The geospace response to variable inputs from the lower atmosphere: a review of the progress made by Task Group 4 of CAWSES-II

Abstract

The advent of new satellite missions, ground-based instrumentation networks, and the development of whole atmosphere models over the past decade resulted in a paradigm shift in understanding the variability of geospace, that is, the region of the atmosphere between the stratosphere and several thousand kilometers above ground where atmosphere-ionosphere-magnetosphere interactions occur. It has now been realized that conditions in geospace are linked strongly to terrestrial weather and climate below, contradicting previous textbook knowledge that the space weather of Earth's near space environment is driven by energy injections at high latitudes connected with magnetosphere-ionosphere coupling and solar radiation variation at extreme ultraviolet wavelengths alone. The primary mechanism through which energy and momentum are transferred from the lower atmosphere is through the generation, propagation, and dissipation of atmospheric waves over a wide range of spatial and temporal scales including electrodynamic coupling through dynamo processes and plasma bubble seeding. The main task of Task Group 4 of SCOSTEP's CAWSES-II program, 2009 to 2013, was to study the geospace response to waves generated by meteorological events, their interaction with the mean flow, and their impact on the ionosphere and their relation to competing thermospheric disturbances generated by energy inputs from above, such as auroral processes at high latitudes. This paper reviews the progress made during the CAWSES-II time period, emphasizing the role of gravity waves, planetary waves and tides, and their ionospheric impacts. Specific campaign contributions from Task Group 4 are highlighted, and future research directions are discussed.

QBO, ENSO, and Solar Cycle Effects in Short‐Term Nonmigrating Tidal Variability on Planetary Wave Timescales From SABER—An Information‐Theoretic Approach

“…Consequently, short‐term (a few days) tidal variability cannot be resolved. We thus employ daily tidal diagnostics from “tidal deconvolution.” The method (Oberheide et al, 2002) has been validated and proven its usefulness for studying the short‐term variability of various diurnal tides using WINDII and SABER data (e.g., Lieberman et al, 2013, 2015; Oberheide et al, 2015; Pedatella et al, 2016).…”

Self‐acceleration and instability of gravity wave packets: 1. Effects of temporal localization

“…In such cases, GW amplitude growth with increasing altitude can be dramatic, yielding amplitudes and momentum fluxes (per unit density) that can be several or many decades larger than near the GW source [e.g., Vadas , ; Fritts and Vadas , ; Fritts and Lund , , hereafter FL11]. These various dynamics have global implications extending into the thermosphere [e.g., Oberheide et al , ; Yiğit and Medvedev , ], but their parameterizations in global models remain simplistic at present [ Kim et al , ].…”

The role of high-resolution geomagnetic field models for investigating ionospheric currents at low Earth orbit satellites

“…From this global analysis, they found that the influence of the diurnal eastward-propagating mode with wavenumber-3, DE3, is particularly strong in determining the longitudinal structure of its amplitude, e.g., during equinoxes and June solstice. This feature was also observed for other parameters in the low-latitude upper atmosphere (see for a review, e.g., Oberheide et al 2015) demonstrating the close relationship between atmospheric tides and ionospheric electrodynamics. Values for EEJ and the eastward electric field are now regularly derived from Swarm observations for each dayside orbit .…”