Collaborative Research: SNOWpack Photodenitrification from the Antarctic and Arctic Cryosphere (SNOWPAAC)

了解大气硝酸盐对南极洲和格陵兰岛极地冰盖的不同来源及其运输路径的重要性，对极地氮氧化物的大气化学具有内在的兴趣。反过来，硝酸盐积雪的表面光解作用使这些冰盖在阳光下成为强氧化表面。试图从冰芯记录中得出大气NOx （= NO + NO2 +?）种类的过去条件或变异性，将需要考虑光反硝化和源传递函数效应。该方法将继续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硝酸盐沉积对南极大陆的敏感性。提出了以下问题：1)在现在和工业化前全新世，对南极洲（和格陵兰岛）来说，硝酸盐的重要来源是什么？2)大气-雪界面活性氮的再循环如何在大型极地冰盖上重新分配硝酸盐？3)它们对冰芯中硝酸盐保存的影响及其解释？这项模拟研究的目标包括重建过去（极地）大气成分，以及更好地了解当代大气活性氮化合物的变异性，这可以从测量极地地区雪、雪和可能的冰芯中保留的硝酸盐浓度中辨别出来。

The importance of knowing the different sources of atmospheric nitrate to the polar ice sheets of Antarctica and Greenland, along with their transport paths, is of intrinsic interest to the atmospheric chemistry of polar NOx species. In turn, surface photolysis of snowpack nitrate renders these ice sheets as strongly oxidizing surfaces during sunlight. Attempts to derive past conditions or variability of atmospheric NOx (= NO + NO2 +?) species from ice core records will need to take photodenitrification and source transfer function effects into account. The approach willcontinue to use a inverse chemical transfer model (adjoint GEOS-Chem) to test the sensitivity of nitrate deposition to the Antarctic continent from various possible sources. The following questions are posed: 1) what are the important sources of nitrate to Antarctia (and Greenland) in the present and in the pre-industrial Holocene? 2) How does the recycling of reactive nitrogen at the atmosphere-snow interface redistribute nitrate across large polar ice sheets? and 3) are their implications for nitrate preservation in ice cores and their interpretation?Goals being pursued in this modeling study include the reconstruction of past (polar) atmospheric composition and a better contemporary understanding of the variability of atmospheric reactive nitrogen compounds as may be discerned from measurements of nitrate concentrations retained in snow, firn and possibly ice cores in polar regions.