Horizontal profiles of longwave and shortwave radiation components over sea ice near Barrow, Alaska during the 2011 melt

An integrated instrument package for measuring and understanding the surface radiation budget of sea ice is presented, along with results from its first deployment. The setup simultaneously measures broadband fluxes of upwelling and downwelling terrestrial and solar radiation (four components separately), spectral fluxes of incident and reflected solar radiation, and supporting data such as air temperature and humidity, surface temperature, and location (GPS), in addition to photographing the sky and observed surface during each measurement. The instruments are mounted on a small sled, allowing measurements of the radiation budget to be made at many locations in the study area to see the effect of small-scale surface processes on the large-scale radiation budget. Such observations have many applications, from calibration and validation of remote sensing products to improving our understanding of surface processes that affect atmosphere-snow-ice interactions and drive feedbacks, ultimately leading to the potential to improve climate modelling of ice-covered regions of the ocean. The photographs, spectral data, and other observations allow for improved analysis of the broadband data. An example of this is shown by using the observations made during a partly cloudy day, which show erratic variations due to passing clouds, and creating a careful estimate of what the radiation budget along the observed line would have been under uniform sky conditions, clear or overcast. Other data from the setup's first deployment, in June 2011 on fast ice near Point Barrow, Alaska, are also shown; these illustrate the rapid changes of the radiation budget during a cold period that led to refreezing and new snow well into the melt season.

Particle fluxes at sediment traps AU9701, south of Australia

Sediment trap moorings were deployed from September 21, 1997 through February 21, 1998 at three locations south of Australia along 140°E: at -47°S in the central Subantarctic Zone (SAZ) with traps at 1060, 2050, and 3850 m depth, at -51°S in the Subantarctic Front with one trap at 3080 m, and at -54°S in the Polar Frontal Zone (PFZ) with traps at 830 and 1580 m. Particle fluxes were high at all the sites (18-32 g/m**2/yr total mass and 0.5-1.4 g organic carbon/m**2/yr at -1000 m, assuming minimal flux outside the sampled summer period). These values are similar to other Southern Ocean results and to the median estimated for the global ocean by Lampitt and Antia [1997], and emphasize that the Southern Ocean exports considerable carbon to the deep sea despite its 'high-nutrient, low chlorophyll' characteristics. The SAZ site was dominated by carbonate (>50% of total mass) and the PFZ site by biogenic silica (>50% of total mass). Both sites exhibited high export in spring and late summer, with an intervening low flux period in December. For the 153 day collection period, particulate organic carbon export was somewhat higher in all the traps in the SAZ (range 0.57-0.84 gC/m**2) than in the PFZ (range 0.31-0.53), with an intermediate value observed at the SAF (0.60). The fraction of surface organic carbon export (estimated from seasonal nutrient depletion, Lourey and Trull [2001]) reaching 1000 m was indistinguishable in the SAZ and PFZ, despite different algal communities.

La incorporación metodológica del tiempo : Un estudio de trayectorias biográficas y laborales a partir de dispositivos longitudinales

Los dispositivos longitudinales son pertinentes para descomponer la complejidad temporal, otorgándole al tiempo (la duración, el orden, la secuencialidad) un status particular. Los mismos permiten comparar prácticas y representaciones en dos momentos del tiempo, pero también ir más allá de los datos puntuales y reconstituir segmentos temporales más amplios. Sean cualitativos o cuantitativos, este tipo de datos cobran interés como reveladores de temporalidades biográficas. Pero los mismos permiten dar cuenta además de la estructuración social dinámica de las sociedades, poniendo en evidencia el cambio, la permanencia y la evolución de las normas sociales a través del modo en que afectan a los individuos a lo largo del tiempo. En la presente ponencia nos proponemos reflexionar sobre la importancia, los aportes y las limitaciones de las estrategias metodológicas longitudinales para el análisis de trayectorias biográficas y laborales. La reflexión se funda en los datos de un panel longitudinal y cualitativo que aborda las trayectorias de jóvenes del Gran Buenos Aires. Los mismos jóvenes han sido observados en tres momentos del tiempo: en 2006 cuando egresaron de su formación (secundaria o formación profesional), en 2008 y en 2011. En cada serie los instrumentos de recolección de datos fueron entrevistas en profundidad, calendarios biográficos mes por mes y tablas de empleo