend analysis and study of the drought condition have been of great concern during the past century because of the attention given to global climate change by the scientific community. The aim of present study was to investigate and analyze the rainfall trends and its affected ...
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Precipitation temporal trend analysis and study of the drought condition have been of great concern during the past century because of the attention given to global climate change by the scientific community. The aim of present study was to investigate and analyze the rainfall trends and its affected drought conditions in Jazmurian basin using non-parametric mann-kendall method and multidimensional comparison of drought indices including Standardized Precipitation (SPI), deciles (DI), the percentage of normal (PNI), Chinese Z (CZI) and the Z score (ZSI) with rainfall data from 24 gauged stations for the period of 1983 to 2013. For this, the drought indices were calculated, and then categorization was performed on the basis of similarity and correlation using cluster analysis method. The results proved a positive and significant increase in the rainfall amount of 1992-1993 and 1995-1996 years. Statistical analysis showed that the highest amount of rainfall occurred in the years of 1992-93, 1995-96 and 2004-2005 and the lowest in the years of 1983, 2000, 2003 and 2005 in the basin. Cluster analysis showed that the ZSI and PN indices with similarity of hundred percent in the diagnosis of wet and dry periods, intensity, duration and continuity were completely similar and had the highest similarity among all the groups. The CZI and SPI with 99.5 percent similarity were in the second level of similarity as well. Validation of the results through the numerical comparison of SPI and CZI indicates the same trend of two indicators and little differences in presenting the drought conditions of Jazmorian basin. However, in assessing the severity of droughts, CZI showed more severe drought condition. Overall, the results showed a greater focus of the drought in the southern east and southern parts of the basin indicating the high probability of drought occurrence potential of the basin. Therefore, the study of drought through CZI and SPI indices in the basin of Jazmorian is suggested for the proper policy making and management of water resources regarding conservation and increasing of the productivity from environmental, economic and social point of views.