Modeling precipitation δ18O variability in East Asia since the Last Glacial Maximum: temperature and amount effects across different timescales
- 1Laboratory for Climate, Ocean and Atmosphere Studies, Dept. of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China
- 2The Center for Climatic Research, The Nelson Institute for Environmental Studies, University of Wisconsin-Madison, Madison, WI, USA
- 3Nanjing University of Information Science and Technology, Nanjing, China
- 4Climate and Global Dynamics, Earth System Laboratory, NCAR, Boulder, CO, USA
- 5Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
Abstract. Water isotopes in precipitation have played a key role in the reconstruction of past climate on millennial timescales and longer. However, for midlatitude regions like East Asia with complex terrain, the reliability behind the basic assumptions of the temperature effect and amount effect is based on modern observational data and still remains unclear for past climate. In the present work, we reexamine the two basic effects on seasonal, interannual, and millennial timescales in a set of time slice experiments for the period 22–0 ka using an isotope-enabled atmospheric general circulation model (AGCM). Our study confirms the robustness of the temperature and amount effects on the seasonal cycle over China in the present climatic conditions, with the temperature effect dominating in northern China and the amount effect dominating in the far south of China but no distinct effect in the transition region of central China. However, our analysis shows that neither temperature nor amount effect is significantly dominant over China on millennial and interannual timescales, which is a challenge to those classic assumptions in past climate reconstruction. Our work helps shed light on the interpretation of the proxy record of δ18O from a modeling point of view.