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Biogeosciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/bgd-6-9161-2009
© Author(s) 2009. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
21 Sep 2009
Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The revised manuscript was not accepted.
Surface energy exchanges above two grassland ecosystems on the Qinghai-Tibetan Plateau
S. Liu1,2, S.-G. Li1, G.-R. Yu1, X.-M. Sun1, L.-M. Zhang1, Z.-M. Hu1, Y.-N. Li3, and X.-Z. Zhang4 1Key Laboratory of Ecosystem Network Observation and Modeling & Synthesis Research Center of Chinese Ecosystem Research Network, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
3Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, China
4Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
Abstract. This paper explores the seasonal and inter-annual variations in surface energy exchanges at an alpine shrub-meadow ecosystem (AM) and an alpine meadow-steppe (AS) on the Qinghai-Tibetan Plateau using the 4–5-year continuous flux measurements by the eddy covariance technique. Although ground solar radiation (Kd) was lower at AM than at AS, net radiation (Rn) was higher at AM than at AS due to the lower surface reflectivity for short-wave radiation (albedo) and the lower ratio of upward long-wave radiation to downward long-wave radiation (Lu/Ld) at AM. The ratio of Rn/Kd was lower (about 0.4) at AS than at AM (about 0.6). In the annual scale, annual precipitation was the most important factor controlling energy partitioning at AS, while temperature, especially during the spring, controlled the inter-annual variations in energy partitioning at AM characterized by low temperature. Vegetation growth played an important role in controlling energy partitioning at seasonal scale at both sites. However, soil water content was also one of major factors affecting Bowen ratio (β) due to the lower soil water-holding capacity at AS as compared with AM. Under non-drought conditions, the influence of vapor pressure deficit (VPD) on energy partitioning at half-hourly scale was stronger at AM than at AS due to higher vegetation cover thereof.
Citation: Liu, S., Li, S.-G., Yu, G.-R., Sun, X.-M., Zhang, L.-M., Hu, Z.-M., Li, Y.-N., and Zhang, X.-Z.: Surface energy exchanges above two grassland ecosystems on the Qinghai-Tibetan Plateau, Biogeosciences Discuss., 6, 9161-9192, https://doi.org/10.5194/bgd-6-9161-2009, 2009.
S. Liu et al.
S. Liu et al.

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