S99 Estimating the stratocumulus-topped marine boundary layer's height using wind profilers

Sunday, 23 January 2011
Aaron Pina, Aeris LLC, Louisville, CO; and L. M. Hartten and L. Bianco

Stratocumulus clouds frequently form over the cold water of the southeastern Pacific Ocean (SEP). Large in area, they affect the Earth's energy budget by blocking and reflecting solar radiation. In this region of atmospheric stability, the height of the boundary layer is at about the same elevation as the top of the stratus deck. In the fall of 2000, a 915-MHz wind profiler was mounted on the R/V Ronald H. Brown to obtain information about the depth of the stratocumulus-topped marine boundary layer at different times and locations. With the tandem of cloud-top heights and ceilometer data (heights of the cloud bases), cloud depth can be determined in order to draw further conclusions on the Earth's radiation budget; however, estimating the height of the stratocumulus-topped marine boundary layer was the scope for this research. Data from daily height-vs-time plots of relevant profiler variables (reflectivity, vertical velocity, and spectral width) for different locations during the cruise in the SEP—near the equator, near the ITCZ, and in the stratocumulus region—were examined. The plots showed data that did not seem to be atmospheric, so a procedure to clean up non-atmospheric data was implemented. The adjusted data were then inserted into a modified version of the Bianco et al. (2008) boundary layer height algorithm. Estimated heights for the marine boundary layer appeared to vary between the surface of the Earth and 1500m. The algorithm was originally designed for convective boundary layers. The near-surface heights are probably erroneous, an artifact of data characteristics expected by the algorithm. The higher, more plausible heights will also need further verification.
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