Chinese Journal of Agrometeorology ›› 2020, Vol. 41 ›› Issue (02): 76-85.doi: 10.3969/j.issn.1000-6362.2020.02.002

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Turbulent Heat Exchange and Partitioning and Its Environmental Controls between the Atmosphere and an Alpine Potentilla Fruticosa Shrublands over the Qinghai- Tibetan Plateau

ZHANG Fa-wei, HAN Yun, LI Hong-qin, LI Ying-nian, CAO Guang-min, ZHOU Hua-kun   

  1. 1. College of Life Sciences, Luoyang Normal University, Luoyang 471934, China; 2. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008; 3. Qinghai Provincial Key Laboratory of Restoration Ecology in Cold Region, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008
  • Online:2020-02-20 Published:2020-03-20

Abstract: The turbulent heat flux plays important role in micro-climate environment and vegetation phenology but its temporal patterns and partitioning characteristics and associated environmental controls remain unclear in alpine shrublands, which is one of the most important vegetation types on the Qinghai-Tibetan Plateau. The continuous turbulent heat flux and routine environmental variables measured by the eddy covariance techniques were analyzed to quantify the exchange and partitioning of sensible heat flux and latent heat flux over an alpine Potentilla fruticosa shrublands on the northeastern Qinghai-Tibetan Plateau. The results showed that (1) the averaged diurnal variations of turbulent heat exchange both exhibited unimodal patterns, peaking at about 13:30 over the whole year-round period. The diurnal heat flux was dominated by sensible heat flux during non-growth season (November to next April) and the beginning and end of growth season (May and October), while by latent heat flux in mid-growth season from June to September; (2) The daily sensible heat flux exhibited a bimodal seasonal pattern, with the largest peak and the second peak appearing in mid-April and beginning October, respectively. The daily latent heat flux presented a unimodal seasonal pattern with a maximum in end July; (3) The diurnal and daily variations of turbulent heat flux were both mainly controlled by solar shortwave radiation; (4) Bowen ratio showed a U-shape seasonal change, while decoupling coefficient, evaporation ratio exhibited a bell-shape seasonal variation. These partitioning indices were controlled by soil temperature during non-growth season and enhanced vegetation index in growth season, respectively. These results revealed that the turbulent heat exchange was determined by solar radiation while the partitioning between sensible heat flux and latent heat flux was regulated by underlying surface temperature and plant coverage in the alpine shrublands.

Key words: Latent heat flux, Sensible heat flux, Eddy covariance technique, Bowen ratio, Decoupling coefficient