TRR 181 Seminar "Variability in the Circulation and Hydrography of Denmark Strait from a High-resolution Numerical Model"

The TRR 181 seminar is held by Mattia Almansi (Johns Hopkins University, Baltimore, USA) on

Variability in the Circulation and Hydrography of Denmark Strait from a High-resolution Numerical Model

at Universität Hamburg on August 30 at 11 am, Bundesstr. 53, room 22/23 (ground floor).

*Abstract*

I will present initial results from a year-long, high-resolution (~2 km) numerical simulation covering the east Greenland shelf and the Iceland and Irminger Seas. The model hydrography and circulation in the vicinity of Denmark Strait show good agreement with available observational datasets.
I'll focus on the variability of the Denmark Strait Overflow (DSO) by characterizing boluses and pulses, which are the two dominant mesoscale features in the strait. On average, boluses (pulses) are 57.1 (27.5) hours long, occur every 3.2 (5.5) days, and are more frequent during summer (winter). Boluses (pulses) increase (decrease) the overflow cross-sectional area, and temperatures around the overflow interface are colder (warmer) by about 2.5°C (1.5°C). Boluses and pulses cross the strait with a slightly different orientation and in both cases the along-strait equatorward flow of dense water is enhanced, but more so for pulses. The cross-stream flow changes direction when these mesoscale features cross the strait and indicates that boluses are associated with veering of the horizontal current while pulses are characterized by backing. The lateral extent of the boluses is much greater than that of the pulses.
The model indicates that the mean southward volume flux of the DSO is about 30% greater in the presence of boluses and pulses. Thus, these features play a major role in controlling the variability of the DSO transport into the Irminger Sea.