Jun Inoue

Ice floe distribution in the Sea of Okhotsk in the period when sea-ice extent is advancing

[1]xa0Ice floe distribution in the Sea of Okhotsk during a cold-air outbreak was investigated by analyzing several thousand of sea-ice images obtained by the aircraft observation on 18 February in 2000. The effective floe size became small (from 10 m to 2 m) within the marginal ice zone (MIZ). The scaling properties of floe distribution are demonstrated by a cumulative number frequency which follows a power law scaling with an exponent α. The value of α increased from 1.5 within the internal ice zone to 2.1 within the MIZ, which means that relatively small ice floes dominate in the MIZ. The effective width of the MIZ estimated by a wave attenuation theory agreed with the observed width, suggesting that the flexural stress of waves penetrating into the ice is one of the possible mechanisms which cause the difference in the scaling property.

Application of Aerosondes to high-resolution observations of sea surface temperature over Barrow Canyon

[1]xa0Continuous observation of sea surface temperature (SST) were obtained for a period of 27 hours over Barrow Canyon on 20–21 September 2002 using a small robotic aircraft called the Aerosonde. These observations demonstrated significant spatial and temporal variations in the SST at scales that would be very difficult to measure using mooring and satellite observations. Over a region of 25 km2, SST values varied from 1–6°C. A sharp SST front with a temperature gradient of 3°C was observed over the northwestern shelf of Barrow Canyon, which moved northward during the observation period. Relatively cold water was transported from the southwest into the region. Current speeds were estimated using the time series of observations. This analysis demonstrates new technology for oceanographic observations and supports previous evidence that the flow through Barrow Canyon has a strongly sheared flow into the Arctic Ocean.