Evaluating urban heat island in the critical local climate zones of an Indian city

Abstract

The rise in global temperature and rapid pace of urbanisation is fuelling the need to understand cities and its climate implication. Measuring urban heat island (UHI) have significant contribution in understanding this inter-relationship. This paper aims at measuring canopy layer heat island (CLHI) in a compact city of Nagpur, India using local climate zone (LCZ) classification. It also accesses the inter-LCZ temperature difference within the city and identifies critical areas that require intervention to curb heat island. The methodology describes LCZs mapping, data collection technique using fixed station points and mobile traverse survey conducted during the month of December 2015 and February 2016 of winter season. The paper adopts rigorous data filtering technique to avoid the errors in reporting UHI of cities having compact and heterogeneous built form like Nagpur. The study covers temperature buffer analysis, sensor lag determination, forecasting, outlier analysis and Pearson – correlation technique. It also examines the thermal anomaly in different LCZ with respect to cities average for identifying critical areas. The result shows that UHI intensity within built LCZ (IUHI), in winter season for Nagpur city, ranges from 1.76 to 4.09°C. The compact low-rise LCZs present at the urban core were found to be warmer than other major LCZ present in the inner areas of the city. The study also reports thermal variation between traditional LCZs and the LCZs with subclasses. The study concludes with identification of critical LCZs in terms of IUHI and suggests the need for intervention.