Observations of Convective Boundary Layer Depth in Chico, California by Scanning Aerosol Lidar

The Raman-shifted Eye-Safe Aerosol Lidar (REAL) was operated on a daily basis from June 2013 through the time of this writing (February 2014). During this period, Range-Height Indicator (RHI) scans were routinely collected to observe the depth of the convective boundary layer (CBL). Objective identification of the CBL was previously developed and applied to other lidar data sets (e.g., Davis et al., 2000). Here, we have applied the algorithm developed by Davis et al. (2000) to the scanning REAL RHI images. This is accomplished by interpolating the polar lidar data to a Cartesian grid and applying the algorithm to all columns of the gridded data. This provides an array of CBL heights as a function of horizontal distance for each scan. The most frequently occurring CBL height for the scan is selected as a measure of CBL height for that time. We plot CBL height as a function of time for each day and compute and examine CBL height statistics for the multi-season observation period. We will present examples of RHI scans, objective CBL heights as identified by the algorithm, and plots of CBL height versus time. We expect this data set to provide confirmatory observations of CBL heights in the Northern Central Valley of California as previously shown by Bianco et al. (2011). One example of a scan image revealing a 400 meter deep CBL on 2 August 2013 at 21:25 UTC is shown below. References: Bianco, L., I. V. Djalalova, C. W. King, and J. W. Wilczak, 2011: Diurnal evolution and annual variability of boundary-layer height and its correlation to other meteorological variables in California's Central Valley, Bound. Layer Meteor., 140, 491-511. Davis, K.J., N. Gamage, C. Hagelberg, D.H. Lenschow, C. Kiemle and P.P. Sullivan, 2000. An objective method for determining atmospheric structure from airborne lidar observations. J. Atmos. Oceanic Tech., 17, 1455-1468.