Quantifying the impact of biomass burning and stratosphere-troposphere exchange on tropospheric ozone using Aura data and 3-D modelling

平流层中的臭氧保护地球上的生命免受有害的紫外线辐射。然而，在对流层，它是一种有害的污染物，增加了肺病的发病率，降低了农作物的生产力。人类活动不会直接排放太多臭氧。然而，它们确实释放出许多参与形成臭氧的化学反应的分子。因此，在我们能够控制臭氧水平之前，我们需要了解这些其他分子来自哪里，以及它们是如何导致臭氧形成的。臭氧前体分子的一个主要来源是燃烧生物质：这也在其他方面造成了糟糕的空气质量。生物质燃烧造成的污染蔓延到全球各地，影响到距离污染源很远的地区。对流层的化学成分很复杂，需要详细的计算机模型才能模拟其行为。因为对流层中的一些臭氧来自平流层，所以使用一个模型来模拟这两个区域和它们之间的空气传输是有利的。Tomcat/SlimCat三维模型就是这种类型的最先进的模型。几十年来，卫星对平流层中的痕量化学物质进行了全球测量。要对对流层做同样的事情要困难得多。AURA是一颗卫星，于2004年7月发射，执行这项任务。四台仪器搭载在AURA上，其中三台进行对流层化学测量。这三种工具的运作方式不同，各有不同的长处和短处。这项提议的目的是更好地了解产生对流层臭氧的过程。为了实现这一点，我们将结合来自Aura的数据和Tomcat/SlimCat模型。首先需要评估模型与测量结果的一致性程度。为了进行这种比较，有必要在进行测量的相同时间和地点以相同的方式从模型中提取数据。评估完成后，我们打算从测量结果向后工作，以估计有多少不同的污染物分子正在排放，从而估计有多少生物质正在燃烧。我们还将估计对流层中有多少臭氧来自平流层。

Ozone in the stratosphere protects life on Earth from harmful ultraviolet radiation. In the troposphere, however, it is a harmful pollutant, increasing the incidence of lung disease and decreasing the productivity of crops. Human activities do not emit much ozone directly. However, they do emit many molecules which participate in chemical reactions which form ozone. So, before we can control the levels of ozone, we need to understand where these other molecules come from and how they cause ozone to form. A major source of ozone precursor molecules is the burning of biomass: this also contributes to poor air quality in other ways. Pollution from biomass burning spreads around the globe, affecting areas at great distances from its sources. The chemistry of the troposphere is complex, requiring detailed computer models in order to simulate its behaviour. Because some of the ozone in the troposphere comes from the stratosphere, it is advantageous to use a single model that simulates both regions and the transport of air between them. The TOMCAT/SLIMCAT three-diemnsional model is a state-of-the-art model of this type. Satellites have made global measurements of trace chemicals in the stratosphere for several decades. To do the same for the troposphere is much more difficult. Aura is a satellite, launched in July 2004, which carries out this mission. Four instruments fly on Aura of which three make measurements of tropospheric chemistry. These three instruments operate in different ways and have very different strengths and weaknesses. The purpose of this proposal is to gain an improved understanding of the processes that produce tropospheric ozone. To achieve this, we will combine data from Aura with the TOMCAT/SLIMCAT model. It will first be necessary to assess the degree to which the model agrees with the measurements. In order for this comparison to be made, it is necessary to extract data from the model at the same times and places and in the same manner as the measurements are made. With this assessment done, we then intend to work backwards from the measurements, in order to estimate how much of various pollutant molecules are being emitted and hence how much biomass is being burned. We will also estimate how much of the ozone in the troposphere comes from the stratosphere.