A satellite-based hybrid algorithm to determine the Priestley-Taylor parameter for global terrestrial latent heat flux estimation across multiple biomes

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Yunjun Yao - , Beijing Normal University (Author)
  • Shunlin Liang - , Beijing Normal University, University of Maryland, College Park (Author)
  • Xianglan Li - , Beijing Normal University (Author)
  • Jiquan Chen - , Michigan State University (Author)
  • Kaicun Wang - , Beijing Normal University (Author)
  • Kun Jia - , Beijing Normal University (Author)
  • Jie Cheng - , Beijing Normal University (Author)
  • Bo Jiang - , Beijing Normal University (Author)
  • Joshua B. Fisher - , Jet Propulsion Laboratory, California Institute of Technology (Author)
  • Qiaozhen Mu - , University of Montana (Author)
  • Thomas Grünwald - , Chair of Meteorology, Chair of Meteorology (Author)
  • Christian Bernhofer - , Chair of Meteorology (Author)
  • Olivier Roupsard - , Centre de coopération internationale en recherche agronomique pour le développement, Tropical Agricultural Research and Higher Education Center (Author)

Abstract

Accurate estimation of the terrestrial latent heat flux (LE) for each plant functional type (PFT) at high spatial and temporal scales remains a major challenge. We developed a satellite-based hybrid algorithm to determine the Priestley-Taylor (PT) parameter for estimating global terrestrial LE across multiple biomes. The hybrid algorithm combines a simple empirical equation with physically based ecophysiological constraints to obtain the sum of the weighted ecophysiological constraints (f(e)) from satellite-based normalized difference vegetation index (NDVI) and ground-measured air temperature (Ta), relative humidity (RH), vapor pressure deficit (VPD) and LE for 2000 to 2009 provided by 240 globally distributed FLUXNET eddy covariance (ECOR) tower sites. Cross-validation analysis indicated that the optimization at a PFT level performed well with a RMSE of less than 0.15 and a R2 between 0.61 and 0.88 for estimated monthly f(e). Cross-validation analysis also revealed good performance of the hybrid-based PT method in estimating seasonal variability with a RMSE of the monthly LE varying from 4.3W/m2 (for 6 deciduous needleleaf forest sites) to 18.1W/m2 (for 34 crop sites) and with a R2 of more than 0.67. The algorithm's performance was also good for predicting among-site and inter-annual variability with a R2 of more than 0.78 and 0.70, respectively. We implemented the global terrestrial LE estimation from 2003 to 2005 for a spatial resolution of 0.05°by recalibrating the coefficients of the hybrid algorithm using Modern Era Retrospective Analysis for Research and Applications (MERRA) meteorological data, Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI product and ground-measured LE. This simple but accurate hybrid algorithm provides an alternative method for mapping global terrestrial LE, with a performance generally improved as compared to other satellite algorithms that are not calibrated with tower. The calibrated f(e) differs for different PFTs, and all driving forces of the algorithm can be acquired from satellite and meteorological observations.

Details

Original languageEnglish
Pages (from-to)216-233
Number of pages18
JournalRemote Sensing of Environment
Volume165
Publication statusPublished - 1 Aug 2015
Peer-reviewedYes

External IDs

Scopus 84930196138
ORCID /0000-0003-2263-0073/work/163765940

Keywords

Sustainable Development Goals

Keywords

  • Ecophysiological constraints, Global latent heat flux, Hybrid algorithm, Plant functional type, Priestley-Taylor parameter