Comparison of sensible heat fluxes by large aperture scintillometry and eddy covariance over two contrasting−climate vineyards

Vendrame, Nadia; Tezza, Luca; Pitacco, Andrea

doi:10.1016/j.agrformet.2020.108002

Cited by 6 publications

(3 citation statements)

References 70 publications

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“…For example, the EC method requires fully developed turbulent fluxes to ensure that the net vertical transfer of water vapor is caused by eddies, and the area must be horizontal and uniform. Moreover, the lack of energy balance closure in EC measurements needs particular attention since the gap can be up to 30 % of available energy (Wilson et al, 2002;Vendrame et al, 2020;Bambach et al, 2022;Allen et al, 2011b). The problem is due to the scale mismatch of energy balance components and unaccounted exchange fluxes on heterogenous landscapes (Foken, 2008).…”

Section: Using In Situ Measurements As the Validation Referencementioning

confidence: 99%

“…The uncertainties due to temporal upscaling are affected by several factors related to location (Jiang et al, 2021). These factors includes vegetation cover, soil moisture (Gentine et al, 2007;Hoedjes et al, 2008), cloud coverage (as discussed in research by Van Niel et al, 2012), cloud frequency (as explored in studies by Xu et al, 2015), air pollution effects (as indicated in research by Zhang et al, 2013), the return interval of the satellite (Alfieri et al, 2017), the timing of the overpass (Jiang et al, 2021), and the number of instantaneous values used for upscaling (Liu, 2021). Consequently, applying a single temporal-upscaling method for the entire globe results in spatially varying uncertainties in RS-ET estimates.…”

Section: Sources Of Uncertainty Evaluatedmentioning

confidence: 99%

See 1 more Smart Citation

Uncertainty assessment of satellite remote-sensing-based evapotranspiration estimates: a systematic review of methods and gaps

Tran,

van der Kwast,

Seyoum

et al. 2023

Hydrol. Earth Syst. Sci.

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Abstract. Satellite remote sensing (RS) data are increasingly being used to estimate total evaporation, often referred to as evapotranspiration (ET), over large regions. Since RS-based ET (RS-ET) estimation inherits uncertainties from several sources, many available studies have assessed these uncertainties using different methods. However, the suitability of methods and reference data subsequently affects the validity of these evaluations. This study summarizes the status of the various methods applied for uncertainty assessment of RS-ET estimates, discusses the advances and caveats of these methods, identifies assessment gaps, and provides recommendations for future studies. We systematically reviewed 676 research papers published from 2011 to 2021 that assessed the uncertainty or accuracy of RS-ET estimates. We categorized and classified them based on (i) the methods used to assess uncertainties, (ii) the context where uncertainties were evaluated, and (iii) the metrics used to report uncertainties. Our quantitative synthesis shows that the uncertainty assessments of RS-ET estimates are not consistent and comparable in terms of methodology, reference data, geographical distribution, and uncertainty presentation. Most studies used validation methods using eddy-covariance (EC)-based ET estimates as a reference. However, in many regions such as Africa and the Middle East, other references are often used due to the lack of EC stations. The accuracy and uncertainty of RS-ET estimates are most often described by root-mean-squared errors (RMSEs). When validating against EC-based estimates, the RMSE of daily RS-ET varies greatly among different locations and levels of temporal support, ranging from 0.01 to 6.65 mm d−1, with a mean of 1.18 mm d−1. We conclude that future studies need to report the context of validation, the uncertainty of the reference datasets, the mismatch in the temporal and spatial scales of reference datasets to those of the RS-ET estimates, and multiple performance metrics with their variation in different conditions and their statistical significance to provide a comprehensive interpretation to assist potential users. We provide specific recommendations in this regard. Furthermore, extending the application of RS-ET to regions that lack validation will require obtaining additional ground-based data and combining different methods for uncertainty assessment.

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Section: Using In Situ Measurements As the Validation Referencementioning

confidence: 99%

Section: Sources Of Uncertainty Evaluatedmentioning

confidence: 99%

Uncertainty assessment of satellite remote-sensing-based evapotranspiration estimates: a systematic review of methods and gaps

Tran,

van der Kwast,

Seyoum

et al. 2023

Hydrol. Earth Syst. Sci.

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show abstract

“…Numerically simulating the water balance across the air-soil interface is one avenue being considered to provide boundary conditions for simulations of deeper flows [20]. The micrometeorological technique of the eddy correlation has been used to measure heat, momentum, and water vapor fluxes for over 30 years [27].…”

Section: Introductionmentioning

confidence: 99%

Short-Term Predictions of Evaporation Using SoilCover at the Near-Surface of a Mine Waste Pile following Heavy Rainfall Events

Kabwe,

Wilson

2023

Geotechnics

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Accurate measurements and predictions of near-surface soil drying and evaporation following heavy rainfall events are often needed for research in agriculture and hydrology. However, such measurements and predictions at mine waste pile and tailing settings are limited. The prediction of evaporation at mine waste piles is essential for many problems in geotechnical engineering, including the design of soil cover systems for the long-term closure of hazardous waste sites, and thus mitigates, for example, the generation of acid mine drainage (AMD) and metal leaching. AMD is one of mining’s most serious threats to the environment. This study investigated the short-term (8 days) and medium-term (27 days) drying rates and evaporative fluxes at the surface and near-surface of the Deilmann South waste-rock (DSWR) pile at the Key Lake uranium mine, northern Saskatchewan, using the gravimetric (GV) method and SoilCover (SC) model, respectively, during and following heavy rainfall events for the environment. The SC simulation results showed that during the weather-controlled stage (Stage I) of the first 5-day period of rainfall events, while the surface was wet, the potential evaporation (PE) was equal to the actual evaporation (AE) (i.e., AE/PE = 1). As the surface became drier on Day 6, the cumulative PE began to separate from the cumulative AE and the surface’s drying rate rapidly diverged from those at the deeper depths. This occurrence signaled the onset of the soil profile property-controlled stage (Stage II). As the drying continued, the surface became desiccated and the slow-rate drying stage (Stage III) was established from Day 7 onward. The SC-simulated AE results were compared to those measured using the eddy covariance (EC) method for the same test period at the DSWR pile in a different study. The comparison showed that the two methods yielded similar AE results, with 18% relative errors. The results of this study provided the opportunity to validate the SC model using actual data gathered under field conditions and to ascertain its ability to accurately predict the PE and AE at the surfaces of mine waste piles.

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Evapotranspiration uncertainty at micrometeorological scales: the impact of the eddy covariance energy imbalance and correction methods

et al. 2022

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Under ideal conditions, evapotranspiration (ET) fluxes derived through the eddy covariance (EC) technique are considered a direct measure of actual ET. Eddy covariance flux measurements provide estimates at a temporal frequency that allows examining sub-daily, daily, and seasonal scale processes and relationships between different surface fluxes. The Grape Remote Sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX) project has collected micrometeorological and biophysical data to ground-truth new remote sensing tools for fine-tuning vineyard irrigation management across numerous sites since 2013. This rich dataset allows us to quantify the impact of different approaches to estimate daily ET fluxes, while accounting for energy imbalance. This imbalance results from the lack of agreement between the total available energy and turbulent fluxes derived by the EC technique. We found that different approaches to deal with this energy imbalance can lead to uncertainty in daily ET estimates of up to 50%. Over the growing season, this uncertainty can lead to considerable biases in crop water use estimates, which in some cases were equivalent to ~ 1/3rd of the total growing season applied irrigation We analyzed ET uncertainty relative to atmospheric meteorological, stability, and advective conditions, and highlight the importance of recognizing limitations of micrometeorological observational techniques, considered state of the art, to quantify ET for model validation and field-scale monitoring. This study provides a framework to quantify daily ET estimates’ uncertainty and expected reliability when using the eddy covariance technique for ground-truthing or model validation purposes.

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Comparison of sensible heat fluxes by large aperture scintillometry and eddy covariance over two contrasting−climate vineyards

Cited by 6 publications

References 70 publications

Uncertainty assessment of satellite remote-sensing-based evapotranspiration estimates: a systematic review of methods and gaps

Uncertainty assessment of satellite remote-sensing-based evapotranspiration estimates: a systematic review of methods and gaps

Short-Term Predictions of Evaporation Using SoilCover at the Near-Surface of a Mine Waste Pile following Heavy Rainfall Events

Evapotranspiration uncertainty at micrometeorological scales: the impact of the eddy covariance energy imbalance and correction methods

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