Summertime Urban Heat Island study for Guwahati City, India

Summertime Urban Heat Island (UHI) effect in Guwahati, a small but rapidly growing city of India, is studied, by using half hourly temperature data measured at four fixed observation sites – two in the urban core and the others at the periphery, away from the city. The in situ measurements were conducted using stationary loggers from the months of May to October 2009 to study the temporal variation. Also, mobile measurements were carried out during the months of June, July and August 2013 to bring out the intra-city temperature variation. The results show existence of UHI above  2 °C. The highest magnitude of daytime Urban Heat Island Intensity (UHII) for the entire period of study was found to be  2.12 °C while highest nighttime UHII was  2.29 °C. Diurnal ranges of temperature (DTR) showed wide variation in each of months included in this study. Higher DTR were experienced in the month of May for all the stations – rural as well as the urban. As the summer progressed, the DTR showed declining trend through the months of June to August and started rising again in September showing the influence of monsoon in air temperature regime. Variation in the average monthly DTR within the season is low in urban stations compared to rural ones. The temperature difference, recorded in the mobile runs, between the urban pockets and the suburban areas, ranged from 1.23 to  0.78 °C.