Spatiotemporal variation of heat fluxes in Beijing with land use change from 1997 to 2017

Abstract

It is meaningful to explore the influence of land use change on urban thermal environment for urban sustainable development and city livability improvement etc. Based on one pixel component arranging comparing algorithm (PCACA), this study estimates three instantaneous heat fluxes of Beijing city from meteorological data and the NDVI, land surface temperature (LST), and albedo products retrieved from Landsat data on September 21, 1997, September 22, 2009 and September 28, 2017. Then the temporal and spatial variation in the heat fluxes of the Beijing with land use change is discussed. The following key points have been found: 1) LST and heat fluxes have distinctly spatial heterogeneity, and significant differences between mountainous and plain areas, and among different land use types in plain area; 2) both LST and heat fluxes have a consistent order of arrangement for different land use types at different times. Forest has the highest latent heat flux (LHF) with an average of 265.7 W/m2, followed by cropland and grassland, and building land has the smallest average of 158.4 W/m2. LST has the reverse order, cropland has the highest average of 24.8 °C, followed by grassland and cropland, water body has the lowest average of 19.2 °C; 3) temporally, urban thermal fluxes vary greatly with land use transition. LHF and sensible heat flux (SHF) will respectively drastically reduce and increase when natural surface changes into building land. These analyses suggest that green spaces play an important role in easing urban heat environment.