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Abstract. Current climate models have difficulty representing realistic wave–mean flow interactions, partly because the contribution from waves with fine vertical scales is poorly known. There are few direct observations of these waves, and most models have difficulty resolving them. This observational challenge cannot be addressed by satellite or sparse ground-based methods. The Strateole-2 long-duration stratospheric superpressure balloons that float with the horizontal wind on constant-density surfaces provide a unique platform for wave observations across a broad range of spatial and temporal scales. For the first time, balloon-borne Global Navigation Satellite System (GNSS) radio occultation (RO) is used to provide high-vertical-resolution equatorial wave observations. By tracking navigation signal refractive delays from GPS satellites near the horizon, 40–50 temperature profiles were retrieved daily, from balloon flight altitude (∼20 km) down to 6–8 km altitude, forming an orthogonal pattern of observations over a broad area (±400–500 km) surrounding the flight track. The refractivity profiles show an excellent agreement of better than 0.2 % with co-located radiosonde, spaceborne COSMIC-2 RO, and reanalysis products. The 200–500 m vertical resolution and the spatial and temporal continuity of sampling make it possible to extract properties of Kelvin waves and gravity waves with vertical wavelengths as short as 2–3 km. The results illustrate the difference in the Kelvin wave period (20 vs. 16 d) in the Lagrangian versus ground-fixed reference and as much as a 20 % difference in amplitude compared to COSMIC-2, both of which impact estimates of momentum flux. A small dataset from the extra Galileo, GLONASS, and BeiDou constellations demonstrates the feasibility of nearly doubling the sampling density in planned follow-on campaigns when data with full equatorial coverage will contribute to a better estimate of wave forcing on the quasi-biennial oscillation (QBO) and improved QBO representation in models.
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Toward Standard Radiosonde Observations of Waves and the Mean State in the 30–40-km Altitude Range Using 3-kg Balloons
Abstract Observations of temperature and wind velocity in the 30–40-km altitude layer have been sparse since elimination of the standard rocketsonde sounding network in the 1990s. In an effort to extend the vertical range of radiosonde observations into the upper stratosphere, experiments were conducted with a 3-kg balloon at Tsukuba, Japan, on 5 November 2019. Using this relatively inexpensive balloon technology, four radiosondes were launched, with two reaching above 40-km altitude. These profiles were compared with satellite and reanalysis data in the 30–40-km layer, which showed an overall good agreement and an ability of radiosondes to capture shorter vertical-scale variations. The ability to quantify gravity wave parameters from the data is described, with application to wave events detected near 38–40 km. This type of balloon will be deployed extensively in an upcoming intensive observation campaign over the Maritime Continent, which will contribute toward achieving standard radiosonde observations in the 30–40-km altitude range. This system extends the ability to provide information regarding gravity wave and planetary wave activity upward to ∼40 km.
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- Award ID(s):
- 1947658
- PAR ID:
- 10400131
- Date Published:
- Journal Name:
- Journal of Atmospheric and Oceanic Technology
- Volume:
- 39
- Issue:
- 6
- ISSN:
- 0739-0572
- Page Range / eLocation ID:
- 849 to 860
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1175/JTECH-D-21-0011.1
