Assessment of observed and model‐derived soil moisture‐evaporative fraction relationships over the United States Southern Great Plains

Ford, Trent W.; Wulff, Ole; Quiring, Steven M.

doi:10.1002/2014jd021490

Cited by 44 publications

(48 citation statements)

References 27 publications

(51 reference statements)

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“…Similar to Williams and Torn [], we found that increasing LAI tended to produce greater EF at the winter wheat site but that this effect saturated around 2.5 m 2 m −2 (Figure a). Additionally, consistent with Ford et al [], we found that the relationship between θ v and EF at the grassland/pasture site was only strong below ~0.28 m 3 m −3 LAI (e.g., Figure b). However, Ford et al [] also found that the relationship between soil moisture and EF was dependent on net radiation, with the EF‐soil moisture relationship weakening at low radiation levels.…”

Section: Discussionsupporting

confidence: 92%

“…Additionally, consistent with Ford et al [], we found that the relationship between θ v and EF at the grassland/pasture site was only strong below ~0.28 m 3 m −3 LAI (e.g., Figure b). However, Ford et al [] also found that the relationship between soil moisture and EF was dependent on net radiation, with the EF‐soil moisture relationship weakening at low radiation levels. Net radiation was not found to be an important variable in our analysis.…”

Section: Discussionsupporting

confidence: 92%

“…However, observation‐based studies of the relationship between soil moisture and surface energy and water fluxes do not corroborate this result; they suggest a weak influence of the land surface on the atmosphere in the SGP [ Ferguson and Wood , ; Phillips and Klein , ]. At the same time, recent research found that land‐atmosphere coupling in the SGP is controlled by factors beyond soil moisture and highlighted atmospheric factors such as wet versus dry conditions [ Santanello et al , ] and daily net radiation [ Ford et al , ]. Also, Williams and Torn [] and Puma et al [] shifted the focus from soil moisture to the influence of vegetation, showing that surface energy partitioning is more strongly controlled by the state of vegetation, as represented by leaf area index (LAI), than by soil moisture.…”

Section: Introductionmentioning

confidence: 99%

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The influence of land cover on surface energy partitioning and evaporative fraction regimes in the U.S. Southern Great Plains

et al. 2017

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Land‐atmosphere interactions are important to climate prediction, but the underlying effects of surface forcing of the atmosphere are not well understood. In the U.S. Southern Great Plains, grassland/pasture and winter wheat are the dominant land covers but have distinct growing periods that may differently influence land‐atmosphere coupling during spring and summer. Variables that influence surface flux partitioning can change seasonally, depending on the state of local vegetation. Here we use surface observations from multiple sites in the U.S. Department of Energy Atmospheric Radiation Measurement Southern Great Plains Climate Research Facility and statistical modeling at a paired grassland/agricultural site within this facility to quantify land cover influence on surface energy balance and variables controlling evaporative fraction (latent heat flux normalized by the sum of sensible and latent heat fluxes). We demonstrate that the radiative balance and evaporative fraction are closely related to green leaf area at both winter wheat and grassland/pasture sites and that the early summer harvest of winter wheat abruptly shifts the relationship between evaporative fraction and surface state variables. Prior to harvest, evaporative fraction of winter wheat is strongly influenced by leaf area and soil‐atmosphere temperature differences. After harvest, variations in soil moisture have a stronger effect on evaporative fraction. This is in contrast with grassland/pasture sites, where variation in green leaf area has a large influence on evaporative fraction throughout spring and summer, and changes in soil‐atmosphere temperature difference and soil moisture are of relatively minor importance.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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The influence of land cover on surface energy partitioning and evaporative fraction regimes in the U.S. Southern Great Plains

et al. 2017

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“…Concurrently, limited surface radiation (e.g., Figure c) reduces sensible heating, thereby inhibiting the land surface's ability to modify the atmosphere through latent and sensible heat fluxes. These conditions are similar to the “energy‐limited” evaporative regime, in which incoming solar radiation, not soil moisture, determines variations in surface evaporative fraction [ Ford et al ., ]. Examples of morning (06:00 LST) and afternoon (12:00 LST) atmospheric profiles from 22 June 2004 over Lamont, Oklahoma, demonstrate such conditions (Figure ).…”

Section: Resultsmentioning

confidence: 99%

Synoptic conditions related to soil moisture‐atmosphere interactions and unorganized convection in Oklahoma

et al. 2015

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Atmospheric modification by anomalously dry or wet soils can both enhance and suppress convective activity. However, the local‐scale and mesoscale feedback governing soil moisture‐precipitation coupling are embedded within the larger synoptic‐scale environment. Despite their importance, synoptic‐scale atmospheric conditions are rarely considered in studies examining soil moisture‐atmosphere interactions. We combine self‐organizing maps of 500 hPa geopotential height, spatial synoptic classification, and Hybrid Single‐Particle Lagrangian Integrated Trajectory model air mass trajectories to determine if the synoptic‐scale environment affects the ability of the land surface to force unorganized convection in Oklahoma. We identify several synoptic patterns that significantly impact the frequency of unorganized convection. Synoptic patterns characterized by midlevel troughs over the Southern Great Plains are less frequently associated with unorganized convective events. These patterns exhibit cool air advection in the midlevel and lower level of the atmosphere and are linked to suppression of convective activity. The synoptic patterns characterized by 500 hPa ridging over the study region are more frequently associated with unorganized convective events. These patterns likely result in increased net radiation, vapor pressure deficit, and more homogenously dry soils. Unorganized convective events that occur during these synoptic conditions initiate preferentially over dry soils. We present evidence that the synoptic‐scale environment can influence whether and how the land surface has an impact on convection.

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“…That is, the sign and magnitude of land–atmosphere interactions are believed to be relatively stable over time. However, the mechanisms through which soil moisture influence air temperature are not static, but vary on diurnal (Gentine et al , ), seasonal (Guo et al , ), inter‐annual (Ford et al , ), and inter‐decadal (Sheffield and Wood, ) timescales. For example, soil moisture heterogeneity across tens‐to‐hundreds of kilometres can modify synoptic conditions on diurnal time scales leading to the generation of mesoscale convective systems (Frye Mote, ; Taylor et al , ).…”

Section: Introductionmentioning

confidence: 99%

Multi‐decadal variability of soil moisture–temperature coupling over the contiguous United States modulated by Pacific and Atlantic sea surface temperatures

Ford

Quiring

Frauenfeld

2016

Intl Journal of Climatology

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Regions of strong land–atmosphere coupling are often depicted as static in time. However, the mechanisms through which the land surface impacts atmospheric conditions vary on sub‐daily to multi‐decadal timescales. Therefore, characterizing the long‐term variability of land–atmosphere interactions may provide a means of predicting when surface‐induced extreme temperature events will be more or less likely to occur. We evaluate the coupling strength between soil moisture, as represented by in situ observations and 1‐month Standardized Precipitation Index (SPI), and subsequent monthly maximum temperature (TMAX) over the contiguous United States. We find that the utility of SPI as a proxy for soil moisture anomalies is limited to the summer, as the correlations between SPI and TMAX are not significantly related in the other seasons. We examine the variability in summer SPI–TMAX coupling in four regions of the United States. In general, we find the strongest relationships between SPI and TMAX in the Southern Great Plains. However, our results demonstrate that the coupling strength varies considerably over time in most regions of the United States. The long‐term variability in SPI–TMAX coupling strength is strongly related to the Pacific Decadal Oscillation in the northwest and midwest United States, and the Atlantic Multidecadal Oscillation in the southeast United States The results of this study suggest that land–atmosphere coupling in the contiguous United States is modulated by multi‐decadal oscillations in Pacific and Atlantic sea surface temperatures.

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Assessment of observed and model‐derived soil moisture‐evaporative fraction relationships over the United States Southern Great Plains

Cited by 44 publications

References 27 publications

The influence of land cover on surface energy partitioning and evaporative fraction regimes in the U.S. Southern Great Plains

The influence of land cover on surface energy partitioning and evaporative fraction regimes in the U.S. Southern Great Plains

Synoptic conditions related to soil moisture‐atmosphere interactions and unorganized convection in Oklahoma

Multi‐decadal variability of soil moisture–temperature coupling over the contiguous United States modulated by Pacific and Atlantic sea surface temperatures

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