Diurnal cycle of surface energy fluxes in high mountain terrain: High‐resolution fully coupled atmosphere‐hydrology modelling and impact of lateral flow

• Published in: Hydrological processes Vol. 35; no. 12
• Main Authors: Zhang, Zhenyu, Arnault, Joël, Laux, Patrick, Ma, Ning, Wei, Jianhui, Kunstmann, Harald
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-12-2021; Wiley Subscription Services, Inc
• Subjects: alpine area; Atmosphere; Atmospheric models; Catchment area; Climate models; complex terrain; Diurnal cycle; Diurnal variations; Energy; Enthalpy; feedback; Flow; fully coupled WRF‐Hydro model; Headwaters; Heat; Heat flux; Heat transfer; Heihe River; Hydrologic models; Hydrologic processes; Hydrology; Latent heat; Latent heat flux; lateral flow; Modelling; Mountainous areas; Mountains; Net radiation; Parameterization; Radiation; Radiation balance; Regional climate models; Regional climates; Resolution; Sensible heat; Sensible heat flux; Sensible heat transfer; Simulation; Soil moisture; Soil surfaces; Surface energy; surface energy fluxes; Surface properties; Surface water; Temporal resolution; Terrain; Vegetation; Weather forecasting
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.14454

Water and energy fluxes are inextricably interlinked within the interface of the land surface and the atmosphere. In the regional earth system models, the lower boundary parameterization of land surface neglects lateral hydrological processes, which may inadequately depict the surface water and energy fluxes variations, thus affecting the simulated atmospheric system through land‐atmosphere feedbacks. Therefore, the main objective of this study is to evaluate the hydrologically enhanced regional climate modelling in order to represent the diurnal cycle of surface energy fluxes in high spatial and temporal resolution. In this study, the Weather Research and Forecasting model (WRF) and coupled WRF Hydrological modelling system (WRF‐Hydro) are applied in a high alpine catchment in Northeastern Tibetan Plateau, the headwater area of the Heihe River. By evaluating and intercomparing model results by both models, the role of lateral flow processes on the surface energy fluxes dynamics is investigated. The model evaluations suggest that both WRF and coupled WRF‐Hydro reasonably represent the diurnal variations of the near‐surface meteorological fields, surface energy fluxes and hourly partitioning of available energy. By incorporating additional lateral flow processes, the coupled WRF‐Hydro simulates higher surface soil moisture over the mountainous area, resulting in increased latent heat flux and decreased sensible heat flux of around 20–50 W/m2 in their diurnal peak values during summertime, although the net radiation and ground heat fluxes remain almost unchanged. The simulation results show that the diurnal cycle of surface energy fluxes follows the local terrain and vegetation features. This highlights the importance of consideration of lateral flow processes over areas with heterogeneous terrain and land surfaces.
High‐resolution fully coupled atmospheric‐hydrological modelling is performed over a high‐alpine headwater catchment area.
Even in extreme climate gradient, the fully coupled model shows the ability in reproducing surface energy fluxes at a diurnal scale.
Lateral flow processes particularly impact the turbulent fluxes (H and LE), which shows the importance of consideration of lateral fluxes in highly heterogeneous terrain and land surface.