بررسي نقش ناهمواري ها در شكل گيري نواحي و خرده نواحي آب و هوايي استان همدان

Investigating the role of irregularities in the formation of regions and sub-regions of Hamadan Province

شرايط اقليمي هر محل در پراكندگي انسان، حيوان و گياه نقش مهمي را ايفا مي كند. لذا هرگونه فعاليت يا برنامه ريزي در زمينه هاي مختلف اقتصادي، كشاورزي و صنعتي در سطح زمين بدون شناخت اقليم امكان پذير نمي باشد، به همين دليل پهنه بندي اقليمي و شناخت مهمترين عوامل و عناصر تاثيرگذار بر هر ناحيه، يكي از راه هاي شناخت شناسنامه ي اقليمي نواحي است. فقدان اطلاع از خرده اقليم هاي نواحي، برنامه ريزي هاي اقتصادي و كشاورزي انسان را با شكست مواجه مي سازد. به طور كلي اقليم يك منطقه، متوسط وضعيت هوا در آن منطقه است و دسترسي به متوسط وضعيت هوا در يك مكان خاص، نيازمند آمار و اطلاعات درازمدت هواشناسي است. براي دريافت شناخت صحيح و جامع از اقليم استان همدان، پهنه بندي اقليمي با روش هاي نوين آماري مانند تحليل عاملي و تحليل خوشه اي طي دوره 20 ساله (1372- 1392) انجام شد. براي اين منظور تعداد 23 متغير اقليمي از 8 ايستگاه هواشناسي انتخاب گرديد. سپس با استفاده از مدل رقومي ارتفاع، بين پارامترهاي هواشناسي و لايه مزبور يك رابطه رگرسيوني چند متغيره اعمال گرديد كه در نهايت يك ماتريس پهنه اي به ابعاد 23 ×88 به دست آمد و مبناي ناحيه بندي قرارگرفت. بررسي اقليم استان با روش تحليل عاملي نشان مي دهد كه اقليم استان ساخته ي 5 عامل است، اين عوامل به ترتيب اهميت عبارتند از: دما و تغييرپذيري آن، ديدافقي، بارش، تندر و تابش. نتايج حاصل از تحليل خوشه اي بر روي 5 عامل اقليمي، وجود 6 ناحيه را در استان همداننشان مي دهد. يافته ها حاكي از آن است كه عوامل اول و دوم به تنهايي 63 درصد رفتار اقليمي را در استان تبيين مي نمايند.

Introduction: The climatic conditions of each site play an important role in the dispersion of humans، animals and plants. Therefore، any activity or planning in different economic، agricultural and industrial fields at the ground level is not feasible without the knowledge of the climate. For this reason، climatic zoning and recognition of the most important factors and factors affecting each area is one of the ways of recognizing the climatic identity of the area. Lack of knowledge of the sub-regions of the country fails to meet the economic and agricultural plans of mankind. In general، the climate of a region is the average of the weather conditions in the region. Access to the average weather conditions in a specific location requires long-term weather information. Data and Methods: In order to obtain the correct and comprehensive knowledge of the climate of Hamedan province، climatic zoning was performed with new statistical methods such as factor analysis and cluster analysis during the 20 years period (1993-2013). For this purpose، 23 variables were selected from 8 meteorological stations. Then، using a digital elevation model، a multivariable regression was applied between the meteorological parameters and the digital elevation model. Finally، a zonal matrix with a dimension of 23 × 88 was obtained. Since the aim of this research was the climate zone of Hamadan province based on altitude، a digital elevation layer (DEM) was used with a resolution of 90 meters. In the following، for climatic zoning، a regression relationship was made between climate parameters and length، width and height of the area. To identify the climatic sub-regions of Hamedan province، the raster data obtained from the zoning were converted to point data. Then، based on the analysis of the main components، the points were analyzed by clustering method and the dominant factors were identified. In this research، the resolution of each of the pixel was 15 × 15 km and a matrix with dimensions of 23 × 88 was developed. Finally، this matrix was clustered into the MATLAB software using the Wardclustering method. Results and discussion: By studying 23 climatic elements، 5 climatic factors were identified and their maps were drawn. These factors include temperature، visibility، rainfall، thunder storm and radiation. Among these factors، the first factor with 37% of the variance of the total data has the most important role in determining the climate diversity of the province. This factor is most commonly observed in the south and southwest of the province and with moving to the north and northeast of the province، this factor is severely reduced. Conclusion: According to the dendrogram، 6 climatic regions were identified and the characteristics of each separate area were investigated.