Chinese Journal of Agrometeorology ›› 2017, Vol. 38 ›› Issue (11): 709-719.doi: 10.3969/j.issn.1000-6362.2017.11.003

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Characteristics of Evapotranspiration and Its Components Simulated Using Shuttleworth-Wallace Model in Rice Paddy Field

WANG Yu, ZHOU Li, JIA Qing-yu, WANG Lei, XU Jun-liang   

  1. 1. College of Forestry, Henan University of Science and Technology, Luoyang 471023, China; 2. Chinese Academy of Meteorological Sciences, Beijing 100081; 3. Institute of Atmospheric Environment, China Meteorological Administration, Shenyang 110016
  • Received:2017-01-10 Online:2017-11-20 Published:2017-11-17

Abstract:

The simulation of evapotranspiration (ET) and its components in croplands is critical for the precise irrigation and accurate estimation of ecosystem productivity. Based on the eddy-covariance flux measurement and ancillary data during 2013-2015, evapotranspiration and its components were simulated using the Shuttleworth-Wallace model (S-W model) in a rice paddy field in Panjin. The controlling mechanism of the ratio of soil evaporation to evapotranspiration (ES/ET) was analyzed with the structural equation modeling (SEM) method. The results showed that: (1) the simulated ET was close to the observed ET in the late growing season, however, it was lower than the observed ET in the early growing season and higher in the peak growing season. (2) As for the seasonal variation, the simulated ET showed a drastic day-to-day fluctuation (0.5-10.4mm·d-1) but no clear seasonal pattern; the plant transpiration (TR) was higher in the peak growing season and lower at the start and the end of the growing season, with the range of 0.1-8.4mm·d-1; ES showed a U-type curve, with the range of 0.1-4.7mm·d-1. (3) The simulated mean annual ET was 892mm during 2013-2015. TR was equal to ES at the annual scale. As for the growing season scale, TR was the main consumer of the ET: TR was close to ES in the transplanting-tillering stage, while in the other growth stages and the whole growing season, TR was more than twice as ES. (4) The SEM results indicated that air temperature (Ta) was the primary controlling factor of the ES/ET (total effect=-0.82). Ta was shown to influence ES/ET both directly (direct effect=-0.50) and indirectly through its regulation on leaf area index (LAI, indirect effect=-0.32). In addition, the LAI and wind speed (WS) were also shown to have significant effects on ES/ET. ES/ET decreased with LAI (total effect=-0.39) and increased with WS (total effect=0.38).

Key words: Structural equation modeling, Eddy covariance, Soil evaporation, Plant transpiration