P2C2: Megadrought--Local versus Remote Causal Factors for Medieval North America

研究人员将调查(1)海洋表面温度(SST)的远程强迫和(2)当地陆地-大气相互作用和反馈对北美中世纪干旱(大约公元900-1300年)的相对作用。在此期间，发生了一系列数十年的干旱，总持续时间比仪器时期发生的任何严重干旱(例如1930年的S沙尘暴)持续的时间都长。具体来说，NCAR社区大气模式(CAM4.0)将被用来研究热带太平洋海温异常的影响和机制，以及北大西洋更为确定和持续的盆地范围暖海温异常对中世纪干旱的影响和机制。此外，根据CAM4.0的输出，天气研究和预报(WRF)模型将被用于评估植被退化和土壤水分在延长、加强或改善干旱方面的作用。特别是，WRF将被用来研究植被退化在中世纪时期美国中部发生的前所未有的风向变化中所起的作用。本科生和研究生将参与这个项目。此外，研究小组将与国家减轻干旱中心(NDMC)和内布拉斯加-林肯大学(UNL)的其他外展组织合作，以提高对特大干旱造成的潜在水危机的认识。该项目与干旱有关的信息还将通过国家旱灾管理中心的季度通讯和NebGuide(联合国后勤基地推广出版物之一)传播，并免费分发给公众。

The researchers will investigate the relative roles of (1) remote forcing of sea surface temperatures (SST) and (2) local land surface-atmosphere interactions and feedbacks on the medieval drought in North America, approximately 900-1300 A.D. During this time, a series of multi-decadal droughts occurred which, in total, lasted longer than any 'severe' drought that has occurred during the instrumental period (e.g. the 1930's Dust Bowl).Specifically, the NCAR community atmospheric model (CAM4.0) will be used to investigate the impacts and mechanisms of SST anomalies in the tropical Pacific as well as the more certain and persistent basin-wide warm SST anomalies in the North Atlantic on medieval drought. Additionally, the Weather Research and Forecast (WRF) model, forced by output from CAM4.0, will be used to evaluate the role of devegetation and soil moisture in prolonging, enhancing, or modifying the drought. In particular, WRF will be used to examine the role of devegetation in the unprecedented wind shift which took place in the central U.S. during the Medieval Period.Undergraduate and graduate students will participate in the project. In addition, the research team will collaborate with the National Drought Mitigation Center (NDMC) and other outreach groups at the University of Nebraska-Lincoln (UNL) to increase awareness of potential water crises due to megadroughts. Drought-related information from the project would also be disseminated through the NDMC's quarterly newsletter and Nebguide (one of the UNL extension publications) and distributed free to the public.