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Ejection of Dust From the Ocean as a Potential Source of Marine Ice Nucleating Particles
Journal of Geophysical Research: Atmospheres ( IF 4.4 ) Pub Date : 2020-10-14 , DOI: 10.1029/2020jd033073
Gavin C. Cornwell 1, 2 , Camille M. Sultana 1 , Marje Prank 3 , Richard E. Cochran 1 , Thomas C. J. Hill 4 , Gregory P. Schill 4 , Paul J. DeMott 4 , Natalie Mahowald 3 , Kimberly A. Prather 1, 5
Affiliation  

Oceans are, generally, relatively weak sources of ice nucleating particles (INPs). Thus, dust transported from terrestrial regions can dominate atmospheric INP concentrations even in remote marine regions. Studies of ocean‐emitted INPs have focused upon sea spray aerosols containing biogenic species. Even though large concentrations of dust are transported over marine regions, resuspended dust has never been explicitly considered as another possible source of ocean‐emitted INPs. Current models assume that deposited dust is not re‐emitted from surface waters. Our laboratory studies of aerosol particles produced from coastal seawater and synthetic seawater doped with dust show that dust can indeed be ejected from water during bubble bursting. INP concentration measurements show these ejected dust particles retain ice nucleating activity. Doping synthetic seawater to simulate a strong dust deposition event produced INPs active at temperatures colder than −13°C and INP concentrations 1 to 2 orders of magnitude greater than either lab sea spray or marine boundary layer measurements. The relevance of these laboratory findings is highlighted by single‐particle composition measurements along the Californian coast where at least 9% of dust particles were mixed with sea salt. Additionally, global modeling studies show that resuspension of dust from the ocean could exert the most impact over the Southern Ocean, where ocean‐emitted INPs are thought to dominate atmospheric INP populations. More work characterizing the factors governing the resuspension of dust particles is required to understand the potential impact upon clouds.

中文翻译:

从海洋喷出的灰尘是海洋冰核颗粒的潜在来源

通常,海洋是冰核颗粒(INPs)的相对较弱的来源。因此,即使在偏远的海洋地区,从陆地地区运来的灰尘也可以控制大气中INP的浓度。海洋排放的INP的研究集中于含有生物物种的海浪气溶胶。即使大量的粉尘在海洋区域上空运输,但从未明确将重悬的粉尘视为海洋排放的INP的另一种来源。当前的模型假定沉积的灰尘不会从地表水中重新排放。我们对沿海海水和掺有粉尘的合成海水产生的气溶胶颗粒的实验室研究表明,气泡破裂期间确实可以从水中喷射出粉尘。INP浓度测量表明,这些喷出的灰尘颗粒保留了冰核活性。掺杂合成海水以模拟强烈的粉尘沉积事件,产生的INP在低于-13°C的温度下具有活性,并且INP的浓度比实验室海喷雾或海洋边界层的测量值大1至2个数量级。这些实验室发现的相关性在加利福尼亚海岸沿线的单颗粒组成测量中得到了强调,在该海岸上至少有9%的尘埃颗粒与海盐混合。此外,全球建模研究表明,海洋中的尘埃再悬浮可能对南部海洋产生最大影响,在南部海洋中,海洋中的INP被认为是大气INP种群的主要来源。为了了解对云的潜在影响,需要开展更多工作来表征尘埃颗粒重悬的因素。
更新日期:2020-12-23
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