عنوان مقاله [English]
The purpose of this study is to establish a proper classification of atmospheric patterns related to hail events and their climatic characteristics in the Zab Basin. Therefore, station data (27-87-96-99 to 100 present weather codes) were used to capture hail from the 3 synoptic stations of the Zab basin over a 24year period (1992-2016).
The NCEP / NCAR database data was also analyzed to analyze the circulation patterns of these events. Cluster analysis on sea level pressure data and geopotential height (۵۰۰ hpa) identified three circulation patterns associated with hail precipitation. Including: 1. Strengthening Sudan's low-pressure system 2. Strengthening European and Siberian high-pressure systems 3. Locating the area east of the Mediterranean Sea. Then, by performing intra-group correlations between each day cluster that was most correlated with other days, it was selected as the day to represent the circulation pattern of that cluster and the basis of the research was analyzed.
Keywords: Synoptic analysis, Northern Highlands, Mediterranean Nave, Hail precipitation, Zab Basin.
Hail is considered one of the most important atmospheric hazards as a consequence of a thunderstorm that damages the environment every year . Hailstorms usually occur from the clouds of cumulonimbus and are often thunderstorms and generally accompanied by thunderstorms, especially in spring. In general, hail is the product of intense convection found in a thunderstorm. To analyze and predict the mechanisms of each climatic phenomenon, one needs to have a detailed understanding of the main components of its climatic systems.
Compared to other countries in the world, Iran has a high rank in the crisis due to natural disasters due to its environmental diversity. As a result, of the 7 natural disasters in the world, 7 have occurred in Iran. According to the FAO (World Food Organization) report, Iran ranks 10th in the world in terms of potential and disaster potential. Given the varied weather conditions in Iran, hailstorms are common. The occurrence of destructive and severe hailstorms as one of the major natural disasters has been reported in many parts of this vast country, with damages in various aspects of economic, agricultural, transport, infrastructure and so on and so on. Hail damages are sometimes greater than hurricanes and hurricanes.
Since hail in the Zab basin annually causes significant damages, especially in agriculture and livestock, the aim of this study was to investigate the synoptic patterns of hail in the Zab basin in order to reduce the damaging effects of this. The climatic phenomenon is on different parts
Area of study
The Zab Minor catchment in the southwestern province of northwestern and northwest of Kurdistan province consists of Piranshahr, Sardasht and Baneh counties and is about 2 km 2
Material and method
In this study, an environmental circulation approach was used to identify the circulation patterns of the days associated with hail in the west of the country. In this study, the code of days associated with the hail of Sardasht, Piranshahr and Baneh synoptic stations (with the longest statistical period between provincial stations) was obtained from the establishment (1992) up to year 2016 from the Meteorological Organization of Iran and then according to the code. The intensity of days associated with the hail event was identified during the study period. To identify large-scale synoptic patterns of day-event hail phenomena, hectopascal altitude and sea-level pressure data from open NCEP / NCAR analysis data on daytime events ranging from 0 ° C to 120 ° C and 0 ° C to 90 ° N They were prepared. Also, to determine the moisture flux of hail event days, Schulz and Benacus moisture flux equation was used.
Discussion and Conclusion
The purpose of this study is to establish an appropriate classification of atmospheric patterns in relation to hail events and the climatic characteristics that cause them in the Zab Basin. Therefore, station data (27-87-96-99 to 100 present weather codes) were used to capture hail from the 3 synoptic stations of the Zab basin over a 24year period (1992-2016).
Using the NCEP / NCAR Center data, it is possible to analyze synoptically and identify the circulation patterns that coincide with these events. Cluster analysis of sea level pressure and geopotential height data revealed three weak, moderate and severe circulation patterns associated with hail precipitation. Finally, in order to identify the most important systems, intra-group correlation was performed between each cluster, and the day that had the highest correlation with other days in one cluster was selected as the representative day of the circulation pattern of the cluster and the basis of this study was analyzed.
In the study of the synoptic patterns of hail precipitation according to the obtained results, the model best justified the hail precipitation in the Zab basin. In the first model, which included low hail precipitation, we observed a contrast between warm and humid low-pressure Sudan systems and high-pressure European cold tabs on the study area.
In the second pattern at sea level with the formation of a low pressure center on Iraq, this low pressure is reinforced by the development of warm and humid air through the Sudanese system and the formation of a high-pressure belt across the northern Iranian strip, which, with its rotation and rotation, drives cold air. The study area has provided conditions for frontalisation in the area
In the third model, Sudan's low sea level is strengthened so that its tongues stretch to the northwest and northwest of Iran, which inject hot and humid air and create convergence conditions over the study area. The Siberian high pressure on the north of Iran is also at its peak, and its tabs and motions cause very cold air to fall over the study area, and in this case the very cold northern and warm southern humid conditions make for the front. The region has created instability and instability
Previous research on hail precipitation or only the role of Sudanese high or low pressure northern Sudan in hail precipitation events has shown that hail precipitation in western Iran necessitates confrontation of air masses. The cold north is warm and humid south and the strongest hailstorms occurred when these air masses penetrated the study area at peak times and created conditions for overburden and instability with the help of high-level currents. They cause severe vertical motions in the atmosphere and, as a result, hail..