Abstract: Polar regions and especially Antarctica are nowadays recognised as exerting a major control upon the global Mean Sea Level (MSL) directly linked to climate changes. Monitoring and understanding the geodynamical behaviour of these regions is then of critical importance. The long-term displacement (or velocity) of reference sites helps constraining the ice sheet evolution prediction models. Several geodetic space techniques, such as GPS, observe displacements of such reference sites. In Antarctica, in addition to numerous GPS stations, four DORIS stations are permanently operating: Belgrano, Rothera, Syowa, Terre Adélie. In addition to the permanent DORIS stations, episodic DORIS campaigns took also place at Dome C / Concordia and on Sorsdal and Lambert glaciers. In this paper, we first present general information concerning the stations and the campaigns (exact location, period of measurements, etc). We then discuss the solutions obtained by different analysis centres (when available) for all DORIS stations in the Antarctic region. In particular, we use several ITRFs (from the early ITRF96 to ITRF2000) to see their impact on the derived velocities in Antarctica. An emphasis is given to the investigation and possible explanation of differences observed between each solution. Finally, we compare at these stations, the results of DORIS observations to the solutions from other geodetic techniques (GPS, VLBI) and to the results of repeated absolute gravity measurements (when available).

Abstract: A database of surface Antarctic snow isotopic composition is constructed using available measurements, with an estimate of data quality and local variability. Although more than 1000 locations are documented, the spatial coverage remains uneven with a majority of sites located in specific areas of East Antarctica. The database is used to analyze the spatial variations in snow isotopic composition with respect to geographical characteristics (elevation, distance to the coast) and climatic features (temperature, accumulation) and with a focus on deuterium excess. The capacity of theoretical isotopic, regional, and general circulation atmospheric models (including “isotopic” models) to reproduce the observed features and assess the role of moisture advection in spatial deuterium excess fluctuations is analyzed.

Abstract: A multiple year-round study of atmospheric dimethyl sulfide (DMS) (from December 1998 to April 2003) as well as sulfur-derived aerosols (methanesulfonic acid (MSA) and non-sea-salt sulfate) (from March 1991 to February 2003) was conducted at Dumont d'Urville, coastal Antarctica. The three sulfur-derived species exhibit a seasonal cycle characterized by maxima in midsummer (January). Whereas the interannual variability of winter levels remains low, a strong interannual variability is shown in summer, particularly for DMS and MSA, and to a lesser extent for non-sea-salt sulfate. Over the 1998–2003 time period, January 2002 stands out with high values for all sulfur species. These interannual variabilities of atmospheric summer levels are examined in the light of seawater chlorophyll a content derived from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) data (themselves compared to field measurements made south of 60°S), oceanic DMS levels estimated from chlorophyll a SeaWiFS data, and various sea-ice indices.

Abstract: To investigate thermoregulatory adjustments at sea, body temperatures (the pectoral muscle and the brood patch) and diving behavior were monitored during a foraging trip of several days at sea in six breeding king penguins Aptenodytes patagonicus. During inactive phases at sea (water temperature: 4-7{degrees}C), all tissues measured were maintained at normothermic temperatures. The brood patch temperature was maintained at the same values as those measured when brooding on shore (38{degrees}C). This high temperature difference causes a significant loss of heat. We hypothesize that high-energy expenditure associated with elevated peripheral temperature when resting at sea is the thermoregulatory cost that a postabsorptive penguin has to face for the restoration of its subcutaneous body fat. During diving, mean pectoral temperature was 37.6 {+/-} 1.6{degrees}C. While being almost normothermic on average, the temperature of the pectoral muscle was still significantly lower than during inactivity in five out of the six birds and underwent temperature drops of up to 5.5{degrees}C. Mean brood patch temperature was 29.6 {+/-} 2.5{degrees}C during diving, and temperature decreases of up to 21.6{degrees}C were recorded. Interestingly, we observed episodes of brood patch warming during the descent to depth, suggesting that, in some cases, king penguins may perform active thermolysis using the brood patch. It is hypothesized that functional pectoral temperature may be regulated through peripheral adjustments in blood perfusion. These two paradoxical features, i.e., lower temperature of deep tissues during activity and normothermic peripheral tissues while inactive, may highlight the key to the energetics of this diving endotherm while foraging at sea.