A field program was carried out in the greater metropolitan area of St. Louis, MO during February and July of 1975 as part of the Regional Air Pollution Study (RAPS). The purpose of the program was to collect atmospheric measurements needed for future studies of the planetary boundary layer (PBL) over urban and industrial areas and surrounding rural areas. The overall goals of the PBL study are to (1) describe the thermodynamic, wind and turbulence fields over the region; (2) determine the magnitude and vertical variation of the vertical fluxes of heat, moisture and momentum as a function of land use; (3) obtain estimates of the exchange coefficients of these variables; and (4) determine the dependence of turbulence intensity on land use. Pilot-balloon stations provided simultaneous measurements of the wind profile with vertical resolution. Tethered-balloon sounding systems yielded thermodynamic and wind profiles. An airplane equipped with meteorological instruments provided measurements of the three components of wind velocity and of high frequency fluctuations in velocity, temperature and humidity. Observational periods, or missions, were scheduled for 3- or 4-hour durations during field experiments. The objectives included (a) mapping missions to delineate the thermodynamic, wind and turbulent fields over the region, (b) flux missions to provide estimates of the true vertical fluxes of momentum, heat and moisture simultaneously with vertical profiles of these variables, and (c) nocturnal missions to provide information on the strength of the nocturnal heat island circulation.

Project Officer: James L. McElroy. Illinois State Water Survey "November 1977"--Cover. "EPA-600/4-77-045"--Cover.