Mixing of dust and NH<sub>3</sub> observed globally over anthropogenic dust sources release_lwv2navztzfrnaowrn3k42lhxe

by P. Ginoux, L. Clarisse, C. Clerbaux, P.-F. Coheur, O. Dubovik, N. C. Hsu, M. Van Damme

Published in Atmospheric Chemistry and Physics by Copernicus GmbH.

Volume 12, Issue 16 p7351-7363 (2012)

Abstract

&lt;strong&gt;Abstract.&lt;/strong&gt; The global distribution of dust column burden derived from MODIS Deep Blue aerosol products is compared to NH&lt;sub&gt;3&lt;/sub&gt; column burden retrieved from IASI infrared spectra. We found similarities in their spatial distributions, in particular their hot spots are often collocated over croplands and to a lesser extent pastures. Globally, we found 22% of dust burden collocated with NH&lt;sub&gt;3&lt;/sub&gt;, with only 1% difference between land-use databases. This confirms the importance of anthropogenic dust from agriculture. Regionally, the Indian subcontinent has the highest amount of dust mixed with NH&lt;sub&gt;3&lt;/sub&gt; (26%), mostly over cropland and during the pre-monsoon season. North Africa represents 50% of total dust burden but accounts for only 4% of mixed dust, which is found over croplands and pastures in Sahel and the coastal region of the Mediterranean. In order to evaluate the radiative effect of this mixing on dust optical properties, we derive the mass extinction efficiency for various mixtures of dust and NH&lt;sub&gt;3&lt;/sub&gt;, using AERONET sunphotometers data. We found that for dusty days the coarse mode mass extinction efficiency decreases from 0.62 to 0.48 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;−1&lt;/sup&gt; as NH&lt;sub&gt;3&lt;/sub&gt; burden increases from 0 to 40 mg m&lt;sup&gt;−2&lt;/sup&gt;. The fine mode extinction efficiency, ranging from 4 to 16 m&lt;sup&gt;2&lt;/sup&gt; g&lt;sup&gt;−1&lt;/sup&gt;, does not appear to depend on NH&lt;sub&gt;3&lt;/sub&gt; concentration or relative humidity but rather on mineralogical composition and mixing with other aerosols. Our results imply that a significant amount of dust is already mixed with ammonium salt before its long range transport. This in turn will affect dust lifetime, and its interactions with radiation and cloud properties.
In application/xml+jats format

Archived Files and Locations

application/pdf  3.5 MB
file_j6smy5hojnfs3hcm2dog7uxkaa
web.archive.org (webarchive)
web.archive.org (webarchive)
www.gfdl.noaa.gov (web)
www.atmos-chem-phys.net (web)
web.archive.org (webarchive)
+ 2 more URLs
application/pdf  
file_jkn6w5gokfgj7m6ckjlx7rkpqa
ntrs.nasa.gov (web)
web.archive.org (webarchive)
Read Archived PDF
Archived
Type  article-journal
Stage   published
Date   2012-08-16
Language   en ?
Container Metadata
Open Access Publication
In DOAJ
In ISSN ROAD
In Keepers Registery
ISSN-L:  1680-7316
Work Entity
access all versions, variants, and formats of this works (eg, pre-prints)
Catalog Record
Revision: d158f45d-f242-42ec-9eaf-370e9324504d
API URL: JSON