ABSTRACT

Two drifting type wave buoys were deployed off Barrow Alaska during the JAMSTEC Mirai cruise in Sep. 10 2016. Both buoys followed the same trajectories until they started to separate, but remained in the same area until Nov. 2. With the selection of an appropriate high-pass filter of the accelerometer record, the observed significant wave height and wave period compared well with the ERA-interim wave. On Sep. 19, a storm approached the area, and significant wave height reached about 4.9 m. This wave is likely not the largest wave in this area, as conjectured from the 38 years ERA-interim reanalysis.

INTRODUCTION

The rate of Arctic sea ice retreat during boreal summer is accelerating. In the last few decades, the ice-covered sea area has reduced by a few million square kilometers (Walsh 2014). Alternatively, the ice-free seas where wind-waves can be generated has increased. In latitudes north of 70° N, the averaged significant wave height during summer exceeded 3 m in some area (Babanin et al. 2014). By 2050, the entire Arctic Ocean is expected to be ice-free (Kohn et al. 2014). As a consequence, the highest observed waves in the Arctic is expected to increase in time. Based on the motion of the ship, Collins et al. (2015) reported that waves close to 5 m significant wave height was observed. Recently, an extensive field campaign was conducted in the interest of identifying the ice and wave interaction in the marginal ice zone (Marginal Ice Zone Program). Extensive in-situ measurements were conducted including a spar type drifting wave buoy in the Beaufort Sea (SWIFT buoy, Thomson 2012). Numerous new findings were made related to the characteristics of ocean waves during break up and formation of the ice sheet in the marginal ice zone. In 2015, the Japanese Ministry of Education, Culture, Sports and Technology initiated the Arctic Challenge for Sustainability (ArCS) Program. The aim of the five year program is to understand climate changes in the Arctic, to predict future changes and assess their socio-economic impact, and to deliver scientific information to stakeholders. The program, therefore, bridges between science and society. One of the focuses of the ArCS research is the Northern Sea Route. Optimum ship routing simulations were conducted (Choi et al. 2014), but wave resistance is not considered. In view of the climate change in the Arctic Ocean and the associated increase in the significant wave height, improvement of the wave forecast skill in the ice-free ocean is crucial. During the 2016 field campaign in the Arcs Project, two newly developed wave buoys were deployed in the ice-free ocean. The aim of this paper is to describe the wave buoy system and the result of the observation conducted from Sep. to Nov. 2016.

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