Polar Lows over the Gulf of Alaska in Conditions of Reverse Shear

Bond, Nicholas A.; Shapiro, M. A.

doi:10.1175/1520-0493(1991)119<0551:plotgo>2.0.co;2

Cited by 40 publications

(14 citation statements)

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“…The features of the meso-scale low families reported by Bond and Shapiro (1991), Kuroda (1991) and the present author are summarized in Table 1. It is commonly recognized in the three cases that the meso-scale low family formed along the zone of strong cyclonic shear within the parent circulation system, either the parent low or the Japan Sea polar airmass convergence zone.…”

Section: Features Of Meso-scale Lowsmentioning

confidence: 65%

“…The meso-scale low families reported by Bond and Shapiro (1991), Kuroda (1991) and the present paper are compared. These three cases showed the following common features: They had the horizontal wavelength of 400-150km and were generated in the shear zone which formed under the influence of the parent circulation system.…”

Section: Features Of Meso-scale Lowsmentioning

confidence: 73%

“…These papers noted that baroclinic instability can explain the growth of the observed disturbances. The pair of polar lows within a synoptic-scale occluded parent low over the Gulf of Alaska, which were studied by Bond and Shapiro (1991), had a wavelength of-400km. The wavetrain of meso-Bscale lows over the Japan Sea reported by Kuroda (1991) showed a wavelength of-150km.…”

Section: Features Of Meso-scale Lowsmentioning

confidence: 99%

“…Some other mechanism, presumably latent heat release in organized deep convections also played an important part in the growth. Bond and Shapiro (1991) demonstrated the development of the "pair of polar lows" over the Gulf of Alaska within a large-scale occluded parent low. Frontogenesis at low-levels occurred as a result of confluence and differential thermal advection between the polar air streams to the west of the parent low and the warm air secluded near the core of the parent low.…”

Section: Introductionmentioning

confidence: 99%

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A Meso-Scale Low Family Formed over the Northeastern Japan Sea in the Northwestern Part of a Parent Polar Low

Ninomiya

1994

Journal of the Meteorological Society of Japan

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Development of a meso-scale low family over the northeastern Japan Sea on 3-4 January 1987 is studied. The meso-scale low family formed in the northwestern part of a parent polar low. Local low-level frontogenesis occurred as a result of the horizontal differential thermal advection between polar air streams from the continent to the southwestern side of the parent polar low and warm air streams from the Pacific to the northwestern side of the polar low. A low-level shear line of WNW-ESE orientation formed in the frontogenesis zone.While upper-air observations showed a thermal gradient of-1.5K/100km and a lateral wind shear of N15 (m/sec)/100km across the shear line, dense surface observations indicated a strong lateral shear of 5-10 (m/sec)/10km within the shear zone of 20-30km width.Two meso-scale lows developed along the shear line with an interval of-200km. Each meso-scale low showed the warm core structure and brought strong gusts of-25m/sec with intense precipitation.While the generation of these lows in the strong shear zone suggested the barotropic process, the mesoscale cyclogenesis in association with the local frontogensis indicated the baroclinic generation process. It was examined whether the observed meteorological parameters would satisfy the criterion of barotropic shear or Eady's type baroclinic instability in the shallow layer obtained from linear instability analyses. It was shown that the maximum growth rates of these instabilities appeared around a wavelength of 200km, although the maximum growth rate of the baroclinic instability calculated from sparse aerological data was considerably smaller than that of the barotropic instability calculated from dense surface data.

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Section: Features Of Meso-scale Lowsmentioning

confidence: 65%

Section: Features Of Meso-scale Lowsmentioning

confidence: 73%

Section: Features Of Meso-scale Lowsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Meso-Scale Low Family Formed over the Northeastern Japan Sea in the Northwestern Part of a Parent Polar Low

Ninomiya

1994

Journal of the Meteorological Society of Japan

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“…During past 5 decades, several theories have been used to explain Polar Low development, such as: baroclinic instability, barotropic instability, Conditional Instability of the Second Kind (CISK) or Wind Induced Surface Heat Exchange (WISHE) instability (Forbes and Lottes 1985;Bond and Shapiro 1991;Kolstad 2006;Kolstad et al 2009;Wu and Petty 2010). Various case studies indicate that usually several mechanisms together lead to the formation of Polar Lows (Nordeng 1990;Mailhot et al 1996).…”

Section: Present Knowledge: Mechanisms Regions and Case Studiesmentioning

confidence: 99%

Toward a Multi-Decadal Climatology of North Pacific Polar Lows Employing Dynamical Downscaling

Chen¹,

Geyer²,

Zahn³

et al. 2012

Terr. Atmos. Ocean. Sci.

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The North Pacific is an area where sub-synoptic Polar Lows frequently form during the cold season, especially over the Bering Sea, Gulf of Alaska and Japan Sea. So far, a multi-decadal climatology of such Polar Lows based on individual cases has not been assembled. Here, we consider dynamical downscaling method for realistically constructing the formation and life cycles of such lows over the past 6 decades without exploiting sub-synoptic information in initial fields. To do so, a regional climate model is conditioned by large-scale information of NCEP re-analyses. We test the approach by examining its skill in simulating ten known cases of North Pacific Polar Lows. Three of these are discussed in some detail.The signatures of all storms emerge in the simulations with additional sub-synoptic details. The tracks of the simulated Polar Lows closely follow the tracks derived from satellite imagery. We conclude that the suggested method is suitable for constructing multi-decade climatologies, including trends and variability, of Polar Lows in the North Pacific by dynamically downscaling NCEP re-analyses.

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Polar Lows

Rasmussen¹

2003

A Half Century of Progress in Meteorology: A Tribute to Richard Reed

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Polar Lows over the Gulf of Alaska in Conditions of Reverse Shear

Cited by 40 publications

References 0 publications

A Meso-Scale Low Family Formed over the Northeastern Japan Sea in the Northwestern Part of a Parent Polar Low

A Meso-Scale Low Family Formed over the Northeastern Japan Sea in the Northwestern Part of a Parent Polar Low

Toward a Multi-Decadal Climatology of North Pacific Polar Lows Employing Dynamical Downscaling

Polar Lows

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