نوع مقاله : مقاله پژوهشی

نویسندگان

• علی اکبر شمسی پور (1) ¹
• سعید سپاسی زنگی آبادی ²
• علی حسینی ³

¹ دانشیار دانشگاه تهران

² دانش آموخته فوق لیسانس، دانشکده جغرافیا، دانشگاه تهران

³ استادیار دانشکده جغرافیا دانشگاه تهران

چکیده

فضاهای شهری به واسطه درهم آمیختگی عناصر انسان‌ساخت و عوارض طبیعی، شرایط محیطی متفاوت و پیچیده‌تری از محیط‌های طبیعی دارند. امروزه در منطقه‌بندی اقلیمی فضاهای شهری رویکرد متخصصان اقلیم شهری بر توجه و استفاده ترکیبی از عوامل شهری و طبیعی است. منطقه‌بندی محلی آب‌وهوا (LCZ)، به طبقه‌بندی آب‌وهوایی فضاهای شهری با توجه و تمرکز بر ساختار فیزیکی و پوشش سطحی شهر می‌پردازد. طبقه‌بندی LCZ دارای 17کلاس با ویژگی‌های پوششی و فیزیکی متفاوت است. برای انجام پژوهش از سه نوع داده‌های هواشناسی، تصاویر ماهواره‌ای و لایه‌های اطلاعات مکانی شهر استفاده شد. تصاویر برای دو دوره زمانی تابستان و زمستان سال 1399؛ لایه‌های اطلاعات مکانی شهر تهران و حومه آن شامل داده‌های کاربری/پوشش اراضی و طبقات ساختمانی شهر؛ داده‌های جوی دما، بارش، سرعت و جهت باد در دوره زمانی 20 ساله از ایستگاه‌های هواشناسی داخل شهر تهیه شدند. فرایند پردازش داده‌ها در SAGA-GIS، نمونه‌برداری در Google Earth و طبقه‌بندی و خروجی اطلاعات در Arc/GIS 10.8.1انجام شد. نتایج طبقه‌بندی اقلیم محلی تهران نشان داد اقلیم‌های محلی با بافت متراکم و ارتفاع متوسط(LCZ2)، و متراکم و کوتاه (LCZ3) غالب هستند. این دو کلاس اقلیم محلی، که با بار گرمای محیطی بالا و ظرفیت تهویه ضعیف شناخته می‌شوند؛ عموما در مرکز و مناطقی از شمال‌شرق تهران متمرکز هستند. همچنین شمال و شمال‌شرق با پهنه‌های پوشش درختی و طبیعی یعنی طبقات اقلیمی LCZA تا LCZC و حومه جنوبی شهر با اراضی کشاورزی و علفزار (LCZD) مشخص شدند؛ این طبقات اقلیمی وجود قابلیت تأمین هوای خنک و مطلوب برای داخل شهر را دارند. در نتیجه تقویت کریدورهای سبز و گذر هوای شمالی ـ جنوبی برای کاهش بار گرمای مرکز شهر و افزایش ظرفیت پویایی آن پیشنهاد می‌شود. بنابر نتایج بدست آمده از منطقه‌بندی اقلیمی عمده مناطق مرکزی شهر تهران از کیفیت محیطی ضعیفی برخوردار است. دلایل اصلی آن را تراکم بالای ساختمانی و کمبود فضای سبز شهری شکل می‌دهد. نتیجه آنها ضعف ظرفیت پویایی هوا و عدم تهویه طبیعی و ایجاد جزیره گرمای شهری در دوره گرم و افزایش فراوانی و شدت آلودگی هوا در دوره سرد می‌باشد.

کلیدواژه‌ها

• بار گرمای محیطی
• طبقه‌بندی اقلیمی
• تهویه طبیعی
• طبقات اقلیم محلی(LCZ)
• شهر تهران

موضوعات

• پایداری شهری

عنوان مقاله [English]

Local Climate Zoning of Tehran metropolitan base on physical structure

نویسندگان [English]

• Aliakbar Shamsipour ¹
• Saeed Sepasi Zangiabadi ²
• Ali Hosseini ³

¹ Associate Professor at University of Tehran

² Graduate in master, Faculty of Geography, University of Tehran.

³ Assistant Prof. at Faculty of Geography, University of Tehran

چکیده [English]

Extended Abstract

Introduction

Urban spaces have different and more complex environmental conditions than natural environments due to the combination of man-made elements and natural features. Today, in the climatic zoning of urban spaces, the approach of urban climate specialists is to pay attention to and use a combination of urban and natural factors. The Local Climate Classification (LCZs) (proposed by Stuart & Oak) 2012 includes a new and systematic classification of places for study. LCZ classifies climates according to the physical structure of the city. LCZs are individually characterized by one or more distinctive features that, for most classes, take into account land cover or height, the distance between trees and buildings. Local Climate Zoning classifies the climate of urban spaces with a focus on the physical structure and surface coverage of the city. The LCZ classification has 17 different classes, each of which represents characteristics. LCZ classes are individually identified by one or more distinctive characteristics that for most classes, land cover or height, the distance between trees and buildings are considered. Classes 1 to 10 pay more attention to the physical structure created by humans. Classes A to G pays more attention to the natural aspect of the city.

Data and Methods

Three types of data (meteorological data, satellite images, and spatial information layers) were used for this study. Satellite images of the city of Tehran for two periods of summer and winter. Information layers of Tehran and its suburbs include land use data, land cover and building floors of Tehran, and atmospheric data of temperature, precipitation, speed, and wind direction in the 20 years of Doshan Tappeh, Geophysical and Mehrabad meteorological stations in Tehran. To create a map of the local climate classes in Tehran, the images in the SAGA-GIS environment have been converted to a spatial resolution of 100 meters. The measured area has been cut and saved in kml format and added to the Google Earth program, where the sample of each climatic class was performed. This stage is the most important and decisive stage of the research, which has been done with sufficient accuracy and patience with many samples.

Results

The city of Tehran has a variety of local climatic classes with a variety of natural and human environments. Tehran is a heterogeneous metropolis in terms of form and performance, and because of this heterogeneity, all LCZ classes in the city are visible. The results of this study were as follows: Local climates with dense texture and medium height (Class 2), and dense and short (Class 3) are predominant. These two classes are local climates, known for their high ambient heat load and poor ventilation capacity; They are generally concentrated in the center and areas northeast of Tehran. inside the metropolis of Tehran, low-rise and mid-rise neighborhoods were obtained. The percentage of mid-rise buildings is much higher, which has made Tehran a mid-rise city in terms of building height. Buildings with green space between them are much less visible. Most of the city's green space is in the form of various parks in the city, which is why LCZ4 to LCZ6 are less visible than LCZ1 to LZC3. Barren lands and agricultural lands are a significant percentage of them outside the city limits. In addition, the building density of building spaces causes impermeable surface coatings, which are also an important factor in creating hot spots and stains. In addition to the above, dense urban spaces along with the narrow passage network show the sky visibility factor (SVF) and low air conditioning capacity. Barren lands with rocky outcrops and without vegetation in the mountainous strip north and east of Tehran have created different climatic classes of urban space. These zones are cooled with low heat capacity and higher altitude during the night, and their high-temperature difference with the urban space, which faces the phenomenon of urban heat island, provides the ability to form a north airflow towards the city. As the mountain range in the north of Tehran is identified as a cool and favorable urban air supply area. The south and southwest sides of Tehran are characterized by two different characteristics of the high distribution of urban centers and agricultural and garden lands. Tehran satellite urban centers receive various factories and industries that are not able to operate in the urban area of Tehran, and this has led to the formation of a local climate class of heavy industry and air pollution zone.

Conclusion

In the obtained classifications, areas with the potential to form with high urban heat load, the ability to cause high pollution in the city. cool air supply and the ability to provide clean air were identified. Also, the percentage of impermeability in the city is higher than in the suburbs. So, the possibility of flooding inside the city is much higher. Areas with low sky visibility have been created in the urban area, which are the same areas that have high heat in the city.

کلیدواژه‌ها [English]

• Climate classification
• Thermal loads
• natural ventilation
• Local climate zones
• Tehran