Lidar measurements of the atmospheric entrainment zone and the potential temperature jump across the top of the mixed layer
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Lidar measurements of the thickness of the atmospheric entrainment zone are presented. The measurements were obtained in central Illinois during 6 days of clear-air convection.
A new method was developed to monitor the potential temperature jump across the entrainment zone. A single early morning temperature sounding and continuous lidar measurements of the mixed-layer height provide potential temperature jump values which agree well with in situ observations.
Lidar measurements of the thickness of the entrainment zone normalized by mixed-layer depth are presented as a function of a ‘convective’ Richardson number; these values show reasonable agreement with published laboratory results. The lidar observations span a wider range of mixed-layer depths and contain higher values of the normalized entrainment rate (dh/dt)/w* than those observed in tank studies. Both lidar and tank results show that simple parcel theory does not properly predict entrainment-zone thickness. During this experiment which examined mostly high entrainment conditions, the normalized entrainment-layer thickness was linearly dependent on entrainment rate.
KeywordsConvection Lidar Mixed Layer Richardson Number Entrainment Rate
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