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A Survey of Atmospheric Gravity Waves Observed by GOLD During Quiet to Moderate Solar and Geomagnetic Activity.

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Title: A Survey of Atmospheric Gravity Waves Observed by GOLD During Quiet to Moderate Solar and Geomagnetic Activity.
Authors: England, Scott L.1 (AUTHOR) englands@vt.edu, Zhang, Shun‐Rong2 (AUTHOR), Evans, Scott3 (AUTHOR), Eastes, Richard W.4 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. Jan2026, Vol. 131 Issue 1, p1-18. 18p.
Subject Terms: *Weather, Gravity waves, Thermosphere, Energy transfer, Ionospheric electron density, Wave mechanics
Company/Entity: United States. National Aeronautics & Space Administration
Abstract: Atmospheric gravity waves (GWs) are believed to transport energy and momentum between different regions of the atmosphere. Historically, observations of these waves from both ground and space have been relatively abundant at altitudes up to the lower thermosphere, and somewhat less abundant in the upper thermosphere and F‐region ionosphere altitudes. Much of what is known of the typical properties and occurrence of these waves at thermospheric altitudes has been inferred from their impacts on the ionospheric density and motion, as direct observations of the neutral atmosphere have been less prevalent. Gravity waves in the middle thermosphere, from ∼120–200 km altitude, have rarely been observed directly and as such, their properties at these altitudes are less well documented. NASA's Global‐Scale Observations of the Limb and Disk (GOLD) mission makes observation of the middle thermosphere during daytime. During dedicated campaigns, GOLD has been able to observe GWs in this region. This study leverages 22 such campaigns during quiet geomagnetic conditions and low to moderate solar activity levels. Waves were observed with typical periods ∼2–4 hr. Leveraging ground‐based observations, the wavelengths were identified to be between ∼1,500–5,000 km, with phase speeds ∼150–600 m/s. The waves observed were seen to propagate primarily meridionally, in agreement with prior daytime mid‐latitude observations. Using observations of the background wind, the energy and momentum fluxes carried by these waves were found. During the quiet conditions observed, the waves were seen to transport energy flux over a wide range of latitudes. Plain Language Summary: The uppermost region of our atmosphere is called the thermosphere. Observation of this region suggests that it is strongly impacted by waves traveling through our atmosphere that can originate either in this region or below. A category of these waves, called atmospheric gravity waves (GW), is believed to carry energy and momentum from where they are generated to other parts of our atmosphere. This study uses observations of atmospheric GWs in the thermosphere to determine their properties and estimate the energy and momentum they carry. The data set comes from a NASA mission called Global‐Scale Observations of the Limb and Disk (GOLD). The data were taken on days when conditions in the atmosphere were relatively quiet, meaning that known sources of very strong waves were not present. As such, the observations may be representative of more typical days. The waves seen have typical wavelengths in the range from 1,500 to 5,000 km and typical periods from 2 to 4 hr. They are seen to move over long distances, at speeds from about 150 m/s up to the sound speed in the thermosphere. Even during these quiet conditions, the energy carried by the waves is seen to be significant. Key Points: 22 GOLD gravity wave (GW) campaigns at low‐moderate activity levels reveal the properties of GWs in the neutral, middle thermosphereThe waves observed have typical periods of 2–4 hr and GOLD can track them as they propagate between equatorial and high latitudesWave amplitudes and intrinsic properties indicate that they transfer energy and momentum over large distances during quiet conditions [ABSTRACT FROM AUTHOR]
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Abstract:Atmospheric gravity waves (GWs) are believed to transport energy and momentum between different regions of the atmosphere. Historically, observations of these waves from both ground and space have been relatively abundant at altitudes up to the lower thermosphere, and somewhat less abundant in the upper thermosphere and F‐region ionosphere altitudes. Much of what is known of the typical properties and occurrence of these waves at thermospheric altitudes has been inferred from their impacts on the ionospheric density and motion, as direct observations of the neutral atmosphere have been less prevalent. Gravity waves in the middle thermosphere, from ∼120–200 km altitude, have rarely been observed directly and as such, their properties at these altitudes are less well documented. NASA's Global‐Scale Observations of the Limb and Disk (GOLD) mission makes observation of the middle thermosphere during daytime. During dedicated campaigns, GOLD has been able to observe GWs in this region. This study leverages 22 such campaigns during quiet geomagnetic conditions and low to moderate solar activity levels. Waves were observed with typical periods ∼2–4 hr. Leveraging ground‐based observations, the wavelengths were identified to be between ∼1,500–5,000 km, with phase speeds ∼150–600 m/s. The waves observed were seen to propagate primarily meridionally, in agreement with prior daytime mid‐latitude observations. Using observations of the background wind, the energy and momentum fluxes carried by these waves were found. During the quiet conditions observed, the waves were seen to transport energy flux over a wide range of latitudes. Plain Language Summary: The uppermost region of our atmosphere is called the thermosphere. Observation of this region suggests that it is strongly impacted by waves traveling through our atmosphere that can originate either in this region or below. A category of these waves, called atmospheric gravity waves (GW), is believed to carry energy and momentum from where they are generated to other parts of our atmosphere. This study uses observations of atmospheric GWs in the thermosphere to determine their properties and estimate the energy and momentum they carry. The data set comes from a NASA mission called Global‐Scale Observations of the Limb and Disk (GOLD). The data were taken on days when conditions in the atmosphere were relatively quiet, meaning that known sources of very strong waves were not present. As such, the observations may be representative of more typical days. The waves seen have typical wavelengths in the range from 1,500 to 5,000 km and typical periods from 2 to 4 hr. They are seen to move over long distances, at speeds from about 150 m/s up to the sound speed in the thermosphere. Even during these quiet conditions, the energy carried by the waves is seen to be significant. Key Points: 22 GOLD gravity wave (GW) campaigns at low‐moderate activity levels reveal the properties of GWs in the neutral, middle thermosphereThe waves observed have typical periods of 2–4 hr and GOLD can track them as they propagate between equatorial and high latitudesWave amplitudes and intrinsic properties indicate that they transfer energy and momentum over large distances during quiet conditions [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2025JA034068