اقلیم شناسی بارش ناحیه خزری.

نوع مقاله : مقاله پژوهشی

نویسندگان

1 استاد اقلیم شناسی، دانشکده علوم انسانی، دانشگاه زنجان، زنجان

2 دانشجوی دکتری تغییرات آب و هوایی/دانشگاه زنجان، زنجان، ایران

چکیده

 
در این پژوهش تلاش شد تا جنبه­های پنهان بارش در ناحیه خزری مورد بررسی و واکاوی قرار گیرد. بدین منظور از داده­های روزانه 385 ایستگاه ‌همدید، اقلیم‌شناسی و باران­سنجی سازمان هواشناسی کشور و ایستگاه‌های باران­سنجی وزارت نیرو طی بازة زمانی 2016-1966 (51 سال) استفاده شد. نقشه‌های بارش روزانه با تفکیک مکانی 3 × 3 کیلومتر ایجاد ­شد. برای هر پیکسل ایجاد شده در نقشه افت و خیز سینوسی بارش 12 ماه سال براساس روش همسازها بررسی گردید. بارش‌های 1، 2، 3، 4/2، 4، 5 و 6 تناوبی در هر سال استخراج گردید. به منظور شناسایی الگوهای مکانی بارش براساس سهم تناوب­های مختلف و نیز پهنه­بندی آن از شگرد تحلیل خوشه­ای براساس فاصلة اقلیدسی و روش ادغام "وارد" استفاده شد. نتایج نشان داد که، در نواحی­ای که بارش­های یک تناوبی وجود داشته، سیستم­های بزرگ مقیاس و در نواحی با بارش­های دو تناوبی، سیستم­های بزرگ مقیاس و عوامل محلی و در نواحی با بارش­های سه، چهار، پنج و شش تناوبی، عوامل محلی هم­چون رشته­کوه­های البرز، دریای خزر و جلگه­ای بودن ناحیه منجر به نزولات جوّی شده­ است. بیش­ترین سهم بارش­های حاصل از سامانه­های بزرگ مقیاس در جنوب­غربی دریای خزر و شرق ناحیه و بیش­ترین سهم بارش­های محلی در ارتفاعات البرز مشاهده شد. این خود بیانگر این است که، در بخش­های ساحلی و جنوب­غرب دریای خزر و شرق ناحیه، بارش متمرکز و در ارتفاعات البرز نامتمرکزتر بوده است. نتایج حاصل از تحلیل خوشه­ای نشان داد که، در ناحیه خزری سه طبقه پراش بارش متمایز را می­توان شناسایی نمود. پراکندگی جغرافیایی این طبقات نشانگر این بود که تفاوت این طبقات متأثر از عرض جغرافیایی و فاصله از دریای خزر است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Precipitation Climatology of the Caspian region

نویسندگان [English]

  • Hossein Asakereh 1
  • Nasrin Varnaseri ghandali 2
1 Associote Prof. in Climatology, Department of Geography, University of Zanjan, Zanjan
2 Geography, Faculty of Humanities, Zanjan, Iran/ Zanjan university, Zanjan, Iran
چکیده [English]

In current research, attempts was made to analyze the hidden aspects of precipitation in the Caspian region. To this end, the daily data of 385 stations, under Meteorological Organization and the Ministry of Energy's supervision was used for the period of 2016-1966 (51 years). These stations were used in order to create maps with a spatial resolution of 3 × 3 km. Sinusoidal behaviors of monthly Precipitation in each map's pixels were investigated. Accordingly, first to sixth harmonics were extracted. Finally, to identify the spatial patterns of precipitation based on the contribution of different periodic and its zoning, the cluster analysis method was used based on the Euclidean distance and the "Ward" method of linkage. The results showed that large-scale systems, and local factors such as the Alborz Mountains, the Caspian Sea have led to different patterns of atmospheric precipitation. The largest share of precipitation from large scale systems in the southwest of the Caspian Sea and the eastern region and the highest share of local precipitation in the Alborz highlands is seen. This suggests that precipitation is concentrated in the coastal and southwest parts of the Caspian Sea and east of the region, and is less concentrated in the Alborz highlands. The results of cluster analysis indicate that in the Caspian region three classes of distinct precipitation diffraction can be identified. The geographical dispersion of these classes shows that the difference between these classes is affected by latitude and distance from the Caspian Sea.

کلیدواژه‌ها [English]

  • Precipitation Climatology
  • Large-scale Systems
  • Local factors
  • Rise and Fall
  • Caspian Region
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