Abstract

The chemical composition of aerosol particles strongly influences the earth’s climate, including their effects as sediments reducing the reflectivity of snow surfaces. Source apportionment and transportation pathways of such particles help to assess their contribution to regional surface-radiative heating. The chemical composition of particles in the free troposphere was studied at the Jungfraujoch (3580 m asl) in the Swiss Alps, using the laser mass spectrometer LAMPAS 2 during the CLACE-1 campaign. Statistical methods and lab measurements of reference particles were used to investigate the source and aging of field-measured particles. Desert sand, igneous rock and river sediment were used as model systems to differentiate between aged and non-aged atmospheric particles. Dried-up snow-water particles showed a particle composition typically found at the measurement site, largely influenced by carbonaceous and organic particles from local sources. During on-line measurements between 17 and 24 March 2000, sand particles from two sandstorm events were a significant source for less-aged mineral particles. Our results show that desert-sand particles can be transported over long distances and that silicate-rich particles in particular are only slightly altered in the atmosphere. We assume that both, the carbonaceous fraction as well as the fresh mineral particles lead to a warming effect at the measurement site due to their intrinsic properties of low solubility and strong light absorption, decreasing the surface reflectivity of the Alpine snow layer. The results allow for a better assessment of environmental influences and particles’ impact on the local climate in the Alpine region at the Jungfraujoch.

Copyright © 2021 American Association for Aerosol Research

摘要

气溶胶颗粒的化学成分强烈影响地球的气候，包括其作为沉积物的作用，从而降低了雪表面的反射率。此类颗粒的来源分配和运输途径有助于评估它们对区域表面辐射加热的贡献。在CLACE-1战役期间，使用激光质谱仪LAMPAS 2在瑞士阿尔卑斯山的少女峰（3580 m asl）研究了自由对流层中粒子的化学组成。参考粒子的统计方法和实验室测量用于研究现场测量粒子的来源和老化。沙漠沙，火成岩和河流沉积物被用作模型系统，以区分老化和非老化的大气颗粒。干snow的雪水颗粒显示出通常在测量地点发现的颗粒成分，很大程度上受到本地来源的碳质和有机颗粒的影响。在2000年3月17日至24日的在线测量中，两次沙尘暴事件产生的沙粒是年龄较小的矿物粒子的重要来源。我们的结果表明，沙漠沙粒可以长距离传输，尤其是富含硅酸盐的粒子在大气中仅发生了微小变化。我们假设碳质馏分和新鲜的矿物颗粒均由于其低溶解度和强光吸收的内在特性而导致测量部位的变暖效应，从而降低了高山积雪层的表面反射率。

版权所有©2021美国气溶胶研究协会