Coupled biosphere-atmosphere chemical data assimilation: improved understanding of the impact of biosphere-atmosphere exchange on atmospheric composition

陆地生物圈在决定大气成分方面起着重要作用；而大气成分的变化反过来又会对生物圈产生重大影响。要可靠地预测由于大气中二氧化碳（CO2）、甲烷（CH4）和臭氧（O3）等温室气体丰度变化而导致的全球气候变化，就需要更好地了解生物圈和大气之间的这种耦合。拟议的研究计划将使用一个耦合的生物圈-大气模型，结合先进的数据同化技术，利用最新的卫星观测和对环境重要的微量气体的地面测量，更好地量化生物圈对对流层组成的影响。特别是，该工作将开发基于四维变分数据同化方法的多物种生物圈-大气数据同化系统，该系统利用大气气体（如CO2， CH4和O3）的卫星观测来优化生物圈模型中控制关键生态系统过程的参数。在陆地表面模拟界已经作出了重大努力，利用数据同化背景下的卫星观测来更好地模拟生物圈过程。同样，大气化学模拟界越来越重视利用对环境具有重要意义的示踪气体日益丰富的天基观测资料，以便更好地了解这些气体的全球分布。拟议的研究计划将把这些群落正在进行的工作联系起来，以更好地了解生物圈对对流层组成变化的贡献。

The terrestrial biosphere plays an important role in determining the composition of the atmosphere; and changes in atmospheric composition, in turn, can significantly impact the biosphere. Reliably predicting global climate change due to changing atmospheric abundances of greenhouse gases, such as carbon dioxide (CO2), methane (CH4), and ozone (O3), will require an improved understanding of this coupling between the biosphere and the atmosphere. The proposed research program will use a coupled biosphere-atmosphere model together with advanced data assimilation techniques to exploit newly available satellite observations and surface measurements of environmentally important trace gases to better quantify the influence of the biosphere on the composition of the troposphere. In particular, the work will develop a multi-species biosphere-atmosphere data assimilation system based on a four-dimensional variational data assimilation approach, which exploits satellite observations of atmospheric gases such CO2, CH4, and O3 to optimize the parameters that govern key ecosystem processes in the biospheric model. There has been significant effort in the land-surface modelling community using satellite observations in a data assimilation context to better model biospheric processes. Similarly, there is increasing focus in the atmospheric chemistry modelling community on exploiting the growing wealth of space-based observations of environmentally important tracer gases to better understand the global distribution of these gases. The proposed research program will link the on-going work in these communities to obtain an improved understanding of the contribution of the biosphere to the changing composition of the troposphere.