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Final results of the CONDORS convective diffusion experiment

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Abstract

TheConvectiveDiffusionObserved byRemoteSensors (CONDORS) field experiment conducted at the Boulder Atmospheric Observatory used innovative techniques to obtain three-dimensional mappings of plume concentration fields, χ/Q, of oil fog detected by lidar and “chaff” detected by Doppler radar. It included extensive meteorological measurements and, in 1983, tracer gases measured at a single sampling arc. Final results from ten hours of elevated and surface release data are summarized here. Many intercomparisons were made. Oil fog χ/Q measured 40m above the arc are mostly in good agreement withSF 6 values, except in a few instances with large spacial inhomogeneities over short distances. After a correction scheme was applied to compensate for the effect of its settling speed, chaff ∫χ dy/Q agreed well with those of oil except in two cases of oil fog “hot spots”. Mass or frequency distribution vs. azimuth or elevation angle comparisons were made for chaff, oil, and wind, with mostly good agreements. Spacial standard deviations, σy and σz, of chaff and oil agree overall and are consistent at short range with velocity standard deviations σvand σw ≈ 0.6w* (the convective scale velocity), as measured atz>100m. Surface release σy is enhanced up to 60% at smallx, consistent with the Prairie Grass measurements and with larger σv and reduced wind speed measured near the surface. Decreased σy at small dimensionless average times is also noted. Finally, convectively scaled ∫χ dy, C y, were plotted versus dimensionlessx andz for oil, chaff, and corrected chaff for each 30–60 min period. Aggregated CONDORSC y fields compare well with laboratory tank and LES numerical simulations; surface-released oil fog compares expecially well with the tank experiments. However, large deviations from the norm occurred in individual averaging periods; these deviations correlated strongly with anomalies in measured ω distributions.

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On assignment to the US Environmental Protection Agency, Atmospheric Research and Exposure Assessment Laboratory, RTP, NC.

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Briggs, G.A. Final results of the CONDORS convective diffusion experiment. Boundary-Layer Meteorol 62, 315–328 (1993). https://doi.org/10.1007/BF00705562

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Keywords

  • Lidar
  • Elevation Angle
  • Convective Diffusion
  • Doppler Radar
  • Surface Release