Controls on surface aerosol number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet
Controls on surface aerosol number concentrations and aerosol-limited cloud regimes over the central Greenland Ice Sheet
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DOI：
10.5194/acp-2021-491
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
H. Guy;I. Brooks;K. Carslaw;B. Murray;V. Walden;M. Shupe;C. Pettersen;D. Turner;C. Cox;W. Neff;R. Bennartz;R. Neely III
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文献类型：
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作者：
H. Guy;I. Brooks;K. Carslaw;B. Murray;V. Walden;M. Shupe;C. Pettersen;D. Turner;C. Cox;W. Neff;R. Bennartz;R. Neely III
本研究提出了在格陵兰冰盖中心（72.58°N，-38.45°E，海拔 3250 m）萨米特站收集的环境表面气溶胶数浓度（凝核 > 20 nm，N20）的第一个完整年度周期（2019-2020）。 2019年地表N20平均浓度为129 cm−3，6小时平均值在1 cm−3至1441 cm−3之间。月平均浓度最高出现在春末和夏季，最低浓度出现在二月（平均值：18 cm−3），这表明与低海拔北极站（纬度 > 66°N）相比，气溶胶浓度中心的季节周期相反。高气溶胶浓度事件与格陵兰岛上空的异常反气旋环流和自由对流层气溶胶下降到地表有关，而低气溶胶浓度事件与格陵兰岛东南部的气旋环流有关，气旋环流驱动上坡气流并增强了前往顶峰途中的降水。雾强烈影响 N20 浓度，在雾形成的前三个小时内，N20 平均减少 20%。所有季节都会出现极低的 N2O 浓度 (< 10 cm−3)，我们建议 10 雾和潜在的云形成可能会受到格陵兰岛中部低气溶胶浓度的限制。
This study presents the first full annual cycle (2019-2020) of ambient surface aerosol number concentration (condensation nuclei > 20 nm, N20) measurements collected at Summit Station, in the centre of the Greenland Ice Sheet (72.58◦ N, -38.45◦ E, 3250 m asl). The mean surface N20 concentration in 2019 was 129 cm−3, with the 6 h mean ranging between 1 cm−3 and 1441 cm−3. The highest monthly mean concentrations occurred during the late spring and summer, with the minimum concentrations occurring in February (mean: 18 cm−3), demonstrating an opposite seasonal cycle in aerosol con5 centrations compared to low altitude Arctic stations (with latitudes > 66◦N). High aerosol concentration events are linked to anomalous anticyclonic circulation over Greenland and the descent of free tropospheric aerosol down to the surface, whereas low aerosol concentration events are linked to cyclonic circulation over south-east Greenland that drives upslope flow and enhances precipitation en-route to Summit. Fog strongly effects N20 concentrations, on average reducing N20 by 20% during the first three hours of fog formation. Extremely low N20 concentrations (< 10 cm−3) occur in all seasons, and we suggest that 10 fog, and potentially cloud formation, can be limited by low aerosol concentrations over central Greenland.