LWS TR&T Focus Teams:
Thermospheric Wind Dynamics During Geomagentic Storms and Their Influence on the Coupled Magnetosphere-Ionosphere-Thermosphere System
Target Description: The role of winds in modifying the ionosphere during geomagnetic disturbances, and how this varies with disturbance magnitude, remains an important unsolved problem in upper atmosphere science. An improved understanding of the global thermospheric wind system and the sources of its variability is essential for improving our ability to develop useful predictive models of satellite drag and ionospheric electron density variations during geomagnetic storms. Thermospheric winds, both horizontal and vertical, are excited in complex ways by magnetospheric energy and momentum inputs at high latitudes, affecting global circulation patterns and electrodynamics. The winds modify thermospheric density and composition, and strongly impact the ionosphere both directly, through ion transport, and indirectly, through influences on the production and loss of plasma and the generation of dynamo electric fields.
Recent observations and modeling developments now permit substantial progress on this question. New global observations from GPS-equipped satellites such as the COSMIC/FORMOSAT-3 constellation, CHAMP and GRACE, from CINDI observations onboard C/NOFS, and expanding ground-based networks, are providing unprecedented global coverage needed to understand the role of neutral wind dynamics. Recent developments in modeling, such as first-principles and empirically based disturbance time wind models, and the development of assimilative models that can derive winds, are useful new resources that permit substantial progress.
Goals and Measures of Success: The primary goals of this focused science topic are to improve modeling and characterization of thermospheric wind processes during disturbed periods and to improve understanding of the role of winds in ionospheric storm time dynamics. Measures of success include improved predictive capability of thermospheric winds based on solar wind inputs; development and application of new direct and indirect wind observations that measure storm-time wind dynamics on global scales; new coordinated data sets of ionospheric electron density, electric fields, and thermospheric properties; and new insights into the spatial/temporal scales of storm-time thermospheric variations that affect terrestrial space weather.
Types of Investigations: Substantial progress on this Focused Science Topic is possible with the following investigations:
• New observation and characterization of global wind field dynamics using direct and indirect measurements from ground and satellite