A continuous satellite‐derived global record of land surface evapotranspiration from 1983 to 2006

TLDR

The study applied a satellite remote sensing–based evapotranspiration algorithm to quantify global terrestrial ET from 1983 to 2006. The algorithm estimates canopy transpiration and soil evaporation via a modified Penman‑Monteith model driven by NDVI‑derived canopy conductance, and open‑water evaporation via a Priestley‑Taylor model, and is applied globally using AVHRR NDVI, NCEP/NCAR meteorology, and NASA/GEWEX radiation data, with parameters tuned and validated against FLUXNET tower measurements. Monthly ET estimates agree well with tower observations (RMSE 13–15 mm month⁻¹, R² ≈ 0.82), and the global ET record captures spatial and temporal patterns and matches basin‑scale water‑balance estimates (RMSE ≈ 186 mm yr⁻¹, R² ≈ 0.80), offering a long‑term, accurately quantified global ET dataset for climate and water‑cycle studies.

Abstract

We applied a satellite remote sensing–based evapotranspiration (ET) algorithm to assess global terrestrial ET from 1983 to 2006. The algorithm quantifies canopy transpiration and soil evaporation using a modified Penman‐Monteith approach with biome‐specific canopy conductance determined from the normalized difference vegetation index (NDVI) and quantifies open water evaporation using a Priestley‐Taylor approach. These algorithms were applied globally using advanced very high resolution radiometer (AVHRR) GIMMS NDVI, NCEP/NCAR Reanalysis (NNR) daily surface meteorology, and NASA/GEWEX Surface Radiation Budget Release−3.0 solar radiation inputs. We used observations from 34 FLUXNET tower sites to parameterize an NDVI‐based canopy conductance model and then validated the global ET algorithm using measurements from 48 additional, independent flux towers. Two sets of monthly ET estimates at the tower level, driven by in situ meteorological measurements and meteorology interpolated from coarse resolution NNR meteorology reanalysis, agree favorably (root mean square error (RMSE) = 13.0–15.3 mm month −1 ; R 2 = 0.80–0.84) with observed tower fluxes from globally representative land cover types. The global ET results capture observed spatial and temporal variations at the global scale and also compare favorably (RMSE = 186.3 mm yr −1 ; R 2 = 0.80) with ET inferred from basin‐scale water balance calculations for 261 basins covering 61% of the global vegetated area. The results of this study provide a relatively long term global ET record with well‐quantified accuracy for assessing ET climatologies, terrestrial water, and energy budgets and long‐term water cycle changes.