shoaieb abkharabat

120-day winds of Sistan are considered as one of the significant phenomenon which has a great impact on the morphology and environment of east and southeast of Iran (Figure.1). The common region for these winds is the border of monsoon region in south of Asia which mainly has sunny and cloudless weather during monsoon period. This condition is due to lack of higher humidity divergence accompanied by tangible decrease of the air on the atmosphere (Salighe, 2010). These winds are the most famous advection system in northern hemisphere whose effects are visible in eastern regions of Iran, west and south of Afghanistan, and northwest of Pakistan(Khosravi, 2008).                                                                                                                       
Data and

In order to evaluate the role of the winds, data network of Geopotential height of 850 hPa (hectopascal) level during a 19-year period (1993-2012) from May to the end of September, the period of 120-day winds of Sistan, were found. These data were of those revisited data of 2.5*2.5 NCEO/NCAR during 2480 days. Then, factor analysis and clustering tests were applied on data network of Geopotential height to classify map patterns (Yarnal, translated by Masoudian, 2006: 100). As a matter of fact 5 clusters were recognized in this study presented in table 1. Dynamic method was used in GrADS software in order to find humidity flux of each region in the quintuplet patterns.

Northern Wind Pattern (120-day wind of Sistan) As a matter of fact 120-day winds of Sistan are a part of northern Trade winds which are the most important source of Caspian Sea high pressure. After passing east of Iran, these winds reach Oman Sea and converge with southern Trade winds. Both of them moved toward Indian Subcontinent and finally enter atmospheric monsoon circulation of south of Asia. High pressure of north of Iran is also a tongue of high pressure Azores which is extended over northern regions of Iran and Caspian Sea by Mediterranean and Black sea Basin. Both existing Gang low during hot period of a year in south of Asia and spreading, its tongues over regions of Middle East make Azores high not be able to penetrate the zone in lower levels of atmosphere (from the earth surface to thelevel 850 hPa.). As a result, Azores high has to locate in northern parts especially north of Iran. Analyzing the curves of geo-potential height, figure (2) precisely shows this phenomenon. Gang low not only is weaken among middle levels of atmospheretongue, but also lost its appearance on Iran Plateau and Arabian Peninsula. Therefore, Azores high tongue also can locate in its normal position and appear with maximum pressure on Iran Plateau and Arabian Peninsula. Figure (3) presents the order of synoptic systems in level 500 hPa. of pattern 1. It shows that Gang low has lost its nature in this level, while Azores high tongue obviously is located on Middle East, especially Iran Plateau and Arabian Peninsula. As a matter of fact atmospheric levels of Geopotential height in pattern 1 (figures 2,3, 4) reveal that as we go away from lower levels of atmosphere to middle levels of atmosphere, Gang low gradually is weaken especially over Iran Plateau and Arabian Peninsula. This situation makes Azores high tongue locate in lower latitude. However, in lower levels (earth surface to level 850 hPa.), as a tongue of Gang comes into some parts of Middle East, expanded tongue of Azores high pressure has to locate on higher latitudes than normal latitudes; on north of Iran Plateau and Caspian Sea.Pattern (2) shows the same order as pattern (1), so it will not be repeated here.In the following, the effect of 120-day winds of Sistan on humidity of the region will be investigated, thus humidity flux is calculated between levels 925-1000 hPa. 850-925 hPa. and 850 -700hPa. Figure (5) shows sum of humidity flux for aforesaid levels of synoptic pattern (1). 120-day winds of Sistan with prevailing north direction in this pattern lead to the formation of a core of humidity flux divergence in east and center of Iran and decrease humidity of the region. As previously mentioned, after passing Iran, Sistan winds reach Oman Sea and north of Indian Ocean, and converge with southern Trade winds. Both of them move toward Indian Subcontinent. In fact, convergence of 120-day Sistan winds (northern Trade winds) and southern Trade winds leads to formation of a strong core of humidity flux convergence on Oman Sea and north of Indian Ocean (figure 5). The sum and average of humidity flux convergence and humidity flux divergence in studied region are presented in table (2).Eastern Wind Pattern The other clusters (3, 4, and 5) have different order from 120-day Sistan winds which are introduced as eastern wind pattern. Unlike clusters (1) and (2), in these clusters (table 1) the wind direction is not northern; in other words, the winds blow with prevailing east direction in east and northeast of Iran, however southeast of Iran experience mild weather at the same time. As synoptic order of pressure system and humidity flux system are mainly the same, pattern (3) will be analyzed precisely. The order of synoptic systems of level 850 hPa. in pattern (3) is presented in figure (5). This map reveals that the contrast between high pressure of north and Gang low differs from northern wind pattern, as on the one hand,the strength and breadth of Gang low increase, while on the other hand the strength and breadth of Azores high tongue (high pressure in north of Iran) decrease. In fact, this condition makes most regions of Iran Plateau in lower levels of atmosphere (1000 hPa, 925 hPa and 850 hPa.) be dominated by Gang low. Besides, this order of synoptic systems eliminates 120-day wind conditions of Sistan and make eastern wind conditions in east and northeast of Iran. Since the orders of synoptic systems of levels 925 hPa. and 1000 hPa are the same as level 850 hPa. they will not be presented here.The orders of synoptic systems in middle levels are different, as in level 700 hPa. Azores high tongue comes to Iran Plateau by Arabian Peninsula (figure 7). This layer of atmosphere is a transition layer from dominance of low pressure pattern in lower layers to high pressure pattern in middle levels and upper atmosphere. Moreover, in level 500 hpa. Azores high tongue dominates Iran Plateau and Arabian Peninsula with more power and breadth. The orders of synoptic systems of clusters 4 and 5 are the same as cluster 3.The sum of humidity flux divergence and humidity flux convergence of pattern 3 are presented in figure (9). In this figure, the core of humidity flux divergence, which covers eastern half and center of Iran, is omitted and a core of humidity flux convergence covers east and southeast of Iran. It can be said that both penetration of Gang low into Iran and lack of 120-day winds provide special conditions in which the zone of humidity flux convergence in north of Indian Ocean moves to southeast of Iran leading to moisture condensation.

In this study 2 patterns of synoptic systems of warm period in east and southeast of Iran were recognized. First pattern (northern wind pattern) makes 120-day winds of Sistan (cluster 1 and 2). In contrast to Gang low tongue, when high pressure of north of Iran and Caspian Sea are in strong mode, it provides the conditions for 120-day winds of Sistan. On the other hand,in contrast to Gang low tongue increasing its influence and spread over Iran Plateau, when the aforesaid high pressure rollbacks of north of Iran and it is weakened, 120-day winds of Sistan stop and second pattern (eastern wind pattern) starts. In this pattern the winds with prevailing east direction cover east and northeast of Iran (clusters 3, 4,and 5). High pressures of Caspian Sea and north of Iran are a tongue of Azores subtropical high pressure which has to move abnormally to higher latitudes due to coming Gang low into lower atmosphere layer. Since Gang low is an inter-tropical convergence zone moving abnormally to higher latitudes in south of Asia, 120-day winds of Sistan are part of northern Trade winds which are flowing from subtropical high pressure (Azores high tongue in north of Iran) to Gang low in south of Asia (inter-tropical convergence zone). After converging with southern Trade winds on north of Indian Ocean, they move toward Indian Subcontinent. 120-day winds of Sistan exclude the entranceof moisture from Oman Sea and Indian Ocean into southeast of Iran (figure 5). However, as 120-day winds of Sistan stop, a core of humidity flux is formed on southeast of Iran providing the entrance of moisture of water areas into southeast of Iran (figure 9). Generally, weakening of Azores subtropical high will help to provide rainfall conditions in southeast by 2 ways: on the one hand, as Azores high pressure is weakened, the influence of decent factors of this high pressure air in levels 700 hPa. and 500 hPa. decreases. As a result ascent conditions are provided in the zone, but on the other hand the weakening of subtropical high pressure in lower levels of atmosphere (1000 hPa to 850 hPa.) also makes expanded Azores tongue weaken and rollback over north of Iran and Caspian Sea leading to stop 120-day Sistan winds. This phenomenon provides appropriate condition to inject moisture from Oman Sea and Indian Ocean to southeast of Iran.

In this study, By studying the synoptic patterns of the lower levels of the atmosphere in the warm period (22 may – 22 sep) of Asia southwest (1996 – 2014), and Using factor analysis and clustering tests and also dynamical equations of convergence / divergence, vorticity and omega; an ridge of eastern winds (Iran ridge) was identified on the Iranian plateau, Which is part of the eastern winds caused by the deployment of India's Monson Trough in South Asia and the expansion of tongue from Ganges to the Asia southwest lowlands. Dynamic conditions of the atmosphere in the eastern part of Iran ridge, A nuclear of the divergence of the lower levels, Provide positive omega and air sinking and flowed eastward toward the west, and as the eastern winds flowing westward. At the same time, the dynamic conditions of the western part of Iran ridge, the nucleus of the convergence of the lower levels, Provide negative omega and climbing air that the flow of the mentioned wind pours into it. Then the air climbed in the western part of Iran ridge at the middle level, creates a core of high levels divergence and It flows to the west. With the arrival of this wind on the eastern half of Iran ridge, a core of higher levels convergence has created and with its descent into the lower levels divergence core in the eastern part of Iran ridge, Complete your cycle (Khorasan-Caspian Cycle). At the middle levels, there are also languages from Azores high on the region, the curvature of the northern part forms the ridge of western winds in northe of Iran and the Caspian Sea. The dynamic conditions of the west and east of this ridge caused the formation of negative core and positive omega that this, in turn, enhances the Khorasan-Caspian cycle.

As a core of wind speed, Low Level Jet (LLJ) of the Persian Gulf is made on the Persian Gulf and its surrounding in the low levels of the atmosphere during the hot period of the year.  Known as north wind, this jet appears in the body of a more extensive current of wind with the northern, northwestern, southern, southeastern direction. North wind often blows from the mountainous regions of Turkey and Iran to the southern regions. Except for topographic reasons, the formation of this wind is influenced by hollow topography of low regions of Mesopotamia and Khouzestan appearing as a corridor. Reaching the Persian Gulf, this phenomenon is intensified as the water area of the Persian Gulf is besieged as a low hollow by Zagros Mountains and Arabic Peninsula aggravating the wind.

Siberian high pressure (SHP) is synoptic system that during the autumn and winter seasons on Asia is religious (Msaudian and Kaviani, 2009: 15). In the cold term of the year, the vast Siberian territory due to the clear sky and away from water sources, the more energy through the long wave radiation loses, thereupon the around air of land gradually adjacent to becomes cold high-pressure center.

Sistan wind is one of the most important atmospheric phenomena of warm period of year in Iran plateau which creates environmental different impacts on its dominated region. In the northern hemisphere during summer monsoon, ITCZ moves to higher northern geographic latitude. South Asia summer monsoon system is one of the phenomena which arises from this movement and a tongue extension of Gang low moues towards west, its domination over southern region of Iran, and its penetration to Khozestan plain and Mesopotamia is also one of this movement outcome. In the meantime, in atmospheric low level, Azores high tongue, in this region of the world also has to remain in north territories of Iran (that is over Caspian sea and its surrounding) more than world-wide average. So that, with the pressure gradient between the Caspian sea high and Gang low generates the Sistan wind system, in a way that can be said that this is northern trade wind which blows in the region. The period used in this study was for 2480 days in 22 years (2012-1993) from May until end of September. The atmospheric circulation types were extracted using daily mean of the 850 hPa geopotential height data for these days between 15°–80°E, 5°–50°N, with a 2.5° (lat) × 2.5° (lon) spatial resolution. These data were retrieved from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis archive. Then the agglomerative hierarchical cluster analysis with the ward algorithm and Euclidean distance were used to identify atmospheric circulation types over Iran in mentioned period of years. Because using hierarchical cluster analysis can take maximized within-group similarity and minimized between-group similarity in data, the groups of days with similar characteristics were determined. Then the calculated within-group correlations were used to identify representative days. The day with highest within-group correlation was representative day of atmospheric circulation types. Finally, 5 atmospheric circulation types were identified in this period in which 2 cluster showed the mechanism of in Sistan winds in the southeast of Iran. Then for representative day of atmospheric circulation types in 2 mentioned clusters, wind speed and direction, as well as the wind convergence in levels of in 1000, 925, 850 and 700 hPa and also the convergence in atmospheric vertical profiles were analyzed. This paper identifies that, this wind has the features of LLJ and its core is often at 850 hPa level which is titled and is known as Sistan LLJ. Its speed continuation also stretches to low levels and to the earth surface, as a result it creates Sistan wind near the surface. On the other hand, along with ITCZ belt anomalous movement to northern hemisphere, the southern trade winds also enter northern hemisphere to reach ITCZ belt and after acquiring humidty from Indian ocean and Arabian sea, they enter Indian subcontinent. Now, the assumption is tested that between these two kinds of blowing systems (Sistan LLJ and southern trades) a region of convergence must be created, then with the continuation of the above convergenced, wind sysrem is identified over north of Arabian sea, Pakistan and Iran coasts. This convergence region which establishes at the time of Sistan LLJ balances with southern trade winds, which determines its location geographic latitude. So that, if Sistan LLJ blows slowly, this convergence region moves to more southern geographic latitudes. also its vertical extension in atmosphere is to the extent that its generating factors (Sistan LLJ and southern trades) exist and when one of these factors, does ascend to the higher level of atmosphere, this convergence region disappears. So that, naturally its establishment can be observed from the earth surface to 750 hPa level, and it often disappears above this level. This convergence region can also be a reason for the issue that during the fact Sistan LLJ the northern trade winds converge with southern trades on Arabian sea. The other indications of these winds are being originated from subtropical high and blowing toward tropical convergence region, so that the Indian monsoon is in fact the southern trades and Sistan LLJ that blow from two sides towards ITCZ.

120-day winds of Sistan are considered as the most important and well-known climatic factors in eastern regions of Iran during hot period. They have various effects on the region. For example, these winds make dust storm, more evapotranspiration and sand prairie in this region. Generally, as these winds have great impacts on the environment and human life, they should be studied from different climatic aspects. Considering the importance of them, this study aimed at evaluating the role of these winds in decreasing the temperature of the region. The results will prove one of the positive environmental aspects of these winds during hot period of year in eastern dessert regions of Iran. Although, most effects of these winds were negative considered as one of the life limiting factors through the east of Iran.
Matarials and The period used in this study was the 2480 days in 22 years (2012-1993) from May until end of September. The atmospheric circulation types were extracted using daily mean of the 850 hPa geopotential height data for these. Then the agglomerative hierarchical cluster analysis with the ward algorithm and Euclidean distance used to identify atmospheric circulation types over Iran in mentioned period of years. Finally, 5 atmospheric circulation type were identified in this period of years. Then wind speed and direction, as well as the wind thermal advection in levels of 1000, 925, 850 and 700 hPa and also the thermal advection of atmospheric vertical profiles were analyzed.
The Position of Maximal Cores of Temperature (Thermal Equator) Figures 4, 5, and 6 present maximal cores of temperature in 1000 hPa level through quintet patterns. As a matter of fact these maximal cores of temperatureimply the position of earth thermal equator. Pattern 1, in which 120- day winds of Sistan cover east and southeast of Iran more intensely and more widely, reveals that maximal temperature covers Iraq and west of Iran, while in the same latitude there is cool weather in east of Iran. Pattern 2 also, in which 120-day winds of Sistan have less intensity and expansion, shows that thermal equator belt of east is penetrating northern latitudes, even though lower temperature is still recorded in east and southeast of Iran, compared with west of Iran and Iraq. Generally, these 2 synoptic patterns reveal that 120-day winds of Sistan with northern direction lead to a decrease in the temperature of east and southeast of Iran. Besides it makes thermal equator belt move to southern latitudes. Figures 5 and 6 show the patterns 3, 4, and 5. In these patterns, 120-day Sistan winds are not dominant in the area which leads to an increase in the temperature of the area and a core formation of maximal temperature in east and southeast of Iran. Unlike patterns 1 and 2, in these patterns eastern regions of Iran have higher temperature than Mesopotamia and west of Iran. As a result, the advection of eastern winds in the region makes thermal equator penetrate northern altitudes as it covers east and southeast of Iran. Due to this phenomenon, eastern regions records much higher temperature than the regions in Mesopotamia and west of Iran, although they are in the same latitude.
Wind advection in eastern and southeastern regions of Iran during hot period of year is considered as one of the most important and most effective climatic phenomena having great impacts on environment and communities. There are two advection orders during this period of year, including the advection of northern winds (120- day winds of Sistan) and eastern winds. Eastern winds mostly cover eastern and northeastern regions of Iran, while northern winds mostly cover eastern and southeastern regions. The calculation of thermal advection during the existence of each wind demonstrates that during the advection of northern winds, a core of negative thermal advection is made in east and southeast of Iran (Fig. 1). As these winds are intensified, the intensity of this negative thermal core increases too (Fig. 1 a). This phenomenon reveals that this is the heat transmission from the dominant regions of this negative thermal advection to surrounding regions which provide cool weather in east and southeast of the country. Besides, vertical profile of atmosphere also proves the altitudinal expansion of this core of negative thermal advection through higher levels. A core of negative thermal advection is made during the advection of eastern winds (Fig. 2 and 3), althoughthis core dominates less regions limiting to eastern regions of Iran. Besides, a core of positive thermal advection is made in southeast of Iran. This phenomenon not only leads to heat aggregation, but also makes a core of maximal temperature in the region and transfers thermal equator to east and southeast of Iran.Moreover, eastern half of Iran shows lower temperature than west of Iran and Mesopotamia during the advection of 120- day winds, while this region shows higher temperature than west of Iran and Mesopotamia in the absence of 120- day winds. Therefore, the advection of northern winds (120- day winds of Sistan) makes thermal equator of the earth move to southern latitudes in southeast of Iran decrease the temperature of the region.

In Iran plateau, with movement of the subtropical high pressure to low latitudes in cold period of year, the emigrant systems of westerlies are dominant atmospheric phenomena in this region and control atmospheric phenomena in this period of year. But in the warm period of year the Sub-Tropical high-pressure is dominant atmospheric pattern in higher level of atmosphere in the Iran plateau. It is the main factor that controls the weather and climate over this region in the middle and lower troposphere as a local to regional scale thermal forcing. Focusing on the source and the path of necessary humidity for summer precipitations in this region, Parand (1991), Alijani (1995) and Najarsaliqe (1998) believed that the humidity of Indian Ocean and Arab Sea in low pressure cyclonic circulation of Pakistan move parallel through southern feet of Himalaya Mountain and penetrate southeast Iran in an east- west direction from Pakistan. In case of existing necessary factors, they ascend and make summer precipitations of the region.
The period used in this study was 78 days in 22 years (2010-1982) from May until end of September. The atmospheric circulation was extracted using daily mean of the 850 hPa geopotential height. Then, the agglomerative hierarchical cluster analysis with the ward algorithm and Euclidean distance are used to identify atmospheric circulation types over Iran in mentioned period of years. Then, we calculated the within-group correlation to identify representative days. The day with the highest within-group correlation was representative day of atmospheric circulation types. Finally, 4 atmospheric circulation types were identified for this summertime precipitation. Humidity flux divergence of the region was calculated by the relationship called horizontal flux divergence, in which in x,y directions (longitude and latitude), (q) stands for small changes of specific humidity, (u) for U component wind, (v) for V component wind.
HFD is horizontal flux divergence, but and stand for the distance in longitude and latitude, respectively. Besides, positive values mark humidity flux convergence, while negative values show humidity flux divergence. In fact, calculated values are dedicated to each level considering the values for special level, as a result, to find the real values of humidity flux for vertical sum. This value should be calculated for the distance of the height level of atmosphere. Following relationship is used in which (vq) stands for HFD, (p) for the level of atmosphere at geo-potential height, and Qvi for vertical sum of humidity flux.
Since the used data are 6-hour, these calculations are done for a 6-hour period. To do the aforesaid calculations for a longer period (2 day) and the distance between several atmospheric levels following equation should be used. In this equation, (t1) and (t2) stand for the beginning and end times of calculating, respectively.
Focusing on these precipitations, 4 patterns were recognized. The humidity flux was studied through 3 levels of atmosphere (lower levels, higher levels and vertical profile of atmosphere). There is a core of humidity flux convergence in southeast Iran in lower levels of atmosphere (1000-750 hPa). Besides, cores of humidity flux divergence on north of Arab Sea, west of Arab Sea and Persian Gulf are responsible for injection of humidity to surrounding regions. A core of humidity flux divergence is also formed in southeast Iran in middle and upper levels of atmosphere. Therefore, the injection of these precipitations happened in lower levels of atmosphere. Vertical profile of atmosphere revealed that, among the patterns, there is humidity flux convergence from the surface to 750 hPa level and humidity flux divergence in upper levels.
Study on summer precipitations of southeast Iran revealed that a tongue from Gang low pressure in l000 and 850 hPa levels penetrate Iran Plateau and Arabian Peninsula, while there is no tangible trace of this low pressure on the region in 700 hPa level. The calculation of humidity flux function is in accordance with the findings of Karimi et al. (2007). Besides, north part of Arab Sea is obviously considered as the most important source of humidity in the region, as a core of humidity flux convergence is made in all patterns from the earth surface to 750 hPa level. Three cores of humidity flux divergence on north part of Arab Sea, west part of Arab Sea and Persian Gulf transfer humidity to surrounding regions. The divergent core of north of Arab Sea and west of this sea are considered to be the most important source to provide humidity for the region, while the core of Persian Gulf is minor. This phenomenon is mainly the result of central and southern Zagros Mountain chains which limit transformation of humidity from Persian Gulf to Iran Plateau. Moreover, there is no core of humidity flux divergence on Oman Sea to transfer humidity to surrounding regions. On the other hand, counter clockwise circulation of air through southern feet of Himalaya Mountain Chain in lower levels of atmosphere can only be seen in pattern 4 (Fig. 4) and slightly in pattern 3 (Fig. 3). Such synoptic order has no role in providing the needed precipitation humidity of southeast Iran, for it is too far from southeast Iran to provide enough humidity. Moreover, a strong core of humidity flux convergence is made in north part and center of Pakistan in which the aforesaid circulation in southern feet of Himalaya penetrates into the area. The atmosphere of the study area can be divided into lower part (1000-750hPa level) and upper part (700- 300 hPa level) through humidity flux convergence and humidity flux divergence, respectively.

Many aspect strongly influence regional climate includes localized surface processes, large-scale patterns, especially mid and upper level tropospheric circulation and many factors control precipitation in the west of Iran includes location of emigrate westerly winds systems, Jet streams location, Humidity Flux and topography. Upper tropospheric jet stream constitutes a significant factor influencing physical processes, includes ascend or descend movements in the lower atmosphere in both synoptical and climatological time scales. Polar jet stream and subtropical jet stream are two main Upper tropospheric jet streams affects climatology mid latitude atmosphere. In this regard, formation of polar jet stream is related to thermal contrast in the polar front because of its proximity to the ground has greater role in providing ascendant atmospheric condition and precipitation. But sub-tropical jet stream locate at upper atmospheric level in tropopause and such condition can’t have a prominent role as polar jet stream in ascendant condition, especially in precipitation. In addition because the subtropical jet stream does not have other factors in polar jet stream such as polar front, dynamic properties of this does not have affect climate feature of earth surface. Typically Jet stream potential can affect divergence and convergence, develop and steer the pressure systems (Farajzadeh et al., 2008) and change control the weather patterns and climate. The Polar jet stream is one of main factors that affect climatology if western Iran in winter.
In addition to jet stream location, the atmospheric moisture budget plays an important role in precipitation and hydrology. Existence of polar jet stream the companied with adequate moisture can lead to heavy rainfall in each region. The objectives of the present study are understand the location of polar Jest Stream during the heavy rains in Western Iran and characteristics of moisture flux from each region of moisture source and their contribution to the rainfall during the mentioned period.
Material and This study focus on western Iran, that extends between the latitudes 33° N and 36° N and the longitudes 46° E and 48° E (Fig 1).
1. The study area For determine the days with heavy rainfall the Mofidi et al (2007) method have been used. Hence the heavy rainfall was the amount of rainfall during the day with equal to or greater than 5% of the average annual precipitation and also over 50 percent of western Iran must receive heavy rainfall. So the 48 days with heavy rainfall for current study have been extracted. The location of PJS were analyzed according to atmospheric circulation types in 75 days with heavy rainfall using daily mean of the 500 hPa geopotential height data for these days between 10°–80°E, 10°–60°N, with a 2.5° (lat) × 2.5° (lon) spatial resolution that’s includes 609 grids. So a 48 × 609 matrix was created. For determine the atmospheric circulation types and location of PJS during heavy rainfall over western Iran an agglomerative hierarchical cluster analysis was applied to the 48×609 matrix using the ward algorithm with Euclidean distance to identify atmospheric circulation types. Then calculated the within-group correlation to identify representative days. In continues, the convergence and divergence of moisture flux from two days prior to representative days was investigated. The convergence and divergence of moisture flux was calculated in 1000 hPa to 500 hPa levels for determine the main source of moisture flux in various atmospheric circulation types and arrangement of polar jet stream in time of heavy rainfall in western Iran. For this purpose, four daily NCEP/NCAR reanalysis data includes specific humidity, zonal and meridional wind speed components (U; V components) for 1000 to 500 hPa have been used.
According to results of hierarchical cluster analysis, 4 groups of atmospheric circulation types affecting the location of polar jet stream in both level of 300 and 500 hPa, associated with heavy rainfall in western Iran was detected. Usually the annual rainfall in western Iran are associated with location of polar jet stream and emigrated systems of westerly winds. In pattern 1, the heaviest rainfall occurred at 00Z. Formation of deep trough in westerly winds on the East Mediterranean, lead to the formation of cut-of-low in both of 500 and 300 hPa levels. Existence of this trough in company with polar jet stream lead to intensification of the unstable condition in the atmosphere of western Iran. So that in both level of 300 and 500 hPa, the west of Iran is located in the second quarter zone of polar jet stream. In this pattern the polar jet stream core in the west of Iran has taken a meridian curve and this issue provides more favorable conditions for convection and ascendant condition in atmosphere. In this pattern the main sources of moisture are West Arabian Sea, Persian Gulf, Red Sea and East Mediterranean is the secondary source that is less important.
In the second pattern, formation of a deep trough on the Red Sea convergence zone provides more favorable conditions for ascendant condition in the west of Iran. The location of polar jet stream in this pattern is in lower latitude in comparison with first pattern and intensify of polar jet stream is less than previous pattern. The main sources of moisture in second pattern are Arabian Sea and Red Sea and also Persian Gulf and Oman Sea are secondary sources for this pattern.
In the third pattern, the expanding of trough in waves of westerly winds was wide, from the Mediterranean Sea to the West of Iran. This issue, decrees of deep and increase of expansion in westerly wind waves, cause decrease in intensify of unstable condition in atmosphere of western Iran. Expansion the core of polar jet stream from east of Africa to west of Iran that located in the second quarter zone of polar jet stream has caused increase of unstable condition in this region. The main sources of moisture in this pattern are Arabian Sea, Gulf of Aden, Red Sea Persian Gulf and Oman Sea. In the fourth pattern, existence of a deep trough on westerly wind waves over the Red Sea lead to increase in intensity of polar jet stream that located in Middle East. So, this condition caused increase of unstable atmospheric condition in western Iran and according to moisture flux lad to heavy rainfall in this region. The main sources of moisture in this pattern are Arabian Sea, Gulf of Aden, Persian Gulf and Oman Sea.
Results of this study show that in all atmospheric circulation type that lead to heavy rainfall in western Iran, this region was located under the second quarter zone of polar jet stream. Therefore this condition provides more favorable conditions for convection and ascendant condition in atmosphere. And also the main sources of moisture in heavy rainfall cases were Arabian Sea, Gulf of Aden, Read Sea, Persian Gulf and Oman Sea.

Today, with the increasing population and the need for strategic and industrial crops the farmers are simulated to grow these kinds of crops. Thus, this subject has now been caused the inappropriate use of land and natural resources. On the other hand, the natural environment resources have limited the ability to use its resources and the climate change intensifies this limit ability. Agriculture is one of the most sensitive parts of human activities to changes in climate parameters. The slightest shift in climatological factors of plant growth, the growth of plant processes affected these changes in the performance and quality of crops. In climate change condition, some natural environments with the most appropriate conditions and resources are provided for the development and optimal use of human and with the least appropriate condition the human manipulation can lead to damages to natural environment. Therefore, to any manipulate and development in environment, before planning to use it, we need to evaluate the potential of the environment. In addition to the potential of environments for the future, due to climate change, it is required to consider any planning. The aim of current study is to provide a land suitability assessment in the condition of climate change. Given the sensitivity of crops to climate change, one of the agricultural products as a sample product has been selected to implement the procedure. One of the strategic and industrial products is Oil-seeds such as canola. Oil-seeds compose the second largest food resources of the world after cereals, and Canola is the third largest source of vegetable oil in the world. A variety of factors and parameters are effective in determination of suitability of any area of land for cultivation and in condition of climate change and changes in temperature and precipitation changes in suitability of lands may be occurred for cultivation of canola. In this study, a new method based on the Geographic Information System (GIS) and climate change model, has been developed for cultivation of canola in West Azerbaijan-Iran. In the first step, the effective criteria (canolaplant requirements) were recognized using library study. In this study, the GIS based on Artificial Neural Network (ANN), Network Analysis (ANP) and LARS-WG, for modeling the land suitably has been developed. Thus, for evaluating the lands suitability, the climatological data such as temperature, precipitation, growth degree day, relative humidity, freezing days, and sunshine hours were collected for the west Azerbaijan Province from synoptic stations data in 1987-2010 associated with the phonologic stages of canola growth. In addition to the climatological data, the earth resources like topographic layers, lands capability, soil depth and land uses were analyzed with focusing on the climatologic and ecological needs of canola. All of canola plant requirements in base period (1987-2010) were simulated for three periods in the future. Therefore, the impact of climate change on temperature, precipitation, solar radiation and relative humidity were modeled using LARS-WG and ANN in the future climate condition. Also for simulating the data of future climate, the HADCAM3 of General Circulation Model and A1B and A2 scenarios were used. The importance of each criterion was completed by experts’ opinions. Due to the interaction of the criteria in the actual world, DEMATEL technique was used to recognize the relations among the criteria. ANP was used after completing the pairwise comparisons questionnaires by expert’s viewpoints. Results and Dissection :In this study, the outputs of the minimum and maximum temperatures, the output rainfall and radiation of the model HADCM3, are used to estimate the relative humidity in the periods 2011-2030, 2046–2065 and 2081-2099. Based on the estimates through modelling in the artificial neural networks, the measures of relative humidity have been simulated. The results of the application of the introduced ANN structure for estimating the relative humidity in different modes of the functions and the number of neurons in the first and middle layers show that ANN have a good ability to estimate the relative humidity in the future periods. Results of ANP show that the most important canola plant requirement is elevation and after that are temperature and rainfall. Implementation of the model shows that in the base period (1987-2010), 15% of lands in study area are in condition of very suitable and 31, 29 and 25% are in suitable, moderate suitable and unsuitable classes, respectively. Based on the results of HADCM3 model, in the second period (2011-2030) the very suitable class is 11% of the province and other classes are 38, 31 and 24 percent of the lands. Thus, in this period the suitable class compared with base period will increase. In the third period, with changes in temperature and rainfall, climate change will cause decrease of lands in condition of unsuitable and very suitable for canola cultivation and the percent of 2 and 3 classes will be increased. In the fourth period, following the changes in temperature and precipitation due to decreases in very suitable class, about 5% of lands and inappropriate lands (about 23 %) will cause decrease in suitable lands for cultivation of canola in West Azerbaijan. The results indicate that the proposed method can well simulate the effects of climate change on Land Suitability Assessment to grow crops. Generally, changes in temperature and precipitation resulted in decreases in the areas of very suitable and suitable lands for cultivation of canola in West Azerbaijan providence. Additionally, the low limits lands will be increased significantly in comparison with the baseline period. As suitable lands for canola cultivation will be changed from 47% in the base period to 34% in the future periods.