Abstract
Abstract. Detailed 3-D structures of Trans-Pacific Asian dust transport occurring during 5–15 May 2007 were investigated using the NASA/CALIOP vertical-resolved measurements and a three-dimensional aerosol model (SPRINTARS). Both CALIOP and SPRINTARS dust extinctions showed a good agreement along the way of the transport from the dust source regions across North Pacific into North America. A vertically two-layered dust distribution was observed over the northeastern Pacific and North America. The lower dust layer originated from a dust storm generated in the Gobi Desert on 5 May. It was transported at an altitude of around 4 km MSL and has mixed with Asian anthropogenic air pollutants during the course of transport. The upper dust layer mainly originated from a dust storm that occurred in the Taklimakan Desert 2–3 days after the Gobi dust storm generation. The upper dust cloud was transported in higher altitudes above the major clouds layer during the Trans-Pacific transport. It therefore has remained unmixed with the Asian air pollutants and almost unaffected by wet removal. The decay of its concentration level was small (only one-half after its long-distance transport crossing the Pacific). Our dust budget analysis revealed that the Asian dust flux passing through the longitude plane of 140° E was 2.1 Tg, and one third of that arrived North America. The cases analyzed in this study revealed that, while the Gobi Desert is an important source that can contribute to the long-range dust transport, the Taklimakan Desert appears to be another important source that can contribute to the dust transport occurring particularly at high altitudes.
Highlights
Trans-Pacific transport of mineral dust and air pollutants originating from Asia to North America is well known, based on ground-based and satellite measurements and dust transport model analyses
We examined the daily change of the Asian dust cloud transport from the source region to North America occurring during 5–15 May 2007
We presented a 3-D analysis of Asian dust transport processes over the Northern Pacific Ocean occurring during 5–15 May 2007, based on the vertical-resolved dust www.atmos-chem-phys.net/9/3137/2009/
Summary
Trans-Pacific transport of mineral dust and air pollutants originating from Asia to North America is well known, based on ground-based and satellite measurements and dust transport model analyses. The average traveling time from Asia to the west coast of North America is approximately 7–10 days Both mineral dust and air pollutants can be transported simultaneously (e.g. Uematsu et al, 1983; Jaffe et al, 1999; Uno et al, 2001; Takemura et al, 2002a). This indirect effect of Asian dust on the climate and its changes has remained unexplored Satellite measurements such as the TOMS (OMI) Aerosol Index (AI) and the RGB image sensing provide useful information for elucidating the dust horizontal distribution and day-by-day transport evolution.
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