title: An increase in the biogenic aerosol concentration as a contributing factor to the recent wetting trend in Tibetan Plateau.
abstract: A significant wetting trend since the early 1980s in Tibetan Plateau (TP) is most conspicuous in central and eastern Asia as shown in the instrumental data and the long-term moisture sensitive tree rings. We found that anomalies in the large-scale oceanic and atmospheric circulations do not play a significant role on the wetting trend in TP. Meanwhile, the weak correlation between local temperature and precipitation suggests that the temperature-induced enhancement of the local water cycle cannot fully explain the wetting trend either. This may indicate the presence of nonlinear processes between local temperature and precipitation. We hypothesize that the current warming may enhance the emissions of the biogenic volatile organic compounds (BVOC) that can increase the secondary organic aerosols (SOA), contributing to the precipitation increase. The wetting trend can increase the vegetation cover and cause a positive feedback on the BVOC emissions. Our simulations indicate a significant contribution of increased BVOC emissions to the regional organic aerosol mass and the simulated increase in BVOC emissions is significantly correlated with the wetting trend in TP.
authors.affiliation: Institute of Geography, Key Laboratory of Humid Subtropical Eco-geographical Process (Ministry of Education), College of Geographical Sciences, Fujian Normal University, Fuzhou 350007, China.|Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Keyan
authors.initials: K
authors.lastname: Fang
authors.affiliation: Department of Physics, PO Box 64, 00014 University of Helsinki, Helsinki, Finland.
authors.forename: Risto
authors.initials: R
authors.lastname: Makkonen
authors.affiliation: Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Zhengtang
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Geosciences and Geography, PO Box 64, 00014 University of Helsinki, Helsinki, Finland.
authors.forename: Heikki
authors.initials: H
authors.lastname: Seppä