Impacts of climate changes on light-stimulated carbon fluxes in the Arctic Ocean: quantification of primary production and photooxidation using satellite remote sensing

在过去的30年里，北冰洋已经失去了50%的永久海冰覆盖，使更多的表面沃茨暴露在直接的太阳辐射之下。这种现象刺激了光驱动的碳过程：浮游植物的初级生产和溶解有机物（DOM）的光氧化。虽然最近已经记录了通过增加光可用性来刺激初级生产者，但这种辐射强迫对DOM的光化学氧化和光驱动的碳通量之间的净平衡的影响迄今为止很少受到关注。事实上，北冰洋表面的DOM主要来源于北方陆地生态系统，这些生态系统储存了全球近三分之一的土壤有机碳。这些生态系统目前正经历着重要的生物地球化学变化，气候变暖，修改的数量和化学性质的陆源DOM，以及相对丰富的有机和无机养分输入北冰洋。在这里，我提出了一个框架，研究光刺激的碳通量在北冰洋之间的净平衡，使用诊断建模方法。因此，将为大气-海洋耦合系统开发一个卫星光谱辐射转移模型，以量化光化学过程并评估初级生产和光氧化之间的净平衡趋势。光化学模型的参数化将以北冰洋考察航行期间收集的实地观测为基础。为了预测这些光化学参数的变化，将根据可观测或可计算的环境参数对其变异性进行研究。这一建议的新奇在于协同使用各种遥感环境参数，这些参数被合并在诊断建模方法中，以回答有关气候变化反馈的基本问题。特别是，这项工作的目的是利用自1997年以来卫星提供的连续海洋颜色观测。这些结果将有助于遥感问题、全球海洋地球化学循环、气候模拟、海洋光合作用和DOM光化学等方面的研究。

During the last 3 decades, the Arctic Ocean has lost 50% of its permanent sea ice cover, exposing more surface waters to direct solar radiation. This phenomenon stimulates light-driven carbon processes: primary production by phytoplankton and photo-oxidation of dissolved organic matter (DOM). While the stimulation of primary producers by increased light availability has been recently documented, the impacts of this radiative forcing on photochemical oxidation of DOM and the net balance between light-driven carbon fluxes has received little attention thus far. Indeed, DOM in the Arctic Ocean surface originates largely from northern terrestrial ecosystems, which store nearly one third of global soil organic carbon. These ecosystems are currently experiencing important biogeochemical transformations under a warming climate, modifying the quantity and chemical character of terrigenous DOM, and the relative abundance of organic and inorganic nutrient inputs into the Arctic Ocean. Here I propose a framework to study the net balance between light-stimulated carbon fluxes in the Arctic Ocean using a diagnostic modelling approach. Therefore, a satellite-based spectral radiative transfer model for the coupled atmosphere-ocean system will be developed to quantify photochemical processes and assess trends in the net balance between primary production and photoooxidation. The parameterization of the photochemical models will be based on in situ observations gathered during research cruises in the Arctic Ocean. In order to predict variation in these photochemical parameters, their variability will be investigated in relation to observable or calculable environmental parameters. The novelty of this proposal resides in the synergetic use of various remotely sensed parameters of the environment merged within a diagnostic modelling approach to answer fundamental questions regarding climate change feedbacks. In particular, the work will aim to exploit the continuous ocean colour observations provided by satellites since 1997. The results should benefit studies focusing on remote sensing problems, global biogeochemical cycles, climate modeling, marine photosynthesis and DOM photochemistry.