نوع مقاله : مقاله پژوهشی

نویسندگان

• بهاره سادات موسوی ¹
• عطاالله عبداللهی کاکرودی ²
• سمانه اروندی ³

¹ دانشجوی دکتری سنجش از دور و سامانه اطلاعات جغرافیایی، دانشگاه تهران

² دانشیار گروه سنجش از دور و GIS، دانشگاه تهران، تهران ایران.

³ دکتری مهندسی آب، معاونت آب و خاک وزارت جهاد کشاورزی، کرج، ایران.

چکیده

گسترش فیزیکی شهری بر تغییرات مکانی و زمانی در خواص بیوفیزیکی سطح، از جمله LST تاثیرگذار بوده و منجر به افزایش دمای سطح طی سال‌های پایش شده است. به طوری که نتایج حاصله در هر سه شهر مورد مطالعه طی سال‌های پایش، روند افزایشی دمای سطح زمین را نشان می‌دهد. بررسی‌ها در شهرها نشان داد که رشد شهری با توجه به محیط جغرافیایی و شرایط طبیعی هر منطقه از الگوهای متفاوتی پیروی می‌کند. براین‌اساس، تغییرات مکانی و زمانی در خواص بیوفیزیکی سطح در میان شهرهای انتخاب شده متفاوت بود. این تفاوت ناشی از شرایط اقلیمی، محیطی و پوشش زمین بود. با توجه به شرایط اقلیمی، میانگین سرسبزی در مناطق با هوای مرطوب (بندر انزلی و شیرگاه) با مناطق با هوای گرم و خشک (کاشان) متفاوت بود. با کاهش پوشش گیاهی سطح، میزان تبخیر و تعرق سطحی کاهش یافته و در نتیجه گرما و خشکی سطح افزایش می‌یابد. میزان سبزینگی در هر سه شهر مورد مطالعه طی سال‌های پایش روند کاهشی داشته است که می‌تواند به دلیل پدیده گسترش شهری باشد. نتایج حاصل از شاخص درخشندگی نشان داد در شهرهای مرطوب یعنی بندرانزلی و شیرگاه میزان درخشندگی که ناشی از عوارض شهری می‌باشد روند افزایشی داشته است. نتایج حاصل از شاخص آب و رطوبت نیز طی سال‌های پایش در شهرهای شیرگاه و بندر انزلی(شهرهای مرطوب) روند افزایشی داشته است. به‌طور کلی با کاهش سبزینگی، درخشندگی، رطوبت و دمای سطح زمین در شهرهای کاشان و شیرگاه افزایش یافته ولی به نظر می‌رسد تاثیر اقلیم محلی و دریا منجر به تعدیل دما در بندر انزلی شده است. نزدیکی به دریا و بالابودن رطوبت (wetness) باعث شده پوشش گیاهی در طی سال‌های پایش کاهش چشمگیری نداشته باشد و در نتیجه منجر به تعدیل دمای سطح شده و از سال ۱۹۹۱ تا ۲۰۲۱ نتایج مربوط به LST تنها یک درجه افزایش دما را نشان می‌دهد. درنتیجه افزایش پوشش گیاهی می‌تواند منجر به افزایش ‌رطوبت آب (wetness) و در نتیجه کاهش دمای سطح شود.

کلیدواژه‌ها

• دمای سطح زمین
• خصوصیات بیوفیزیکی سطح
• تغییرات مکانی و زمانی
• توسعه شهری
• سنجش از دور

موضوعات

• جغرافیای شهری

عنوان مقاله [English]

The Effect of Climatic Conditions on Spatial-Temporal Changes and Urban Tasseled Cap Characteristics Using Satellite Images (Case study: Kashan, Shirgah, Bandar Anzali cities, Iran)

نویسندگان [English]

• Bahare sadat mousavi ¹
• Ata A. Kakroodi ²
• samane Arvandi ³

¹ Department of physical Geography, Faculty of Geography, University of Tehran, Tehran, Iran.

² Department of physical Geography, Faculty of Geography, University of Tehran, Tehran, Iran.

³ Ministry of Agriculture-Jahad, Deputy of water and soil, Karaj, Iran.

چکیده [English]

Introduction

Globally, the physical growth of cities is recognized as a significant threat to natural and ecological resources, with a variety of effects including land use change, increased pollution, increased earth surface temperatures, and climate change in both urban and non-urban areas. Planning to minimize the negative environmental effects of urban growth can be aided by quantifying and monitoring the changes caused by urban development in the Tasseled cap of the surface. Urban management and planning can be derived from the quantitative and qualitative effects of climatic conditions on the type and amount of changes in the Tasseled cap of the surface due to physical expansion of the cities. Furthermore, weather conditions are the primary and effective factor on the type and amount of changes in the Tasseled cap properties of the surface. Considering field measurement is a time-consuming and expensive technique, remote sensing technology will be helpful and effective to overcome this challenge because of its large and continuous coverage, immediate access, and availability of data at various local, regional, and global scales.



Theoretical Framework

The land surface temperature rises as a result of urbanization (LST). In general, at the patch scale, the more compact the urban growth was, the more easily the surface warmed. In majority of the temperature zones, it was found that edge expansion and infilling had significant and favorable correlations with LST. Positive correlations were found in the warm temperature and plateau climatic zones, while negative correlations were seen in the subtropical and intermediate temperature zones, indicating that the influence of outliers on LST had opposite effects in these regions. The findings also demonstrated that LST was significantly influenced in diverse ways by patch area, industrial firm density, population density, and road density. This study further verified the existence of a scale effect; moreover, the results of patch-scale research based on the microscopic perspective were deemed to be more accurate. Overall, understanding the quantitative relationships between UGP and LST is helpful for assessing the complexity of urban climates and for providing a scientific basis for planners and urban managers to optimize urban layouts, (Rao etal., 2021: 105314).

Conclusion

Urban physical expansion has influenced spatial and temporal changes in Tasseled cap, including LST, and has led to an increase in surface temperature during the monitoring years. Results from the three cities under study over the monitoring years indicated an upward trend in earth's surface temperature. Surveys conducted in cities revealed that the geographic setting and regional factors influence the patterns of urban expansion. As a result, there were variations in the spatial and temporal changes in Tasseled cap between the chosen cities. This difference caused by climatic, environmental and land cover conditions. According to the climatic conditions, the average greenness in areas with wetness weather (Bandar Anzali and Shirgah) was different from areas with hot and dry weather (Kashan). The reduction of surface vegetation, due to reduction in the amount of surface evaporation and transpiration so the heat and dryness of the surface increases. In all three of the studied cities, there has been a decline in the amount of greenness during the monitoring years, which may be related to the phenomenon of urbanization. The brightness index data demonstrated a rising tendency in the quantity of brightness caused by urban influences in the humid cities of Bandar Anzali and Shirgah. The results of the water and wetness index have also increased during the monitoring years in the cities of Shirgah and Bandar Anzali (wet cities). However, it appears that the influence of the local climate and the sea has led to a change in temperature in Bandar Anzali. In general, with the reduction in greenness, brightness, wetness, and warmth of the earth's surface increased in Kashan and Shirgah. The vegetation cover has not decreased during the years of monitoring due to the area's proximity to the sea and high levels of precipitation, which has contributed to an adjustment of the surface temperature. From 1991 to 2021, the LST findings revealed just a one-degree increase in temperature. Because of this, an increase in vegetation may cause a rise in moisture, which in turn causes a drop in surface temperature.

This study was conducted with the aim of investigating the effect of different weather conditions on changes in the biophysical properties of the surface due to urban expansion. The nominating difference of this study compared to previous studies is the evaluation of the effect of various climatic conditions changes in biophysical characteristics caused by cities physical growth.

The studied cities in this research are located in different climates, the results showed that the physical development of the cities in each them during the monitoring years (1991 to 2021) had different effects on the temperature and biophysical characteristics of the surface. It shows that planning in these cities should be different according to the climatic conditions of each city, so managers and urban planners should consider the climatic conditions.

Also, the design of the urban space based on the climatic conditions of each region has the great importance to control and improve thermal conditions of the urban environment. It is suggested that in future studies, climatic conditions and land cover changes due to the physical growth of cities should be considered for different cities.

کلیدواژه‌ها [English]

• Urban development
• spatial and temporal variations
• Earth'
• s surface temperature
• and Tasseled cap properties