The effect of soil moisture and atmospheric conditions on the development of shallow cumulus convection: A coupled large-eddy simulation–land surface model study

Chlond, Andreas; Boehringer, Otto; Auerswald, Torsten; Mueller, Frank

doi:10.1127/metz/2014/0576

Cited by 6 publications

(5 citation statements)

References 52 publications

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“…Modelling studies (e.g. Ek and Holtslag, 2004;Haiden, 2007;Huang and Margulis, 2011;Chlond et al, 2014;Bhowmick and Parker, 2018) suggest that the influence of soil moisture on shallow cloud development depends heavily on thermal stability conditions and vertically integrated atmospheric moisture content. Unfortunately, we do not have the necessary vertical information to assess the atmospheric stability conditions on the day of the flight.…”

Section: Discussionmentioning

confidence: 99%

A case‐study of land–atmosphere coupling during monsoon onset in northern India

Barton

Taylor

Parker

et al. 2019

Quart J Royal Meteoro Soc

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This article presents a land–atmosphere case‐study for a single day during monsoon onset, incorporating data from a research aircraft, satellite products and model outputs. The unique aircraft observations reveal temperature and humidity contrasts of up to 5 K and 4 g/kg in the planetary boundary layer induced by spatial variations in soil moisture. Both antecedent rain and irrigation were found to be drivers of this atmospheric variability. There is also evidence of soil moisture‐induced mesoscale circulations above some surfaces. This is the first time such responses have been observed in situ over India. Soil moisture‐driven temperature anomalies are larger than those found in previous observational studies in the African Sahel. Moreover, irrigation in the region is extensive, unlike in the Sahel, and has a similar atmospheric effect to antecedent rainfall. This implies that historical changes in irrigation practices are likely to have had an important influence on mesoscale processes within the Indian monsoon. We also examine evidence linking soil moisture and cloud formation. Above wetter soils we observed a suppression of shallow cloud, whilst the initiation of deep convection occurred mostly in areas affected by wet–dry soil moisture boundaries. To investigate the impact of soil moisture heterogeneity on large‐scale wind flow, three model depictions of the day are assessed: the European Centre for Medium‐Range Weather Forecasts ERA‐Interim and ERA5 reanalyses, and a high‐resolution (1.5 km) simulation generated using the Indian National Centre for Medium Range Weather Forecasting regional convection‐permitting Unified Model. We find evidence indicating surface flux uncertainties in the models lead to ∼3.5 hPa anomalies in the monsoon trough. This does affect the simulation of monsoon circulation and rainfall. Better representation of mesoscale land–atmosphere coupling is likely to improve the depiction of convection within weather and climate models over India.

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Section: Discussionmentioning

confidence: 99%

A case‐study of land–atmosphere coupling during monsoon onset in northern India

Barton

Taylor

Parker

et al. 2019

Quart J Royal Meteoro Soc

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“…Surface soil moisture heterogeneity on scales of tens of kilometers is reported to be important for rainfall initiation (Taylor et al, ) and afternoon rainfall can be favored over regions dryer than surrounding areas (Guillod et al, ). Cloud cover, not always associated with precipitation, can be higher over either wetter or dryer soils depending on the moisture content and stability of the overlying free atmosphere (Chlond et al, ; Huang & Margulis, ). Soil moisture can also interact with near‐surface temperature.…”

Section: Introductionmentioning

confidence: 99%

Global Effects of Superparameterization on Hydrothermal Land‐Atmosphere Coupling on Multiple Timescales

Qin

Pritchard

Kooperman

et al. 2018

J Adv Model Earth Syst

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Many conventional General Circulation Models (GCMs) in the Global Land‐Atmosphere Coupling Experiment (GLACE) tend to produce what is now recognized as overly strong land‐atmosphere (L‐A) coupling. We investigate the effects of cloud Superparameterization (SP) on L‐A coupling on timescales beyond diurnal where it has been recently shown to have a favorable muting effect hydrologically. Using the Community Atmosphere Model v3.5 (CAM3.5) and its Superparameterized counterpart SPCAM3.5, we conducted soil moisture interference experiments following the GLACE and Atmospheric Model Intercomparison Project (AMIP) protocols. The results show that, on weekly‐to‐subseasonal timescales, SP also mutes hydrologic L‐A coupling. This is detectable globally, and happens through the evapotranspiration‐precipitation segment. But on seasonal timescales, SP does not exhibit detectable effects on hydrologic L‐A coupling. Two robust regional effects of SP on thermal L‐A coupling have also been explored. Over the Arabian Peninsula, SP reduces thermal L‐A coupling through a straightforward control by mean rainfall reduction. More counterintuitively, over the Southwestern US and Northern Mexico, SP enhances the thermal L‐A coupling in a way that is independent of rainfall and soil moisture. This signal is associated with a systematic and previously unrecognized effect of SP that produces an amplified Bowen ratio, and is detectable in multiple SP model versions and experiment designs. In addition to amplifying the present‐day Bowen ratio, SP is found to amplify the climate sensitivity of Bowen ratio as well, which likely plays a role in influencing climate change predictions at the L‐A interface.

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“…Huang and Margulis () investigated the impact of soil moisture and atmospheric stability on cloud development using a coupled LES and LSM and found that cloud cover fraction increases with increasing soil moisture only in case of strong atmospheric stability, while the opposite has been observed in case of weak atmospheric stability. Chlond et al () investigated the effect of soil moisture on the development of shallow cumulus convection and found that soil moisture and cloud cover coupling are positive in most of the cases. Using a cloud resolving model with prescribed dry and wet patches in soil moisture, Chen and Avissar () found that land surface soil moisture affects the timing of onset of clouds and the intensity and distribution of precipitation.…”

Section: Introductionmentioning

confidence: 99%

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

Han

Brdar

Kollet

2019

J Adv Model Earth Syst

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In this study, the impact of varying soil moisture heterogeneity (spatial variance and structure) on the development of the convective boundary layer and shallow cumulus clouds was investigated. Applying soil moisture heterogeneity generated via spatially correlated Gaussian random fields based on a power law model and idealized atmospheric vertical profiles as initial conditions, three sets of large-eddy simulations provide insight in the influence of soil moisture heterogeneity on the ensuing growth of the convective boundary layer and development of shallow cumulus clouds. A sensitivity on the strong, weak, and unstructured soil moisture heterogeneity is investigated. The simulation results show that domain-averaged land surface sensible heat and latent heat flux change strongly with changing soil moisture variance because of the interactions between surface heterogeneity and induced circulations, while domain means of soil moisture are identical. Vertical profiles of boundary layer characteristics are strongly influenced by the surface energy partitioning and induced circulations, especially the profiles of liquid water and liquid water flux. The amount of liquid water and liquid water flux increases with increasing structure. In addition, the liquid water path is higher in case of strongly-structured heterogeneity because more available energy is partitioned into latent heat and more intensive updrafts exist. Interestingly, the increase of liquid water path with increasing soil moisture variance only occurs in the strongly structured cases, which suggests that soil moisture variance and structure work conjunctively in the surface energy partitioning and the cloud formation.Plain Language Summary The land surface is heterogeneous with respect to, for example, land use, plant cover, soil moisture, and topography over a wide range of spatial scales, which strongly influences the atmospheric boundary layer. In this study, the impact of soil moisture heterogeneity on the development of the convective boundary layer and shallow cumulus clouds was investigated. The results from a series of large-eddy simulations show that soil moisture heterogeneity impacts significantly on the surface energy partitioning, the convection boundary layer development and the cloud formation. Interestingly, the stronger soil moisture heterogeneity, the more available energy is partitioned into latent heat flux and the higher liquid water path in the atmosphere.

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The effect of soil moisture and atmospheric conditions on the development of shallow cumulus convection: A coupled large-eddy simulation–land surface model study

Cited by 6 publications

References 52 publications

A case‐study of land–atmosphere coupling during monsoon onset in northern India

A case‐study of land–atmosphere coupling during monsoon onset in northern India

Global Effects of Superparameterization on Hydrothermal Land‐Atmosphere Coupling on Multiple Timescales

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

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