Stratéole/Vorcore—Long-duration, Superpressure Balloons to Study the Antarctic Lower Stratosphere during the 2005 Winter

Abstract

In September and October 2005, the Stratéole/Vorcore campaign flew 27 superpressure balloons from McMurdo, Antarctica, into the stratospheric polar vortex. Long-duration flights were successfully achieved, 16 of those flights lasting for more than 2 months. Most flights were terminated because they flew out of the authorized flight domain or because of energy shortage in the gondola. The atmospheric pressure (1-Pa precision) was measured every minute during the flights, whereas air temperature observations (0.25-K accuracy) and balloon positions (absolute GPS observations, 10-m accuracy) were obtained every 15 min. Fifteen-minute-averaged horizontal velocities of the wind were deduced from the successive balloon positions with a corresponding accuracy Շ0.1 m s Ϫ1 . The collected dataset (more than 150 000 independent observations) provides a thorough high-resolution sampling of the polar lower stratosphere in the Southern Hemisphere from its wintertime state up to the establishment of the summer circulation in December-January. Most of the balloons stayed inside the vortex until its final breakdown, although a few were ejected toward the midlatitudes in November during filamention events associated with an increase in planetary wave activity. The balloons behaved as quasi-Lagrangian tracers during the first part of the campaign (quiescent vortex) and after the vortex breakdown in early December. Large-amplitude mountain gravity waves were detected over the Antarctic Peninsula and caused one flight termination associated with the sudden burst in the balloon superpressure.

Gravity waves over Antarctica and the Southern Ocean: consistent momentum fluxes in mesoscale simulations and stratospheric balloon observations

“…The balloon observations from the Vorcore campaign (Hertzog et al, 2007) provide a unique database of in situ measurements well adapted to quantifying GWs, with a large spatial and temporal coverage. The simulations were run with the WRF model, with a resolution of x = 20 km and 120 levels in a domain 10 000 × 10 000 km centred on the Pole.…”

“…Superpressure balloons are well suited for observing internal GWs; because the balloons drift as quasi-Lagrangian tracers, they provide direct access to the intrinsic frequencies of the phenomena they sample. The Vorcore campaign (Hertzog et al, 2007) consisted of 27 super-pressure balloons launched during the austral spring of 2005, from 5 September to 28 October. The last balloon fell on 1 February 2006.…”

Recent developments in gravity‐wave effects in climate models and the global distribution of gravity‐wave momentum flux from observations and models

“…Hence these balloons drift on constant-density (isopycnic) surfaces in the atmosphere, and are capable of long-duration flights (up to several months) that cover wide geographical areas (TWERLE Team, 1977;Hertzog et al, 2007). Observations of meteorological variables made at regular time intervals along the flight permit detection of disturbances associated with gravity waves.…”

Sensitivity study for mesoscale simulations of gravity waves above Antarctica during Vorcore

“…The Vorcore campaign provided significant advances for observations of momentum fluxes due to gravity waves (Hertzog et al, 2007). Twenty-seven superpressure balloons were launched into the Southern Polar Vortex in September and October 2005 and flew along isopycnal surfaces until February 2006, behaving as quasi-Lagrangian tracers between 16 and 19 km altitude, recording temperature, winds and pressure every 15 min.…”