Polar lows in the Labrador Sea: A case study

Abstract

In this paper, we will describe our analysis of a polar low event that occurred in the Labrador Sea during the winter of 1992. As there are unfortunately no in-situ observations of this event, we will rely on satellite data as well as the high-resolution objective analaysis from the ECMWF to document the environment in which the low developed and the structure of the low itself. We will show that the polar low developed during a cold air outbreak that was precipitated by the passage of an intense synoptic-scale low. The polar low appears to have developed along a linear cloud feature as the result of an interaction between a low-level diabatically induced potential vorticity anomaly and an upper-level potential vorticity anomaly that propagated into the area from the Canadian Arctic. We will also show that with the TOMS and TOYS retrievals for total column ozone, we are able to identify a signature of the upper-level potential vorticity anomaly. In its mature state, we will show that there were very strong winds, and as a result large fluxes of sensible and latent heat, associated with the polar low. In summary, the 1992 Labrador Sea polar low provides one with an excellent opportunity to study air-sea interactions and the coupling between the troposphere and stratosphere. The realization that the strong heating of the atmosphere and the concomitant cooling of the ocean associated with these storms may be sufficient to initiate downwelling events in the ocean may represent a hitherto undocumented link between the fast and slow climate systems that deserves further attention.

Emergent Relationships Among Sea Ice, Longwave Radiation, and the Beaufort High Circulation Exposed Through Parameter Uncertainty Analysis

“…pressure system. Somewhat along those, lines Moore et al () argue that the interaction between the tropospheric polar vortex and surface circulation features is enhanced in regions of low tropospheric static stability where surface heating increases penetration depths of upper level circulation anomalies. Moore et al () reported that the anomalous warm winter of 2017 that saw record sea ice minimums accompanied reversal of surface winds and general motion departing from the normal anticyclonic activity over the Beaufort Sea.…”

Collapse of the 2017 Winter Beaufort High: A Response to Thinning Sea Ice?

“…During the winter of 2017, this so‐called tropospheric polar vortex shifted northward and intensified relative to climatology (Figure b). The interaction between the tropospheric polar vortex and the surface circulation feature is enhanced in regions of low tropospheric static stability, that is, regions with reduced vertical temperature gradients that can occur due to surface heating, since this increases the penetration depth of upper level circulation anomalies (Moore et al, ). Figure also shows that tropospheric static stability throughout the Arctic was reduced during the winter of 2017 as compared to climatology.…”

A polar low over The Labrador Sea: Interactions with topography and an upper‐level potential vorticity anomaly, and an observation by RADARSAT‐1 SAR

“…A source of energy for these systems is thought to the large air-sea fluxes of heat and moisture that are often associated with them [Shapiro et al, 1987;Moore et al, 1996]. Recently, evidence has been presented that the development of polar lows in the Labrador Sea region often occurs in conjunction with upper-level potential vorticity anomalies [Moore et al, 1996;Pagowski and Moore, 2001]. These anomalies can interact with and intensify surface circulations through a mechanism first suggested by Kleinschimdt in 1951 [Hoskins et al, 1985].…”

“…Moist processes, in particular latent heat released by convection, have also been discussed as contributing to the formation and intensification of polar lows [Rasmussen, 1979;Emanuel and Rotunno, 1989]. A source of energy for these systems is thought to the large air-sea fluxes of heat and moisture that are often associated with them [Shapiro et al, 1987;Moore et al, 1996]. Recently, evidence has been presented that the development of polar lows in the Labrador Sea region often occurs in conjunction with upper-level potential vorticity anomalies [Moore et al, 1996;Pagowski and Moore, 2001].…”