Post on 12-Jan-2016
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Extremely stable boundary layer on the Antarctic plateauC. genthon, M. Town, D. Six, V. Favier, LGGE, France
L. Genoni, A. Pellegrini, ENEA, ItalyC. Pouzenc, SIRENE, France
genthon@lgge.obs.ujf-grenoble.fr
We acknowledge:IPEV and PNRA for support on the field, IPEV programs CONCORDIASI AND CALVA
INSU and CNES for other support
Reference: Genthon et al, 2010. Atmospheric boundary layer measurements and ECMWF analyses during summer at Dome C, Antarctica. J. Geophys. Res., 115, D05104, doi:10.1029/2009JD012741
Climate Change 2007: Working Group I: The Physical Science BasisChapter 11: Regional Climate ProjectionsSub-chapter 11.8: The Polar Regions
Excerpt: « ... Processes that are not particularly well represented in the models are clouds, planetary boundary layer processes and sea ice... »
Predicted winter surface warming, 2090/2100 – 2000/2010IPSLCM4 IPCC (°C)...
Dome C, Antarctica
Latitude 75°06.06S Longitude 123°20.74E Altitude 3300m
A permanent station, Concordia, jointly operated by the French and Italian polar institutes (IPEV, PNRA)
Dome C selected as a « hot spot » for CLMIP5 / IPCC AR5
.... and upper air
A 45-m boundary layer profiling system was deployed in early 2008
The observations for the austral summer 2008, convective layer in the early afternoon, strong
wind shear at night, are challenging for the ECMWF (and other) model (Genthon et al.
2010)
Because of extremely cold temperatures and massive frost deposition, many instruments failed during the winter of 2008. They were subsequently improved and almost a full winter could finally be continuously sampled in 2009
Inversions of more than 0.7°C / m along the tower, more than 2°C / m locally, have been observed. This is only partially reproduced by the ECMWF model
On the other hand, the chronological march of temperature is reproduced, including the occurrence and timing of warm events in winter during which surface temperature rises from -70°C to -30° within a day or so
Other results (not shown): Relative humidity is consistently higher at the top of the tower, and in fact close to saturation, than at the (colder) surface: Moisture is brought to the lower atmosphere by subsidence from the free troposphere rather than by surface evaporation ; Strong wind shears are observed, that can only be sustained because of high static stability / strong stratification
OBS
ECMWF