Evaluation of Soil Moisture Effects on the Generation and Modification of Mesoscale Circulations

Ookouchi, Yasumasa; Segal, M.; Kessler, R.C.; Pielke, R. A.

doi:10.1175/1520-0493(1984)112<2281:eosmeo>2.0.co;2

Cited by 222 publications

(115 citation statements)

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“…Conversely, there was a tendency for local maxima in along-track wind to occur close to where the aircraft flew from a wet to a dry surface. Thus zones of horizontal divergence were located approximately over the wet patches, consistent with earlier studies [e.g., Ookouchi et al, 1984]. A further divergent flow was identified over the cool, well-vegetated patch (14.6 -14.9°N) within the dry soil region.…”

Section: Variability At the Surface And In The Planetary Boundary Layersupporting

confidence: 89%

“…[2] The impact on the planetary boundary layer (PBL) of mesoscale variations in surface properties such as vegetation cover and soil moisture has been a subject of research for over two decades [e.g., Ookouchi et al, 1984;Mahfouf et al, 1987]. There have been many modelling studies which have shown that surface heterogeneity can generate sea-breeze-like circulations (see a summary by Segal and Arritt [1992] of such Non-classical Mesoscale Circulations, or NCMCs).…”

Section: Introductionmentioning

confidence: 99%

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An observational case study of mesoscale atmospheric circulations induced by soil moisture

Taylor

Parker

Harris

2007

Geophysical Research Letters

164

167

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[1] Numerical and theoretical studies have shown that mesoscale gradients in land surface properties can induce circulations in the atmosphere. This study provides the first well-resolved observations of such flows induced by soil moisture from recent rainfall, and is based on aircraft data in the Sahel. Satellite imagery was used to identify fine scale soil moisture features within a wet zone spanning 160 km. Above the wet soil, the planetary boundary layer was up to 3 K cooler, 3 gkg À1 moister and extended to only half the depth of nearby drier areas. Mesoscale perturbations to the background flow were found, consistent with low level divergence over wet soil and convergence in drier areas. The soil moisture and atmospheric wind patterns were statistically coherent on wavelengths down to 20 km. These results suggest that mesoscale convergence lines forced by soil moisture may play a significant role in the meteorology of the Sahel. Citation: Taylor, C. M., D. J. Parker, and P. P.Harris (2007), An observational case study of mesoscale atmospheric circulations induced by soil moisture, Geophys.

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Section: Variability At the Surface And In The Planetary Boundary Layersupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

An observational case study of mesoscale atmospheric circulations induced by soil moisture

Taylor

Parker

Harris

2007

Geophysical Research Letters

164

167

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“…The altered u Ã in 33L, compared to 31L, modified the surface wind convergence and local convection forcing, a feature that is consistent with the findings in Colle and Yuter (2007). Consequently, areas of convection further differed between the two simulations due to the convection processes, and could be affected by model-generated thermal circulations due to sensible heat flux gradients induced by cloud shading and soil wetness contrasts (e.g., Ookouchi et al 1984;Segal et al 1986). …”

Section: April 2009 a L I G O E T A Lsupporting

confidence: 71%

On the Impact of WRF Model Vertical Grid Resolution on Midwest Summer Rainfall Forecasts

Aligo

Gallus

Segal

2009

Weather and Forecasting

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Weather Research and Forecast (WRF) model exploratory sensitivity simulations were performed to determine the impact of vertical grid resolution (VGR) on the forecast skill of Midwest summer rainfall. Varying the VGR indicated that a refined VGR, while adopting the widely used North America Regional Reanalysis (NARR) for initial and lateral boundary conditions, does not necessarily result in a consistent improvement in quantitative precipitation forecasts (QPFs). When averaged over a variety of microphysical schemes in an illustrative case, equitable threat score (ETS) and bias values actually worsened with a greater overpredicted rainfall for half of the rainfall thresholds when the VGR was refined. Averaged over strongly forced cases, ETS values worsened for all rainfall thresholds while biases mostly increased, indicating a further overprediction of rainfall when the number of levels was increased. Skill improved, however, for all rainfall thresholds when the resolution above the melting level was increased. Skill also improved for most rainfall thresholds when the resolution in the surface layer was increased, which is attributed to better-resolved surface turbulent momentum and thermal fluxes. Likewise, a refined VGR resulted in improvements in weakly forced cases, which are governed mostly by thermodynamic forcing and are sensitive to vertical profiles of temperature and moisture. Application of the factor separation method suggested that the refined VGR more frequently had a negative impact on skill through the interaction between lower-atmospheric processes and microphysical processes above the melting level. KeywordsAgronomy, atmospheric process, equitable threat score, illustrative case, lateral boundary conditions, melting levels, microphysical process, negative impacts, quantitative precipitation forecast, reanalysis, sensitivity simulation, summer rainfall, surface layers, thermal fluxes, turbulent momentum, vertical grids, WRF model, atmospheric thermodynamics, climate prediction, rainfall, weather forecasting Varying the VGR indicated that a refined VGR, while adopting the widely used North America Regional Reanalysis (NARR) for initial and lateral boundary conditions, does not necessarily result in a consistent improvement in quantitative precipitation forecasts (QPFs). When averaged over a variety of microphysical schemes in an illustrative case, equitable threat score (ETS) and bias values actually worsened with a greater overpredicted rainfall for half of the rainfall thresholds when the VGR was refined. Averaged over strongly forced cases, ETS values worsened for all rainfall thresholds while biases mostly increased, indicating a further overprediction of rainfall when the number of levels was increased. Skill improved, however, for all rainfall thresholds when the resolution above the melting level was increased. Skill also improved for most rainfall thresholds when the resolution in the surface layer was increased, which is attributed to better-resolved surface turbulent momentum ...

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“…Figure 4 summarizes the results of several numerical studies of l as a function of the time of day and the land-surface sensible heat flux. In these studies, high Anthes (1978), Physick (1980), Troen (1982), Ookouchi et al (1984), Segal et al (1988Segal et al ( , 1997, Yan and Anthes (1988), Sha et al (1991), Shen (1998), Tijm et al (1999b), Miao et al (2003), Marshall et al (2004), Antonelli andRotunno (2007) Porson et al (2007a), Kala et al (2010) Area of heated surface Magnitude of l, h, u, w increase with increasing scale of heated surface (up to order 50-100 km) Constructive and destructive interactions between SB and urban circulations. Distance to ocean and size of urban area important Neumann and Mahrer (1974), Mahrer and Segal (1985), Yan and Anthes (1988), Yoshikado (1990Yoshikado ( , 1992, Xian and Pielke (1991), Yang (1991), Ado (1992), Kusaka et al (2000), Kida (2002, 2004), Savijarvi and Matthews (2004), Lemonsu et al (2006), Courault et al (2007), Freitas et al (2007), Thompson et al (2007), Cheng and Byun (2008), Dandou et al (2009) Shoreline gradients in H l reduced due to gradients in H Schlunzen (1990) Water temperature SB relatively insensitive to changes in water temperature unless water temperature is high enough to induce boundary-layer convection or moderate V g exists …”

Section: Land-surface Sensible Heat Flux (H )mentioning

confidence: 99%

“…Spatial heterogeneities in the land-surface sensible heat flux associated with islands or strips of land with different soil moisture or vegetation type resulting in "inland breezes" are also applicable to understanding sea breezes for small water body dimensions (Ookouchi et al 1984;Segal et al 1988;Mahrt et al 1994;Courault et al 2007). The intensity of inland breeze circulations caused by the difference in land-surface sensible heat fluxes between two land-surface types is typically weaker than a sea breeze, in part due to the enhanced turbulent mixing on the "moist" land side compared to the negligible thermal plumes noted over water (Segal and Arritt 1992;Yan and Anthes 1988).…”

Section: Water Body Dimensions (D) and Shoreline Curvature (R )mentioning

confidence: 99%

Sea and Lake Breezes: A Review of Numerical Studies

Crosman

Horel

2010

Boundary-Layer Meteorol

267

225

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Numerical studies of sea and lake breezes are reviewed. The modelled dependence of sea-breeze and lake-breeze characteristics on the land surface sensible heat flux, ambient geostrophic wind, atmospheric stability and moisture, water body dimensions, terrain height and slope, Coriolis parameter, surface roughness length, and shoreline curvature is discussed. Consensus results on the influence of these geophysical variables on sea and lake breezes are synthesized as well as current gaps in our understanding. A brief history of numerical modelling, an overview of recent high-resolution simulations, and suggestions for future research related to sea and lake breezes are also presented. The results of this survey are intended to be a resource for numerical modelling, coastal air quality, and wind power studies.

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Evaluation of Soil Moisture Effects on the Generation and Modification of Mesoscale Circulations

Cited by 222 publications

References 0 publications

An observational case study of mesoscale atmospheric circulations induced by soil moisture

An observational case study of mesoscale atmospheric circulations induced by soil moisture

On the Impact of WRF Model Vertical Grid Resolution on Midwest Summer Rainfall Forecasts

Sea and Lake Breezes: A Review of Numerical Studies

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