During the 2001-2002 southern summer, PNRA organized the XVII Antarctic scientific expedition that took place at the Italian Base of Terra Nova Bay. During this expedition, the GEOFIT team (University of Torino) measured temperature, humidity and wind velocity fluctuations at 3 levels by means of fast response sonic anemometers and hygrometers on the Hells Gate ice shelf. By means of these measurements (carried out at the frequency 21 Hz), the heat, water vapor and momentum turbulent fluxes were derived. The computation of turbulent fluxes can be critical in the Antarctic regions, where the ice topography is complex and, in addition, the mast holding the instruments is often put up on the iceand can slightly tilt during time. Another problem that can arise are the vibrations of the instruments during the intense katabatic wind episodes. Turbulent fluxes for the period Dec 2001-Jan 2002 were calculated by filtering the measured data. Three different techniques (double and triple rotation, and planar fit) were applied to correct the possible misalignments of the sonic anemometer. The advantages and disadvantages of these three methodologies in complex terrain and during katabatic and no-katabatic wind event are presented and discussed.
Methods for the Optimal Computation of Turbulent Heat Fluxes: Application on Data Collected at Hells Gate, Antarctica
RICHIARDONE, Renzo;MANFRIN, Massimiliano;FERRARESE, SILVIA;LONGHETTO, Arnaldo
2005-01-01
Abstract
During the 2001-2002 southern summer, PNRA organized the XVII Antarctic scientific expedition that took place at the Italian Base of Terra Nova Bay. During this expedition, the GEOFIT team (University of Torino) measured temperature, humidity and wind velocity fluctuations at 3 levels by means of fast response sonic anemometers and hygrometers on the Hells Gate ice shelf. By means of these measurements (carried out at the frequency 21 Hz), the heat, water vapor and momentum turbulent fluxes were derived. The computation of turbulent fluxes can be critical in the Antarctic regions, where the ice topography is complex and, in addition, the mast holding the instruments is often put up on the iceand can slightly tilt during time. Another problem that can arise are the vibrations of the instruments during the intense katabatic wind episodes. Turbulent fluxes for the period Dec 2001-Jan 2002 were calculated by filtering the measured data. Three different techniques (double and triple rotation, and planar fit) were applied to correct the possible misalignments of the sonic anemometer. The advantages and disadvantages of these three methodologies in complex terrain and during katabatic and no-katabatic wind event are presented and discussed.
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