OCE-RIG: The impact of submesoscale processes on oligotrophic carbon cycling and the sensitivity of this interaction to climatically driven changes

概述：人为引起的变暖已经开始改变全球海洋，并有可能改变海洋碳汇。据推测，未来混合层深度的变化和向海洋表面输送营养物质是影响海洋初级生产和碳循环的主要过程。这两个过程都受到亚中尺度（1 ~ 10 km）物理动力的显著影响。然而，目前用于了解气候敏感性的全球气候模型并没有解决这些重要特征，因此缺少影响海洋碳循环的基本机制。在这个项目中，PI将开发一种新的生物地球化学和生态系统模型，在一个可用于大规模模拟计算的框架中捕捉亚中尺度过程对碳循环的影响。空间异质性动态浮游生物（SHiP）模型将代表亚网格尺度上的资源环境分布，并将包括五个浮游植物功能群，以及浮游植物生长的光、氮和磷限制。本研究将集中在两个低营养站点，百慕大大西洋时间序列站（BATS）和夏威夷海洋时间序列站（HOT）。SHiP模型将用于探索由APEX/ISUS剖面硝酸盐浮子捕获的观测亚中尺度动力学对初级生产、物种动力学和碳输出通量的影响。还将进行一系列模式模拟，以研究BATS和HOT的碳循环对亚中尺度锋形成频率和强度变化的敏感性，例如在未来气候情景下可能发生的变化。最后，将测量驱动的船舶模拟与理想的区域海洋模拟系统模拟进行比较，该模拟系统明确解决了亚中尺度动力学问题。知识价值：亚中尺度过程已被证明对海洋物理有重大影响，然而，这些过程在碳循环中所起的作用尚不清楚。本研究将基于观测分析亚中尺度特征对少营养环流群落组成和功能的影响，以及这种相互作用对气候驱动变化的敏感性。此外，这项工作将验证一种将亚中尺度动力学影响机械地纳入粗分辨率模型的新方法。该研究将为探索气候变化对全球碳循环的影响提供一个计算上易于处理的框架，同时包括亚中尺度过程的影响。更广泛的影响：与该项目相关的研究者和学生将与南加州大学的邻里学术倡议（NAI）合作，开发一个海洋科学模块，包括在海洋研究船上的实地考察。美国国立大学致力于提高南加州大学周围学区的高中毕业率和大学入学率，该学区主要服务于拉丁裔/西班牙裔和非裔美国人社区。该模块还将使学生接触海洋学，并帮助当地高中教师制定海洋科学课程计划，以纳入他们的课程。

Overview: Anthropogenically induced warming has begun to change the global oceans and has the potential to alter the ocean carbon sink. Future changes in mixed layer depth and the delivery of nutrients into the surface ocean are hypothesized to be the primary processes that will impact primary production and carbon cycling in the ocean. Both of these processes are significantly impacted by submesoscale physical dynamics (1-10 km). However, current global climate models used to understand climate sensitivity do not resolve these important features, and so are missing a fundamental mechanism impacting ocean carbon cycling. In this project, the PI will develop a novel biogeochemical and ecosystem model that captures the impact of submesoscale processes on carbon cycling in a framework that is computationally tractable for large-scale simulations. The Spatially Heterogeneous Dynamic Plankton (SHiP) model will represent a distribution of resource environments at the subgridscale and will include five phytoplankton functional groups, as well as light, nitrogen, and phosphorus limitation on phytoplankton growth. This research will focus on two oligotrophic sites, the Bermuda Atlantic Time-series Station (BATS) and the Hawaii Ocean Time-series (HOT). The SHiP model will be used to explore the impact of the observed submesoscale dynamics captured by the APEX/ISUS profiling nitrate floats on primary production, species dynamics, and carbon export flux. A suite of model simulations will also be conducted to investigate the sensitivity of carbon cycling at BATS and HOT to changes in the frequency and intensity of submesoscale front formation, such as might occur under future climate scenarios. Finally, the measurement-driven SHiP simulations will be compared against an idealized Regional Ocean Modeling System simulation that explicitly resolves submesoscale dynamics.Intellectual Merit: Submesoscale processes have been shown to have a significant impact on ocean physics, however, the role that these processes play in carbon cycling remains unknown. This study will provide an observation-based analysis of the impact of submesoscale features on community composition and function in oligotrophic gyres and the sensitivity of this interaction to climatically driven changes. In addition, this work will validate a novel approach for mechanistically incorporating the impact of submesoscale dynamics into coarse-resolution models. This research will provide a computationally tractable framework for exploring the impact of changes in climate on global carbon cycling while including the impact of submesoscale processes. Broader Impacts: The investigator and students associated with this project will collaborate with the Neighborhood Academic Initiative (NAI) at USC to develop an ocean sciences module including a field trip on an oceanographic research vessel. The NAI strives to improve high school graduation and college matriculation rates in the school district surrounding USC, which serves predominantly Latino/Hispanic and African-American communities. The module will also expose the students to oceanography, and help local high school teachers develop an ocean sciences lesson plan to incorporate into their curriculum.