Convective Snowfalls Linked to the Interaction of a Boundary-Layer Front with a Mesoscale Cyclone Near Terra Nova Bay,Antarctica |
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Authors: | Roberto Bove Grigioni Paolo |
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Institution: | (1) Italian National Weather Service, Short-Medium Range Forecasts Department, Centro Nazionale di Meteorologia e Climatologia Aeronautica (CNMCA), military airport “M. De Bernardi”, Via di Pratica di Mare, 45, 00040 Pomezia (RM), Italy;(2) Ente per le Nuove Tecnologie, l’Energia e l’Ambiente, (ENEA)-CLIM-OSS, S.P. Anguillarese, 301, 00060 S.M. di Galeria (RM), Italy |
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Abstract: | During the XXII Italian expedition in Antarctica, in the summer of 2007, severe weather conditions associated with deep convective
instability and heavy coastal precipitation occurred around the Terra Nova Bay area in the presence of an upper level trough
and energetic katabatic winds flowing from the Ross Ice Shelf over the open sea. In this case study we document an example
of boundary-layer frontal movement across the Ross Sea and mesocyclone development in conjunction with the frontal movement.
A westward fast moving boundary-layer front, generated by the leftward turning katabatic airstream to the east of Ross Island,
was observed propagating as a baroclinic wave disturbance in an easterly direction across the Ross Sea, merging later with
a mesocyclone approaching Terra Nova Bay from offshore. The observed inertial trajectory and an estimation of the radius of
curvature suggest that the vigorous katabatic airstream was sustained by the strengthening of a surface mesocyclonic circulation
settled over the north-eastern Ross Ice Shelf, triggered by a sub-synoptic upper level trough passing over the area. We hypothesise
that baroclinic instability in the low levels plays an important role in the development of a mesoscale vortex and for triggering
convective precipitation. |
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Keywords: | Antarctica Boundary-layer cold front Katabatic wind Mesoscale cyclogenesis Snowfall |
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