• Haldun Karan

      Articles written in Journal of Earth System Science

    • Wind and thermodynamic profiler observations of a late-mature gust front

      Haldun Karan

      More Details Abstract Fulltext PDF

      High temporal and vertical resolutions of kinematic and thermodynamic characteristics of a late-mature gust front are presented using the Mobile Integrated Profiling System andWeather Surveillance Radar 88 Doppler data. As the gust front passed over the Mobile Integrated Profiling System vertical velocities and the horizontal wind field with 1 and 1.5 min temporal resolutions, respectively, were sampled within the gust front updrafts, gust frontal head and body structures. A 12-channel microwave profiling radiometer was used to delineate the thermodynamic properties with 5–6 min temporal and 100 m vertical resolution. Lidar backscatter from the 0.906 𝜇m ceilometer was also used to demonstrate the cloud field and the gust front depth. The gust front structurally and dynamically resembled laboratory simulated density current, and was composed of an elevated forward protrusion of a nose, and a turbulent mixing region at the top behind the head. The updrafts associated with the gust front that was moving into a stable layer were not surface rooted. Rather, the updrafts less than 3.5 $ms^{−1}$ were observed 500 m above ground level during the gust front passage. These updrafts were present from above the nose level to top of the head. The observations indicated that kinematic and thermodynamic characteristics of the atmospheric boundary layer significantly influenced the propagation speed, updraft characteristics, and overall structural organization of the gust front. The observations validated that observed propagation speed of the gust front was in close agreement with the calculated propagation speed by integrating the buoyancy term within the gust front depth.

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