Downscaling Satellites Land Surface Temperature over Urban Environments

With growing number of world's population living in urban areas, the rapid urban expansion has become a major source for local environmental consequences with implications in human health and safety such as heat stress. Urban areas consist of surfaces with distinct thermal, physical and hydrological properties. The urban heat island (UHI) with significant energy, health, and societal impact is among the major environmental issues in urban regions. High spatio-temporal land surface temperatures are essential to study UHI and heat storage in the cities. Here, we develop a multi-sensor LST data with 5-min temporal and 30m spatial resolution by downscaling the Geostationary Operational Environmental Satellites - R series (GOES-R) LST data to the resolution of LandSat observations (30m) over New York City. The linear regression model used to downscale GOES-R to Landsat 8 spatial resolution every 5 minutes accounted the systematic differences between the two satellites by removing the average of Landsat 8 temperature from GOES-R LST observations. Downscaling LST for different surfaces especially in urban areas has temperature dependency and observations from different time of the day with fine spatial resolution are required to overcome this issue. For the validation, the results were compared with the ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) LST with varying acquisition time that is appropriate to evaluate the capability of proposed downscaling method to account for diurnal variability. In addition, we use using a series of high-resolution infrared cameras and Unmanned Aerial Vehicles (UAV) infrared equipment to evaluate predicted temperatures and define the diurnal variability LST over each urban surface type. Results revealed that the proposed model is able to reasonably estimate LST in urban regions. The results and methods of this study based on satellite observations could be applicable in any urban area in the world.