Evaluation of the Surface Urban Energy and Water Balance Scheme (SUEWS) at a Dense Urban Site in Shanghai: Sensitivity to Anthropogenic Heat and Irrigation

The Surface Urban Energy and Water balance Scheme (SUEWS) is used to investigate the impact of anthropogenic heat flux (Q_F) and irrigation on surface energy balance partitioning in a central business district of Shanghai. Diurnal profiles of Q_F are carefully derived based on city-specific hourly electricity consumption data, hourly traffic data and dynamic population density. Q_F is estimated to be largest in summer (mean daily peak 236 W m^-2). When Q_F is omitted, the SUEWS sensible heat flux (Q_H) reproduces the observed diurnal pattern generally well, but the magnitude is underestimated compared to observations for all seasons. When Q_F is included, the Q_H estimates are improved in spring, summer and autumn, but poorer in winter indicating winter Q_F is overestimated. Inclusion of Q_F has little influence on the simulated latent heat flux (Q_E), but improves the storage heat flux estimates except in winter. Irrigation, both amount and frequency, has a large impact on Q_E. When irrigation is not considered, the simulated Q_E is underestimated for all seasons. The mean summer daytime Q_E 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 Q_F and irrigation in urban land surface models - terms not generally considered in many previous studies.