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

研究人员将研究(1)海面温度（SST）的远程强迫和(2)当地陆地表面-大气相互作用和反馈对中世纪北美干旱的相对作用，大约在公元900-1300年。在此期间，发生了一系列几十年的干旱，总的来说，持续时间比仪器期间发生的任何“严重”干旱（例如20世纪30年代的沙尘暴）都要长。具体而言，NCAR群落大气模式（CAM4.0）将用于研究热带太平洋海温异常以及北大西洋更确定和持续的海温异常对中世纪干旱的影响和机制。此外，天气研究与预报（WRF）模式，由CAM4.0的输出强制，将用于评估退化植被和土壤湿度在延长、加强或改变干旱中的作用。特别是，WRF将用于研究在中世纪期间发生在美国中部的前所未有的风向转变中植被退化的作用。本科生和研究生将参与该项目。此外，研究小组将与国家干旱缓解中心（NDMC）和内布拉斯加大学林肯分校（UNL）的其他外展团体合作，提高对特大干旱造成的潜在水危机的认识。该项目有关干旱的资料也将通过减灾委员会的季度通讯和Nebguide（联合国图书馆的一种推广出版物）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.