The Polar Oceans Program of the Alaska SAR Facility

The science plan for the Alaska SAR Facility (ASF) focuses on earth surface characteristics that are of interest within the overall concept of global change and that show significant regional, seasonal and interannual variations resulting in changes in the strength of their radar returns. The polar oceans, with the continuous motion and deformation of the pack ice and the changes in the surface state of the surrounding open seas, offer excellent opportunities for such research. Because such studies require both frequent and detailed analysis of Synthetic Aperture Radar (SAR) data, a Geophysical Processor System (GPS) has been developed to speed the extraction of useful geophysical information from SAR data sets. The system will initially produce three main types of products: (a) sets of ice motion vectors obtained by automated computer tracking of identifiable ice floes on sequential images, (b) the areal extent and location of several different ice types and open water and (c) a characterization of the wave state in ice-free regions as well as within the ice in the marginal ice zone at locations where significant wave penetration occurs. Details of these analysis procedures are described. Initially the GPS is planned to process 10 image pairs/day for ice motion, 20 images/day for ice type variations and 1 image/day for wave information, with a total estimated processing time of 13 hours. A variety of projects plan to utilize the SAR data stream in studies of ice, lead and polynya dynamics and thermodynamics. A common feature of these research programs will be attempts to provide, via the coupling of the SAR data with ice property and ice dynamics models, improved estimates of the heat and mass fluxes into both the atmosphere and the ocean as affected by the characteristics of the ice cover.Key words: SAR, radar, sea ice, image analysis, remote sensingMots clés: RAAS, radar, glace de mer, analyse d’images, télédétectio

MEMS enablement and analysis of the Miniature Autonomous Submersible Explorer

The miniature autonomous submersible explorer (MASE) was designed as a vehicle for astrobiology science by Behar et al. [1]. This paper focuses on the MASE concept and extrapolates a future design based on microelectromechanical systems (MEMS), multifunctional microsystems (MMS), and three-dimensional multichip modules (3-D-MCM). Miniaturization of the electronics increases the payload volumes and power capabilities significantly and this is the main rationale for pursuing extreme miniaturization. The original MASE vehicle accommodated 1–2 instruments while the MEMS enhanced miniature autonomous submersible explorer (MEMSEMASE) accommodates up to six instruments. It is shown that the occupied area of the electronics components is reduced eight times, and the volume 25 times. The vehicle is shaped as a tube with 5 cm in diameter and 20 cm in length and can support 8 W continuously over 5 h. The maximum range is 25 km while the typical onboard instrumentation is conductivity, temperature, depth (CTD), and a high resolution camera. An optical fiber is used for bidirectional communication with the vessel. The goal of this enriched concept is to present an extremely miniaturized submersible design. The vehicle volume is defined to fit inside host vehicles with the goal of future deployment on Europa, oceans on Earth, and bore holes.The paper will focus on showing how electronics can be densely packed into micromachined silicon modules and how these can be designed and interconnected theoretically

The role of Antarctic sea ice in global climate change

Taking a distinct interdisciplinary focus, a critical view is presented of the current state of research concerning Antarctic sea-ice/atmosphere/ocean interaction and its effect on climate on the interannual timescale, with particular regard to anthropogenic global warming. Sea-ice formation, morphology, thickness, extent, seasonality and distribution are introduced as vital factors in climatic feedbacks. Sea-ice / atmosphere interaction is next discussed, emphasizing its meteorological and topographical influences and the effects of and on polar cyclonic activity. This leads on to the central theme of sea ice in global climate change, which contains critiques of sea-ice climatic feedbacks, current findings on the representation of these feedbacks in global climatic models, and to what extent they are corroborated by observational evidence. Sea-ice/ocean interaction is particularly important. This is discussed with special reference to polynyas and leads, and the use of suitably coupled sea-ice/ocean models. A brief review of several possible climatic forcing factors is presented, which most highly rates a postulated ENSO-Antarctic sea-ice link. Sea-ice/atmosphere/ocean models need to be validated by adequate observations, both from satellites and ground based. In particular, models developed in the Arctic, where the observational network allows more reasonable validation, can be applied to the Antarctic in suitably modified form so as to account for unique features of the Antarctic cryosphere. Benefits in climatic modelling will be gained by treating Antarctic sea ice as a fully coupled component of global climate