Three-dimensional simulation of quasiperiodic perturbations attributed to solar activity effects in the middle atmosphere
Abstract
Weak atmospheric perturbations induced in the upper stratosphere and their role for the generation of temperature and wind fluctuations are studied using a mechanistic 3-D numerical model of the middle atmosphere with prescribed simple flow patterns. The aim of the simulation experiments is to explore the dynamical response of the atmosphere to possible forcing by solar activity effects at time scales between about 2 and 4 weeks (solar rotation). This forcing is modeled by temperature perturbations of different spatial structure (and with a period of 13.6 d only, to save computer time). Special emphasis is given to the investigation of downward propagation of the perturbations. The experiments show that mean zonal wind fields with reduced inertial stability at lower latitudes lead to detectable dynamical responses of roughly the same magnitude as found from statistical studies below the level of forcing. The spatial structure of the response signal crucially depends on the latitudinal extension of the forcing which results in a modulation of the prescribed flow by transient wave-like disturbances of planetary scale.
- Publication:
-
Annales Geophysicae
- Pub Date:
- August 1986
- Bibcode:
- 1986AnGeo...4..287D
- Keywords:
-
- Atmospheric Temperature;
- Middle Atmosphere;
- Solar Activity Effects;
- Solar Terrestrial Interactions;
- Three Dimensional Models;
- Wind Variations;
- Atmospheric Models;
- Geopotential Height;
- Solar Rotation;
- Stratosphere;
- Zonal Flow (Meteorology)