@misc{DallmeyerClaussenWangetal.2012, author = {Dallmeyer, Anne and Claussen, Martin and Wang, Yongbo and Herzschuh, Ulrike}, title = {Spatial variability of Holocene changes in the annual precipitation pattern}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {905}, issn = {1866-8372}, doi = {10.25932/publishup-43277}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432771}, pages = {20}, year = {2012}, abstract = {This study provides a detailed analysis of the mid-Holocene to present-day precipitation change in the Asian monsoon region. We compare for the first time results of high resolution climate model simulations with a standardised set of mid-Holocene moisture reconstructions. Changes in the simulated summer monsoon characteristics (onset, withdrawal, length and associated rainfall) and the mechanisms causing the Holocene precipitation changes are investigated. According to the model, most parts of the Indian subcontinent received more precipitation (up to 5 mm/day) at mid-Holocene than at present-day. This is related to a stronger Indian summer monsoon accompanied by an intensified vertically integrated moisture flux convergence. The East Asian monsoon region exhibits local inhomogeneities in the simulated annual precipitation signal. The sign of this signal depends on the balance of decreased pre-monsoon and increased monsoon precipitation at mid-Holocene compared to present-day. Hence, rainfall changes in the East Asian monsoon domain are not solely associated with modifications in the summer monsoon circulation but also depend on changes in the mid-latitudinal westerly wind system that dominates the circulation during the pre-monsoon season. The proxy-based climate reconstructions confirm the regional dissimilarities in the annual precipitation signal and agree well with the model results. Our results highlight the importance of including the pre-monsoon season in climate studies of the Asian monsoon system and point out the complex response of this system to the Holocene insolation forcing. The comparison with a coarse climate model simulation reveals that this complex response can only be resolved in high resolution simulations.}, language = {en} } @article{TianHerzschuhDallmeyeretal.2013, author = {Tian, Fang and Herzschuh, Ulrike and Dallmeyer, Anne and Xu, Qinghai and Mischke, Steffen and Biskaborn, Boris}, title = {Environmental variability in the monsoon-westerlies transition zone during the last 1200 years - lake sediment analyses from central Mongolia and supra-regional synthesis}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {73}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, number = {2}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2013.05.005}, pages = {31 -- 47}, year = {2013}, abstract = {A high resolution multi proxy (pollen, grain size, total organic carbon) record from a small mountain lake (Lake Khuisiin; 46.6 degrees N, 101.8 degrees E; 2270 m a.s.l.) in the south eastern Khangai Mountains of central Mongolia has been used to explore changes in vegetation and climate over the last 1200 years. The pollen data indicates that the vegetation changed from dry steppe dominated by Poaceae and Artemisia (ca AD 760-950), to Larix forest steppe (ca AD 950-1170), Larix Betula forest steppe (ca AD 1170-1380), meadow dominated by Cyperaceae and Poaceae (ca AD 1380-1830), and Larix Betula forest steppe (after similar to AD 1830). The cold-wet period between AD 1380 and 1830 may relate to the Little Ice Age. Environmental changes were generally subtle and climate change seems to have been the major driver of variations in vegetation until at least the early part of the 20th century, suggesting that either the level of human activity was generally low, or the relationship between human activity and vegetation did not alter substantially between AD 760 and 1830. A review of centennial scale moisture records from China and Mongolia revealed that most areas experienced major changes at ca AD 1500 and AD 1900. However, the moisture availability since AD 1500 varied between sites, with no clear regional pattern or relationship to present day conditions. Both the reconstructions and the moisture levels simulation on a millennium scale performed in the MPI Earth System Model indicate that the monsoon-westerlies transition area shows a greater climate variability than those areas influenced by the westerlies, or by the summer monsoon only.}, language = {en} }