On the discrepancy between eddy covariance and lysimetry-based surface flux measurements under strongly advective conditions

Alfieri, Joseph G.; Kustas, William P.; Prueger, John H.; Hipps, L. E.; Evett, Steven R.; Basara, Jeffrey B.; Neale, Christopher M. U.; French, Andrew N.; Colaizzi, Paul D.; Agam, Nurit; Cosh, Michael H.; Chávez, José L.; Howell, Terry A.

doi:10.1016/j.advwatres.2012.07.008

Cited by 91 publications

(75 citation statements)

References 80 publications

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“…Alfieri et al [30] noted that the EC flux measurements of H and LE had incomplete energy balance closure with respect to Fig. 2.…”

Section: Energy Balance Closure For Ec Flux Measurementsmentioning

confidence: 99%

“…The impact of this variation in LAI on model-measurement comparisons is discussed below. A detailed analysis of the impact of variability in vegetation cover on measured fluxes is presented by Alfieri et al [30].…”

Section: Datamentioning

confidence: 99%

“…A linear interpolation as a function of time based on growing degree days was used by Colaizzi et al [31] for estimating LAI, plant height and width between vegetation sampling dates. The LAI estimates for the lysimeters and areas surrounding the EC towers were estimated using a sigmoidal relationship between the ground-based LAI samples and remotely sensed vegetation index imagery from aircraft [30]. An interpolation algorithm providing daily LAI estimates was based on an exponential relationship with day of year [30].…”

Section: Datamentioning

confidence: 99%

“…The LAI estimates for the lysimeters and areas surrounding the EC towers were estimated using a sigmoidal relationship between the ground-based LAI samples and remotely sensed vegetation index imagery from aircraft [30]. An interpolation algorithm providing daily LAI estimates was based on an exponential relationship with day of year [30].…”

Section: Datamentioning

confidence: 99%

“…2 in [2]). A detailed description of the instrumentation and post processing of the EC/surface energy balance measurements is described in [30]. The local meteorological data of air temperature, wind speed, vapor and atmospheric pressure came from the EC towers at nominally 2 m above ground level (agl).…”

Section: Datamentioning

confidence: 99%

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Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area

Kustas

Alfieri

Anderson

et al. 2012

Advances in Water Resources

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Evett, Steven R.; Neale, Christopher M. U.; French, Andrew N.; Hipps, Lawrence E.; Chávez, José L.; Copeland, Karen S.; and Howell, Terry A., "Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area" (2012 a b s t r a c tApplication and validation of many thermal remote sensing-based energy balance models involve the use of local meteorological inputs of incoming solar radiation, wind speed and air temperature as well as accurate land surface temperature (LST), vegetation cover and surface flux measurements. For operational applications at large scales, such local information is not routinely available. In addition, the uncertainty in LST estimates can be several degrees due to sensor calibration issues, atmospheric effects and spatial variations in surface emissivity. Time differencing techniques using multi-temporal thermal remote sensing observations have been developed to reduce errors associated with deriving the surface-air temperature gradient, particularly in complex landscapes. The Dual-Temperature-Difference (DTD) method addresses these issues by utilizing the Two-Source Energy Balance (TSEB) model of [1], and is a relatively simple scheme requiring meteorological input from standard synoptic weather station networks or mesoscale modeling. A comparison of the TSEB and DTD schemes is performed using LST and flux observations from eddy covariance (EC) flux towers and large weighing lysimeters (LYs) in irrigated cotton fields collected during BEAREX08, a large-scale field experiment conducted in the semi-arid climate of the Texas High Plains as described by [2]. Model output of the energy fluxes (i.e., net radiation, soil heat flux, sensible and latent heat flux) generated with DTD and TSEB using local and remote meteorological observations are compared with EC and LY observations. The DTD method is found to be significantly more robust in flux estimation compared to the TSEB using the remote meteorological observations. However, discrepancies between model and measured fluxes are also found to be significantly affected by the local inputs of LST and vegetation cover and the representativeness of the remote sensing observations with the local flux measurement footprint.Published by Elsevier Ltd.

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“…Alfieri et al [30] noted that the EC flux measurements of H and LE had incomplete energy balance closure with respect to Fig. 2.…”

Section: Energy Balance Closure For Ec Flux Measurementsmentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

Section: Datamentioning

confidence: 99%

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Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area

Kustas

Alfieri

Anderson

et al. 2012

Advances in Water Resources

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Temperature regimes and turbulent heat fluxes across a heterogeneous canopy in an Alaskan boreal forest

et al. 2015

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We evaluate local differences in thermal regimes and turbulent heat fluxes across the heterogeneous canopy of a black spruce boreal forest on discontinuous permafrost in interior Alaska. The data were taken during an intensive observing period in the summer of 2013 from two micrometeorological towers 600 m apart in a central section of boreal forest, one in a denser canopy (DC) and the other in a sparser canopy, but under approximately similar atmospheric boundary layer (ABL) flow conditions. Results suggest that on average 34% of the half-hourly periods in a day are nonstationary, primarily during night and during ABL transitions. Also, thermal regimes differ between the two towers; specifically between midnight and 0500 Alaska Standard Time (AKST) it is about 3°C warmer at DC. On average, the sensible heat flux at DC was greater. For midday periods, the difference between those fluxes exceeded 30% of the measured flux and over 30 W m À2 in magnitude more than 60% of the time. These differences are due to higher mechanical mixing as a result of the increased density of roughness elements at DC. Finally, the vertical distribution of turbulent heat fluxes verifies a maximum atop the canopy crown (2.6 h) when compared with the subcanopy (0.6 h) and above canopy (5.1 h), where h is the mean canopy height. We argue that these spatial and vertical variations of sensible heat fluxes result from the complex scale aggregation of energy fluxes over a heterogeneous canopy.

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Reintroducing radiometric surface temperature into the Penman‐Monteith formulation

Mallick

Boegh

Trebs

et al. 2015

Water Resources Research

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116

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Here we demonstrate a novel method to physically integrate radiometric surface temperature (T R ) into the Penman-Monteith (PM) formulation for estimating the terrestrial sensible and latent heat fluxes (H and kE) in the framework of a modified Surface Temperature Initiated Closure (STIC). It combines T R data with standard energy balance closure models for deriving a hybrid scheme that does not require parameterization of the surface (or stomatal) and aerodynamic conductances (g S and g B ). STIC is formed by the simultaneous solution of four state equations and it uses T R as an additional data source for retrieving the ''near surface'' moisture availability (M) and the Priestley-Taylor coefficient (a). The performance of STIC is tested using high-temporal resolution T R observations collected from different international surface energy flux experiments in conjunction with corresponding net radiation (R N ), ground heat flux (G), air temperature (T A ), and relative humidity (R H ) measurements. A comparison of the STIC outputs with the eddy covariance measurements of kE and H revealed RMSDs of 7-16% and 40-74% in half-hourly kE and H estimates. These statistics were 5-13% and 10-44% in daily kE and H. The errors and uncertainties in both surface fluxes are comparable to the models that typically use land surface parameterizations for determining the unobserved components (g S and g B ) of the surface energy balance models. However, the scheme is simpler, has the capabilities for generating spatially explicit surface energy fluxes and independent of submodels for boundary layer developments.

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On the discrepancy between eddy covariance and lysimetry-based surface flux measurements under strongly advective conditions

Cited by 91 publications

References 80 publications

Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area

Evaluating the two-source energy balance model using local thermal and surface flux observations in a strongly advective irrigated agricultural area

Temperature regimes and turbulent heat fluxes across a heterogeneous canopy in an Alaskan boreal forest

Reintroducing radiometric surface temperature into the Penman‐Monteith formulation

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