Multi-temporal trajectory of the urban heat island centroid in Beijing, China based on a Gaussian volume model

Abstract

The trajectory of the urban heat island (UHI) centroid in three dimensions indicates the overall variation of the intensity and distribution of the UHI. This study applied the Gaussian volume model on the daily MODIS/LST products from 2000 to 2012 to derive the UHI centroid in Beijing on a multi-temporal scale. The trajectories indicated that (1) on a diurnal scale during July–September, the daytime and nighttime centroids of the UHI were primarily located in the Xicheng district near the city center, and the mean intensity was from 2.12 to 2.97 °C. The daytime centroid was in the south of the nighttime centroid and demonstrated a higher intensity and a larger core area, where Aqua obtains a higher intensity than Terra. The movement of the UHI centroid was also more significant in the north–south direction than in the east–west direction; (2) on a monthly scale, the daytime centroid moved from the northeast to the southwest by (1.85, 2.91) km from July to September, and the intensity varied from 2.16 °C (September) to 3.09 °C (August), while the nighttime centroid generally moved anticlockwise from January to December, and the intensity varied from 1.98 °C (July) to 3.07 °C (January); and (3) on an annual scale, the daytime UHI centroid in August and the nighttime UHI centroid moved toward the northeast by (2.15, 1.31) km and (0.43, 0.89) km, respectively. There was a dramatic change in the UHI prior to 2008, which was most likely caused by the numerous preparation projects for the 2008 Beijing Olympic Games. Correlation analysis demonstrated that the hot and medium-hot landscapes exhibited positive contributions to the variation of the horizontal location of UHI centroid, and NDVI and albedo showed positive contributions to the variations of daytime (less than 10%) and nighttime (close to 50%) UHI centroids, respectively. Also, we discussed the relationship between Z-dimension of UHI centroid and other UHI indicators, and the impact of missing data. This study presents scientific insights for urban planning and management in Beijing and motivates the investigation of comprehensive changes in UHI of other metropolises worldwide.

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