كليدواژه :
سامانه هاي همديد , الگوي بندالي , ناوه و پشته , روزهاي برفي , زاهدان
چكيده فارسي :
اﻣﺮوزه ﭘﺎﯾﺶ و واﮐﺎوي ﻫﻤﺪﯾﺪ- آﻣﺎري روزﻫﺎي ﺑﺮﻓﯽ در ﯾﮏ ﻗﻠﻤﺮو ﮔﺮم و ﺧﺸﮏ ﺑﻪ دﻟﯿﻞ ﻣﺎﻫﯿﺖ ذﺧﯿﺮهﮔﺎﻫﯽ ﺑﺮف در ﺗﺄﻣﯿﻦ آبﻫﺎي ﺳﻄﺤﯽ و زﯾﺮزﻣﯿﻨﯽ، از اﻫﻤﯿﺖ ﺑﺎﻻﯾﯽ ﺑﺮﺧﻮردار اﺳﺖ. در اﯾﻦ راﺳﺘﺎ، ﭘﮋوﻫﺶ ﺣﺎﺿﺮ ﺑﻪ ﺑﺮرﺳﯽ آب و ﻫﻮاﺷﻨﺎﺧﺘﯽ روزﻫﺎي ﺑﺮﻓﯽ زاﻫﺪان از ﺳﺎل 1976 در ﯾﮏ ﺑﺎزة 40 ﺳﺎﻟﻪ ﭘﺮداﺧﺖ و ﺑﺮاي ﻧﯿﻞ ﺑﻪ اﯾﻦ ﻫﺪف، از دو ﭘﺎﯾﮕﺎه داده اﺳﺘﻔﺎده ﺷﺪ. ﭘﺎﯾﮕﺎه ﻧﺨﺴﺖ؛ ﮐﺪﻫﺎي ﻫﻮاي ﺣﺎﺿﺮ ﻣﺮﺑﻮط ﺑﻪ ﭘﺪﯾﺪه ﺑﺮف اﺳﺖ ﮐﻪ ﺑﻪﺻﻮرت روزاﻧﻪ از ﺳﺎزﻣﺎن ﻫﻮاﺷﻨﺎﺳﯽ ﮐﺸﻮر ﺑﺮداﺷﺖ ﺷﺪ. ﭘﺎﯾﮕﺎه دوم؛ ﻣﺮﺑﻮط ﺑﻪ دادهﻫﺎي روزاﻧﻪ ﻓﺸﺎر ﺗﺮاز درﯾﺎ و ارﺗﻔﺎع ژﺋﻮﭘﺘﺎﻧﺴﯿﻞ در ﺗﺮاز ﻣﯿﺎﻧﯽ وردﺳﭙﻬﺮ از ﻣﺮﮐﺰ ﭘﯿﺶﺑﯿﻨﯽ ﻣﺤﯿﻄﯽ ﺳﺎزﻣﺎن ﻣﻠﯽ ﺟﻮ و اﻗﯿﺎﻧﻮسﺷﻨﺎﺳﯽ آﻣﺮﯾﮑﺎ اﺳﺖ. ﺑﺎ ﺷﮕﺮد ﻣﺤﯿﻄﯽ ﺑﻪ ﮔﺮدﺷﯽ و ﺗﮑﻨﯿﮏ ﺧﻮﺷﻪاي، اﻟﮕﻮﻫﺎي ﺟﻮي ﻣﻮﺟﺪ روزﻫﺎي ﺑﺮﻓﯽ ﺷﻨﺎﺳﺎﯾﯽ ﮔﺮدﯾﺪ. ﻧﺘﺎﯾﺞ واﮐﺎويﻫﺎ ﻧﺸﺎن داد ﮐﻪ ﺑﺎرش ﺑﺮف در زاﻫﺪان ﺑﻪﺻﻮرت ﻣﺘﻤﺮﮐﺰ در ﻓﺼﻮل ﮔﺬار ﭘﺎﯾﯿﺰ و زﻣﺴﺘﺎن )ﻣﺎهﻫﺎي دﺳﺎﻣﺒﺮ، ژاﻧﻮﯾﻪ، ﻓﻮرﯾﻪ و ﻣﺎرس( رﻫﻨﻤﻮد دارد. در ﺗﺮاز درﯾﺎ ﻧﯿﺰ اﻟﮕﻮﻫﺎي ادﻏﺎﻣﯽ ﭘﺮﻓﺸﺎرﻫﺎي ﻣﻬﺎﺟﺮ ﺳﯿﺒﺮي- ﺧﺰر ﺑﺎ ﻓﺮاواﻧﯽ 32/5 درﺻﺪ و ﭘﺮﻓﺸﺎر ﺳﯿﺒﺮي- ﻗﻔﻘﺎز ﺑﺎ 20 درﺻﺪ، ﺑﯿﺸﺘﺮﯾﻦ ﻧﻘﺶآﻓﺮﯾﻨﯽ را در رﺧﺪاد ﺑﺎرش ﺑﺮفﺑﺎزي ﻣﯽﮐﻨﺪ. ﻫﻤﭽﻨﯿﻦ در ﺗﺮازﻫﺎي ﻣﯿﺎﻧﯽ وردﺳﭙﻬﺮ، ﻧﺎوه ﺗﺮﮐﻤﻨﺴﺘﺎن ﺑﻪ دﻟﯿﻞ ﻫﻢﺟﻮاري ﺑﺎ اﯾﺮان و ﻧﻘﺶ ﺑﻨﺪاﻟﯽ آن )ﮐﻢ ارﺗﻔﺎع ﺑﺮﯾﺪه(، ﻣﻮﺟﺪ 42/5 درﺻﺪ و اﻟﮕﻮي ﺑﻨﺪال اﻣﮕﺎي اروﭘﺎ ﻧﯿﺰ، 25 درﺻﺪ از ﻓﺮاواﻧﯽ روزﻫﺎي ﺑﺮﻓﯽ را ﺗﺒﯿﯿﻦ ﻣﯽﮐﻨﺪ. ﺑﻪ ﻧﻈﺮ ﻣﯽرﺳﺪ، ﻓﻌﺎﻟﯿﺖ ﻫﻢزﻣﺎن اﻏﺘﺸﺎﺷﺎت ﺟﻮي در ﺳﺎﻣﺎﻧﻪﻫﺎي ﻗﻮي و ﭘﺮﻓﺸﺎر ﻣﻬﺎﺟﺮ ﺳﯿﺒﺮي، اروﭘﺎ، ﻗﻔﻘﺎز، روﺳﯿﻪ و ﺧﺰر از ﯾﮏﺳﻮ و ﺗﻘﻮﯾﺖ ﻧﺎوهﻫﺎي ﻋﻤﯿﻖ ﻋﺮضﻫﺎي ﺟﻨﺐﻗﻄﺒﯽ و ﮔﺴﺘﺮش آن ﺑﻪ ﻋﺮضﻫﺎي ﭘﺎﯾﯿﻦﺗﺮ از ﺳﻮي دﯾﮕﺮ، ﺳﺒﺐ ﺗﺸﺪﯾﺪ ﺷﯿﻮ ﻓﺸﺎر و دﻣﺎ، اﺳﺘﯿﻼي ﺳﺮﻣﺎ و رﺧﺪاد ﺑﺮف ﺧﻮاﻫﺪ ﺷﺪ.
چكيده لاتين :
In this regard, the present study investigated the climatic of the Zahedan snow days since 1976 over a period of 40 years. To achieve this goal, two databases were used. First databases; the present weather codes are related to the snow phenomenon, which was collected daily from the Meteorological Organization. The second database, relates to the daily data of sea level pressure and geopotential height in the troposphere from National Center for Environmental Prediction (NCEP). With Environmental to Circulation Technic and cluster analysis, weather patterns causing snow days, identified. The results of the analysis showed that, snowfall in Zahedan is concentrated in autumn and winter seasons (December, January, February and March). At sea level pressure, integration patterns of Siberian-Caspian high-pressure migrants with 32.5% and Siberian-Caucasian highs with 20%, play the most roles in snowfall event. Also in the middle troposphere, Turkmenistan's ridge and Blocks (cut-off high) account for 42.5% and the European omega block pattern accounts for 25% of the snowfall frequency. It seems that the simultaneous activity of atmospheric disturbances in the immigrant high pressure systems of the Siberian, European, Caucasian, Russian and Caspian, deep ridge polar latitudes and its extension to the lower latitudes, It will exacerbate showers and temperatures, cold weather and snowfall.
