UNDERSTANDING THERMAL FLUXES IN AND AROUND PUNE CITY USING REMOTELY SENSED DATA

摘要

Soaring temperatures of cities due to urbanisation leading to possible formation of an Urban Heat Island (UHI) is becoming a growing concern for India, a developing country, with the 2nd highest population in the world. Pune is no exception to that. Over the last few decades, the increasing urban landscape of the Pune city has led to fluctuations in the daily temperatures and disturbance in the thermal fluxes. To understand the nature and the consequences of this phenomenon, it is imperative to study the temperature changes and come up with a model that can quantify these changes. Whereas numerous studies have made use of satellite images for UHI analysis, only a few of these have paid significant attention to the analysis of long term changes. Our research aims to study the temperature profile of Pune city with the help of the Landsat-7 satellite imagery. The Land Surface Temperature (LST) and Land Use Land Cover (LULC) data extracted from these images is compared to find the correlation between the two. We used Hilbert Huang Transform (HHT) for analysing trends across the North-South and East-West extent of the city. The results are then compared with the Vegetation, Impervious and Soil (VIS) classification of the cross section to identify the relation of the trend with the classification. The results obtained show that the areas with residential, industrial have an average surface temperature of around 46 °C. That is higher by 2-3 degree on an average (5-6 degree worst case) than immediate surrounding vegetated region - indicating mild urban heat island effect. But because of physical geography of the region the outermost surrounding is covered with barren land, dry grass open area etc. and have similar temperatures to that of core of the city. Thus the observations indicate very specific temperature variation along the North-South and East-West cross sections of the city.