Saeed Jahahnbakhsh Asl; Hamid Mirhashemi; Masoomeh Tadayyon
Volume 19, Issue 51 , April 2015, , Pages 107-125
Abstract
In this study to identify the synoptic patterns causing heavy rainfall in East Azarbaijan province used with Environment- circulation pattern. Thus, beginning with the use of statistical methods limit type with return periods of ten-thousand-year, precipitation index for the 9 synoptic stations and climatology ...
Read More
In this study to identify the synoptic patterns causing heavy rainfall in East Azarbaijan province used with Environment- circulation pattern. Thus, beginning with the use of statistical methods limit type with return periods of ten-thousand-year, precipitation index for the 9 synoptic stations and climatology located at the province was determined and finally 25 days was analyzed as day's high Heavy. The clustering of the 1000 hPa geopotential height level these days, were identified three patterns of spring cyclone, deformation and winter cyclone as the creator of this precipitation patterns. Synoptic analysis of this patterns showed that the low pressure at polar latitudes move to down and troughs on the Mediterranean and the Middle East that it has spread. Next to the tropical high pressure and subsequent ridge are moved to higher latitudes. There are conditions in the planetary patterns, increased temperature and pressure gradient zonal and meridional circulation of establishing Cut-off low and blocking high system is in the region. Research area within the affected system has been up and down simultaneously. Thermodynamic analysis using data from the radio station of Tabriz probe showed that the potential instability in the event of heavy rain on the atmospheric vertical profile has prevailed. In fact, because the study area in this period of low and high latitudes is dominated systems and the systems at different height levels of temperature and humidity differences are great together, a stratification of temperature, moisture in the atmosphere will be created and established conditions of potential instability
Saeed Jahanbakhsh; Majid Rezaee Banafshe; Marziyeh Esmaeelpour; Masoomeh Tadayoni
Volume 16, Issue 40 , September 2012, , Pages 25-46
Abstract
Accurate estimating of potential evapotranspiration is essential for many studies related to agriculture and water balance. This study was carried out with the aim of surveying models for estimating potential evapotranspiration in the southern basin of Aras river. For this purpose, the monthly data of ...
Read More
Accurate estimating of potential evapotranspiration is essential for many studies related to agriculture and water balance. This study was carried out with the aim of surveying models for estimating potential evapotranspiration in the southern basin of Aras river. For this purpose, the monthly data of 6 stations including mean air temperature, minimum and maximum temperature, wind speed, sunshine hours, mean and minimum relative humidity were used in the statistical period of 20 years (1986-2005).
After reconstruction missing values and controlling stations for being reference (well irrigated) or non reference, potential evapotranspiration values were computed applying 9 methods (FAO- Penman- Monteith, Blanney-Criddle, Hargreaves-Samani, Makkink, Turc, ASCE standardized method, Kimberly- Penman, Penman and Priestly-Taylor) in REF-ET software. For determining best method, calculated potential evapotranspiration values were compared with evaporation pan values by using correlation coefficient and root mean square difference. Results indicated that there was significant correlation between Blanney-Criddle and pan evaporation values. Therefore, Blanney-Criddle model was selected as the best model for the study area. Afterwards, based on the above mentioned model and also the use of interpolation technique, the potential iso-evapotranspiration map was drawn for the southern basin of the ArasRiver.
