Bayesian multimodel estimation of global terrestrial latent heat flux from eddy covariance, meteorological, and satellite observations

Yao, Yunjun; Liang, Shunlin; Li, Xianglan; Hong, Yang; Fisher, Joshua B.; Zhang, Nannan; Chen, Jiquan; Cheng, Jie; Zhao, Shaohua; Zhang, Xiaolin; Jiang, Bo; Sun, Ling; Jia, Kun; Wang, Kaicun; Yang, Chen; Mu, Qiaozhen; Feng, Fei

doi:10.1002/2013jd020864

Cited by 176 publications

(141 citation statements)

References 118 publications

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“…One possible solution to address this inherent model limitation is to assemble a mosaicked product based on the predictive skill of the model(s) over particular biomes or climate zones. Another approach might be to develop an ensemble product using a suitable multi-model blending technique, such as a Bayesian Model Averaging approach (Hoeting et al, 1999;Yao et al, 2014). Either way, it is clear that further multi-model assessments are required for progressing global-scale flux characterisation and to ensure a robust and representative product is developed.…”

Section: Discussionmentioning

confidence: 99%

The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally gridded forcing data

McCabe

Ershadi

Jiménez³

et al. 2016

Geosci. Model Dev.

142

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Abstract. Determining the spatial distribution and temporal development of evaporation at regional and global scales is required to improve our understanding of the coupled water and energy cycles and to better monitor any changes in observed trends and variability of linked hydrological processes. With recent international efforts guiding the development of long-term and globally distributed flux estimates, continued product assessments are required to inform upon the selection of suitable model structures and also to establish the appropriateness of these multi-model simulations for global application. In support of the objectives of the Global Energy and Water Cycle Exchanges (GEWEX) LandFlux project, four commonly used evaporation models are evaluated against data from tower-based eddy-covariance observations, distributed across a range of biomes and climate zones. The selected schemes include the Surface Energy Balance System (SEBS) approach, the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model, the PenmanMonteith-based Mu model (PM-Mu) and the Global Land Evaporation Amsterdam Model (GLEAM). Here we seek to examine the fidelity of global evaporation simulations by examining the multi-model response to varying sources of forcing data. To do this, we perform parallel and collocated model simulations using tower-based data together with a global-scale grid-based forcing product. Through quantifying the multi-model response to high-quality tower data, a better understanding of the subsequent model response to the coarse-scale globally gridded data that underlies the LandFlux product can be obtained, while also providing a relative evaluation and assessment of model performance.Using surface flux observations from 45 globally distributed eddy-covariance stations as independent metrics of performance, the tower-based analysis indicated that PT-JPL provided the highest overall statistical performance (0.72; 61 W m −2 ; 0.65), followed closely by GLEAM (0.68; 64 W m −2 ; 0.62), with values in parentheses representing the R 2 , RMSD and Nash-Sutcliffe efficiency (NSE), respectively. PM-Mu (0.51; 78 W m −2 ; 0.45) tended to underestimate fluxes, while SEBS (0.72; 101 W m −2 ; 0.24) overestimated values relative to observations. A focused analysis across specific biome types and climate zones showed considerable variability in the performance of all models, with no single model consistently able to outperform any other. Results also indicated that the global gridded data tended to reduce the performance for all of the studied models when compared to the tower data, likely a response to scale mismatch and issues related to forcing quality. Rather than relying on any single model simulation, the spatial and temporal variability at both the tower-and grid-scale highlighted the potential benefits of developing an ensemble or blended evaporation product for global-scale LandFlux applications. Challenges related to the robust assessment of the LandFlux product are also discussed.

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Section: Discussionmentioning

confidence: 99%

The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally gridded forcing data

McCabe

Ershadi

Jiménez³

et al. 2016

Geosci. Model Dev.

142

132

View full text Add to dashboard Cite

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“…Although we correct ET by Twine et al [43] method, the inaccuracy in the measured data still exists, such as the energy imbalance issue, with H + LE < R n − G (H: sensible heat flux; LE: latent heat flux) [61]. The mismatches in scale among different datasets may also lead to differences between the simulated and measured values.…”

Section: The Performance Of the Ms-pt Algorithm In Estimating Etmentioning

confidence: 99%

Satellite-Derived Spatiotemporal Variations in Evapotranspiration over Northeast China during 1982–2010

et al. 2017

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Evapotranspiration (ET) is a critical process for the climate system and water cycles. However, the spatiotemporal variations in terrestrial ET over Northeast China over the past three decades calculated from sparse meteorological point-based data remain large uncertain. In this paper, a recently proposed modified satellite-based Priestley-Taylor (MS-PT) algorithm was applied to estimate ET of Northeast China during 1982-2010. Validation results show that the square of the correlation coefficients (R 2 ) for the six flux tower sites varies from 0.55 to 0.88 (p < 0.01), and the mean root mean square error (RMSE) is 0.92 mm/d. The ET estimated by MS-PT has an annual mean of 441.14 ± 18 mm/year in Northeast China, with a decreasing trend from southeast coast to northwest inland. The ET also shows in both annual and seasonal linear trends over Northeast China during 1982-2010, although this trend seems to have ceased after 1998, which increased on average by 12.3 mm per decade pre-1998 (p < 0.1) and decreased with large interannual fluctuations post-1998. Importantly, our analysis on ET trends highlights a large difference from previous studies that the change of potential evapotranspiration (PET) plays a key role for the change of ET over Northeast China. Only in the western part of Northeast China does precipitation appear to be a major controlling influence on ET.

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“…It is clear that equation (6) Because the original SEMI-Penman algorithm includes the variety of land cover (e.g., pastures, crop fields, forests) and the revised algorithm also considers the effects of the alpine meadow, we find the revised algorithm is sufficiently representative for the purpose of estimating terrestrial LE in the TRHR. In this study, the observed EC data is considered as accurately 'true' value to revise the LE algorithm, but approximately 20-50 W/m 2 of the EC measured errors and approximately 0.8 of energy closure ratio ((LE +H)/(R n − G)) will also lead to large uncertainties when estimating LE in the TRHR (Wilson et al 2002;Foken 2008;Mahrt 2010 Yao et al 2014a). This spatial mismatch between the flux tower site footprints and gridded footprints will also cause large uncertainties for LE estimation.…”

Section: Evaluation Of Algorithm Performance In Estimating Lementioning

confidence: 99%

Satellite evidence for no change in terrestrial latent heat flux in the Three-River Headwaters region of China over the past three decades

et al. 2016

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Terrestrial latent heat flux (LE) in the Three-River Headwaters region (TRHR) of China plays an essential role in quantifying the amount of water evaporation and carbon sink over the high altitude Tibetan Plateau (TP). Global warming is expected to accelerate terrestrial hydrological cycle and to increase evaporation. However, direct field observations are lacking in this region and the long-term variability in LE remains uncertain. In this study, we have revised a semi-empirical Penman LE algorithm based on ground eddy covariance (EC) observations from an alpine grass site and provided new satellitebased evidence to assess LE change in the TRHR during 1982-2010. Our results show that the average annual terrestrial LE in the TRHR is about 38.8 W/m 2 and there is no statistically significant change in annual LE from 1982 to 2010. We also found that during the same time period, terrestrial LE over the east region of the TRHR significantly decreased, on average, by 0.7 W/m 2 per decade, which was driven primarily by the surface incident solar radiation (R s ) limitation, offsetting the increased LE over the west region of the TRHR caused by the increased precipitation (P ) and soil moisture (SM ).

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Bayesian multimodel estimation of global terrestrial latent heat flux from eddy covariance, meteorological, and satellite observations

Cited by 176 publications

References 118 publications

The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally gridded forcing data

The GEWEX LandFlux project: evaluation of model evaporation using tower-based and globally gridded forcing data

Satellite-Derived Spatiotemporal Variations in Evapotranspiration over Northeast China during 1982–2010

Satellite evidence for no change in terrestrial latent heat flux in the Three-River Headwaters region of China over the past three decades

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