The Regional Evapotranspiration of the Amazon

Werth, David; Avissar, Roni

doi:10.1175/1525-7541(2004)005<0100:treota>2.0.co;2

Cited by 95 publications

(82 citation statements)

References 26 publications

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“…However, unlike studies that point to a significant increase in temperature for areas that experienced deforestation (e.g. Sud et al, 1996;Lean and Rowntree, 1997;Werth and Avissar, 2004), our results suggest that only moderate warming occurred in deforested areas over the United States. Moreover, the relatively large standard deviation in this change class (0.41°C) shows a great variability within areas that experienced deforestation.…”

Section: Observation Reanalysis and Omr Trendscontrasting

confidence: 99%

Impacts of land use land cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis

Fall

Niyogi

Gluhovsky

et al. 2009

Intl Journal of Climatology

182

101

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ABSTRACT:We investigate the sensitivity of surface temperature trends to land use land cover change (LULC) over the conterminous United States (CONUS) using the observation minus reanalysis (OMR) approach. We estimated the OMR trends for the 1979-2003 period from the US Historical Climate Network (USHCN), and the NCEP-NCAR North American Regional Reanalysis (NARR). We used a new mean square differences (MSDs)-based assessment for the comparisons between temperature anomalies from observations and interpolated reanalysis data. Trends of monthly mean temperature anomalies show a strong agreement, especially between adjusted USHCN and NARR (r = 0.9 on average) and demonstrate that NARR captures the climate variability at different time scales. OMR trend results suggest that, unlike findings from studies based on the global reanalysis (NCEP/NCAR reanalysis), NARR often has a larger warming trend than adjusted observations (on average, 0.28 and 0.27°C/decade respectively).OMR trends were found to be sensitive to land cover types. We analysed decadal OMR trends as a function of land types using the Advanced Very High Resolution Radiometer (AVHRR) and new National Land Cover Database (NLCD) 1992-2001 Retrofit Land Cover Change. The magnitude of OMR trends obtained from the NLDC is larger than the one derived from the 'static' AVHRR. Moreover, land use conversion often results in more warming than cooling.Overall, our results confirm the robustness of the OMR method for detecting non-climatic changes at the station level, evaluating the impacts of adjustments performed on raw observations, and most importantly, providing a quantitative estimate of additional warming trends associated with LULC changes at local and regional scales. As most of the warming trends that we identify can be explained on the basis of LULC changes, we suggest that in addition to considering the greenhouse gases-driven radiative forcings, multi-decadal and longer climate models simulations must further include LULC changes.

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Section: Observation Reanalysis and Omr Trendscontrasting

confidence: 99%

Impacts of land use land cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis

Fall

Niyogi

Gluhovsky

et al. 2009

Intl Journal of Climatology

182

101

View full text Add to dashboard Cite

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“…The seasonal METRIC ET patterns as well as FT ET observed in Rondônia during 2000 and 2002 show a decreasing trend in RJA during June to August. These observations agree with patterns found in other studies using flux tower data [3][4][5][6][7]46].…”

Section: Monthly and Seasonal Average Etsupporting

confidence: 92%

“…Flux tower-derived ET provide field-based monitoring data and have been used as reference points to calibrate and evaluate regional and global climate models, however they do not have representative spatial coverage to characterize spatial variability of ET across the vast Amazon forest area [7]. …”

Section: Introductionmentioning

confidence: 99%

Evaluation of Landsat-Based METRIC Modeling to Provide High-Spatial Resolution Evapotranspiration Estimates for Amazonian Forests

et al. 2017

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While forest evapotranspiration (ET) dynamics in the Amazon have been studied both as point estimates using flux towers, as well as spatially coarse surfaces using satellite data, higher resolution (e.g., 30 m resolution) ET estimates are necessary to address finer spatial variability associated with forest biophysical characteristics and their changes by natural and human impacts. The objective of this study is to evaluate the potential of the Landsat-based METRIC (Mapping Evapotranspiration at high Resolution with Internalized Calibration) model to estimate high-resolution (30 m) forest ET by comparing to flux tower ET (FT ET) data collected over seasonally dry tropical forests in Rondônia, the southwestern region of the Amazon. Analyses were conducted at daily, monthly and seasonal scales for the dry seasons (June-September for Rondônia) of 2000-2002. Overall daily ET comparison between FT ET and METRIC ET across the study site showed r 2 = 0.67 with RMSE = 0.81 mm. For seasonal ET comparison, METRIC-derived ET estimates showed an agreement with FT ET measurements during the dry season of r 2 >0.70 and %MAE <15%. We also discuss some challenges and potential applications of METRIC for Amazonian forests.

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“…Although the Amazon forest is recognized as an important component of the regional and global climate system, the spatial and temporal variability of its hydrological functions is not completely understood; therefore, evaluating the seasonal and spatial variations of the water fluxes in the tropics is important (Werth and Avissar, 2004). These variations mainly depend on the characteristics of the vegetation, on energy processes and on water availability (Hasler and Avissar, 2007).…”

Section: Introductionmentioning

confidence: 99%

Analysis of biological and meteorological controls of evapotranspiration in pristine forests and a pasture site in Amazonia

Paulino¹,

Randow²,

Randow³

2017

Rev. ambiente água

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This work studied the behavior and seasonality of evapotranspiration influenced by biotic and abiotic factors through analysis of diurnal variation of aerodynamic resistance (ra), stomatal resistance (rs) and decoupling factor (Ω). This index was proposed by Jarvis and McNaughton (1986) as an indicative of the control of these resistances on the evapotranspiration of vegetation. Selection of representative data from wet and dry seasons from a primary forest in Central Amazonia and a primary forest and a pasture sites in Southwestern Amazonia had shown that: (i) ra is about 20 s.m-1 in both forests in both seasons, and ranges from 70 to 100 s.m-1 in the pasture site; (ii) rs varies both throughout the day and seasonally, with medians increasing from 40 in the morning, to 150 s.m-1 in late afternoon, in the wet season in the forests and from 50 to 160 s.m-1 in the pasture. These values increase in the dry season, with the forests rs ranging from 50 up to 500 s.m-1 and pasture rs starting from 140 s.m‑1 and reaching up to more than 1800 s.m-1 in the dry afternoons; (iii) Ω ranges from 0.5 to 0.8 during the wet season, and reduces to values below 0.5 in the afternoons during the dry season, indicating that, although a strong influence of net radiation in the evaporative loss is present, to a large extent the evapotranspiration fluxes are coupled to the biotic control of stomatal closure in the vegetation, especially in the pasture and during dry periods.

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The Regional Evapotranspiration of the Amazon

Cited by 95 publications

References 26 publications

Impacts of land use land cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis

Impacts of land use land cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis

Evaluation of Landsat-Based METRIC Modeling to Provide High-Spatial Resolution Evapotranspiration Estimates for Amazonian Forests

Analysis of biological and meteorological controls of evapotranspiration in pristine forests and a pasture site in Amazonia

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