نوع مقاله : مقاله پژوهشی
نویسندگان
1 دانشجوی دکتری جغرافیا دانشگاه خوارزمی تهران
2 دکتری جغرافیا، استاد دانشگاه خوارزمی تهران
3 دکتری جغرافیا، عضو هیأت علمی پژوهشگاه هواشناسی و علوم جوّ تهران، دانشیار پایه 12،
4 دکتری هواشناسی، عضو هیأت علمی پژوهشگاه هواشناسی و علوم جوّ، دانشیار پایه 20
چکیده
کلیدواژه‌ها
عنوان مقاله [English]
نویسندگان [English]
In the upper level (300 hPa) a widespread positive vorticity has seen on the Mediterranean and the Black Sea. In this level, the length of summertime became more than ago from 1990s and the negative vorticity has increased in the recent decades. In the 500 hPa level the positive vorticity intensity on the Cyprus and Turkish area has decreased from 1990s. The cold season in the lower level is finished earlier than middle level because at this time air is warmer than sea but at the middle level the cold period takes longer so in this level cold air mass privates yet. There is an increasing trend of negative vorticity in the west and positive vorticity in the east of the Caspian sea in the cold period of the 850 hPa level that is in agreement with a decreasing of the intensity of Siberian high pressure and a weakening of the Black Sea low pressure system from 1980s.
کلیدواژه‌ها [English]
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