title: Evaporative cooling over the Tibetan Plateau induced by vegetation growth.
abstract: In the Arctic, climate warming enhances vegetation activity by extending the length of the growing season and intensifying maximum rates of productivity. In turn, increased vegetation productivity reduces albedo, which causes a positive feedback on temperature. Over the Tibetan Plateau (TP), regional vegetation greening has also been observed in response to recent warming. Here, we show that in contrast to arctic regions, increased growing season vegetation activity over the TP may have attenuated surface warming. This negative feedback on growing season vegetation temperature is attributed to enhanced evapotranspiration (ET). The extra energy available at the surface, which results from lower albedo, is efficiently dissipated by evaporative cooling. The net effect is a decrease in daily maximum temperature and the diurnal temperature range, which is supported by statistical analyses of in situ observations and by decomposition of the surface energy budget. A daytime cooling effect from increased vegetation activity is also modeled from a set of regional weather research and forecasting (WRF) mesoscale model simulations, but with a magnitude smaller than observed, likely because the WRF model simulates a weaker ET enhancement. Our results suggest that actions to restore native grasslands in degraded areas, roughly one-third of the plateau, will both facilitate a sustainable ecological development in this region and have local climate cobenefits. More accurate simulations of the biophysical coupling between the land surface and the atmosphere are needed to help understand regional climate change over the TP, and possible larger scale feedbacks between climate in the TP and the Asian monsoon system.
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China; shen.miaogen@gmail.com slpiao@pku.edu.cn.
authors.forename: Miaogen
authors.initials: M
authors.lastname: Shen
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China; Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China; shen.miaogen@gmail.com slpiao@pku.edu.cn.
authors.forename: Shilong
authors.initials: S
authors.lastname: Piao
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91011;
authors.forename: Su-Jong
authors.initials: SJ
authors.lastname: Jeong
authors.affiliation: Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, NY 12222;
authors.forename: Liming
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Laboratoire des Sciences du Climat et de l'Environnement, UMR 1572 Commissariat à l'Energie Atomique-CNRS, Université de Versailles St-Quentin-en-Yvelines, 91191 Gif-sur-Yvette, France;
authors.forename: Philippe
authors.initials: P
authors.lastname: Ciais
authors.affiliation: Department of Earth Sciences, University of Gothenberg, 405 30 Gothenberg, Sweden;
authors.forename: Deliang
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;
authors.forename: Mengtian
authors.initials: M
authors.lastname: Huang
authors.affiliation: School of Earth and Environmental Sciences, Seoul National University, Seoul 151-747, Korea;
authors.forename: Chun-Sil
authors.initials: CS
authors.lastname: Jin
authors.affiliation: Laboratoire de Météorologie Dynamique, CNRS, Université Pierre et Marie Curie-Paris 6, 75252 Paris, France;
authors.forename: Laurent Z X
authors.initials: LZ
authors.lastname: Li
authors.affiliation: Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;
authors.forename: Yue
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Earth and Environment, Boston University, Boston, MA 02215;
authors.forename: Ranga B
authors.initials: RB
authors.lastname: Myneni
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Gengxin
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China; Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yangjian
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China; Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China;
authors.forename: Tandong
authors.initials: T
authors.lastname: Yao
mesh_terms: D000383:Agriculture; D001208:Asia; D002980:Climate; D057231:Climate Change; D003198:Computer Simulation; D004463:Ecology; D005843:Geography; D015233:Models, Statistical; D008962:Models, Theoretical; D018526:Plant Transpiration; D006109:Poaceae; D013696:Temperature; D018609:Tibet; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water
keywords: Tibetan Plateau; climate change; evapotranspiration; feedback; vegetation