Evaluation of the intensity of urban heat islands during heat waves using local climate zones in the semi-arid, continental climate of Tehran

Increasing land surface temperature (LST) and urban heat island intensity (UHII) have been reported to be closely associated with a large number of environmental issues. Understanding LST and UHII rise in cities during heatwaves is crucial for implementing mitigation measures. This paper aims to explain these variations in response to LST and UHII during a heat wave in the metropolis of Tehran in Iran. 13 heat waves were selected and evaluated during the years 2000 to 2020. The average LST was 3.34 degrees C higher at the same time as the heat wave event compared to the period without the wave. Despite the increase in LST during the heat wave occurrence, UHII experienced lower values compared to the time without the wave. The outputs in this regard show that the average UHII value for the period without a heat wave is 5.11 degrees C, while during the heat wave, its rate is 3.62 degrees C. The maximum intensity of the heat island for both periods before and at the same time as the heat wave is related to man-made compact midrise buildings and heavy industry. Extra-local factors during heat waves can lead to diminish land use diversity and vegetation density's effectiveness in reducing UHII.