Abstract: Abstract  We review the results obtained in the frequency range of Pc3 (22-100 mHz) and Pc4 (7-22 mHz) pulsations at Italian Antarctic stations in the southern polar cap (“Mario Zucchelli”, at Terra Nova Bay, TNB, 80?.S; “Concordia”, the Italian/French base at Dome C, DMC, 89?.S). The absence of a midnight enhancement in the pulsation power suggests a negligible substorm influence at extreme latitudes, while the sharp noon enhancement, which appears only at TNB, is determined by the closer proximity of the station to cusp related phenomena. The relationship between the frequency of the band-limited signals and the interplanetary magnetic field strength, the cone angle influence, and the higher correlation of the Pc3 power with the solar wind speed in the morning hours suggest a global scenario in which upstream waves would be mainly responsible for the mid-frequency activity in the polar cap. However, the polarization pattern is odd with respect to the predictions for tailward propagating modes.

Abstract: We report site-testing results obtained in the nighttime during the polar autumn and winter at Dome C. These results were collected during the first Concordia winterover by A. Agabi. They are based on seeing and isoplanatic angle monitoring, as well as in situ balloon measurements of the refractive index structure constant profiles C2n(h). Atmosphere is divided into two regions: (1) a 36 m high surface layer responsible for 87% of the turbulence, and (2) a very stable free atmosphere above, with a median seeing of 0.36“ +/- 0.19” at an elevation of h=30 m. The median seeing measured with a differential image motion monitor placed on top of an 8.5 m high tower is 1.3“ +/- 0.8”.

Abstract: Frost flowers, intricate featherlike crystals that grow on refreezing sea ice leads, have been implicated in lower atmospheric chemical reactions. Few studies have presented chemical composition information for frost flowers over time and many of the chemical species commonly associated with Polar tropospheric reactions have never been reported for frost flowers. We undertook this study on the sea ice north of Barrow, Alaska to quantify the major ion, stable oxygen and hydrogen isotope, alkalinity, light absorbance by soluble species, organochlorine, and aldehyde composition of seawater, brine, and frost flowers. For many of these chemical species we present the first measurements from brine or frost flowers. Results show that major ion and alkalinity concentrations, stable isotope values, and major chromophore (NO3- and H2O2) concentrations are controlled by fractionation from seawater and brine. The presence of these chemical species in present and future sea ice scenarios is somewhat predictable. However, aldehydes, organochlorine compounds, light absorbing species, and mercury (part 2 of this research and Sherman et al. (2012)) are deposited to frost flowers through less predictable processes that probably involve the atmosphere as a source. The present and future concentrations of these constituents in frost flowers may not be easily incorporated into future sea ice or lower atmospheric chemistry scenarios. Thinning of Arctic sea ice will likely present more open sea ice leads where young ice, brine, and frost flowers form. How these changing ice conditions will affect the interactions between ice, brine, frost flowers and the lower atmosphere is unknown.

Abstract: The humoral modulation of resting muscle heat production of chickens (Gallus
domesticus) was investigated in vitro. The resting distal lower limb was perfused
via the popliteal artery at 25 degrees C without erythrocytes at constant flow.
The preparation was stable for at least 3 hr, showing a constant oxygen uptake
(MO2) and perfusion pressure as well as adequately maintaining muscle energy
charge and creatine phosphate: creatine ratio. Noradrenaline (NOR), adrenaline
(ADR) and serotonin (5-HT) each caused a dose-dependent rise in perfusion
pressure. NOR and ADR evoked increased MO2 at low doses eventually followed by
decreased MO2 at higher agonist concentrations. 5-HT gave smaller but
qualitatively similar MO2 effects. The actions of 50 nM NOR were blocked by
prazosin (10 microM) and nitroprusside (0.5 mM), but not altered by propranolol
(10 microM). NOR-induced stimulatory MO2 changes in the presence of
pharmacological concentrations (1 microM) of glucagon were more pronounced and
the thermogenic concentration range of NOR was increased. Taken together, these
in vitro findings demonstrate a potential for vasoconstrictor-controlled muscle
nonshivering thermogenesis in birds as in marsupials and mammals, suggesting that
vascular control of muscle MO2 may be a widespread biological mechanism. The
possible implications of these findings for avian nonshivering thermogenesis are
discussed.

Abstract: The structure of the snowpack near Barrow was studied in March–April 2009. Vertical profiles of density, specific surface area (SSA) and thermal conductivity were measured on tundra, lakes and landfast ice. The average thickness was 41 cm on tundra and 21 cm on fast ice. Layers observed were diamond dust or recent wind drifts on top, overlaying wind slabs, occasional faceted crystals and melt-freeze crusts, and basal depth hoar layers. The top layer had a SSA between 45 and 224 m2 kg-1. All layers at Barrow had SSAs higher than at many other places because of the geographical and climatic characteristics of Barrow. In particular, a given snow layer was remobilized several times by frequent winds, which resulted in SSA increases each time. The average snow area index (SAI, the dimensionless vertically integrated SSA) on tundra was 3260, higher than in the Canadian High Arctic or in the Alaskan taiga. This high SAI, combined with low snow temperatures, imply that the Barrow snowpack efficiently traps persistent organic pollutants, as illustrated with simple calculations for PCB 28 and PCB 180. The average thermal conductivity was 0.21 Wm-1 K-1, and the average thermal resistance on tundra was 3.25 m2 K W-1. This low value partly explains why the snow-ground interface was cold, around -19°C. The high SAI and low thermal resistance values illustrate the interplay between climate, snow physical properties, and their potential impact on atmospheric chemistry, and the need to describe these relationships in models of polar climate and atmospheric chemistry, especially in a climate change context.