title: Leaf onset in the northern hemisphere triggered by daytime temperature.
abstract: Recent warming significantly advanced leaf onset in the northern hemisphere. This signal cannot be accurately reproduced by current models parameterized by daily mean temperature (T(mean)). Here using in situ observations of leaf unfolding dates (LUDs) in Europe and the United States, we show that the interannual anomalies of LUD during 1982-2011 are triggered by daytime (Tmax) more than by nighttime temperature (T(min)). Furthermore, an increase of 1 °C in Tmax would advance LUD by 4.7 days in Europe and 4.3 days in the United States, more than the conventional temperature sensitivity estimated from T(mean). The triggering role of Tmax, rather than the T(min) or T(mean) variable, is also supported by analysis of the large-scale patterns of satellite-derived vegetation green-up in spring in the northern hemisphere (>30 °N). Our results suggest a new conceptual framework of leaf onset using daytime temperature to improve the performance of phenology modules in current Earth system models.
authors.affiliation: 1] Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Center for Excellence in Tibetan Earth Science, Chinese Academy of Sciences, Beijing 100085, China [2] CAS Center for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100085, China [3] Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Shilong
authors.initials: S
authors.lastname: Piao
authors.affiliation: Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Jianguang
authors.initials: J
authors.lastname: Tan
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544-1003, USA.
authors.forename: Anping
authors.initials: A
authors.lastname: Chen
authors.affiliation: 1] Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China [2] Department of Biology, University of Antwerp, Universiteitsplein 1, Wilrijk 2610, Belgium.
authors.forename: Yongshuo H
authors.initials: YH
authors.lastname: Fu
authors.affiliation: LSCE, UMR CEA-CNRS, Bat. 709, CE, L'Orme des Merisiers, Gif-sur-Yvette F-91191, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Ciais
authors.affiliation: Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Biology, University of Antwerp, Universiteitsplein 1, Wilrijk 2610, Belgium.
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Janssens
authors.affiliation: Department of Biology, University of Antwerp, Universiteitsplein 1, Wilrijk 2610, Belgium.
authors.forename: Sara
authors.identifier: 0000000198125837
authors.initials: S
authors.lastname: Vicca
authors.affiliation: Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
authors.forename: Zhenzhong
authors.initials: Z
authors.lastname: Zeng
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91011, USA.
authors.forename: Su-Jong
authors.initials: SJ
authors.lastname: Jeong
authors.affiliation: Sino-French Institute for Earth System Science, 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, 675 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
authors.forename: Ranga B
authors.initials: RB
authors.lastname: Myneni
authors.affiliation: 1] Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China [2] LSCE, UMR CEA-CNRS, Bat. 709, CE, L'Orme des Merisiers, Gif-sur-Yvette F-91191, France.
authors.forename: Shushi
authors.initials: S
authors.lastname: Peng
authors.affiliation: Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Center for Excellence in Tibetan Earth Science, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Miaogen
authors.initials: M
authors.lastname: Shen
authors.affiliation: 1] CREAF, Cerdanyola del Valles, Barcelona 08193, Spain [2] CSIC, Global Ecology Unit CREAF-CSIC-UAB, Cerdanyola del Valles, Barcelona 08193, Spain.
authors.forename: Josep
authors.identifier: 0000000272150150
authors.initials: J
authors.lastname: Peñuelas
mesh_terms: D005060:Europe; D008954:Models, Biological; D008962:Models, Theoretical; D010507:Periodicity; D018515:Plant Leaves; D063809:Satellite Imagery; D012621:Seasons; D013696:Temperature; D014481:United States