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"Continuous in-situ temperature observations from the AWGs were consistent with occasional satellite-derived SSTs from MODIS." nautical miles. Nearly 900,000 tem- perature measurements were recorded and transmitted, forming a data set that shows the Beaufort Sea was anoma- lously warm in the summer of 2011. Data and Results When the AWGs crossed the conti- nental shelf break for the first time on August 2, an 11° C surface layer was detected along with a sharp tempera- ture contrast exceeding 8° C between the surface and 6 meters depth. These values initially caused project engi- neers to suspect a fault in the equip- ment. A review of the cloud-limited and hence sparse MODIS (Moderate Resolution Imaging Spectroradiom- eter) sea-surface temperature (SST) and true-color satellite imagery showed that the AWGs had encountered the boundary of a large Mackenzie River discharge plume. Over the course of the mission, con- tinuous in-situ temperature observa- tions from the AWGs were consistent with occasional satellite-derived SSTs from MODIS. Together the two sources indicate a 6º to 12° C surface layer as- sociated with the plume that was at least 6-meters thick and 74,000 square kilometers in extent. Elevated tempera- tures in the surface layer of the Beau- fort Sea persisted into early autumn and contributed to regional surface air temperature (SAT) anomalies from 4° C to more than 10° C in September and October (relative to the standard 1981 to 2010 reference climatology). SAT anomalies over the Beaufort and oth- er western Arctic marginal seas were the largest observed anywhere in the Northern Hemisphere in 2011. All MODIS SST and true-color imagery obtained since 2000 was reviewed to place the AWG observa- tions in spatial and temporal context. The review was sufficient to determine that the Wave Gliders were primarily operating in a Mackenzie River plume in 2011 and to identify whether it was present in some other years. However, due to the high degree of cloudiness over the region in summer, the use- ful retrieval rate is about 10 percent. This is not enough to allow a complete analysis of the sea-surface environ- ment based on satellite data alone, and highlights the utility and critical need of continuous, all-weather surface and subsurface sampling provided by the Wave Glider. Raw and calibrated Wave Glider sea temperature data and calibrations, satellite imagery, animations of sea ice motion in 2011 and plume propaga- tion in 2008, and maps of a variety of other variables are available at www. pmel.noaa.gov/arctic/glider and are archived at the National Ocean Data Center. Future Plans To further develop the AWG, more sensors will be added to study in-situ ocean heat content and surface flux measurements. The planned sensor suite includes short- and long-wave ra- diometers; air temperature and relative humidity; sea temperature profiles and conductivity; and basic wave data. NOAA and Liquid Robotics also plan to integrate two cameras into the sensing package: a conventional cam- era for situational awareness, naviga- tion and sea-state estimation, and an all-sky camera for observing cloud fraction and structure. Conclusions High-quality, cost-effective and broadly distributed ocean measure- ments are key to understanding and predicting our ocean and atmosphere. This is particularly valid in an under- sampled and rapidly changing Arctic. Surface temperature can be observed by satellites, but these measurements are infrequently available because of cloud cover, and they yield no infor- mation about the total heat storage in the wind-mixed layer. Autonomous systems such as the AWGs can fill this observation gap. The proof-of-concept deployment of two AWGs in the summer of 2011 demonstrated that high-quality tem- perature measurements from the upper www.sea-technology.com When size, performance and robustness matter Inertial Measurement Unit Key features • Small size, low weight and low cost • ITAR free • Insensitive to magnetic fi elds • Solid state - high reliability • Low gyro bias instability (0.5°/h) • Low gyro noise (0.15°/√h) • ±10g acceleration input range • Low accelerometer bias instability (0.05mg) • 3 inclinometers for accurate leveling • Compensated digital output, RS422 • Customer confi gurable output for mat, sampling rate and fi lter settings • Auxiliary input Sensonor AS sales@sensonor.com www.sensonor.com SEPTEMBER 2012 / st 31