National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 2001

Lidar measurements during Aerosols99

Voss, K.J., E.J. Welton, P.K. Quinn, J. Johnson, A.M. Thompson, and H.R. Gordon

J. Geophys. Res., 106(D18), 20,821–20,831, doi: 10.1029/2001JD900217 (2001)

The Aerosols99 cruise (January 14 to February 8, 1999) went between Norfolk, Virginia, and Cape Town, South Africa. A Micropulse lidar system was used almost continually during this cruise to profile the aerosol vertical structure. Inversions of this data illustrated a varying vertical structure depending on the dominant air mass. In clean maritime aerosols in the Northern and Southern Hemispheres the aerosols were capped at 1 km. When a dust event from Africa was encountered, the aerosol extinction increased its maximum height to above 2 km. During a period in which the air mass was dominated by biomass burning from southern Africa, the aerosol layer extended to 4 km. Comparisons of the aerosol optical depth (AOD) derived from lidar inversion and surface Sun photometers showed an agreement within ±0.05 RMS. Similar comparisons between the extinction measured with a nephelometer and particle soot absorption photometer (at 19 m altitude) and the lowest lidar measurement (75 m) showed good agreement (±0.014 km–1). The lidar underestimated surface extinction during periods when an elevated aerosol layer (total AOD > 0.10) was present over a relatively clean (aerosol extinction <0.05 km–1) surface layer, but otherwise gave accurate results.

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