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| Titel |
A pervasive and persistent Asian dust event over North America during spring 2010: lidar and sunphotometer observations |
| VerfasserIn |
P. Cottle, K. Strawbridge, I. McKendry, N. O'Neill, A. Saha |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 9 ; Nr. 13, no. 9 (2013-05-02), S.4515-4527 |
| Datensatznummer |
250018623
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| Publikation (Nr.) |
 copernicus.org/acp-13-4515-2013.pdf |
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| Zusammenfassung |
| Among the many well-documented cases of springtime trans-Pacific transport of
crustal dust from Asia to North America (significant events include those of
1998, 2001, and 2005), the events of March and April 2010 were extraordinary
both in the extent of the dust distribution and in the unique meteorological
conditions that caused the dust layers in the free troposphere to linger and
be detectable across Canada and the northern United States for over a month.
This study focuses on extending previous research by combining data from
CORALNet (Canadian Operational Research Aerosol Lidar Network) lidars in Vancouver, BC, and Egbert, ON, with AERONET (AErosol RObotic NETwork) sunphotometer
retrievals and model results from HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) and NAAPS (Navy Aerosol Analysis and Prediction System) to monitor the arrival
and distribution of dust layers across North America. This is the first
documented instance of lidar detection of Asian dust from the Egbert CORALNet
installation, where layers identified as dust using depolarization ratios
corresponded with retrievals of coarse-mode optical depth at the co-located
AEROCAN/AERONET site. In Vancouver dust layer depolarization ratios varied
from 0.27 for dust above 6 km to less than 0.10 for the first
1.5–2 km above the surface. Similar layers of elevated dust exhibited
much lower volume depolarization ratios for all altitudes in Egbert, ON, where
maximum depolarization ratios stayed below 0.15 for all layers from
2–8 km with no clear variation with altitude, or over time. The
relative lack of variation is an indication that as the layers of dust were
transported across North America the rates of change in their optical
properties slowed. HYSPLIT back trajectories performed throughout the free
troposphere above these sites showed a majority of air parcels originating
from central Asia on the days in question. Using these techniques, it was
shown that elevated layers of aerosol reaching the west coast of North
America as early as 17 March also included dust from the same central Asian
sources, extending the known duration of the 2010 event by almost a full
month. |
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