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Geology topics

J.A. Johannessen

Publications and source records attributed to J.A. Johannessen.

2 recordsLinked to original sources

Ice-edge eddies in the Fram Strait marginal ice zone

Five prominent ice-edge eddies in Fram Strait on the scale of 30 to 40 kilometers were observed over deep water within 77°N to 79°N and 5°W to 3°E. The use of remote sensing, a satellite-tracked buoy, and in situ oceanographic measurements showed the presence of eddies with orbital speeds of 30 to 40 centimeters per second and lifetimes of at least 20 days. Ice ablation measurements made within one of these ice-ocean eddies indicated that melting, which proceeded at rates of 20 to 40 centimeters per day, is an important process in determining the ice-edge position. These studies give new insight on the formation, propagation, and dissipation of ice-edge eddies.

Science↗

Norwegian remote sensing experiment in a marginal ice zone

The Norwegian Remote Sensing Experiment in the marginal ice zone north of Svalbard took place in fall 1979. Coordinated passive and active microwave measurements were obtained from shipborne, airborne, and satellite instruments together with in situ observations. The obtained spectra of emissivity (frequency range, 5 to 100 gigahertz) should improve identification of ice types and estimates of ice concentration. Mesoscale features along the ice edge were revealed by a 1.215-gigahertz synthetic aperture radar. Ice edge location by the Nimbus 7 scanning multichannel microwave radiometer was shown to be accurate to within 10 kilometers.

Svalbard↗