Seasonal and Spatial Characteristics of Urban Heat Islands (UHIs) in Northern West Siberian Cities

Abstract

Anthropogenic heat and modified landscapes raise air and surface temperatures in urbanized areas around the globe. This phenomenon is widely known as an urban heat island (UHI). Previous UHI studies, and specifically those based on remote sensing data, have not included cities north of 60 • N. A few in situ studies have indicated that even relatively small cities in high latitudes may exhibit significantly amplified UHIs. The UHI characteristics and factors controlling its intensity in high latitudes remain largely unknown. This study attempts to close this knowledge gap for 28 cities in northern West Siberia (NWS). NWS cities are convenient for urban intercomparison studies as they have relatively similar cold continental climates, and flat, rather homogeneous landscapes. We investigated the UHI in NWS cities using the moderate-resolution imaging spectroradiometer (MODIS) MOD 11A2 land surface temperature (LST) product in 8-day composites. The analysis reveals that all 28 NWS cities exhibit a persistent UHI in summer and winter. The LST analysis found differences in summer and winter regarding the UHI effect, and supports the hypothesis of seasonal differences in the causes of UHI formation. Correlation analysis found the strongest relationships between the UHI and population (log P). Regression models using log P alone could explain 65-67% of the variability of UHIs in the region. Additional explanatory power-at least in summer-is provided by the surrounding background temperatures, which themselves are strongly correlated with latitude. The performed regression analysis thus confirms the important role of the surrounding temperature in explaining spatial-temporal variation of UHI intensity. These findings suggest a climatological basis for these phenomena and, given the importance of climatic warming, an aspect that deserves future study.

Trend Analysis of Urban Heat Island Intensity According to Urban Area Change in Asian Mega Cities

“…where, T u and T s are mean temperatures of the urban area and the surrounding areas of the urban area, respectively (See Equation (1)). We have excluded the water bodies while calculating UHI intensity because they can influence the temperature significantly [21]. For calculating the seasonal average temperature, spring was defined as March-May, summer as June-August, autumn as September-November, and winter as December-February [18,29].…”

“…Jin et al [20] used Moderate Resolution Imaging Spectroradiometer (MODIS) images to identify the differences in surface temperature between the urban and suburban areas of Beijing, New York, and Phoenix, but were unable to identify the UHI change trends because they performed single-year analysis instead of long-term analysis. In the study of Asian mega cities by Tran et al [14] and in that of northwest Siberia by Miles and Esau [21], the change in UHI intensity based on the season and its correlation with related variables were verified using MODIS images. Zhou et al [9] analyzed the difference in UHI intensity based on the area of each city using MODIS images.…”

“…In the case of studies that used remotely sensed datasets, only a short-term analysis was performed because of the limitation of temporal resolution. In addition, for the three aforementioned studies [9,14,21], images from different periods were used for each city, and no trend regarding long-term change was confirmed.In this study, global climate modeling data, which is a combination of observation and remote-sensing data, were used for comparative analysis of long-term change in UHI intensity based on city and season. Climatologies at high resolution for the Earth's land surface areas (CHELSA) data were used as the global climate modeling data.…”

“…In the case of studies that used remotely sensed datasets, only a short-term analysis was performed because of the limitation of temporal resolution. In addition, for the three aforementioned studies [9,14,21], images from different periods were used for each city, and no trend regarding long-term change was confirmed.…”

A high density urban temperature network deployed in several cities of Eurasian Arctic

“…These works did not have their focus on the high latitudes, and therefore include only a few arctic cities (found above 63 • N) in their analysis. A regional study of West Siberian cities was reported in Miles and Esau (2017). This study utilized the LST data product from the MODerate resolution Imaging Spectroradiometer (MODIS).…”