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

摘要大气中活性态氮的形成、输送和循环过程对全球空气质量、大气养分沉积和控制大气长期氧化能力具有重要意义。NOx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的(极地)大气成分，并通过更好地解释当代大气活性氮化合物的变异性，这可以从对南极大陆雪、雪和冰芯中保留的硝酸盐浓度的测量中看出。该方法将使用反向化学转移模型(伴随的GEOS-Chem)来测试硝酸盐沉积对来自各种可能来源的南极冰的敏感性。通过将积雪辐射传输子程序集成到化学输送模式中，将南极内陆和沿海一些观测站点的积雪NOx通量的计算与观测进行比较，以确定光反硝化速率的参数。利用开发的建模工具需要研究的另一个问题是，在雪面上经历光解的硝酸盐浓度中，有多少被回收回大气中，或者保存在积累的冰中。

AbstractThe 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.