Abstract. The vertical flux of particles smaller than 10/xm for a saline playa surface, the particle size composition of which was classified as loam-textured, was estimated for a highly wind-erodible site on the playa of Owens (dry) Lake in California. The ratio of this vertical flux to the horizontal flux of total airborne material through a surface perpendicular to the soil and to the wind, Fa/qtot , is 2.75 x 10 -4 m -1. This is consistent with that ratio for sand-textured soils and suggests that the binding energy and size of saltating particles for the tested surface material at Owens Lake is of the same order as that for sandier soils. The horizontal mass flux of saltating grains, q, in the reported wind erosion event is 51.3% of the total horizontal mass flux qtot. Therefore the ratio of F,/q is 5.4 x 10 -4 m -•.

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Sea‐salt aerosol particles in the lowest tens of meters above the ocean are, typically, more than three‐fourths water on a volume basis. Calculations herein indicate that aqueous‐phase conversion of sulfur dioxide dissolved in the water associated with sea‐salt particles (sea‐salt aerosol water) supported the production of 2–8 nmol m−3 of nonsea‐salt sulfate (nssSO4=) during the Marine Aerosol and Gas Exchange (MAGE) experiment intensives. This production is based on ozone oxidation of dissolved SO2 in sea‐salt aerosol water and accounts for sulfur gas and ozone mass transfer limitations as a function of sea‐salt particle size. Measurements showed that 1–15 nmol m−3 of nssSO4= was actually present in the sea‐salt particle mode except for four enhanced concentration cases due to continental sulfur input. The range in predicted, as well as observed, nssSO4= was primarily due to variability in sea‐salt aerosol water volume. The nssSO4= produced by ozone oxidation of sulfur dioxide, being in the sea‐salt particle mode with observed volume geometric median diameter of 3.5–5 μm, is dry deposited at a fairly rapid rate. The remainder, being large‐particle cloud condensation nuclei, may contribute little to cloud albedo over the global oceans. The two papers following this one, Kim et al. (this issue) on aerosol size distribution and water content and Parfai et al. (this issue) on compositional variations of sea‐salt‐mode aerosol particles observed by electron microscopy, complement and support results presented here. All three present results of the MAGE experiment and precede a forthcoming special issue of the Journal of Geophysical Research‐Atmospheres on MAGE (B. Huebert, guest editor).

A joint United States/Russian/French collaborative experiment was undertaken in March 1993 and March 1996. Projects LODE I and II (Lake Owens Dust Experiments) took place on the anthropogenically desertified playa (dry lakebed) and surrounding regions of Owens Lake, in east-central California. One of the five parts of Project LODE was to determine relationships between optical depth and flux of dust emitted from the dry lake. Project LODE II included subsequent dust plume measurements and size distributions obtained through April 1996, to further refine the flux measurements for distinct mineral aerosol source regions at Owens Lake.Size distributions of dust aerosol were determined and aerosol optical depths were calculated from sunphotometer solar extinction measurements taken downwind in plumes coming from the emissive areas of Owens Lake. This source was visually observed for 10 measured dust storms. The plume mass was calculated to be 1Á5 Â 10 9 g using ground-based measurements and !1Á6 Â 10 9 g from satellite data. Project LODE II results were found to be consistent with LODE I results for the south end of the playa, but flux values were found to be reduced for the northeastern portion of the playa by comparison. Vertical flux values estimated by sunphotometry were found to be consistent with values estimated via a micrometeorological method.

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