Browsing by Author "Fritts, David C."

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    Dynamics of the equatorial mesosphere observed using the Jicamarca MST radar during June and August 1987
    (American Meteorological Society, 1992-12) Fritts, David C.; Yuan, Li; Hitchman, Matthew H.; Coy, Lawrence; Kudeki, Erhan; Woodman Pollitt, Ronald Francisco
    The Jicamarca MST radar was used in two campaigns during June and August 1987 to measure wave influences, flow variability, and mean structure in the equatorial stratosphere and mesosphere. This paper presents observations of motions and momentum fluxes in the mesosphere during each campaign. A companion paper by Hitchman et al. addresses the mean structure and fluxes as well as comparisons with other datasets. Results presented here indicate that the equatorial mesosphere is dynamically very active, with considerable gravity-wave and tidal motions and persuasive evidence of inertial instability and wave-filtering processes. Vertical velocities at high frequencies are comparable to those observed at other locations. Hourly mean horizontal motions and momentum fluxes are Iikewise large and variable, exhibiting enormous vertical shears and strong modulation of the wave spectrum and momentum fluxes at higher frequencies. Daily mean profiles revea! persistent structures with vertical scales of -6-10 km, vertical shears ofthe meridional velocity of -0.03 s-1, and large mean momentum fluxes. Also discussed are the implications of these observations for wave forcing and instability in the equatorial middle atmosphere.
    Palabras clave:IonosphereAtmospheric PhysicsMesosphere
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    Fine-scale characteristics of temperature,wind, and turbulence in the lower atmosphere (0–1,300 m) over the south Peruvian coast
    (Springer, 2012-10-12) Balsley, Ben B.; Lawrence, Dale A.; Woodman Pollitt, Ronald Francisco; Fritts, David C.
    We report results of preliminary high-resolution in situ atmospheric measurements through the boundary layer and lower atmosphere over the southern coast of Perú. This region of the coast is of particular interest because it lies adjacent to the northern coastal edge of the sub-tropical south-eastern Pacific, a very large area of ocean having a persistent stratus deck located just below the marine boundary layer (MBL) inversion. Typically, the boundary layer in this region during winter is topped by a quasi-permanent, well-defined, and very large temperature gradient. The data presented herein examine fine-scale details of the coastal atmosphere at a point where the edge of this MBL extends over the coastline as a result of persistent onshore flow. Atmospheric data were gathered using a recently-developed in-house constructed, GPS-controlled, micro-autonomous-vehicle aircraft (the DataHawk). Measured quantities include high-resolution profiles of temperature, wind, and turbulence structure from the surface to 1,300 m.
    Palabras clave:Coastal boundary layerFine-scale measurementsIn situ measurements