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Unexpected vertical structure of the Saharan Air Layer and giant dust particles during AER-D

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Unexpected vertical structure of the Saharan Air Layer and giant dust particles during AER-D

dc.contributor.author	Marenco, Franco
dc.contributor.author	Ryder, Claire
dc.contributor.author	Estellés Leal, Víctor
dc.contributor.author	O'Sullivan, Debbie
dc.contributor.author	Brooke, Jennifer
dc.contributor.author	Orgill, Luke
dc.contributor.author	Lloyd, Gary
dc.contributor.author	Gallagher, Martin
dc.date.accessioned	2019-04-10T13:49:50Z
dc.date.available	2019-04-10T13:49:50Z
dc.date.issued	2018
dc.identifier.uri	http://hdl.handle.net/10550/69836
dc.description.abstract	The Saharan Air Layer (SAL) in the summertime eastern Atlantic is typically well mixed and 3-4 km deep, overlying the marine boundary layer (MBL). In this paper, we show experimental evidence that at times a very different structure can be observed. During the AERosol properties - Dust (AER-D) airborne campaign in August 2015, the typical structure described above was observed most of the time, and was associated with a moderate dust content yielding an aerosol optical depth (AOD) of 0.3-0.4 at 355 nm. In an intense event, however, an unprecedented vertical structure was observed close to the eastern boundary of the basin, displaying an uneven vertical distribution and a very large AOD (1.5-2), with most of the dust in a much lower level than usual (0.3-2 km). Estimated dust concentrations and column loadings for all flights during the campaign spanned 300-5500 and 0.8-7.5 g m−2, respectively. The shortwave direct radiative impact of the intense dust event has been evaluated to be as large as −260±30 and −120±15 W m−2 at the surface and top of atmosphere (TOA), respectively. We also report the correlation of this event with anomalous lightning activity in the Canary Islands. In all cases, our measurements detected a broad distribution of aerosol sizes, ranging from ∼0.1 to ∼80 µm (diameter), thus highlighting the presence of giant particles. Giant dust particles were also found in the MBL. We note that most aerosol models may miss the giant particles due to the fact that they use size bins up to 10-25 µm. The unusual vertical structure and the giant particles may have implications for dust transport over the Atlantic during intense events and may affect the estimate of dust deposited to the ocean. We believe that future campaigns could focus more on events with high aerosol load and that instrumentation capable of detecting giant particles will be key to dust observations in this part of the world.
dc.language.iso	eng
dc.relation.ispartof	Atmospheric Chemistry and Physics, 2018, num. 18, p. 17655-17668
dc.source	Marenco, Franco Ryder, Claire Estellés Leal, Víctor O'Sullivan, Debbie Brooke, Jennifer Orgill, Luke Lloyd, Gary Gallagher, Martin 2018 Unexpected vertical structure of the Saharan Air Layer and giant dust particles during AER-D Atmospheric Chemistry and Physics 18 17655 17668
dc.subject	Termodinàmica atmosfèrica
dc.title	Unexpected vertical structure of the Saharan Air Layer and giant dust particles during AER-D
dc.type	journal article	es_ES
dc.date.updated	2019-04-10T13:49:50Z
dc.identifier.doi	https://doi.org/10.5194/acp-18-17655-2018
dc.identifier.idgrec	126885
dc.rights.accessRights	open access	es_ES