Three-Dimensional Observations of a Deep Convective Chimney in the Greenland Sea during Winter 1988/89

Abstract

Abstract All available temperature data, including moored thermistor, hydrographic, and tomographic measurements, have been combined using least-squares inverse methods to study the evolution of the three-dimensional temperature field in the Greenland Sea during winter 1988/89. The data are adequate to resolve features with spatial scales of about 40 km and larger. A chimney structure reaching depths in excess of 1000 m is observed to the southwest of the gyre center during March 1989. The chimney has a spatial scale of about 50 km, near the limit of the spatial resolution of the data, and a timescale of about 10 days. The chimney structure breaks up and disappears in only 3–6 days. A one-dimensional vertical heat balance adequately describes changes in total heat content in the chimney region from autumn 1988 until the time of chimney breakup, when horizontal advection becomes important. A simple, one-dimensional mixed layer model is surprisingly successful in reproducing autumn to winter bulk temperatur...