HR: 17:45h
AN: C34A-08    [Abstracts]
TI: Eddy correlations measurements of turbulent fluxes over a high altitude glacier in the Bolivian Andes
AU: * sicart, j
EM: sicart@msem.univ-montp2.fr
AF: IRD - Greatice, 300, avenue du Professeur Emile Jeanbrau, montpellier, 34 095, France
AU: chazarin, j
EM: chazarin@msem.univ-montp2.fr
AF: IRD - Greatice, 300, avenue du Professeur Emile Jeanbrau, montpellier, 34 095, France
AU: lejeune, y
EM: Yves.Lejeune@meteo.fr
AF: Meteo France, CEN, 1441 rue de la Piscine, Saint Martin d'Hères, 38406, France
AU: six, d
EM: six@lgge.obs.ujf-grenoble.fr
AF: CNRS, LGGE, LGGE, BP 96, Saint Martin d'Hères, 38402, France
AU: wagnon, p
EM: patrick@lgge.obs.ujf-grenoble.fr
AF: IRD- Greatice, LGGE, BP 96, Saint Martin d'Hères, 38402, France
AB: The turbulent fluxes remain poorly known on tropical glaciers characterized by very dry air at high altitude and low thermal seasonality. Different studies based on the bulk method have shown that sublimation can be important during the dry season, reducing the energy available for melting. However, uncertainties on the bulk method are large, especially when the catabatic wind causes a wind speed maximum at low height. Eddy-correlations measurements have been conducted at 5050 m elevation on the Zongo Glacier in Bolivia (16°S) from July to September 2007 as part of the ‘TAG' project (Turbulence et Ablation Glaciaire). Concomitant measurements of all radiation components, snow surface temperature and of vertical gradients over 6 meters of air temperature and wind speed were carried out. The site was approximately level within several hundred meters, with drainage winds prevailing at night and most of the day. The results show that in this dry and thin atmosphere, surface temperatures below freezing are maintained with significant cooling of the surface due to sublimation and very low long-wave radiation input. The resulting latent heat flux rates exceeded 100 W m2 at times and were generally matched by opposing sensible heat fluxes. A comparisons with eddy correlation measurement conducted in summer 2006 on the St Sorlin glacier, French Alps, was also investigated.
DE: 0720 Glaciers
DE: 0740 Snowmelt
DE: 0762 Mass balance (1218, 1223)
DE: 0764 Energy balance
SC: Cryosphere [C]
MN: 2007 Fall Meeting