R/V Mirai Cruise MR15-03

In this cruise, to examine physical and chemical characteristics of an eddy that contains the Pacific-origin summer water in an area around the Barrow Canyon off the coast of Alaska, and to study the temporal variation of the eddy and its impact on the lower-trophic level ecosystem, we conducted ship-based observations of ADCP, TurboMAP (turbulent measurements), PRR (underwater spectral irradiance and radiance measurements), CTD/water samplings, XCTD, UCTD, GPS drifting buoys, and plankton nets. We also deployed a sediment trap in this area to investigate particle transports by the eddy. Furthermore, we recovered and re-deployed moorings to estimate transports of the Pacific-origin summer and winter waters and the associated heat and freshwater (salt) fluxes, and to study their seasonal variations.
On the other hand, in an area around the Hanna Canyon, a downstream area of the eddy passage, we conducted ship-based observations of TurboMAP (turbulent measurements), PRR (underwater spectral irradiance and radiance measurements), CTD/water samplings, and plankton nets to examine physical and chemical characteristics of the water there and distributions of phyto- and zooplanktons. Another sediment trap was deployed in this area to study the spatial variation of particles with the migration of the eddy. This area is also located in a passage of the Pacific-origin winter water. Thus, the sediment trap may capture the seasonal variation and an eddy formation of the winter water.
In the Chukchi Sea, we set an observation line along the 168.75W meridian near the U.S.-Russia border from the Bering Strait to the shelf slope. Along this line, we conducted ship-based observations of TurboMAP (turbulent measurements), PRR (underwater spectral irradiance and radiance measurements), CTD/water samplings, and plankton nets to examine physical and chemical characteristics of waters and wide-area distributions of phyto- and zooplanktons from a biological hotspot in the southern Chukchi Sea, where is one of the most biologically productive regions of the world's oceans, to a lower productive region in the northern end of the sea.
Along the cruise track, we performed observations of radiosonde, Doppler radar, general meteorology, air sampling, sky radiometer, MAX-DOAS (Multi-Axis-Differential Optical Absorption Spectroscopy), disdrometers, sea surface water monitoring, sea bottom topography, gravity, and magnetic fields. In addition, magnetic total force intensity was measured by towing an instrument, Cesium precession magnetometer, in the North Pacific Ocean.
Note that the field experiment in an area off the coast of Siberia, where the data are extremely scarce, was canceled due to a heavy sea ice condition.