Accession Number : ADA188355

Title :   Coincident Lidar and Aircraft Observations of Entrainment into Thermals and Mixed Layers.

Descriptive Note : Journal article,

Corporate Author : AIR FORCE GLOBAL WEATHER CENTRAL OFFUTT AFB NE

Personal Author(s) : Crum, Timothy D ; Stull, Roland B ; Eloranta, Edwin W

PDF Url : ADA188355

Report Date : Jul 1987

Pagination or Media Count : 16

Abstract : Coincident observations of the daytime convective boundary layer over Oklahoma were made with the NCAR Queen Air aircraft and the University of Wisconsin ground-based lidar. The two data sets have been merged to provide a unique visual representation of the temperature, moisture, vertical velocity, turbulent kinetic energy and the momentum fluxes in a field of thermals. These data show that horizontal moisture profiles observed in thermals penetrating the entrainment zone tend to exhibit more of a top-hat profile than the corresponding temperature or vertical velocity profiles. The specific humidities observed at various heights including cloud base 1) are frequently nearly constant along the horizontal tracks within each thermal; 2) show thermal-to-thermal variability; and 3) have values nearly the same as found in the surface layer. This paper also proposes the concept of an intromission zone describing the zone of lateral entrainment at the edges of active thermals. For the data studied here, a lateral entrainment velocity of 0.3 m per sec was observed. Keywords include: Weather, Weather reconnaissance aircraft, Physics, Atmospheric physics, Meteorology, Meteorological phenomena, Meteorological instruments, Atmospheric profiles, Temperature, Moisture, Thermal fields, Convective boundary layer, Horizontal moisture zone, Vertical velocity, Lateral entrainment, Intromission zone, Weather instrumentation, Weather measuring instruments, Lidar, and Aircraft weather observations.

Descriptors :   *ATMOSPHERIC PHYSICS, *METEOROLOGICAL DATA, *METEOROLOGICAL INSTRUMENTS, *METEOROLOGICAL PHENOMENA, *METEOROLOGY, *OPTICAL RADAR, *THERMAL PROPERTIES, *WEATHER, *WEATHER RECONNAISSANCE AIRCRAFT, AIR, AIRCRAFT, BOUNDARY LAYER, CONVECTION, DATA BASES, ENTRAINMENT, GROUND LEVEL, HORIZONTAL ORIENTATION, INSTRUMENTATION, KINETIC ENERGY, LAYERS, MEASURING INSTRUMENTS, MIXED LAYER(MARINE), MOISTURE, MOMENTUM, PHYSICS, PROFILES, SURFACES, TURBULENCE, VELOCITY, VERTICAL ORIENTATION, VISION, WISCONSIN

Subject Categories : Meteorology
      Atmospheric Physics
      Active & Passive Radar Detection & Equipment
      Patrol and Reconnaissance Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE