Collaborative Research: P2C2--Constraining Cloud and Convective Parameterizations Using Paleoclimate Data Assimilation

这项研究的总体目标是开发一个新的框架，通过整合古气候数据和气候模式模拟来推进云和对流过程的模式表示。具体地说，该研究战略包括三个主要目标：(1)使用广泛的云和对流参数集对末次冰期最大(LGM)、中期全新世(MH)和工业化前(PI)时间段进行完全耦合的、启用同位素的模拟；(2)分别使用海洋表面温度(SST)和水同位素替代对扰动参数集(PPE)进行古气候数据同化；(3)使用LGM、MH和PI同化的后验数据来确定哪些云和对流参数与代理数据最匹配，然后使用这些参数集进行当代和加倍的二氧化碳(CO2)实验，以计算平衡气候敏感性的狭义估计。平衡气候敏感性(ECS)是一个关键的气候度量指标，它量化了全球平均地表温度对大气CO2相对于PI水平加倍的响应。在未来的预测中，水文气候、极端温度和气候系统的其他方面的变化与模型的ECS密切相关。几十年来，尽管使用了多条证据，但对ECS的估计仍然很宽。这种传播的一个持久来源与云和对流过程有关，这些过程发生的规模太小，无法明确解决，因此需要在气候模型中表示参数。这个项目试图解决这个问题。潜在的更广泛的影响包括与NASA合作改善气候模型、高中教师和研究生的学期和暑期实习经验，通过花园州路易斯·斯托克斯少数民族参与联盟让本科生参与研究。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。

The general goal of the research is to develop a new framework for advancing model representations of cloud and convective processes by integrating paleoclimate data and climate model simulations. Specifically, the research strategy consists of three main objectives: (1) conduct fully coupled, isotope-enabled simulations for the Last Glacial Maximum (LGM), mid-Holocene (MH), and pre-industrial (PI) time periods using a wide ensemble of cloud and convective parameter sets; (2) perform paleoclimate data assimilation on the perturbed parameter ensemble (PPE) using sea surface temperature (SST) and water isotope proxies, respectively; and (3) use the posteriors from the LGM, MH, and PI assimilations to identify which cloud and convection parameters provide the best match to the proxy data, then conduct present-day and doubled carbon dioxide (CO2) experiments with these parameter sets to calculate a narrowed estimate of equilibrium climate sensitivity.Equilibrium climate sensitivity (ECS) is a key climate metric that quantifies the rise in global mean surface temperature in response to doubling of atmospheric CO2 relative to PI levels. Changes in hydroclimate, temperature extremes, and other aspects of the climate system in future projections are closely tied to a model’s ECS. For decades, estimates of ECS have remained wide despite improvements from using multiple lines of evidence. One persistent source of this spread is related to cloud and convective processes, which occur at scales too small to be explicitly resolved, and thus require parameterizations to be represented in climate models. This project seeks to address this issue.The potential Broader Impacts include improvement in climate models, school term and summer internship experience for a high school teacher and graduate student in collaboration with NASA, involvement of undergraduate students in research through the Garden State Louis Stokes Alliance for Minority Participation.This 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.