Collaborative Research: VOCALS--Climate Simulation and Operational Forecasting Using a Regional Earth System Modeling Framework

东南太平洋VOCALS（VAMOS Ocean-Cloud-Atmosphere-Land Study，VAMOS是美国季风系统变率项目）区域是一个全球重要的区域耦合气候系统，涉及向赤道风、地形沟道、干旱陆缘、上升流、海洋地球化学循环、海洋层云和气溶胶。VOCALS项目的一个主要动机是，全球模式在这一地区的误差降低了整个热带太平洋的模拟质量，对模拟和预测的全球气候产生重大影响。这是很难或不可能解决这些错误直接在全球模型与目前可用的计算资源，因为机制，确定平均状态和变异性具有更精细的空间尺度比全球模型可以解决。此外，这些机制不适合于独特的和物理上受限制的治疗。更复杂的是，这些机制涉及地球系统所有主要组成部分之间的相互作用，包括大气、海洋和陆地表面的物理过程，以及自然和人为对海洋和大气化学的影响。模拟这些相互关联的过程需要在物理和化学子模式中耦合大气、海洋和陆地成分的高分辨率（几公里）。在本项目中，将开发一个区域地球系统模拟框架，将大气模式耦合到陆地表面模式和海洋模式。大气模式包括化学输运和过程模式，而区域海洋模式则包括完整的海洋地球化学模式。这一框架将用于阐明VOCALS区域的气候动力学，并通过仔细的实验设计和模型验证以及数据解释研究来利用VOCAL雷克斯（区域实验）测量结果。在VOCALS雷克斯之后，将使用完整的地球系统模型对VOCAL雷克斯周期进行回顾性模拟。模拟的高分辨率旨在通过将测量结果置于地理和气候变化的背景下来提高测量结果的可解释性，并提高测量结果对模型验证和评估的有用性。对过去60年VOCALS区域的模拟将把VOCALS-REx观测和模拟放在气候变率的背景下。最后，VOCALS区域将从NCAR CCSM（国家大气研究中心社区气候系统模型）全球解决方案中缩小尺度，将通过仔细开发和基于VOCALS-REx的区域模型验证获得的现实主义放在主要全球气候模型的错误背景下。所有这些模拟都将在同一模型网格上进行，以便将模型解与观测值以及模型解之间进行系统比较。这些模拟将为分析决定VOCALS地区气候的连锁物理和化学过程提供机会。其中包括研究自然和人为气溶胶的地理分布;这些气溶胶对云特性的影响和云对气溶胶清除的影响;物理系统中复杂和高度结构化的耦合，决定了诸如层云数量和上升流等关键气候变量;以及控制二甲基硫（DMS）海气通量的海洋学过程。该项目的更广泛影响在于其对建设科学研究人力基础设施的贡献。通过与秘鲁和智利同事的互动，调查人员将促进国际科学合作，并将培训研究生和博士后研究员。该项目将留下建模基础设施的遗产，因为第一次将整体区域地球系统方法如此系统地应用于任何区域。将开发的建模框架可以作为地球系统建模的原型，为气候预测和气候应用服务。最后，PI建议利用VOCALS-REx现场活动期间采取的独特测量，以了解VOCALS区域的联锁物理和化学动力学，并诊断全球模型误差中大的持续误差的原因，可能为改善气候预测铺平道路。

The VOCALS (VAMOS Ocean-Cloud-Atmosphere-Land Study - VAMOS is the Variability of the American Monsoon System project) region within the Southeast Pacific is a globally important regional coupled climate regime involving equatorward winds, orographic channeling, arid land margins, upwelling currents, oceanic biogeochemical cycling, marine stratus clouds, and aerosols. A principal motivation for the VOCALS project is that global model errors in this region degrade the quality of their simulations throughout the tropical Pacific, with substantial impacts on the modeled and predicted global climate. It is difficult or impossible to address these errors directly in global models with currently available computational resources, because the mechanisms that determine the mean state and variability have much finer spatial scales than global models can resolve. Moreover, these mechanisms do not lend themselves to unique and physically constrained treatments. A further complication is that the mechanisms involve interactions among all major components of the Earth system, including physical processes in the atmosphere, ocean, and land surface, as well as natural and anthropogenic influences on marine and atmospheric chemistry. Simulating these interlocking processes requires high resolution (several kilometers) with coupled atmosphere, ocean, and land components in both physical and chemical submodels.In this project a regional Earth-system modeling framework will be developed, with an atmospheric model coupled to a land surface model and an oceanic model. The atmospheric model includes chemical transport and process models, while the regional oceanic model contains full biogeochemistry. This framework will be used to explicate the climate dynamics of the VOCALS region and to leverage VOCAL REx (Regional Experiment) measurements through careful experimental design and model-validation and data-interpretation studies.First, meteorological and aerosol forecasts will be provided for VOCALS REx during the campaign. After VOCALS REx, a retrospective simulation of the VOCAL REx period will be carried out using the full Earth-system model. The simulation's high resolution is intended to increase the interpretability of measurements by placing them in geographical and climate-variability context and to enhance the usefulness of measurements for model validation and evaluation. A simulation of the VOCALS region covering the past 60 years will place the VOCALS-REx observations and simulations in the context of climate variability. Finally, the VOCALS region will be downscaled from an NCAR CCSM (National Center for Atmospheric Research Community Climate System Model) global solution, placing the realism gained through careful development and VOCALS-REx-based validation of the regional model in the context of the errors in a major global climate model. All these simulations will be performed on the same model grid to allow for systematic comparison of model solutions with observations and with each other. The simulations will provide opportunities for analyses of interlocking physical and chemical processes that determine the climate of the VOCALS region. These include studies of the geographical distribution of natural and anthropogenic aerosols; the impact of these aerosols on cloud properties and the effects of clouds on aerosol scavenging; the intricate and highly-structured couplings in the physical system determining key climate variables such as stratus amount and upwelling; and the oceanographic processes controlling air-sea fluxes of DMS (dimethyl sulfide).Broader impacts of this project are in its contributions to building human infrastructure for science research. Through interactions with colleagues in Peru and Chile, the investigators will foster international scientific collaboration, and they will train graduate students and postdoctoral fellows. The project will leave a legacy of modeling infrastructure, as the first time a holistic regional Earth-systems approach has been applied so systematically to any region. The modeling framework to be developed can serve as a prototype for Earth-system modeling in the service of climate prediction and climate applications. Finally, the PIs propose to capitalize on the unique measurements to be taken during the VOCALS-REx field campaign to understand the interlocking physical and chemical dynamics of the VOCALS region and to diagnose the causes of large, persistent errors in global models errors, potentially paving the way for improvements in climate predictions.