The objective of the boundary layer component of SGP97 was to determine the influence of soil moisture variations on the local surface energy budget and development of the convective boundary layer. The NRC Twin Otter and NOAA Long-EZ atmospheric research aircraft each made 27 flux-measuring flights over rural Oklahoma between June 18 and July 17, 1997. Ian MacPherson has constructed intercomparisons between the flux aircraft and tower flux measurement using the 1.5-m ER01 tower operated by the USDA /ARS over rangeland near El Reno, the 4.5-m tower operated by the University of Nebraska over tallgrass prairie in northern Oklahoma, and the 3-m tower operated by NOAA/ATDD on rangeland south of Chickasha. Good agreement is found for net radiation data and in the fluxes of momentum and sensible and latent heat, with more scatter in some of the C02 flux data.
Ron Dobosy has conducted intercomparisons between the two flux aircraft from flights in formation near the ground, at the midlevel in the convective boundary layer and near the boundary-layer top. The comparison is particularly encouraging for the difficult to measure fluctuating velocity components. To study spatial variability of the atmospheric boundary layer in response so surface evaporation, over 150 passes were flown over the "El Reno" track. Jielun Sun has studied spatial variations of surface moisture fluxes related to variations in surface land use. L. Mahrt has examined spatial variations of the moisture field related to rapid growth of the mixed layer during the morning transition period.
C.J. Senff, K.J. Davis, D.H. Lenschow, E.V. Browell and S. Ismail have been analyzing data from the NASA Langley Research Center's LIDAR Atmospheric Sensing Experiment (LASE) flown on a NASA-P3 aircraft . The LASE instrument is an airborne, downward-looking differential absorption LIDAR system capable of measuring water vapor concentration as well as aerosol backscatter with high horizontal and vertical resolution in the atmospheric boundary layer (ABL). One of the objectives of the LASE deployment during SGP97 is to study the effect of soil moisture variations on the water vapor budget in the ABL. Christa Peters-Lidard has documented the vertical structure of the boundary layer with her instrumented tethered balloon.