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On the attribution of changing pan evaporation in a nature reserve in SW China

Authors

  • Guangyong You,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing, China
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  • Yiping Zhang,

    Corresponding author
    1. Ailaoshan Station for Subtropical Forest Ecosystem Studies (ASSFE), Chinese Ecosystem Research Networks, Jingdong, Yunnan, China
    2. National Forest Ecosystem Research Station at Ailaoshan, Jingdong, Yunnan, China
    • Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
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  • Yuhong Liu,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
    2. Ailaoshan Station for Subtropical Forest Ecosystem Studies (ASSFE), Chinese Ecosystem Research Networks, Jingdong, Yunnan, China
    3. National Forest Ecosystem Research Station at Ailaoshan, Jingdong, Yunnan, China
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  • Qinghai Song,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
    2. Graduate School of the Chinese Academy of Sciences, Beijing, China
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  • Zhiyun Lu,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
    2. Ailaoshan Station for Subtropical Forest Ecosystem Studies (ASSFE), Chinese Ecosystem Research Networks, Jingdong, Yunnan, China
    3. National Forest Ecosystem Research Station at Ailaoshan, Jingdong, Yunnan, China
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  • Zhenghong Tan,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
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  • Chuansheng Wu,

    1. Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, China
    2. Ailaoshan Station for Subtropical Forest Ecosystem Studies (ASSFE), Chinese Ecosystem Research Networks, Jingdong, Yunnan, China
    3. National Forest Ecosystem Research Station at Ailaoshan, Jingdong, Yunnan, China
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  • Youneng Xie

    1. Jingdong Bureau of National Nature Reserve, Jingdong, Yunnan, China
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Correspondence to: Yiping Zhang, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China

E-mail: yipingzh@xtbg.ac.cn

Abstract

Negative trends of measured pan evaporation are widely reported. Studies of the factors that underlie this reduction in pan evaporation have not reached a consensus about the controlling factors. Most studies employ statistical analysis (correlation analysis or stepwise regression) to identify the controlling climatic variables; in contrast, few studies have employed physical-based theories. In addition, observations of pan evaporation and related climatic variables are reported to be influenced by anthropogenic activities. Consequently, the observed trends of climatic variables in a nature reserve would be useful for understanding regional climate change. The present study site is located in Ailaoshan National Nature Reserve, SW China, which is free of anthropogenic activity. In this study, we firstly applied the adjusted PenPan model to estimate the pan evaporation. Then, using this physical-based model, we identified a positive trend in pan evaporation, with a much larger increase in the dry season than in the wet season. The model results indicate that the change in the aerodynamic component is larger than that in the radiative component. In contrast to the reduction in wind speed and sunshine hours that has been reported in previous studies at various sites, we found that wind speed and sunshine hours have increased in recent decades, thereby explaining the increase of the pan evaporation rate. Wind speed made the greatest contribution to the change in pan evaporation, followed by sunshine duration. This study indicates that the potential evaporation has increased at this site despite the widely reported reduction in measured pan evaporation. During the dry season, the availability of water for agriculture and agroforestry could be threatened. Copyright © 2012 John Wiley & Sons, Ltd.

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