Showing 8 results for Khosravi
Ghasem Keikhosravi,
Volume 17, Issue 47 (12-2017)
Abstract
In this study, precipitation simulated annual and seasonal in East and North-East of Iran ,in 1987-2011, by using RegCM4 dynamic model in two case; with and without using post-processing technique. The required data for RegCM4 model with NetCDf format, received from ICTP center. For the implementation of the main dynamic model, Convective precipitation test scheme and the horizontal resolution, performed for 2007. According to the test, Kuo Schema had less error than Emmanuel and Gurl schemes in Precipitation and region temperature modeling. Horizontal resolution selected 30 Km. After model implementation with Gurl schema and 30 Km horizontal resolution, Precipitation and temperature output post- processed using MA model. According to results, in the study area, during 2006-2011 verification period, average annual rainfall raw bias of RegCM4 model was calculated and post-processed equal to 8.3 millimeter and 61.04 respectively. Briefly in the annual time scale, in 75% of studied stations, post-processing is effective and MA model is more efficient. In seasonal scale, bias error of average precipitation is equal to 54.99 millimeter in the winter, 27011 millimeters in the spring, -3.6 millimeter in the summer and 7.21 millimeter in the fall. Simulation of the temperature data in the stations using RegCM4 and MA model in north-east of Iran, revealed high performance. Bias error of average temperature is equal to -2.78 for RegCM4 model and post-processed equal to -0.05. In all stations, modeled Annual temperature and observational data has difference less than 0/1 ° C. In seasonal scale, the mean bias error range according ° C is equal to -4.1 in the winter, -4.09 in the spring, -1.8 in the summer and -1.5 in the fall.
Dr Younes Khosravi, Mehdi Dostkamian, Allah Morad Taherian, Amin Shiri Karim Vand,
Volume 18, Issue 50 (3-2018)
Abstract
Survey of advection of cold waves in Iran is the main aim of this study. In this regard, 45 synoptic stations were employed and studied. In order to investigate the thermal advection of cold waves, 1000, 850, 700 and 500 hp levels were reviewed and analyzed. Results indicated that cold waves in Iran most affected thermal advection caused by Tibet- Siberia, Siberias integrated Turkmenistan high-pressure, High pressure belt of Siberia - East Europe High pressure, Siberian high-pressure multi-core pattern and High-pressure belt of East of Caspian Sea integrated Black Sea High pressure. In the meantime, thermal advection of Siberian high pressure has been more impressive than other patterns. This system moved towards lower latitudes by anti-cyclone moving, So the cold weather of northern latitudes loss in lower latitudes North East of Iran, North West and Central parts of Iran. However, when Siberian high pressure combined with other patterns, its role in the advection of cold air have been considerable
Mr Soleiman Pirouzzadeh, Mahmood Khosravi, Samad Fotohi,
Volume 19, Issue 52 (3-2019)
Abstract
Studies show that 14 provinces are impacted by wind erosion and the movement of sand dunes. The sand originated from the shores of Oman Sea is the most important environmental hazards that threaten the already large number of rural settlements. Sands of marine origin are available on the beach and away from the sea of dunes in addition of marine origin, Predictive models for planning sustainable use of land use and land cover in a country like Iran that land use is changing rapidly, there is an urgent need; To detect and predict changes in land cover changes overview to better manage natural resources and protect marginal lands beaches and is very effective long-term policy measures. The aim of this paper is modeling and prediction of changes in land-use in 2035 by using CA Markov model and Landsat satellite images in the West of Zarabad,( The coasts of Makran). Then to determine the changes in the movement of sand dunes in the study area ranged from twenty-three years (1991-2014), satellite imageries from Landsat 7 and 8(ETM+ sensor) with 15 and 30 meters spatial resolution , was used. The 1991, 2001and 2014 month August images were used, this images from website of the US Geological Survey (USGS) have been prepared. Finally, these images by using Geographic Information System (GIS), ENVI and IDRISI softwares were analyzed. The results showed that the changes in the region the largest increase in the interest of sand dunes in the year 1991 (25.561) km², in 2001 (10 . 568) km², and in 2014 (45.578), and the increase of (17.198) km², has experienced. The results also estimated that in future (2035) sand dunes area increase to 592.45 km².This increase in area of sand dunes occur in the absence of proper and efficient management is done in order to stabilize the sand. This increase resulted from changed moorland 162 km²of land area (27%) and 12 kilometers of vegetation (2%) and 23 km² of fluvial (3.4%). These changes makes heavily exposed about 6 villages (Karti,Gnjk, Sohroki, Pyvshk, Vanak and Kalirak) to the movement of running sands.
Esmail Heydari Alamdarloo, Hassan Khosravi, Sahar Nasabpour Molaei,
Volume 19, Issue 54 (9-2019)
Abstract
Proper climate and adequate knowledge tourism and can be as an attractive or unpleasant factor for tourists. The purpose of this research is to evaluate the tourism climate of Yazd province as one of the most important provinces in the arid regions of the country. For determining the tourism presence comfort in the Yazd province, Tourism Climate Index (TCI) was used. In order to investigate tourism climate index data from 17 meteorological stations was used. Then by calculation sub-indexes and TCI, zoning of TCI and sub-indexes for Yazd province was done with ArcGIS environment. The results showed that October, May, November and April are the best months for tourism activities in Yazd province, and January, July, February and December have the lowest average of TCI index respectively. The most changes in TCI occurs in July and the lowest changes is in October. According to Scott & McBoyle classification, the TCI annual classification shows that Yazd province is placed in two classes: Bi-modal shoulder peak and Dry season peak. Generally, the mountainous area with an altitude of more than 2,700 to 3,000 meters and their surrounding areas when rainfall and lower temperatures is not a limiting factor have the best tourism conditions in the dry season. Other areas with less height of 2700 to 3000 meters have the best climatic conditions for tourism in the spring and autumn.
Ali Bahri, Younes Khosravi,
Volume 20, Issue 58 (9-2020)
Abstract
Considering the vast application of sea surface temperature in climatic and oceanic investigations, this parameter was studied in Oman Sea from 1986 to 2015. The SST was surveyed using trend analysis and Global and local Moran’s I spatial autocorrelation. In trend analysis, the Mann-Kendall test was used to determine the trend of SST changes and the Sen's Estimator method was used to examine the slope of the changes. Using these methods, it was found that during January, February and December, there was no significant ascending trend in SST values, and only parts of the Strait of Hormuz had a significance descending trend. On the other hand, there was no significant descending trend in March, and the ascending trend in the SST was seen in the southern part of the Oman Sea. Other months of the year had a significant ascending and descending trend in different parts of the Oman Sea, which October had the highest ascending trend. In the annual time scale, it was also found that the southern parts of the Oman Sea had ascending trend in the SST value and Western parts had a descending trend. The occurred changes in the high amounts (positive and negative) were corresponding to the significance ascending and descending trends. The results of Global Moran for the annual time scale indicated an ascending trend of autocorrelation values and cluster patterns of SST data over time, using the local Moran analysis, it was found that warm clusters of SST are increasing in the Oman Sea, and on the other hand, cold clusters of this parameter have been reduced over 30 years. According to the results of trend and spatial autocorrelation analysis, it has been found that SST have been increasing in different parts of the Oman Sea during 30 years, so climate change and global warming may have affected this region.
Mr Asadollah Mollazehi, Dr Mohammadreza Pudineh, Dr Mahmood Khosravi, Dr Mohsen Armesh, Mr Aliasghar Dehvari,
Volume 20, Issue 58 (9-2020)
Abstract
Today, due to climate change, natural hazards and how to deal with them are among the most important concerns of researchers in environmental planning and crisis management. The purpose of this study is the assessment of the potential flood risk in Sarbaz drainage basin. For this purpose, the databases including elevation, slope, geological characteristics, soil characteristics, precipitation, vegetation, land use, and vector layers of the main channel, streams and drainage densities of the basin were used. By using the questionnaire and experts' opinion as well as hierarchical analysis, the weight of influences of each layer was calculated in basin flooding. Each of these layers was classified based on the flood potential from low to high-risk scale and eventually merged with the weighted overlay model in Geographic Information System. The results showed that main streams, land use, and precipitation are the most important components in the flood risk of the Sarbaz river drainage basin. From the total area of the Sarbaz basin, only 0.5% has a high to extremely high flood potential, and the central areas of the basin have the highest potential for flood due to topography and special hydrographic conditions. In addition, the main river basin districts towards the outlet of the basin as well as parts of the margins of important sub-streams have the highest flood potential. Despite the limited area of the high-risk zone, due to population density and agricultural land, the importance of this area is very high in crisis management.
Zahra Hedjazizadeh, Aras Khosravi, Seyed Asaad Hosseini, Alireza Rahimi, Ali Reza Karbalaee Doree,
Volume 21, Issue 63 (12-2021)
Abstract
One of the most important energy sources in the world is solar energy, which is a renewable resource and does not cause any damage to the environment. Which all of these features justify using it as a clean energy source and economically viable cost.. Due to the relatively large area of the Iran in low latitudes and relatively dry climatic conditions, in terms of solar energy utilization it uses excellent conditions. Solar power plants are considered as power generation and transmission networks whose is important that the location features of their construction sites are effective in reducing the risk of investing in solar energy. In this study, using geographic information system and fuzzy valuation method for the criteria and method of weighing (AHP), was considered the potential of the Kavir & desert region and Makran coast for the purpose of obtaining energy from the sun. For this purpose, were used the 14 criteria related to the climatic, infrastructural, and technical and physical conditions of the area. In order to overlap the fuzzy layers were used the usual operators, Gamma, Product and also the Sum Weighted Overlay operator to compare and present the appropriate result. Each of the operators has a different sensitivity to the fuzzy overlap of the layers. For this reason, was considered the Gamma 0.9 operator, due to the high sensitivity for building power plants with high electrical power generation and the Sum Weighted Overlay operator, for the construction of smaller capacity plants. In the overlay map, using the Gamma 0.9 operator, about 2%, and in the overlay map with the weighted operator, about 33% of the study areas were found to be very suitable for the construction of solar power plants.
Engineer Amenh Khosravi, Doctor Mahmood Azari,
Volume 22, Issue 66 (9-2022)
Abstract
The study of meteorological characteristics and its variability is important in assessing the climate change impacts for water resources management. Trend analysis of hydrological and meteorological time series is a method for determining the change in climate variables that is performed with different parametric and non-parametric methods. In this research, the annual, seasonal and monthly trends were analyzed regarding rainfall and temperature time series for 1986-2017 in 28 stations of Kashafroud basin in the Northeast of Iran. For this purpose, the annual, seasonal and monthly trends were evaluated using non-parametric Mann Kendall and Pettitt test at 95% level significance. The results showed the trend for the monthly maximum temperature in spring and winter and also the annual trend for all stations was increasing, whereas the summer and autumn pattern differed. The trend of minimum temperature in all seasons and stations do not have a uniform pattern. The results of precipitation trend indicated that the annual precipitation of the basin had not changed and did not have a significant trend in 5% level of significance. Precipitation of the basin in the winter decreased. There was an increasing trend in the Southern half of the basin in autumn. The noticeable decrease of precipitation in winter season especially during January and February with an increase in November can be a serious challenge for water resource management of basin during the dry season.
