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Title: Comparing evapotranspiration from Eddy covariance measurements, water budgets, remote sensing, and land surface models over Canada a, b

Here, this study compares six evapotranspiration ET products for Canada's landmass, namely, eddy covariance EC measurements; surface water budget ET; remote sensing ET from MODIS; and land surface model (LSM) ET from the Community Land Model (CLM), the Ecological Assimilation of Land and Climate Observations (EALCO) model, and the Variable Infiltration Capacity model (VIC). The ET climatology over the Canadian landmass is characterized and the advantages and limitations of the datasets are discussed. The EC measurements have limited spatial coverage, making it difficult for model validations at the national scale. Water budget ET has the largest uncertainty because of data quality issues with precipitation in mountainous regions and in the north. MODIS ET shows relatively large uncertainty in cold seasons and sparsely vegetated regions. The LSM products cover the entire landmass and exhibit small differences in ET among them. Annual ET from the LSMs ranges from small negative values to over 600 mm across the landmass, with a countrywide average of 256 ± 15 mm. Seasonally, the countrywide average monthly ET varies from a low of about 3 mm in four winter months (November-February) to 67 ± 7 mm in July. The ET uncertainty is scale dependent. Larger regions tendmore » to have smaller uncertainties because of the offset of positive and negative biases within the region. More observation networks and better quality controls are critical to improving ET estimates. Future techniques should also consider a hybrid approach that integrates strengths of the various ET products to help reduce uncertainties in ET estimation.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5] ;  [6] ;  [7] ;  [1] ;  [6]
  1. Canada Centre for Mapping and Earth Observation, Ottawa, ON (Canada)
  2. Princeton Univ., Princeton, NJ (United States)
  3. Univ. of Montana, Missoula, MT (United States); Univ. of Maryland, College Park, MD (United States)
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  5. Thunen Institute of Climate-Smart Agriculture, Braunschweig (Germany)
  6. The Univ. of British Columbia, Vancouver, BC (Canada)
  7. NOAA, Oak Ridge, TN (United States); Oak Ridge Assoc. Univ., Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Hydrometeorology
Additional Journal Information:
Journal Volume: 16; Journal Issue: 4; Journal ID: ISSN 1525-755X
Publisher:
American Meteorological Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Evapotranspiration; Remote sensing; Surface observations; Model comparison; Ecological models; BOREAL ASPEN FOREST; AIR CO2 ENRICHMENT; ENERGY-EXCHANGE; CLIMATE MODELS; USE EFFICIENCY; UNITED-STATES; NORTH-AMERICA; TEMPERATE; CARBON; MODIS
OSTI Identifier:
1333655