Collaborative Research: P2C2--Assimilation of Cool and Warm Season Moisture Reconstructions and Atmospheric Conditions Over North America for the Past Millennium

合作研究：P2C2——过去千年北美冷暖季水分重建和大气条件的同化

• 批准号: 1702894
• 负责人: Song Feng
• 金额: $ 29.91万
• 依托单位: University of Arkansas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-06-15 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702894&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Assimilation; Cool

Droughts and floods have had a major impact on the economy and ecosystems in the United States (US) during the instrumental period. All of these hydroclimate extremes exhibited noticeable seasonal variability, suggesting that the seasonality is an important component of variability and forcing behind drought and wetness regimes. There is robust evidence from paleoclimate records that the U.S. was struck by more intense, long lasting, and widespread drought and wet episodes during the last two thousand years. However, many of the available proxy records cannot resolve the seasonality of droughts and pluvials. Therefore, the discrete seasonality of hydroclimate variations needs to be specified in proxy reconstructions to the extent possible to provide the most realistic estimation of past climate. The research outlined in this project is a plan to estimate discrete cool and warm season surface moisture and associated atmospheric states on an annual basis over North America during the last millennium using an offline data assimilation approach. These new estimations will then be used to understand the atmospheric circulation and large-scale forcing of cool and warm season droughts and pluvials on interannual, decadal, and centennial time scales.The research will reconstruct gridded cool and warm season moisture and three dimensional atmospheric states across North America during the last millennium using paleoclimate data assimilation (PDA) techniques. The explicit seasonal reconstructions will be based on the North American Seasonal Drought Atlas (NASDA) and a subset of existing annual tree ring chronologies with restricted seasonal climate responses. The paleoclimate data assimilation uses dynamical models to infer spatial relationships within and between climate fields. Therefore, the estimated seasonal moisture and atmospheric states are physically and dynamically consistent. The cool and warm season moisture and atmospheric states will all be exactly dated and annually resolved. The new reconstructions will provide an unprecedented opportunity to quantify the cross-season coherency and casual mechanisms of major drought and pluvial events during the last millennium. This project will examine whether the physical processes that initiated, sustained and/or diminished past droughts or pluvials in North America could vary at different time scales. Specifically, the new reconstructions will be used to test hypotheses concerning: 1) the ocean-atmospheric forcing of cool and warm season hydroclimate over North America, 2) the climate dynamics responsible for persistent droughts and pluvials on seasonal basis, 3) the linkages between cool and warm season hydroclimate variability, and 4) the causal mechanisms for individual hydroclimate extremes.The potential Broader Impacts (B.I.) include the development of an online and interactive atlas of cool and warm season moisture and atmospheric states for each year over the past millennium. This atlas will include maps of cool and warm season moisture, sea level pressure, 500hPa geopotential height and other key variables. Users from academic communities and the general public will be able to access the detailed seasonal atmospheric information for any particular year or group of years. The seasonal reconstructions will also provide an objective framework to evaluate the impacts of hydroclimate extremes on social and ecological changes during the prehistoric, colonial, and modern eras. The researchers will collaborate with the Arkansas State Climate Office to promote the awareness of potential water issues associated with droughts and pluvials. This project will also support one graduate studentThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

干旱和洪水对美国(美国)的经济和生态系统在工具时期产生了重大影响。所有这些水气候极端事件都表现出明显的季节性变化，这表明季节性是干旱和潮湿状况背后的变异性和强迫的重要组成部分。从古气候记录中有强有力的证据表明，在过去的2000年里，美国遭受了更强烈、持续时间更长、范围更广的干旱和潮湿事件。然而，许多可用的代理记录无法解决干旱和暴雨的季节性问题。因此，水文气候变化的离散季节性需要在代理重建中明确，以尽可能提供对过去气候的最现实估计。该项目中概述的研究是一项计划，利用离线数据同化方法估计北美在过去千年期间每年的冷暖季节地表湿度和相关大气状态。这些新的估计将被用来理解年际、年代际和百年尺度上冷暖季干旱和暴雨的大气环流和大尺度强迫。研究将使用古气候数据同化(PDA)技术重建过去1000年北美地区冷暖季湿度和三维大气状态的网格。明确的季节重建将基于北美季节性干旱地图集(NASDA)和现有年轮年表的子集，这些年轮年表的季节性气候反应有限。古气候数据同化使用动力模型来推断气候场内和气候场之间的空间关系。因此，估计的季节湿度和大气状态在物理和动态上是一致的。凉爽和温暖的季节、湿度和大气状态都将被准确地确定日期并每年解决。新的重建将提供一个前所未有的机会，以量化过去千年期间重大旱灾和洪涝事件的跨季节连贯性和偶然机制。该项目将研究在北美引发、持续和/或减少过去干旱或暴雨的物理过程是否会在不同的时间尺度上有所不同。具体地说，新的重建将被用来检验以下假设：1)北美上空冷季和暖季水气候的海洋-大气强迫，2)造成季节性持续干旱和暴雨的气候动力学，3)冷季和暖季水气候变率之间的联系，以及4)个别水气候极端的原因机制。潜在的更广泛的影响(B.I.)包括编制一份关于过去千年每年冷暖季节、湿度和大气状况的在线互动地图集。这份地图集将包括凉季和暖季湿度、海平面气压、500hPa位势高度和其他关键变量的地图。来自学术界和普通公众的用户将能够获取任何特定年份或年份组的详细季节性大气信息。季节性重建还将提供一个客观框架，以评估史前、殖民和现代时代极端水文气候对社会和生态变化的影响。研究人员将与阿肯色州气候办公室合作，提高人们对与干旱和暴雨相关的潜在水问题的认识。该项目还将支持一名研究生。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

The summer precipitation response of latewood tree‐ring chronologies in the southwestern United States

• DOI: 10.1002/joc.6997
• 发表时间: 2021-01
• 期刊: International Journal of Climatology
• 作者: I. Howard;D. Stahle;M. Torbenson;D. Griffin

Dynamics, Variability, and Change in Seasonal Precipitation Reconstructions for North America

• DOI: 10.1175/jcli-d-19-0270.1
• 发表时间: 2020-04-01
• 期刊: JOURNAL OF CLIMATE
• 影响因子: 4.9
• 作者: Stahle, David W.;Cook, Edward R.;Crawford, Christopher J.
• 通讯作者: Crawford, Christopher J.

Tree-Ring Reconstruction of Single-Day Precipitation Totals over Eastern Colorado

科罗拉多州东部单日降水总量的树轮重建

• DOI: 10.1175/mwr-d-19-0114.1
• 发表时间: 2020
• 期刊: Monthly Weather Review
• 影响因子: 3.2
• 作者: Howard, Ian M.;Stahle, David W.
• 通讯作者: Stahle, David W.

Anthropogenic megadrought

人为特大干旱

• DOI: 10.1126/science.abb6902
• 发表时间: 2020
• 期刊: Science
• 影响因子: 56.9
• 作者: Stahle, David W.