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| تعداد مقالات | 67,865 |
| تعداد مشاهده مقاله | 115,398,933 |
| تعداد دریافت فایل اصل مقاله | 90,167,352 |
اثر تغییرات گردش‌های جوی عرض‌های میانی بر موقعیت ناوه مدیترانه و رخداد بارش های فوق سنگین ایران | ||
| فیزیک زمین و فضا | ||
| مقالات آماده انتشار، پذیرفته شده، انتشار آنلاین از تاریخ 24 دی 1402 اصل مقاله (4.69 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22059/jesphys.2024.367094.1007571 | ||
| نویسندگان | ||
| نبی میرزایی* 1؛ بهلول علیجانی2؛ زهرا حجازی زاده3؛ محمد دارند4؛ محمد حسین ناصرزاده5 | ||
| 1گروه آموزشی آب و هواشناسی دانشگاه خوارزمی تهران | ||
| 2استاد اقلیم شناسی و مدیر قطب علمی تحلیل فضایی مخاطرات محیطی، دانشگاه تربیت معلم | ||
| 3گروه جغرافیا آب و هواشناسی دانشگاه خوارزمی تهران | ||
| 4عضو هیأت علمی دانشکده منابع طبیعی دانشگاه کردستان | ||
| 5گروه جغرافیا دانشگاه خوارزمی تهران | ||
| چکیده | ||
| در این پژوهش اثر گردش بزرگ مقیاس عرض‌های میانی بر موقعیت ناوه مدیترانه برای بارش‌های فوق‌سنگین طی بازه زمانی 1979 تا 2022 بررسی شد. در این راستا با استفاده از شاخص تموج تغییرات تموج و با تحلیل همدیدی الگوی گردسی جو برای150 بارش فوق سنگین کشور تحلیل شد. نتایج نشان داد که بارش‌های فوق سنگین تحت تاثیر تقویت ناوه اطلس، گسترش جریانات از سمت اروپا و شکل‌گیری ناوه مدیترانه رخ می دهد. شکل‌گیری ناوه اطلس سبب افزایش دامنه امواج، شکل‌گیری پشته برروی اروپا و ناوه مدیترانه می شود. با شکل‌گیری این الگو، ناوه مدیترانه تغییرات طول و عرض جغرافیایی 8 درجه را نسبت به میانگین خود تجربه می‌کند. تغییرات مکانی ناوه مدیترانه به دلیل تغییرات نصف‌النهاری امواج باد غربی برروی اروپا و موقعیت ارتفاع زیاد جنب‌حاره است. متغییرترین قسمت باد غربی منطبق بر بلاکینگ شرق اطلس و ناوه مدیترانه است که با تشدید شیو بین ارتفاع زیاد و کم‌ارتفاع، جریانات نصف النهاری شده و مقدار تموج افزایش می‌یابد. این شرایط منجر به تقویت پشته اروپا، افزایش دامنه امواج، تکوین بندال و گسترش ناوه مدیترانه تا عرض 25 درجه می‌شود. تکوین بلاکینگ اطلس سبب تقویت پشته برروی اروپا و گسترش جریانات به سمت مدیترانه می‌شود. همچنین گسترش نصف‌النهاری ارتفاع زیاد اروپایی منجر به تشدید شیو فشار، شارش جریانات سرد شمالی، تشدید جبهه‌ز‌ایی، تعمیق ناوه مدیترانه تا دریای سرخ می شود. همزمان با تقویت ناوه مدیترانه گسترش شرق‌سوی واچرخند عربستان علاوه بر اینکه منجر به گسترش شرق‌سوی ناوه مدیترانه می‌شود، رطوبت مناسبی نیز برای رخداد بارش‌های فوق سنگین کشور تامین می‌کند. | ||
| کلیدواژه‌ها | ||
| ناوه مدیترانه؛ شاخص تموج؛ بارش فوق سنگین؛ ایران | ||
| عنوان مقاله [English] | ||
| The effect of mid-latitude atmospheric circulation changes on the position of the Mediterranean trough and the occurrence of super heavy precipitation in Iran | ||
| نویسندگان [English] | ||
| nabi mirzaei1؛ Mohammad Darand4؛ | ||
| 1Department of Meteorology, Kharazmi University, Tehran | ||
| 4Department of Climatology, Faculty of Natural Resources, University of Kurdistan | ||
| چکیده [English] | ||
| Spatial variations of pressure patterns under the influence of large-scale atmospheric circulation creation different conditions in terms of the intensity of synoptic systems affecting on extreme climatic phenomena. Regarding the investigation of large-scale patterns, not only the changes of extreme events are considered, but also the changes and developments of synoptic systems on a regional scale are studied. Weather extremes have a great significance for society, as they pose a threat to human life and can result in enormous economic damage and disruption. The physical understanding and timely prediction of extreme weather events are of enormous importance to society regarding associated impacts. Extreme precipitation events (EPEs) is one of the most frequent natural hazards that affects the domain, eventually leading to floods. Synoptic systems in mid-latitudes such as blocking, ridge and troughs cause spatial changes in westerly waves. Spatial variations of atmospheric waves occur when, which normally move from west to east, change their main direction to the north or south. The occurrence of precipitation in the Middle East is related to the changes in waves and the position of the Mediterranean trough. Extreme precipitation events in the Middle East often result from tropical-extratropical interaction, whereby midlatitude forcing and poleward transport of tropical moisture are of central importance. The Mediterranean Sea region is considered to be one of the most important and major areas for circulation in the Northern Hemisphere, so that most of Iran's rain cyclones are formed over the Mediterranean Sea. In other words, Iran's rainfall in the cold period of the year is influenced by the Mediterranean circulation patterns. Evidence shows that the large-scale atmospheric circulation over the North Atlantic plays an important role in the Mediterranean circulation changes. We investigated the effect of mid-latitude atmospheric circulation changes on the position of the Mediterranean trough and the occurrence of super heavy precipitation in Iran. In this research, two category of upper atmosphere data were used. The first is daliy precipitation data for 350 stations were made available by the Iranian Meteorological Organization (IRIMO). The second dataset is the geopotential height, relative vorticity, potential vorticity, U, V-component of wind and Relative humidity extracted from the European Centre for Medium-Range Weather Forecasts (ECMWF-ERA5) reanalysis with grids at 0.25×0.25 resolution. In this regard, 150 extreme and widespread rains were identified, then using the sinuosity index, the changes of the most frequent contours (550, 565 and 575 decimeters) during the precipitations were identified over the North Atlantic and Mediterranean. The aim of this study was to find the relationship between the spatial variations of the upper level waves over the North Atlantic and the Mediterranean (-80° W to 70° E, 10° N to 60° N). According to sinuosity index, the minimum sinuosity value is about 1 indicating zonal flow. Any sinuosity value greater than 1 indicates an increase in atmospheric waves. The spatial changes of the Mediterranean trough are due to the meridian changes of currents over the North Atlantic, Europe. The blocking system over the Atlantic was responsible for both the amplification of the downstream trough, as well as the formation and expansion of the trough is towards the Eastern Mediterranean. The results show that extremely heavy and widespread rains occur under the influence of the formation of the Mediterranean trough and the expansion of currents from the European side and the strengthening of the North Atlantic trough. The results showed that the position and changes of the Mediterranean trough are Associated with the circulation pattern of the North Atlantic. Multiple Atlantic trough are associated with each case of Mediterranean trough downstream. The formation of the Atlantic trough causes an increase in the range of atmospheric waves and the formation of a ridge over Europe and the development of the Mediterranean trough. Under these conditions the Mediterranean Sea experiences 8 longitudinal and latitudinal changes compared to its average. Therefore, the spatial variations of the Mediterranean trough are due to the meridian changes of the European flows and the expansion of the high north side (tropical side) downstream of the western wind. Simultaneously with the formation of blocking over Europe in its eastern part, the dynamic ridge causes the transfer of cold currents over the Mediterranean, which strengthens and expands the Mediterranean trough to the east. These conditions, with the strengthening of the conditions of ascent and eastward movement of the Mediterranean trough, the Arabian Subtropical Anticyclone (ASA) also expands to eastward. During the heavy rains of Iran, by strengthening the conditions of ascent and expands to eastward to the Mediterranean trough, the ASA also expands to the east. Therefore, with the location of the ASA over the northern Indian Ocean, the Arabian Sea, and the Oman Sea, more moisture is provided in the atmosphere, which is accompanied by the intensification of extremely intense and widespread Precipitation. In general, the position of the Mediterranean trough during heavy rains is such that the western and southwestern regions of the country receive the most Precipitation. These conditions are more severe due to the orographic factor of ascent caused by the Zagros mountains in this region. | ||
| کلیدواژه‌ها [English] | ||
| Mediterranean trough, sinuosity index, super heavy precipitation, Iran | ||
| مراجع | ||
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آمار تعداد مشاهده مقاله: 264 تعداد دریافت فایل اصل مقاله: 154 |
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