Observational Study of the 'Interstate 5' Dust Storm Case

摘要

On 29 November 1991 a series of collisions involving 164 vehicles occurred onInterstate 5 in the San Joaquin Valley in California in a dust storm that reduced visibility to near zero. The accompanying high surface winds are hypothesized to result from intense upper tropospheric downward motion that led to the formation of a strong upper front and tropopause fold and that transported high momentum air downward to midlevels where boundary layer processes could then mix it to the surface. The objectives of the research presented in this paper are to document the event, to provide support for the hypothesis that both upper level and boundary layer processes were important, and to determine the structure of the mesoscale circulations in this case for future use in evaluating the Navy's mesoscale data assimilation system.