Urban storage heat flux variability explored using satellite, meteorological and geodata

The storage heat flux (Delta Q(S)) is the net flow of heat stored within a volume that may include the air, trees, buildings and ground. Given the difficulty of measurement of this important and large flux in urban areas, we explore the use of Earth Observation (EO) data. EO surface temperatures are used with ground-based meteorological forcing, urban morphology, land cover and land use information to estimate spatial variations of Delta Q(S) in urban areas using the Element Surface Temperature Method (ESTM). First, we evaluate ESTM for four "simpler" surfaces. These have good agreement with observed values. ESTM coupled to SUEWS (an urban land surface model) is applied to three European cities (Basel, Heraklion, London), allowing EO data to enhance the exploration of the spatial variability in Delta Q(S). The impervious surfaces (paved and buildings) contribute most to Delta Q(S). Building wall area seems to explain variation of Delta Q(S) most consistently. As the paved fraction increases up to 0.4, there is a clear increase in Delta Q(S). With a larger paved fraction, the fraction of buildings and wall area is lower which reduces the high values of Delta Q(S).