تحليل سينوپتيكي بارش هاي حوضه هاي اترك وگرگان رود (39 بارش فراگير)

Synoptic Analysis of Rainfall in Atrak and Gorganroud Basins (39 Pervasive Rainfall)

به منظور تحليل سينوپتيكي بارش هاي حوضه هاي اترك و گرگانرود در شمال شرق ايران، 39روز با بارش فراگير بيش از 7 ميليمتر طيّ دوره ي آماري 6 ساله (2002-1997) انتخاب شد. سپس داده هاي شبكه بندي شده ي فشارسطح دريا مربوط به (65-10 عرض جغرافيايي و 80- 5 طول جغرافيايي) با تفكيك مكاني (2.5×2.5) درجه مربوط به روزهاي منتخب بارشي از پايگاه داده (NCEP/NCAR) استخراج گرديد. بر روي اين داده ها تحليل عاملي و سپس تحليل خوشه بندي سلسله مرتبي با روش ادغام ward انجام گرفت بر اساس اين تحليل 6 الگوي سينوپتيكي در سطح زمين تشخيص داده شد كه بر اين اساس الگوهاي مربوط به سطح 500 نيز استخراج گرديد. نتايج نشان مي دهد در الگوهاي سطح زمين تقابل يك مركز پر فشار نسبتاً قوي در سمت غرب يا شمال غرب و مركز كم فشاري در مرزهاي شرقي ايران كاملاً مشهود است. علاوه برآن الگوهاي استخراج شده براي ارتفاع ژيوپتانسيل در سطح 500 نيز همواره حضور يك فرود را بر روي ايران نشان مي دهد.

Synoptic climatology term was used for the first time in U.S.A Air force at 1940s decade. Their goal of this field is to analyze the previous frequencies of climatic components and forecast the atmospheric condition based on the computations. Synoptic climatology provides useful tools for the researchers in the fields of atmosphere, environment and geography sciences and at the present it is the most rapid way to recognize the relationship between environmental processes and atmospheric cycles. today, the study of relevant different phenomenon of the climate including draughts, severe rainfalls, pollution and storms and . . .by the use of synoptic methods presents a more acceptable results and more reliable predictions. Aatrak and Gorganrood are the most important rivers in northeastern part of Iran and Caspian Sea catchment area. Wide farmlands and numerous cities and towns with considerable population and also different water structures including bridges and dams are located in this area and being affected by the discharge fluctuations. Since the type and rate of rainfalls has an important and determinant role on the catchment area reactions , knowing the dominant Synoptic patterns may be efficient to forecast pervasive rainfalls or heavy rain falls flood discharge and can be considered and used in different economical activities and planning particularly agriculture, transportation , tourism and ...