An automatic collector to monitor insoluble atmospheric deposition: application for mineral dust deposition

摘要

Deposition is one of the key terms of the mineral dust cycle. However, dustdeposition remains poorly constrained in transport models simulating theatmospheric dust cycle. This is mainly due to the limited number of relevantdeposition measurements. This paper aims to present an automatic collector(CARAGA), specially developed to sample the total (dry and wet) atmosphericdeposition of insoluble dust in remote areas. The autonomy of the CARAGA canrange from 25 days to almost 1 year depending on the programmed samplingfrequency (from 1 day to 2 weeks respectively). This collector is used tosample atmospheric deposition of Saharan dust on the Frioul islands in the Gulfof Lions in the Western Mediterranean. To quantify the mineral dust mass indeposition samples, a weighing and ignition protocol is applied. Almost 2years of continuous deposition measurements performed on a weekly samplingbasis on Frioul Island are presented and discussed with air masstrajectories and satellite observations of dust. Insoluble mineraldeposition measured on Frioul Island was 2.45 g m for February toDecember 2011 and 3.16 g m for January to October 2012. Nine majormineral deposition events, measured during periods with significant MODISaerosol optical depths, were associated with air masses coming from thesouthern Mediterranean Basin and North Africa.