نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشگاه شهید بهشتی تهران- دانشکده علوم زمین- گروه جغرافیای طبیعی
2 استادیار مرکز سنجش از دور و GIS دانشکده علوم زمین دانشگاه شهید بهشتی
3 استاد گروه اقلیم شناسی دانشکده علوم زمین دانشگاه شهید بهشتی
4 مسئول آزمایشگاه گروه سنجش از دور و GIS دانشکده علوم زمین دانشگاه شهید بهشتی
5 مدرس دانشگاه پیام نور واحد پرند تهران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
In this study, the climatology of cut-off lows systems at the level of 500 hPa of the northern hemisphere effective on heavy rainfall in Iran has been discussed. The ECMWF reanalysis data were used to identify and track cut-off lows that lasted for more than 48 hours in the statistical period of 33 years (1986-2018). For this purpose, geopotential data, orbital wind data, and temperature data at the level of 500 hPa also were used. Identification of cut-off lows systems was performed using the Tibaldi-Multeni algorithm with auto-detection capability. Based on the results, 632 cut-off lows with a lifespan of more than 2 days were identified during the statistical period. The highest frequency of occurrence of this phenomenon was determined during a year (28 events) and the lowest frequency with (10 events). The highest incidence of cut-off lows was in March, January, and October and the lowest incidence was in July. In terms of seasonality, the highest frequency of events was in winter, and spring and the lowest frequency was in summer. The highest percentage of the impact of cut-off lows on heavy rainfall was in the northwest and northeast and the lowest percentage of the impact of cut-off lows on heavy rainfall was in the southeast region of Iran. In total, the share of cut-off lows in heavy rainfall of Iranian study stations was 8.02%, and the northwest region with 8.13% compared to the total amount of heavy rainfall in Iran.
کلیدواژه‌ها [English]
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