Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign
<p>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 observation...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-12-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/22/15379/2022/acp-22-15379-2022.pdf |
| _version_ | 1797985301894791168 |
|---|---|
| author | B. Cao J. S. Haase M. J. Murphy M. J. Alexander M. Bramberger A. Hertzog |
| author_facet | B. Cao J. S. Haase M. J. Murphy M. J. Alexander M. Bramberger A. Hertzog |
| author_sort | B. Cao |
| collection | DOAJ |
| description | <p>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 (<span class="inline-formula">∼20</span> km) down to 6–8 km altitude, forming an orthogonal pattern of observations over a broad area (<span class="inline-formula">±400</span>–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.</p> |
| first_indexed | 2024-04-11T07:15:54Z |
| format | Article |
| id | doaj.art-c0377bc41be24ed3ac8ece28cd5dde4b |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-11T07:15:54Z |
| publishDate | 2022-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-c0377bc41be24ed3ac8ece28cd5dde4b2022-12-22T04:37:59ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242022-12-0122153791540210.5194/acp-22-15379-2022Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaignB. Cao0J. S. Haase1M. J. Murphy2M. J. Alexander3M. Bramberger4A. Hertzog5Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USAInstitute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USAInstitute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA, USANorthWest Research Associates, Boulder Office, Boulder, CO, USANorthWest Research Associates, Boulder Office, Boulder, CO, USALaboratoire de Météorologie Dynamique, Sorbonne Université, École Polytechnique, CNRS, Palaiseau, France<p>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 (<span class="inline-formula">∼20</span> km) down to 6–8 km altitude, forming an orthogonal pattern of observations over a broad area (<span class="inline-formula">±400</span>–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.</p>https://acp.copernicus.org/articles/22/15379/2022/acp-22-15379-2022.pdf |
| spellingShingle | B. Cao J. S. Haase M. J. Murphy M. J. Alexander M. Bramberger A. Hertzog Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign Atmospheric Chemistry and Physics |
| title | Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign |
| title_full | Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign |
| title_fullStr | Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign |
| title_full_unstemmed | Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign |
| title_short | Equatorial waves resolved by balloon-borne Global Navigation Satellite System radio occultation in the Strateole-2 campaign |
| title_sort | equatorial waves resolved by balloon borne global navigation satellite system radio occultation in the strateole 2 campaign |
| url | https://acp.copernicus.org/articles/22/15379/2022/acp-22-15379-2022.pdf |
| work_keys_str_mv | AT bcao equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign AT jshaase equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign AT mjmurphy equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign AT mjalexander equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign AT mbramberger equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign AT ahertzog equatorialwavesresolvedbyballoonborneglobalnavigationsatellitesystemradiooccultationinthestrateole2campaign |