Satellite-based reconstruction and spatiotemporal variability analysis of actual evapotranspiration in the Jinshajiang River basin, China

To obtain a high-quality record of actual evapotranspiration (ETA) with which to investigate water cycle changes in the context of climate change, this study developed a method for reconstruction of ETA based on gravity satellite observations. The proposed method used GLDAS assimilated land surface water storage data to downscale GRACE equivalent water thickness to finer spatial resolution. Then, subbasin-level monthly ETA data for the Jinshajiang River basin were reconstructed based on the water balance during 2002-2016. Results showed that: ① The reconstructed ETA data (ETRecon) had high quality and compared well with three satellite-retrieval products, i.e., ETPLSH, ETJung, and ETMODIS; the strongest correlation was with the ETPLSH product (r=0.82) and the lowest root mean squared difference was with the ETJung data. ② Multiyear mean ETA in the study area was 410.8 mm/a with a gradient of increase from northwest to southeast. Temporally, it showed a significant upward trend during 2002-2016. ③ Seasonally, summer ETA was highest and it showed an upward trend over the study period; conversely, ETA in winter had the lowest value and it showed trivial change temporally. © 2021, Editorial Board of Advances in Water Science. All right reserved.