GOES Multispectral Signatures of Nocturnal Stratocumulus

Dr. Melanie A. Wetzel

Division of Atmospheric Sciences, Desert Research Institute

Data collected during the July 2001 DYCOMS-II (Dynamics and Chemistry of Marine Stratocumulus-II) project offshore southern coastal California are being used to evaluate night-time evolution in marine boundary layer (MBL) cloud fields as observed with satellite remote sensing techniques and mesoscale model forecasts. GOES multispectral imagery obtained at 15-minute intervals in near-infrared and thermal infrared channels during research flights by the NCAR C-130 provides a unique opportunity to characterize changes in cloud top temperature, cloud fraction and cloud microphysical parameters as nocturnal radiative cooling progresses. Temporal analysis of the GOES data reveals that the cloud layer becomes more homogeneous during the night, with a decrease in the spatial average and standard deviation for both the near-IR and IR brightness temperatures within the research area. These observations suggest a strengthening of the inversion in association with the radiative cooling at cloud top. Verification of the satellite-observed multispectral signatures for evolving stratocumulus is possible through use of datasets collected aboard the NCAR aircraft by several research groups, including the University of Wyoming, that have collaborated during the DYCOMS program.