Abstract/Summary

The Surface Urban Energy and Water balance Scheme (SUEWS) is used to investigate the impact of anthropogenic heat flux (QF) and irrigation on surface energy balance partitioning in a central business district of Shanghai. Diurnal profiles of QF are carefully derived based on city-specific hourly electricity consumption data, hourly traffic data and dynamic population density. QF is estimated to be largest in summer (mean daily peak 236 W m-2). When QF is omitted, the SUEWS sensible heat flux (QH) reproduces the observed diurnal pattern generally well, but the magnitude is underestimated compared to observations for all seasons. When QF is included, the QH estimates are improved in spring, summer and autumn, but poorer in winter indicating winter QF is overestimated. Inclusion of QF has little influence on the simulated latent heat flux (QE), but improves the storage heat flux estimates except in winter. Irrigation, both amount and frequency, has a large impact on QE. When irrigation is not considered, the simulated QE is underestimated for all seasons. The mean summer daytime QE is largely overestimated compared to observations under continuous irrigation conditions. Model results are improved when irrigation occurs with a 3-day frequency, especially in summer. Results are consistent with observed monthly out-door water use. This study highlights the importance of appropriately including the QF and irrigation in urban land surface models - terms not generally considered in many previous studies.