Analyzing the Diurnal Cycle of Urban Land Surface Temperature using Satellite Remote Sensing and in-situ Application

Urbanization plays a big role in the modification of surfaces and atmospheric temperature. These city areas are densely populated and plastered with conventional urban materials and less vegetation and moisture. As a result, built-up areas typically capture more of the sun’s energy which contributes to the heat island effect. The heat capacity of urban land surfaces is much higher compared to vegetated land covers. This study examines and compares the results of urban land surface temperature obtained from ground-based data and a diversity of remote sensing platforms including satellites and Unmanned Aerial Vehicles (UAVs). The diurnal variation of each surface is evaluated in this project to understand its effects on heat transfer in urban environments. Land surface temperature of various surfaces in New York is measured with a series of hand held thermal infrared cameras and one Unmanned Aerial Vehicle (UAV) infrared camera. It also provides a thorough analysis of the ground observations of different land surfaces by using a flux tower that collects measurements of all surface energy balance components for the first time in urban regions. The flux tower was deployed on materials such as concrete, asphalt and rooftops to take the measurements through eddy covariance method. Additionally, the satellite observations from NOAA's latest generation of Geostationary Operational Environmental Satellites (GOES), known as the GOES-R Series, Landsat, and the Moderate Resolution Imaging Spectroradiometer (MODIS) LST products were compared to the precise locations of the ground-based data collected from the thermal cameras. Daily observations and diurnal measurements were obtained on each surface and the differences in the response of each surface type to energy balance were studied. Distinct behavior of temperature variations over major urban surfaces was found. Asphalt surfaces showed the highest temperatures with high diurnal amplitude. The urban land surface variations were taken seasonally and the results were studied. The analysis of the measured data also revealed how much vegetated area can help in lowering the average temperature in developed urban regions. The results of this study can provide a valuable source of information in developing a heat stress product for cities when high resolution LST data from different surfaces are used to predict their corresponding air temperature. Moreover, the results of this study will shed some light in understanding of energy storage in urban regions by providing a valuable boundary condition information at the surface for urban canopy models.