Dayside Upper-Thermospheric Density Fluctuations as Observed by GRACE and GRACE-FO at ∼500 km Height

Park, Jaeheung; van den IJssel, J.A.A.; Siemes, C.

doi:10.1029/2022JA030976

Dayside Upper-Thermospheric Density Fluctuations as Observed by GRACE and GRACE-FO at ∼500 km Height

Title

Dayside Upper-Thermospheric Density Fluctuations as Observed by GRACE and GRACE-FO at ∼500 km Height

Author

Park, Jaeheung (Korea Astronomy and Space Science Institute; Korea University of Science and Technology)
van den IJssel, J.A.A. (TU Delft Astrodynamics & Space Missions)
Siemes, C. (TU Delft Astrodynamics & Space Missions)

Date

2023

Abstract

We statistically investigate fluctuation amplitudes (normalized to the background values) of dayside low-/mid-latitude upper-thermospheric mass density as observed by the Gravity Recovery and Climate Experiment (GRACE) and GRACE-Follow-On (GRACE-FO) spacecraft at ∼500 km altitude between 2002 and 2022. There are three new findings in our results. First, the climatology closely replicates previous studies on stratospheric and upper-thermospheric gravity waves (GWs) below the GRACE(-FO) altitudes. For example, in low-latitude regions, the fluctuations are stronger above continents than in the oceanic area. Mid-latitude fluctuations prefer the local winter hemisphere to the summer, and the South American/Atlantic region in June solstice hosts stronger fluctuations than in any other low-/mid-latitude locations or seasons. Fluctuations are more intense under lower solar activity. The above-mentioned consistency of the GRACE(-FO) results with previous lower-altitude GW studies confirms that GWs can penetrate up to 500 km. Second, the anti-correlation of upper-thermospheric GW with solar activity, which has been earlier reported for multi-year time scales, can also be identified on the scale of the solar rotation period (∼27 days). Third, we demonstrate asymmetry between pre-noon and post-noon GWs. The former exhibits stronger GW activity, which may result from the colder thermosphere being more favorable for intense mass density fluctuations via secondary/tertiary GW generation.

Subject

accelerometer
GRACE
GRACE-FO
gravity wave
upper thermosphere

To reference this document use:

http://resolver.tudelft.nl/uuid:dc1fcfb8-51b4-44d1-bf7b-e17605ed6125

DOI

https://doi.org/10.1029/2022JA030976

ISSN

2169-9380

Source

Journal Of Geophysical Research-Space Physics, 128 (1)

Part of collection

Institutional Repository