Estimating Soil Heat Flux for Alfalfa and Clipped Tall Fescue Grass

Payero, José O.; Neale, Christopher M. U.; Wright, James L.

doi:10.13031/2013.18459

Cited by 21 publications

(3 citation statements)

References 33 publications

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“…The net radiation (Rn E ) was measured using a four-way net radiometer (CNR1, Kipp and Zonen Inc., Delft, The Netherlands) and soil heat flux (G E ) was obtained using soil heat flux plates buried at a depth of 0.08 m (HFT3, Campbell Scientific Inc., Logan, UT, USA). In addition, soil temperature was measured by four soil thermocouples (TCAV, Campbell Scientific Inc., Logan, UT, USA) positioned at 0.02 and 0.06 m depth above each heat flux plate [35]. Four plates were installed under tree rows and four other plates were located between rows.…”

Section: Energy Balance Component Measurementsmentioning

confidence: 99%

Calibration of METRIC Model to Estimate Energy Balance over a Drip-Irrigated Apple Orchard

et al. 2017

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A field experiment was carried out to calibrate and evaluate the METRIC (Mapping EvapoTranspiration at high Resolution Internalized with Calibration) model for estimating the spatial and temporal variability of instantaneous net radiation (Rn i), soil heat flux (G i), sensible heat flux (H i), and latent heat flux (LE i) over a drip-irrigated apple (Malus domestica cv. Pink Lady) orchard located in the Pelarco valley, Maule Region, Chile (35 • 25 20 LS; 71 • 23 57 LW; 189 m.a.s.l.). The study was conducted in a plot of 5.5 hectares using 20 satellite images (Landsat 7 ETM+) acquired on clear sky days during three growing seasons (2012/2013, 2013/2014 and 2014/2015). Specific sub-models to estimate G i , leaf area index (LAI) and aerodynamic roughness length for momentum transfer (Z om) were calibrated for the apple orchard as an improvement to the standard METRIC model. The performance of the METRIC model was evaluated at the time of satellite overpass using measurements of H i and LE i obtained from an eddy correlation system. In addition, estimated values of Rn i , G i and LAI were compared with ground-truth measurements from a four-way net radiometer, soil heat flux plates and plant canopy analyzer, respectively. Validation indicated that LAI, Z om and G i were estimated using the calibrated functions with errors of +2%, +6% and +3% while those were computed using the standard functions with error of +59%, +83%, and +12%, respectively. In addition, METRIC using the calibrated functions estimated H i and LE i with error of +5% and +16%, while using the original functions estimated H i and LE i with error of +29% and +26%, respectively.

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Section: Energy Balance Component Measurementsmentioning

confidence: 99%

Calibration of METRIC Model to Estimate Energy Balance over a Drip-Irrigated Apple Orchard

et al. 2017

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“…CNR-1, Kipp & Zonen) y un set de platos de flujo de calor (mod. HFP01-SC) junto a termopares para estimar el flujo de calor del suelo (Payero et al, 2005). Tanto el anemómetro sónico como el analizador de gases se ubicaron a 3,0 m sobre el suelo.…”

Section: áRea De Estudio Y Medidas En Campounclassified

Seguimiento de los flujos de calor sensible y calor latente en vid mediante la aplicación del balance de energía METRIC

et al. 2015

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Resumen: En este trabajo se presenta el seguimiento de los flujos de energía en un cultivo de vid bajo riego, obtenidos a partir del modelo de balance de energía METRIC (Allen et al., 2007b). Este modelo resulta operativo al utilizar un método de calibración interna definido a partir de la selección de píxeles con valores extremos dentro de la escena. De esta manera se obtuvieron mapas de radiación neta (Rn), flujo de calor en suelo (G), calor sensible (H), calor latente (LE), evapotranspiración (ET) y coeficiente de cultivo (Kc). Estos valores fueron validados con registros obtenidos en el sitio, utilizando una torre de flujos turbulentos (covarianza de torbellinos). El RMSE fue 43 W m

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“…The row orientation of the vineyards' trellis introduced sunlit and shading patterns that can affect G. To account for this effect, G (W m −2 ) was measured at three positions spatially representative of the vineyard soil (i.e., the area covered by plants, at 0.75 m and 1.5 m from the plant row). G was calculated by correcting the heat fluxes measured by the flux plates by accounting for the effects of soil moisture content [31]. In each of the three G measurement positions, a Heat Fux Plate (HFP1) (Hukseflux, Delft, The Netherlands) was placed and buried at 8 cm deep along with two chrome-constantan thermocouples (TCAV, Type E) at 2 and 4 cm depths, together with a volumetric moisture reflectometer CS616 (Campbell Sci.…”

Section: Ec Measurementsmentioning

confidence: 99%

Effects of Surface Heterogeneity Due to Drip Irrigation on Scintillometer Estimates of Sensible, Latent Heat Fluxes and Evapotranspiration over Vineyards

Geli

González-Piqueras

Neale

et al. 2019

Water

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Accurate estimates of sensible (H) and latent (LE) heat fluxes and actual evapotranspiration (ET) are required for monitoring vegetation growth and improved agricultural water management. A large aperture scintillometer (LAS) was used to provide these estimates with the objective of quantifying the effects of surface heterogeneity due to soil moisture and vegetation growth variability. The study was conducted over drip-irrigated vineyards located in a semi-arid region in Albacete, Spain during summer 2007. Surface heterogeneity was characterized by integrating eddy covariance (EC) observations of H, LE and ET; land surface temperature (LST) and normalized difference vegetation index (NDVI) data from Landsat and MODIS sensors; LST from an infrared thermometer (IRT); a data fusion model; and a two-source surface energy balance model. The EC observations showed 16% lack of closure during unstable atmospheric conditions and was corrected using the residual method. The comparison between the LAS and EC measurements of H, LE, and ET showed root mean square difference (RMSD) of 25 W m−2, 19 W m−2, and 0.41 mm day−1, respectively. LAS overestimated H and underestimated both LE and ET by 24 W m−2, 34 W m−2, and 0.36 mm day−1, respectively. The effects of soil moisture on LAS measurement of H was evaluated using the Bowen ratio, β. Discrepancies between HLAS and HEC were higher at β ≤ 0.5 but improved at 1 ≥ β > 0.5 and β > 1.0 with R2 of 0.76, 0.78, and 0.82, respectively. Variable vineyard growth affected LAS performance as its footprints saw lower NDVILAS compared to that of the EC (NDVIEC) by ~0.022. Surface heterogeneity increased during wetter periods, as characterized by the LST–NDVI space and temperature vegetation dryness index (TVDI). As TVDI increased (decreased) during drier (wetter) conditions, the discrepancies between HLAS and HEC, as well as LELAS and LEEC Re decreased (increased). Thresholds of TVDI of 0.3, 0.25, and 0.5 were identified, above which better agreements between LAS and EC estimates of H, LE, and ET, respectively, were obtained. These findings highlight the effectiveness and ability of LAS in monitoring vegetation growth over heterogonous areas with variable soil moisture, its potential use in supporting irrigation scheduling and agricultural water management over large regions.

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Estimating Soil Heat Flux for Alfalfa and Clipped Tall Fescue Grass

Abstract: ABSTRACT. Soil heat flux (G) is an important component of evapotranspiration (ET) modeling (Allen et al., 1996;Clothier et al., 1986 Allen et al. (1998), but that uses a single equation for both daytime and nighttime instead of two separate equations.

Cited by 21 publications

References 33 publications

Calibration of METRIC Model to Estimate Energy Balance over a Drip-Irrigated Apple Orchard

Calibration of METRIC Model to Estimate Energy Balance over a Drip-Irrigated Apple Orchard

Seguimiento de los flujos de calor sensible y calor latente en vid mediante la aplicación del balance de energía METRIC

Effects of Surface Heterogeneity Due to Drip Irrigation on Scintillometer Estimates of Sensible, Latent Heat Fluxes and Evapotranspiration over Vineyards

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