Response of Convective Boundary Layer and Shallow Cumulus to Soil Moisture Heterogeneity: A Large‐Eddy Simulation Study

Han, Cunbo; Brdar, Slavko; Kollet, Stefan

doi:10.1029/2019ms001772

Cited by 9 publications

(10 citation statements)

References 57 publications

(97 reference statements)

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“…Studies have shown that surface heterogeneities influence the vertical profile of atmospheric states, which is more pronounced under a well‐formed SC condition. (Hadfield et al ., 1992; Patton et al ., 2005; Huang and Margulis, 2009; Han et al ., 2019a). We decompose the wind into three parts based on Equation to study the impact of ambient winds in conjunction with surface heterogeneity on the CBL.…”

Section: Resultsmentioning

confidence: 99%

Large‐eddy simulation of soil moisture heterogeneity‐induced secondary circulation with ambient winds

Zhang

Poll

Kollet

2023

Quart J Royal Meteoro Soc

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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−2 and various ambient winds with different speeds (0 to 16 m⋅s−1) 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−1. 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 (−Zi/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.

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Section: Resultsmentioning

confidence: 99%

Large‐eddy simulation of soil moisture heterogeneity‐induced secondary circulation with ambient winds

Zhang

Poll

Kollet

2023

Quart J Royal Meteoro Soc

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“…Although the scale range of mesoscale surface heterogeneity is a rough estimation based only on the two time scales τ ∗ and τ e , the findings of multiple studies (e.g., Han et al., 2019; Patton et al., 2005; Taylor et al., 2012, 2011) have supported this scale range for mesoscale surface heterogeneity that significantly influences on the CBL and, further, moist convection. For example, Patton et al.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Han et al. (2019) reported that the horizontal flow generated by soil moisture heterogeneity at the scale of approximately 20 km is the strongest based on their LES results with river‐like soil moisture patterns across a range of approximately 1–100 km.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, Taylor et al (2012) observed preferential afternoon precipitation over locally drier soil on scales of 50-100 km compared to surrounding areas, particularly in semiarid regions. Recently, Han et al (2019) reported that the horizontal flow generated by soil moisture heterogeneity at the scale of approximately 20 km is the strongest based on their LES results with river-like soil moisture patterns across a range of approximately 1-100 km.…”

mentioning

confidence: 99%

“…Although the scale range of mesoscale surface heterogeneity is a rough estimation based only on the two time scales τ * and τ e , the findings of multiple studies (e.g., Han et al, 2019;Patton et al, 2005;Taylor et al, 2012Taylor et al, , 2011 have supported this scale range for mesoscale surface heterogeneity that significantly influences on the CBL and, further, moist convection. For example, Patton et al (2005) suggested that the strongest CBL response occurs with surface heat flux heterogeneity at the scale of approximately 5-15 km, based on the results from a large eddy simulation (LES) coupled to a land surface model.…”

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confidence: 99%

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Response of Moist Convection to the Spectral Feature of the Surface Flux Field at Model Resolution Across the Gray Zone

Ryu

Kang

2022

JGR Atmospheres

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The Weather Research and Forecasting model is run at the effective resolution Δf across the gray zone, or the “terra incognita”, at which Δf ∼ l, where l is the scale of energy‐containing turbulent eddies. We examine the developments of afternoon moist convection over different multiscale features of the surface flux field as a function of the model grid spacing Δ that varies from 100 m to 1 km. Numerical experiments demonstrate that the model performs better under heterogeneous than homogeneous surface conditions in the gray zone in terms of the spatial distribution of moist convection. This improved performance is due to the explicit resolvability of the mesoscale temperature and humidity perturbations, which are critical for the growth of deep moist convection over the heterogeneous surface condition. However, under both heterogeneous and homogeneous surface conditions, the timing and intensity of moist convection vary with the model resolution. Compared with that in the large eddy simulation at Δ = 100 m, the earlier onset of moist convection at coarser resolutions appears to be related to the overestimated total buoyancy fluxes and total kinetic energy near the surface. That is, the more intense vertical mixing near the surface might induce a warmer surface layer, which yields individual cell updrafts strong enough to penetrate the capping inversion. In addition, misrepresentation of the diluting effects of entrainment on the penetrating updrafts in coarser‐resolution simulations could be responsible for the rapid development of deep convection instead of a gradual transition from shallow to deep moist convection.

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Orographic Rainfall Mechanism During MJO Over Sumatra Island

Satiadi,

Purwaningsih,

Harjupa

et al. 2024

Springer Proceedings in Physics

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Response of Convective Boundary Layer and Shallow Cumulus to Soil Moisture Heterogeneity: A Large‐Eddy Simulation Study

Cited by 9 publications

References 57 publications

Large‐eddy simulation of soil moisture heterogeneity‐induced secondary circulation with ambient winds

Large‐eddy simulation of soil moisture heterogeneity‐induced secondary circulation with ambient winds

Response of Moist Convection to the Spectral Feature of the Surface Flux Field at Model Resolution Across the Gray Zone

Orographic Rainfall Mechanism During MJO Over Sumatra Island

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