TY  - JOUR
A1  - Zhang, Lijie
A1  - Poll, Stefan
A1  - Kollet, Stefan
T1  - Large‐eddy simulation of soil moisture heterogeneity‐induced secondary circulation with ambient winds
Y1  - 2023-01-03
VL  - 149
IS  - 751
SP  - 404
EP  - 420
JF  - Quarterly Journal of the Royal Meteorological Society
DO  - 10.1002/qj.4413
PB  - John Wiley & Sons
CY  - Ltd.
N2  - Land surface heterogeneity in conjunction with ambient winds influences the convective atmospheric boundary layer by affecting the distribution of incoming solar radiation and forming secondary circulations. This study performed coupled large‐eddy simulation (ICON‐LEM) with a land surface model (TERRA‐ML) over a flat river corridor mimicked by soil moisture heterogeneity to investigate the impact of ambient winds on secondary circulations. The coupled model employed double‐periodic boundary conditions with a spatial scale of 4.8 km. All simulations used the same idealized initial atmospheric conditions with constant incident radiation of 700 W⋅m<sup>−2</sup> and various ambient winds with different speeds (0 to 16 m⋅s<sup>−1</sup>) and directions (e.g., cross‐river, parallel‐river, and mixed). The atmospheric states are decomposed into ensemble‐averaged, mesoscale, and turbulence. The results show that the secondary circulation structure persists under the parallel‐river wind conditions independently of the wind speed but is destroyed when the cross‐river wind is stronger than 2 m⋅s<sup>−1</sup>. The soil moisture and wind speed determine the influence on the surface energy distribution independent of the wind direction. However, secondary circulations increase advection and dispersive heat flux while decreasing turbulent energy flux. The vertical profiles of the wind variance reflect the secondary circulation, and the maximum value of the mesoscale vertical wind variance indicates the secondary circulation strength. The secondary circulation strength positively scales with the Bowen ratio, stability parameter (−Z<sub>i</sub>/L), and thermal heterogeneity parameter under cross‐river wind and mixed wind conditions. The proposed similarity analyses and scaling approach provide a new quantitative perspective on the impact of the ambient wind under heteronomous soil moisture conditions on secondary circulation.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/11519
ER  -