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: 1702423
• 负责人: Gregory Hakim
• 金额: $ 14.51万
• 依托单位: University of Washington
• 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 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1702423&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.

干旱和洪水对美国经济和生态系统产生了重大影响。所有这些极端水文气候都表现出明显的季节性变化，表明季节性是干旱和潮湿状况背后的变化和强迫的重要组成部分。古气候记录中有强有力的证据表明，在过去两千多年里，美国遭受了更强烈、更持久、更广泛的干旱和潮湿事件。 然而，许多可用的代理记录无法解决干旱和雨雪的季节性问题。因此，需要在代理重建中尽可能指定水文气候变化的离散季节性，以提供对过去气候最现实的估计。 该项目概述的研究是一项计划，使用离线数据同化方法来估计上个千年期间北美每年离散的冷季和暖季表面湿度以及相关的大气状态。这些新的估计将用于了解年际、十年和百年时间尺度上的大气环流以及冷暖季干旱和雨雪的大规模强迫。该研究将重建网格化的冷暖季湿度和三维大气状态上个千年期间使用古气候数据同化（PDA）技术横跨北美。明确的季节性重建将基于北美季节性干旱地图集（NASDA）和现有的年度树木年轮年表的子集，其中季节性气候响应受到限制。古气候数据同化使用动力学模型来推断气候场内部和气候场之间的空间关系。因此，估计的季节性湿度和大气状态在物理和动态上是一致的。冷暖季节湿度和大气状态都将被准确记录并每年解析。新的重建将为量化上个千年期间重大干旱和雨灾事件的跨季节一致性和偶然机制提供前所未有的机会。该项目将研究北美过去引发、持续和/或减少干旱或雨雪的物理过程是否会在不同的时间尺度上发生变化。具体来说，新的重建将用于检验以下假设：1）北美地区冷暖季水文气候的海洋-大气强迫，2）季节性持续干旱和雨雪的气候动态，3）冷季和暖季水文气候变化，以及 4) 个别极端水文气候的因果机制。潜在的更广泛影响 (B.I.) 包括开发一个在线交互式地图集过去千年每年的冷暖季湿度和大气状态。 该地图集将包括冷暖季湿度、海平面压力、500hPa 位势高度和其他关键变量的地图。 来自学术界和公众的用户将能够访问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的框架来评估史前、殖民和现代时期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雨雪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价值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

Local Regions Associated With Interdecadal Global Temperature Variability in the Last Millennium Reanalysis and CMIP5 Models

• DOI: 10.1029/2019jd030426
• 发表时间: 2019-09
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: L. Parsons;G. Hakim

Do Multi‐Model Ensembles Improve Reconstruction Skill in Paleoclimate Data Assimilation?

• DOI: 10.1029/2020ea001467
• 发表时间: 2021-03
• 期刊: Earth and Space Science
• 影响因子: 3.1
• 作者: L. Parsons;D. Amrhein;S. Sanchez;R. Tardif;M. K. Brennan;G. Hakim

Coupled Atmosphere–Ocean Reconstruction of the Last Millennium Using Online Data Assimilation

• DOI: 10.1029/2020pa003959
• 发表时间: 2021-03
• 期刊: Paleoceanography and Paleoclimatology
• 影响因子: 3.5
• 作者: W. Perkins;G. Hakim

Climate Model Teleconnection Patterns Govern the Niño-3.4 Response to Early Nineteenth-Century Volcanism in Coral-Based Data Assimilation Reconstructions

气候模型遥相关模式控制 Niño-3.4 对基于珊瑚的数据同化重建中十九世纪早期火山活动的响应

• DOI: 10.1175/jcli-d-20-0549.1
• 发表时间: 2021
• 期刊: Journal of Climate
• 影响因子: 4.9
• 作者: Sanchez, Sara C.;Hakim, Gregory J.;Saenger, Casey P.
• 通讯作者: Saenger, Casey P.

Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling

• DOI: 10.5194/cp-15-1251-2019
• 发表时间: 2018-09
• 期刊: Climate of the Past
• 影响因子: 4.3
• 作者: R. Tardif;G. Hakim;W. Perkins;K. Horlick;M. Erb;J. Emile‐Geay;D. Anderson;E. Steig;D. Noone