The dataset contains manual recordings transcribed into electronic format, following the ASPeCt (Antarctic Sea Ice Processes and Climate) protocol, for inclusion in the cruise data set. Although the observations are necessarily subjective to each person's individual biases, when taken as a whole, the data set revealed some statistically valid trends in winter sea ice conditions of Western ... Antarctica in the Bellingshausen/Amundsen Sea.
Throughout cruise NBP07-09 a team of 9 volunteers made 192 observations of local sea ice conditions over a period of 63 days broken up into two voyages. The protocol used was devised by the ASPeCt working group of the Scientific Committee of Antarctic Research (SCAR). This data set was supplemented by estimates of the number of icebergs.
This process entailed making qualitative observations every hour (GMT) of sea ice conditions, weather, and iceberg conditions from the bridge of the RVIB Nathaniel B. Palmer and recording them onto the ASPeCt standard log sheets. The observations included recording the latitude, longitude, overall sea ice concentration, and conditions for the primary, secondary, and tertiary ice types observed. The ice type descriptions incorporated the concentration of each ice type with regards to the overall concentration, ice type, ice thickness, floe size, topography, snow cover, and snow depth. The air/water temperature, wind speed, and direction were recorded from the vessel’s underway data acquisition system (DAS). NOAA's meteorological observation weather codes were used to identify the weather conditions for precipitation and visibility. Observations incorporated ice conditions within 1km from the ship per the ASPeCt protocol, and used radar images to estimate approximate icebergs within 6 nautical miles. In order to help determine the scale of ice thickness, an inflatable ball 0.5 meters in diameter was installed on the starboard side of the ship to gauge ice thickness more accurately as an ice piece was being turned on edge by the ship. Additionally, two time lapse cameras were installed with a 5 second shutter speed to help capture the ice conditions from the starboard side and the ice tower. Ultimately night observations were made by the light emitted from the ship at a range of a few tens of meters.
ASPeCt is an expert working group of the SCAR whose aim is to help improve and standardize understanding of the Antarctic sea ice zone through ongoing field programs, remote sensing and numerical modeling. Towards the end of the cruise as the spring season was approaching, the ice edge seemed to retreat per images transmitted from radar images such as Radarsat and Envisat. With these resources, and the ASPeCt observations, we can determine preliminary ice conditions for this region to set a precedent for future studies. The observational data set has been contributed to an archive consisting of over 100 similar cruise data sets that in aggregate provide a circumpolar view of Antarctic sea ice properties.
sackley at pol.net, Stephen.ackley at utsa.edu
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Ozsoy-Cicek, B., Kern, S., Ackley, S.F., Xie, H., Tekeli, A.E. (May 2011), Intercomparisons of Antarctic sea ice properties from ship observations, active and passive microwave satellite observations in the Bellingshausen Sea, Deep Sea Research II, 58, 9-10, 1092-1111, doi:10.1016/j.dsr2.2010.10.031, http://www.sciencedirect.com/science/article/pii/S0967064510003164