Turbulence in the middle atmosphere: A review

• Autor: Woodman Pollitt, Ronald Francisco
• Formato: objeto de conferencia
• Fecha de Publicación: 1980
• Institución: Instituto Geofísico del Perú
• Repositorio: IGP-Institucional
• Lenguaje: inglés
• OAI Identifier: oai:repositorio.igp.gob.pe:20.500.12816/579
• Enlace del recurso: http://hdl.handle.net/20.500.12816/579
• Nivel de acceso: acceso abierto
• Materia: Stratosphere; Turbulence; Stratospheric winds; http://purl.org/pe-repo/ocde/ford#1.05.01

The stratosphere is characterized for being highly statically stable. lt takes considerable energy to interchange parcels of air from different altitudes; thus, turbulence is normally inhibited, Wind shears of the order of 40 m/sec per kilometer are necessary to overcome the stabilizing effect of negative buoyancy if turbulence is to occur. Shears close to these values do exist in narrow but horizontally exten­sive layers as a consequence of internal gravity waves and the two­dimensional (horizontal) turbulent character of mesoscale stratospheric winds. Shorter wavelength waves, superimposed on these shears, make the local shear exceed the threshold (Richardson number < 0.25) for Kelvin­Helmholtz instabilities to occur and in turn, to break into turbulence. In addition, the shear of these waves may be enhanced by a nonlinear unstable amplification of those gravity waves whose phase velocity matches the local wind velocity. As a consequence, turbulence in the stratosphere occurs intermittently, in extensive layers from ten to a few hundred kilometers in extent, and only a few ten to a few hundred meters in thickness.