Document Type : Original Article
Assistant Professor of Climatology, Geography and Urban Planning Department, University of Mazandaran, Babolsar
This research tries to investigate the nighttime land surface temperature (NLST) (22:30) in Tehran City and its suburbs by using MODIS satellite images from 2000 to 2021. In this regard, NLST characteristics in the urban and suburbs of Tehran were obtained through the MOD11A2 Version 6 product. These data provide an average 8-day per-pixel land surface temperature with a 1-kilometer spatial resolution in a 1200 by 1200 km grid. The NLST time series were obtained for the urban and suburbs, through which the nighttime surface urban heat island (NSUHI) time series were calculated. The results showed that the trend of NLST in the urban is completely different from suburbs. Although NLST shows a significant declining trend in the suburbs, it does not show any significant trend in the urban, Hence the further increase of NLST in the suburbs has caused the downward trend of NSUHI. The results of Mann-Kendall showed that the NSUHI time series had experienced a decreasing trend seasonally and annually, which is significant at the 99% confidence level. Although the earth has become warmer in recent years, the rate of warming in the urban and suburbs has not been the same, so NSUHI in Tehran has recorded a significant downward trend seasonally and annually.