Investigating the synergies between the Urban Heat Island (UHI) and Heatwaves (HWs)

Abstract South Asian cities are now experiencing high-intensity of heatwaves. Heatwaves (HWs) severely threaten human health, particularly in urbanized areas more susceptible to the urban heat island (UHI) effect. Due to climate change, heatwaves are becoming stronger, coupled with the intensity of urbanization, exacerbating the thermal risk for urbanites. Explored the synergistic interaction of UHI with HWs and non-HWs periods were investigated in Lahore city. Lahore's climate is subtropical, with relatively dry, moderate winters and extremely hot summers. The city has a distance of 2,179.55 mi (3,507.65 km) north of the equator. A strong relationship was observed between UHI and heatwaves. Land surface temperature (LST) measured by satellite is a widely used indicator for analyzing heatwaves. It has a wider spatial coverage compared to surface air temperature measured at weather stations. Measured the UHI intensity with both datasets. The UHI was analyzed during HWs and non-heatwaves using the heat index method, while SUHI intensity was analyzed using the MFOZs method. The LULC revealed the change in urban built-up class was 56.87% over the last 24 years. It was observed that a high population density zone has more urban heat island intensity. The peak average temperature difference during heatwave and non-heatwave was 5.15°C. During heatwaves, the difference in peak surface temperature was 14°C in the daytime and 6.74°C at night time.