CGRG Bibliography of Canadian Geomorphology
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Author : Gill, T.E.; Vet, R.; Biscaye, P.E.; Paktunc, D.; Bory, A.; Doggett, A.L.; Conway, I.V.F.; and Lance, N.
Date : 2002.
Title : A trans-North-America dust storm 6-7 April 2001: mineral aerosol transport from Mexico and the southwestern USA to Canada.
Publication : American Geophysical Union 2002 Fall Meeting, Moscone Center, San Francisco, California, 6-10 December 2002.
Issue :
Page(s) :
Abstract
A major dust storm impacted large parts of southwestern North America in Chihuahua, Mexico, and in Texas and New Mexico, USA, on 6 April, 2001. During the following two days, precipitation chemistry samples collected in the Province of Ontario, Canada and in central Pennsylvania, USA by the Canadian Air and Precipitation Monitoring Network (CAPMoN) were found to contain unusually large amounts of dust. Meteorological analysis of air mass trajectories and geochemical characterization of the particles in the precipitation samples attribute the dust to the Mexico-US dust storm of 6 April. On 5 April 2001, a strong jet maximum with winds exceeding 150 kts passed through the base of a deep upper-level trough extending into northern Mexico. Downward mixing of high-momentum air facilitated emission of dust plumes by the morning of 6 April within a "hotspot" region of playas and disturbed soils in the Chihuahuan Desert of northern Mexico. These plumes merged and advected into southeastern New Mexico and western Texas. Separately, a rapidly deepening surface cyclone in Colorado, a dryline across the Texas Panhandle, and a Pacific cold front entering from the west caused widespread wind erosion across the Southern High Plains of Texas and New Mexico. Large mineral aerosol plumes converged over the Southern High Plains region late in the afternoon of 6 April, causing dust-storm conditions in the vicinity of Lubbock, Texas. Major and trace element analysis suggest a regional co-genesis of all of the dust samples. Mineralogical (XRD) analysis yields a very similar dust composition for four of the rain sampling locations in Ontario. The other two -- one located near Sault Saint Marie, Ontario and the other in central Pennsylvania -- have some mineralogical affinities to the others, but are also different. Air mass trajectories from the Chihuahuan Desert/eastern New Mexico/western Texas region during the period of the dust storm indicate that dust was transported to the receptor sites along two different transport paths. The dust generated in the northern Chihuahuan Desert source region apparently was transported to the north, incorporated into the circulation of the cyclone, and eventually wet-deposited across northern Ontario. The dust generated in the southern Chihuahuan Desert source region was apparently transported to the northeast and eventually wet-deposited in southern Ontario and central Pennsylvania. Sr and Nd isotopic compositions of the washed-out dust tend to confirm this meteorological analysis of its provenance. The composition of the particles in the precipitation samples was also compared to the composition of dry dustfall from the 6 April event at Lubbock, Texas. Major differences were found between the latter and the wet-precipitation samples from farther north, suggesting that the dust in Lubbock comprised a composite of local particles generated along the path of the dust storm as it moved from the Chihuahuan Desert into west Texas. The dusts from this intra-North American event are mineralogically and isotopically distinct from those that arrived in North America from Eastern Asia several days afterward.
Bibliography of Canadian Geomorphology