Abstract. Nitrate (NO₃⁻), an abundant aerosol in polar snow, is a complex environmental proxy to interpret owing to the variety of its sources and its susceptibility to post-depositional processes. During the last glacial period, when the dust level in the Antarctic atmosphere was higher than today by a factor up to ~25, mineral dust appears to have a stabilizing effect on the NO₃⁻ concentration. However, the exact mechanism remains unclear. Here, we present new and highly resolved records of NO₃⁻ and non-sea salt calcium (nssCa²⁺, a proxy for mineral dust) from the Roosevelt Island Climate Evolution (RICE) ice core for the period 26–40 kilo years Before Present (ka BP). This interval includes seven millennial-scale Antarctic Isotope Maxima (AIM) events, against the background of a glacial climate state. We observe a significant correlation between NO₃⁻ and nssCa²⁺ over this period and especially during AIM events. We put our observation into a spatial context by comparing the records to existing data from east Antarctic cores of EPICA Dome C (EDC), Vostok and central Dome Fuji. The data suggest that nssCa²⁺ is contributing to the effective scavenging of NO₃⁻ from the atmosphere through the formation of Ca(NO₃)₂. The geographic pattern implies that the process of Ca(NO₃)₂ formation occurs during the long-distance transport of mineral dust from the mid-latitude source regions by Southern Hemisphere Westerly Winds (SHWW) and most likely over the Southern Ocean. Since NO₃⁻ is dust-bound and the level of dust mobilized through AIM events is mainly regulated by the latitudinal position of SHWW, we suggest that NO₃⁻ may also have the potential to provide insights into paleo-westerly wind pattern during the events.

中文翻译：

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RICE冰芯，南极西部的矿尘对冰川硝酸盐记录的影响及其环境意义

摘要。硝酸盐（NO ₃ ^- ），在极地冰雪丰富的气雾剂，是一个复杂的环境代理由于各种其来源和其易感性后沉积过程来解释。在过去的冰期间，当在南极大气中的粉尘水平是高于今天由因数高达〜25℃，矿尘似乎具有对NO有稳定作用₃ ^-的浓度。但是，确切的机制仍不清楚。在这里，我们目前还没有新的和高分辨率的记录，₃ ^-和非海盐钙（nssCa ²⁺，是罗斯福岛气候演变（RICE）冰芯的26到40千年前的存在（ka BP）。在冰川期气候状态的背景下，这一间隔包括七次千年规模的南极同位素最大值（AIM）事件。我们观察NO之间的显著相关性₃ ^-和nssCa ²⁺在此期间，特别是在AIM事件。通过将记录与来自南极东部EPICA Dome C（EDC），沃斯托克和富士中部圆顶的现有数据进行比较，我们将观测结果置于空间背景中。数据表明，nssCa ²⁺正在促进NO的有效清除₃ ^-通过Ca的形成从大气（NO ₃）₂。地理格局表明，Ca（NO ₃）_2的形成过程发生在南半球西风（SHWW）从中纬度源区进行矿物粉尘的长距离运输期间，最有可能在南大洋上空进行。由于NO ₃ ^-灰尘结合和灰尘的水平，通过AIM事件主要是由SHWW的纬度位置调节动员，我们建议NO ₃ ^-也可能有事件期间提供深入了解古西风模式的潜力。