Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

IF value: 5.153
IF5.153
IF 5-year value: 5.460
IF 5-year
5.460
CiteScore value: 7.8
CiteScore
7.8
SNIP value: 1.623
SNIP1.623
IPP value: 4.91
IPP4.91
SJR value: 2.092
SJR2.092
Scimago H <br class='widget-line-break'>index value: 123
Scimago H
index
123
h5-index value: 65
h5-index65
Preprints
https://doi.org/10.5194/hess-2020-590
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/hess-2020-590
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  21 Nov 2020

21 Nov 2020

Review status
This preprint is currently under review for the journal HESS.

Long-term relative decline in evapotranspiration with increasing runoff on fractional land surfaces

Ren Wang1,2, Pierre Gentine3,4, Jiabo Yin5, Lijuan Chen1,2, Jianyao Chen6, and Longhui Li1,2 Ren Wang et al.
  • 1School of Geographical Sciences, Nanjing Normal University, Nanjing 210023, China
  • 2Key Laboratory for Geographical Environment Evolution, Ministry of Education, Nanjing, 210023, China
  • 3Earth and Environmental Engineering Department, Columbia University, New York, NY 10027, USA
  • 4Earth Institute, Columbia University, New York, NY 10025, USA
  • 5State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
  • 6School of Geography and Planning, Sun Yat-sen University, Guangzhou 510275, China

Abstract. Evapotranspiration (ET) accompanied by water and heat transport in the hydrological cycle is a key component in regulating surface aridity. Existing studies on changes in surface aridity have typically estimated ET using semi-empirical equations or parameterizations of land surface processes, which are based on the assumption that the parameters in the equation are stationary. However, plant physiological effects and its response to a changing environment are dynamically modifying ET, thereby challenging this assumption and limiting the estimation of long-term ET. In this study, the latent heat flux (ET in energy units) and sensible heat flux were retrieved for recent decades on a global scale using machine learning approach and driven by ground-based observations from flux towers and weather stations. The study resulted in several findings, namely that the evaporative fraction (EF) – the ratio of latent heat flux to available surface energy – exhibited a relatively decreasing trend on fractional land surfaces; In particular, the decrease in EF was accompanied by an increase in long-term runoff as assessed by precipitation (P) minus ET, accounting for 27.06 % of the global land areas. The signs were indicative of reduced surface conductance, which further emphasized that land-surface vegetation has major impacts on regulating the water and energy cycles, as well as aridity variability.

Ren Wang et al.

Interactive discussion

Status: open (until 16 Jan 2021)
Status: open (until 16 Jan 2021)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement

Ren Wang et al.

Viewed

Total article views: 206 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
157 46 3 206 10 0 0
  • HTML: 157
  • PDF: 46
  • XML: 3
  • Total: 206
  • Supplement: 10
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 21 Nov 2020)
Cumulative views and downloads (calculated since 21 Nov 2020)

Viewed (geographical distribution)

Total article views: 202 (including HTML, PDF, and XML) Thereof 201 with geography defined and 1 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Saved

No saved metrics found.

Discussed

No discussed metrics found.
Latest update: 25 Nov 2020
Publications Copernicus
Download
Short summary
Assessment of changes in global water cycle has been a challenge. This study estimate long-term global evapotranspiration (ET) for recent decades using machine learning and ground observations. The results show that normalized ET experienced a relative decline on fractional land, and the decline was typically accompanied by an increase in long-term runoff in 27.06 % of the global land areas. The finding emphasized that surface vegetation have a great impact in regulating water and energy cycles.
Assessment of changes in global water cycle has been a challenge. This study estimate long-term...
Citation