Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign S. Lossow1, M. Khaplanov1, J. Gumbel1, J. Stegman1, G. Witt1, P. Dalin2, S. Kirkwood2, F. J. Schmidlin3, K. H. Fricke4, and U. Blum4 1Department of Meteorology, Stockholm University, 10691 Stockholm, Sweden 2Swedish Institute of Space Physics, 98128 Kiruna, Sweden 3NASA Goddard Space Flight Center, Wallops Island, VA 23681, USA 4Physikalisches Institut der Universität Bonn, 53115 Bonn, Germany
Abstract. The Hygrosonde-2 campaign took place on 16 December 2001 at Esrange/Sweden
(68° N, 21° E) with the aim to investigate the small scale
distribution of water vapour in the middle atmosphere in the vicinity of the
Arctic polar vortex. In situ balloon and rocket-borne measurements of water
vapour were performed by means of OH fluorescence hygrometry. The combined
measurements yielded a high resolution water vapour profile up to an altitude
of 75 km. Using the characteristic of water vapour being a dynamical tracer
it was possible to directly relate the water vapour data to the location of
the polar vortex edge, which separates air masses of different character inside and outside
the polar vortex. The measurements probed extra-vortex air in the altitude
range between 45 km and 60 km and vortex air
elsewhere. Transitions between vortex and extra-vortex usually coincided
with wind shears caused by gravity waves which
advect air masses with different water vapour volume mixing ratios.
From the combination of the results from the Hygrosonde-2
campaign and the first flight of the optical hygrometer in 1994
(Hygrosonde-1) a clear picture of the characteristic water
vapour distribution inside and outside the polar vortex can be drawn.
Systematic differences in the water vapour concentration
between the inside and outside of the polar vortex can be observed
all the way up into the mesosphere. It is also evident that
in situ measurements with high spatial resolution are needed to fully
account for the small-scale exchange processes in the polar winter middle atmosphere.
Citation: Lossow, S., Khaplanov, M., Gumbel, J., Stegman, J., Witt, G., Dalin, P., Kirkwood, S., Schmidlin, F. J., Fricke, K. H., and Blum, U.: Middle atmospheric water vapour and dynamics in the vicinity of the polar vortex during the Hygrosonde-2 campaign, Atmos. Chem. Phys., 9, 4407-4417, doi:10.5194/acp-9-4407-2009, 2009.