Origin and structure of a numerically simulated polar low over Hudson
                        Bay

Albright, Mark D.; Reed, Richard J.; Ovens, David

doi:10.3402/tellusa.v47i5.11578

Cited by 36 publications

(31 citation statements)

References 18 publications

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“…Roch et al, 1991). The evolution of the surface pressure in our case resembles the HB10 case in Albright et al (1995) obtained with an enlarged sea and a straight ice‐edge (see their Fig. 11), but with quite a similar structure to their control run (see their Fig.…”

Section: Diagnostic Analysis Of a Polar Low Developmentsupporting

confidence: 74%

“…This low was absent in a simulation with complete sea‐ice cover in Hudson Bay (e.g. Gachon 1999; Albright et al, 1995).…”

Section: Diagnostic Analysis Of a Polar Low Developmentmentioning

confidence: 92%

“…The case studied here is a polar low developing over open water in Hudson Bay, and it is associated with large surface diabatic fluxes. As noted in the introduction, this polar low has also been investigated by Roch et al (1991) and Albright et al (1995). To complete these previous works, we further analyse here the role of forcing interactions on the low development.…”

Section: Diagnostic Analysis Of a Polar Low Developmentmentioning

confidence: 95%

“…The importance of the open water for the formation of the simulated low was revealed by the failure of a closed low to form in the experiment with complete sea‐ice cover over Hudson Bay. To expand the earlier results of Roch et al (1991), Albright et al (1995) used the MM4 mesoscale model of Pennsylvania State University‐National Center for Atmospheric Research (PSU‐NCAR), with a 20‐km grid mesh and 28 sigma levels, in order to simulate this polar low over Hudson Bay. They made a set of experiments to test the sensitivity of the development to various prescriptions of the surface fluxes, condensation heating, sea‐surface temperature and the configuration of the ice boundary.…”

Section: Introductionmentioning

confidence: 99%

“…They made a set of experiments to test the sensitivity of the development to various prescriptions of the surface fluxes, condensation heating, sea‐surface temperature and the configuration of the ice boundary. In their conclusions, Albright et al (1995) state that this polar low developed as a consequence of latent heat release in organized deep convection that formed when an upper‐level cold low moved over a relatively warm body of open water from which large fluxes of heat and moisture took place. Baroclinic forcing at high levels appeared to play little direct role in this low development.…”

Section: Introductionmentioning

confidence: 99%

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The effects of interactions between surface forcings in the development of a model-simulated polar low in Hudson Bay

Gachon¹,

Laprise²,

Zwack

et al. 2003

Tellus A

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A 30-km version of the Canadian Regional Climate Model is used to simulate a polar low development in early December 1988 over the Hudson Bay. This polar low is quantitatively analyzed in detail, in the initial and mature stages of its development, in order to understand physically how sea surface conditions influence this mesocyclone. This analysis is realized via the description of the effects of different atmospheric forcings (i.e. thermal and vorticity advection, and turbulent and convective fluxes) on the polar low development (called the direct effects) using the diagnostic equations of omega and vorticity tendency. Also, the effects of forcing interactions on subsequent cyclone development (called the indirect effects) is analyzed via the diagnostic equations of vorticity and thermal advection tendencies. In the early stage of development, a low-level cyclogenesis appears over the northwestern Hudson Bay essentially due to diabatic forcings in the context of low-level cold air advection. Progressively, the synergetic effect of time rate of changes in advection terms, resulting from surface diabatic and stress forcings, favours low-level cyclogenesis and baroclinicity over open water near the sea-ice margin, whose shape is determinant for the deepening and tracking of the polar low. In the mature stage, the growth in advection terms becomes the main factor of cyclone intensification with the increase in low-level convection. Forcings are maximum near the surface and differ substantially from the vertical structure found in classical extratropical cyclones. In the upper troposphere they appear to play a secondary role in this polar low development. Finally, the polar low studied here is primarily the result of combined forcing interactions near the sea-ice edge, which are responsible for vorticity and thermal advection changes at low levels. It is also found that the indented sea-ice shape is a favourable factor for the local surface cyclogenesis due to the formation of local Laplacians of diabatic and thermal forcings.

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Section: Diagnostic Analysis Of a Polar Low Developmentsupporting

confidence: 74%

“…This low was absent in a simulation with complete sea‐ice cover in Hudson Bay (e.g. Gachon 1999; Albright et al, 1995).…”

Section: Diagnostic Analysis Of a Polar Low Developmentmentioning

confidence: 92%

Section: Diagnostic Analysis Of a Polar Low Developmentmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The effects of interactions between surface forcings in the development of a model-simulated polar low in Hudson Bay

Gachon¹,

Laprise²,

Zwack

et al. 2003

Tellus A

View full text Add to dashboard Cite

show abstract

Re‐examining the roles of surface heat flux and latent heat release in a “hurricane‐like” polar low over the Barents Sea

2016

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Polar lows are intense mesoscale cyclones that occur at high latitudes in both hemispheres during winter. Their sometimes evidently convective nature, fueled by strong surface fluxes and with cloud-free centers, have led to some polar lows being referred to as "arctic hurricanes." Idealized studies have shown that intensification by hurricane development mechanisms is theoretically possible in polar winter atmospheres, but the lack of observations and realistic simulations of actual polar lows have made it difficult to ascertain if this occurs in reality. Here the roles of surface heat fluxes and latent heat release in the development of a Barents Sea polar low, which in its cloud structures showed some similarities to hurricanes, are studied with an ensemble of sensitivity experiments, where latent heating and/or surface fluxes of sensible and latent heat were switched off before the polar low peaked in intensity. To ensure that the polar lows in the sensitivity runs did not track too far away from the actual environmental conditions, a technique known as spectral nudging was applied. This was shown to be crucial for enabling comparisons between the different model runs. The results presented here show that (1) no intensification occurred during the mature, postbaroclinic stage of the simulated polar low; (2) surface heat fluxes, i.e., air-sea interaction, were crucial processes both in order to attain the polar low's peak intensity during the baroclinic stage and to maintain its strength in the mature stage; and (3) latent heat release played a less important role than surface fluxes in both stages.

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Extratropical cyclone climatology across eastern Canada

Plante

Son

Atallah

et al. 2014

Intl Journal of Climatology

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Extratropical cyclone (ETC) tracks across eastern Canada are examined by applying a Lagrangian tracking algorithm to the lower-tropospheric relative vorticity field of reanalysis data. Both the seasonal cycle and the interannual variability of ETCs are quantified in terms of overall cyclone frequency, intensity, and regions of development and decay. We find that ETCs travelling to eastern Canada tend to develop over the Rockies, the Great Lakes and the US East Coast. The ETCs are most intense over Newfoundland and the North Atlantic Ocean, confirming previous findings. While ETCs at cities along the Atlantic coastline (e.g. St. John's) are dominated by East Coast cyclones (which are intense in winter), those inland (e.g. Toronto) track primarily from the Great Lakes. ETCs that develop over the Gulf of Mexico affect eastern Canada infrequently, but those that do tend to be intense. The interannual variability of the wintertime ETCs is influenced by the El Niño-Southern Oscillation (ENSO). Significant ENSO-related variability is found over most regions of southern Canada, except on the east coast. Although ETCs at Toronto are significantly modulated by ENSO, no visible changes are found at St. John's. These ENSO-related ETC changes are mostly due to the shifts in ETC development regions, with minor changes in the travelling direction of ETCs.

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Origin and structure of a numerically simulated polar low over Hudson Bay

Cited by 36 publications

References 18 publications

The effects of interactions between surface forcings in the development of a model-simulated polar low in Hudson Bay

The effects of interactions between surface forcings in the development of a model-simulated polar low in Hudson Bay

Re‐examining the roles of surface heat flux and latent heat release in a “hurricane‐like” polar low over the Barents Sea

Extratropical cyclone climatology across eastern Canada

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