Cooperative Institute for Research in Environmental Sciences

Science Rendezvous > 2009 Posters
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Vertical Aerosol Structure And Aerosol Mixed Layer Heights Determined With Scanning Shipborne Lidars During The TexAQS II Study Study

B.J. McCarty¹,² , C.J. Senff¹,² , S.C. Tucker¹,² , W.L. Eberhard¹ , R.D. Marchbanks¹,² , J.L. Machol¹,² , W.A. Brewer¹

¹ Cooperative Institute for Research in Environmental Sciences, University of Colorado-Boulder 80309, ² NOAA Earth Systems Research Laboratory, 325 Broadway, Boulder, CO, 80305

The NOAA Earth Systems Research Laboratory (ESRL) deployed the Ozone Profiling Aerosol lidar (OPAL) on the R/V Ronald H. Brown during the summer of 2006 for the Texas Air Quality Study (TEXAQS II). Calibrated aerosol backscatter profiles were determined from data collected at 355 nm wavelength using a modified Klett retrieval method. OPAL employs a unique scan sequence that consists of staring at multiple angles between 2 and 90 degrees, which is repeated approximately every 90 seconds. Blending the data from the various elevation angles allows the extension of the aerosol backscatter profiles down to near the surface (approximately 10 meters ASL), while maintaining a high spatial resolution (5 meters). Successful application of this technique requires the aerosol distribution to be sufficiently horizontally homogeneous over several kilometers. Estimates of aerosol mixed layer height were determined by applying a Haar wavelet transform method to the calibrated aerosol backscatter profiles to detect the gradient that is often present at the top of the boundary layer. Co-located on the R/V Ronald H. Brown was NOAA/ESRL’s High Resolution Doppler LIDAR, (HRDL). Aerosol mixed layer heights were also estimated using the data from the 2 micron Doppler lidar. A comparison of the mixed layer height as determined by each of the lidar’s observations was used to choose the boundary of the layer likely connected with the surface. The vertical structure of aerosols in the lower troposphere, in particular the presence of aerosol layers above the boundary layer, is important in understanding radiative effects of aerosols. We will present aerosol backscatter structure in the lower troposphere encountered during the TexAQS II study as well as a comparison of relative aerosol content in the free troposphere compared to that within the boundary layer.