Collaborative research: Quantifying the Sensitivity of Antarctic Snowpack Nitrate to Primary NOx Sources and Photodenitrification: Implications for the Ice Core Record

大气中活性态氮的形成、运输和再循环过程对全球空气质量、大气营养物沉积和控制大气的长期氧化能力具有重要意义。氮氧化物气体（NOx = NO + NO2）也是重要的温室气体。这项模拟研究的最终目标是了解过去（极地）大气成分，并通过更好地计算当代大气活性氮化合物的可变性，这可以从南极大陆的雪、雪和冰芯中保留的硝酸盐浓度的测量中辨别出来。该方法将使用逆化学转移模型（附带GEOS-Chem）来测试来自各种可能来源的南极冰对硝酸盐沉积的敏感性。通过将积雪辐射传输子程序整合到化学输运模式中，将利用在南极内陆和沿海观测点计算的积雪氮氧化物通量与观测的通量进行比较来参数化光反硝化速率。使用开发的建模工具要研究的另一个问题是，在雪表面进行光解作用的硝酸盐浓度有多少会被再循环到大气中，或者保存在增加的冰中。

The processes that form, transport and recycle the reactive forms of nitrogen in the atmosphere are important in global air quality, atmospheric nutrient deposition, and for controlling the long term oxidation capacity of the atmosphere. The NOx gases (NOx = NO + NO2) are also important greenhouse gases. The ultimate goal being pursued in this modeling study is the understanding of past (polar) atmospheric composition, and through a better accounting of the variability of contemporary atmospheric reactive nitrogen compounds as may be discerned from measurements of nitrate concentrations retained in snow, firn and ice cores on the Antarctic continent. The approach will use a inverse chemical transfer model (adjoint GEOS-Chem) to test the sensitivity of nitrate deposition to Antarctic ice from various possible sources. By integrating a snowpack radiative transfer subroutine into the chemical transport model, comparisons of calculated with observed fluxes of snowpack NOx at some observed inland and coastal Antarctic sites are to be used to parameterize photdenitrification rates. An additional question to be investigated with the developed modeling tools is what fraction of the nitrate concentration undergoing photolysis at the snow surface is recycled back to the atmosphere, or else preserved in the accreting ice.