Razieh Pilehvaran; Zahra Rastgu; Sara Karami; Behrooz Moradpour
Abstract
Introduction: Natural hazards such as floods, earthquakes, landslides, etc. frequently occur in Iran and other parts of the world, causing considerable economic, social, and environmental problems. In recent years, dust outbreaks in the west and southwest of Iran have been rising, becoming one of the ...
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Introduction: Natural hazards such as floods, earthquakes, landslides, etc. frequently occur in Iran and other parts of the world, causing considerable economic, social, and environmental problems. In recent years, dust outbreaks in the west and southwest of Iran have been rising, becoming one of the most important environmental challenges in the region.Material and methods: In this research, a number of intense dust episodes have been selected out of 15 years (2004-2018) of the statistical period, in the warm and cold seasons over the western and southwestern parts of the country. At the first step, in order to detect and observe the intensity of the dust concentration over the study area, the MODIS AOD product from the Deep blue and Dark target algorithms has been analyzed using the ENVI software, and the generated images have been displayed in the ArcGIS software. In the second step, dust source detection has been carried out by the WRF/Chem simulation of the dust concentration and tracking the dust path using the HYSPLIT Lagrangian model.Results and discussion: The results of the simultaneous study of dust detection using satellite imagery, the simulation of dust concentration using the WRF-Chem coupled model, and the particle movement pattern with the HYSPLIT model showed that East of Syria and northern Iraq in the case studies of the warm season and the west and center of Iraq in the case studies of the cold season are the main sources of dust episodes in the west and southwest of Iran.Conclusion: Studying the source and transport of dust with the aid of WRF-Chem simulations and the HYSPLIT Lagrangian model provided a complementary decision making to predict the direction of dust motions and using the results in the air quality prediction and management.
Farshad Soleimani Sardoo; Tayebeh Mesbahzadeh; Ali Salajeghe; Gholamreza Zehtabian; Abbas Ranjbar; Mario Marcello miglietta; Sara Karami
Abstract
Introduction: Today, dust is a major challenge for human societies. Dusts have a significant impact on the Earth's radiation budget, global biochemical cycles, soil formations, and chemical compounds in the atmosphere. This phenomenon can affect public health indicators. The Iranian Central Plateau is ...
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Introduction: Today, dust is a major challenge for human societies. Dusts have a significant impact on the Earth's radiation budget, global biochemical cycles, soil formations, and chemical compounds in the atmosphere. This phenomenon can affect public health indicators. The Iranian Central Plateau is located in arid and semi-arid climates; it is more likely to face this phenomenon than other regions. Dust management and control depend on identifying critical hotspots and stabilizing the harvesting area. The aim of this study was to identify internal dust sources using the vertical dust flux parameter. Material and methods: Kavir and Loot deserts cover a large area of the Iranian Central Plateau. In this study, the WRF-Chem model and GOCART and AFWA wind erosion schemas were used to identify dust springs. Emission fluxes were used to detect dust springs. In this regard, a severe storm was selected on 05/22/2018 by WRF-Chem model for simulation. In order to verify and select the best wind erosion schematic of the Iranian Central Plateau, the data of MERRA2 re-analysis database and surface dust concentration values were used. Results and discussion: The results showed that the outputs of GOCART and AFWA schemas were different. The GOCART schemas identified three strong dust sources in the study area that were located in the Jazmourian Basin, the Loot Basin, and the Central Desert (Kavir Desert), but the AFWA schemas were able to identify only one weak source in the Loot area. The results showed that Loot Desert Center, south of Jazmourian Basin, as well as Dasht-e Kavir Desert Center (Central Desert) are known as internal dust sources. So that from one square meter of these areas, it is possible for 5800 micrograms of dust to rise into the atmosphere per second. Due to the fact that the storm lasted for 12 hours, about 2 tons and 505 kg of dust were transferred to the atmosphere from each hectare of internal dust springs. The results of the GOCART schema were more consistent with the three-hour time-series data of the MERRA2 re-analysis database and were selected as the best wind erosion schematic in the Iranian Central Plateau. Conclusion: The results showed that the WRF-Chem model had a good ability to resemble the dust flux in the study area. The results of the GOCART and AFWA schemas were different. The AFWA model estimated the internal dust sources to be very weak. However, the GOCART model well detected internal dust sources.
Amirhossein Nikfal; Abbas Ranjbar Saadatabadi; Sara Karami; Saviz Sehatkashani
Volume 15, Issue 1 , April 2017, , Pages 115-126
Abstract
Introduction: Although in recent years several dust models have been investigated for the Middle East, we need to undertake more studies on verification of dust numerical models for the Middle East given the vast expansion of the region and the creation of new dust sources. Several researchers such as ...
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Introduction: Although in recent years several dust models have been investigated for the Middle East, we need to undertake more studies on verification of dust numerical models for the Middle East given the vast expansion of the region and the creation of new dust sources. Several researchers such as Marticorena and Bergametti (1995), Shao et al. (1996), Marticorena et al. (1997), and Shao et al. (2004) have contributed to the development of integrated physical wind erosion models which can be coupled with meteorological models. The parameterizations used in these models include processes such as salination and creep of sand particles.Materials and methods: In this study, numerical simulation and observational techniques were used in order to analyze the dust storm that occurred in Tehran on June 2nd. 2014. The WRF/Chem V3.6.1 model was carried out for two days from 1 to 3 June 2014 by GFS analysis data for the initial and boundary conditions. For this study, an advanced MADE-SORGAM scheme such as the aerosol scheme was used. This scheme is based on the dynamic modal model for particulate matters in Europe. Particulate matters in the MADE aerosol scheme are modelled in the three modes of Aitken (less than 0.1 micro-meter), accumulation (between 01 to 2 micrometers) and coarse (greater than 2 micro-meters).Results and discussion: For the verification of the model WRF/Chem using post-processing programmemes, PM10 distribution maps are provided alongsides its concentration. The coupling of the small-scale deformation field with a lower tropospheric cool pool as a result of mid-tropospheric cloud precipitation resulted in the genesis of Tehran’s dust storm. The results of the model WRF/Chem for PM10 and the surface winds on 2 June 2017 is shown. In terms of dust distribution, the model could determine the main internal dust source and differentiate it from the dust mass originating from eastern Iraq. Because of some limitations in the MADE aerosol scheme for the regions with high topographical features, its results might show over- and/or underestimations. Also if there are errors in the land use data and the erosion properties of soil, the model results may show a discrepancy from the real measurements. Some regions of the simulation domain such as the eastern Caspian Sea and Turkmenistan often show a high concentration of dust which, by comparing them to optical thickness data of MODIS satellite, is determined to be consistent with reality. Conclusion: In general, the results of the WRF/Chem model in this study proves its practical aspects and capability in modelling and predicting of air quality, especially for dust particles from natural emission sources such as aeolian and erodible soils. There have been considerable changes in land use and the likelihood of erosion of soils in recent years due to factors such as climate change and vegetation loss in the Middle East region. However, the geographical data used in the pre-processing unit of the WRF model belongs to previous years and this can result in errors in the results; therefore, consideration of the fact that, on the regional scale, the geographical data with high impact in dust emission modelling must be enhanced and corrected is of great importance.
