Articles | Volume 2, issue 1
https://doi.org/10.5194/wcd-2-19-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/wcd-2-19-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
15 Jan 2021
Research article |
| 15 Jan 2021
| 15 Jan 2021
Polar lows – moist-baroclinic cyclones developing in four different vertical wind shear environments
Patrick Johannes Stoll
CORRESPONDING AUTHOR
Department of Physics and Technology, Arctic University of Norway, Tromsø, Norway
Thomas Spengler
Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway
Annick Terpstra
Geophysical Institute, University of Bergen, and Bjerknes Centre for Climate Research, Bergen, Norway
Rune Grand Graversen
Department of Physics and Technology, Arctic University of Norway, Tromsø, Norway
Norwegian Meteorological Institute, Tromsø, Norway
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Patrick Johannes Stoll
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Kristine Flacké Haualand and Thomas Spengler
Weather Clim. Dynam., 2, 695–712, https://doi.org/10.5194/wcd-2-695-2021, https://doi.org/10.5194/wcd-2-695-2021, 2021
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Given the recent focus on the influence of upper tropospheric structure in wind and temperature on midlatitude weather, we use an idealised model to investigate how structural modifications impact cyclone development. We find that cyclone intensification is less sensitive to these modifications than to changes in the amount of cloud condensation, suggesting that an accurate representation of the upper-level troposphere is less important for midlatitude weather than previously anticipated.
Cited articles
Balasubramanian, G. and Yau, M.: The life cycle of a simulated marine cyclone:
Energetics and PV diagnostics, J. Atmos. Sci., 53,
639–653, 1996. a
Blechschmidt, A.-M.: A 2-year climatology of polar low events over the Nordic
Seas from satellite remote sensing, Geophys. Res. Lett., 35, L09815, https://doi.org/10.1029/2008GL033706, 2008. a
Businger, S. and Reed, R. J.: Cyclogenesis in cold air masses, Weather
Forecast., 4, 133–156, 1989. a
Charney, J. G. and Eliassen, A.: On the growth of the hurricane depression,
J. Atmos. Sci., 21, 68–75, 1964. a
Claud, C., Heinemann, G., Raustein, E., and McMurdie, L.: Polar low le Cygne:
satellite observations and numerical simulations, Q. J.
Roy. Meteor. Soc., 130, 1075–1102, 2004. a
Claud, C., Duchiron, B., and Terray, P.: Associations between large-scale
atmospheric circulation and polar low developments over the North Atlantic
during winter, J. Geophys. Res.-Atmos., 112, D12101, https://doi.org/10.1029/2006JD008251, 2007. a
Copernicus Arctic Regional Reanalysis Service: CARA, availabe at:
https://climate.copernicus.eu/copernicus-arctic-regional-reanalysis-service, last access: 11 June 2020. a
Dacre, H., Hawcroft, M., Stringer, M., and Hodges, K.: An extratropical cyclone
atlas: A tool for illustrating cyclone structure and evolution
characteristics, B. Am. Meteorol. Soc., 93,
1497–1502, 2012. a
Davis, C. A. and Emanuel, K. A.: Potential vorticity diagnostics of
cyclogenesis, Mon. Weather Rev., 119, 1929–1953, 1991. a
De Boor, C.: A practical guide to splines, Springer, New York, USA, 1978. a
Emanuel, K. A.: An air-sea interaction theory for tropical cyclones. Part I:
Steady-state maintenance, J. Atmos. Sci., 43, 585–605,
1986. a
Emanuel, K. A. and Rotunno, R.: Polar lows as arctic hurricanes, Tellus A, 41,
1–17, 1989. a
Føre, I., Kristjánsson, J. E., Saetra, Ø., Breivik, Ø.,
Røsting, B., and Shapiro, M.: The full life cycle of a polar low over the
Norwegian Sea observed by three research aircraft flights, Q. J.
Roy. Meteor. Soc., 137, 1659–1673, 2011. a
Furevik, B. R., Schyberg, H., Noer, G., Tveter, F., and Röhrs, J.: ASAR and
ASCAT in polar low situations, J. Atmos. Ocean. Tech.,
32, 783–792, 2015. a
Harrold, T. and Browning, K.: The polar low as a baroclinic disturbance,
Q. J. Roy. Meteor. Soc., 95, 710–723, 1969. a
Haualand, K. F. and Spengler, T.: Direct and Indirect Effects of Surface Fluxes
on Moist Baroclinic Development in an Idealized Framework, J.
Atmos. Sci., 77, 3211–3225, https://doi.org/10.1175/JAS-D-19-0328.1, 2020. a, b, c
Hersbach, H. and Dee, D.: ERA5 reanalysis is in production, ECMWF Newsletter,
147, 5–6, 2016. a
Holton, J. and Hakim, G.: An Introduction to Dynamic Meteorology, vol. 5, Elsevier Science, Academic Press, New York, USA, 2013. a
Jonassen, M. O., Chechin, D., Karpechko, A., Lüpkes, C., Spengler, T.,
Tepstra, A., Vihma, T., and Zhang, X.: Dynamical processes in the Arctic
atmosphere, in: Physics and Chemistry of the Arctic Atmosphere,
Springer, Cham, Switzerland, 1–51, https://doi.org/10.1007/978-3-030-33566-3_1,
2020. a
Kolstad, E. W. and Bracegirdle, T.: Sensitivity of an apparently hurricane-like
polar low to sea-surface temperature, Q. J. Roy. Meteor. Soc., 143, 966–973, 2017. a
Kolstad, E. W., Bracegirdle, T. J., and Zahn, M.: Re-examining the roles of
surface heat flux and latent heat release in a “hurricane-like” polar low
over the Barents Sea, J. Geophys. Res.-Atmos., 121,
7853–7867, 2016. a
Kristjánsson, J. E., Barstad, I., Aspelien, T., Føre, I., Godøy, Ø., Hov, Ø., Irvine, E., Iversen, T., Kolstad, E., Nordeng, T. E., McInnes, H., Randriamampianina, R., Reuder, J., Saetra, Ø., Shapiro, M., Spengler, T., and Ólafsson, H.: The Norwegian IPY-THORPEX: Polar lows and Arctic fronts during the 2008
Andøya campaign, B. Am. Meteorol. Soc., 92,
1443–1466, 2011. a
Kuo, Y.-H., Low-Nam, S., and Reed, R. J.: Effects of surface energy fluxes
during the early development and rapid intensification stages of seven
explosive cyclones in the western Atlantic, Mon. Weather Rev., 119,
457–476, 1991a. a
Laffineur, T., Claud, C., Chaboureau, J.-P., and Noer, G.: Polar lows over the
Nordic Seas: Improved representation in ERA-Interim compared to ERA-40 and
the impact on downscaled simulations, Mon. Weather Rev., 142,
2271–2289, 2014. a
Mansfield, D.: Polar lows: The development of baroclinic disturbances in cold
air outbreaks, Q. J. Roy. Meteorol. Soc., 100,
541–554, 1974. a
Markowski, P. and Richardson, Y.: Mesoscale meteorology in midlatitudes,
John Wiley & Sons, Chichester, UK, https://doi.org/10.1002/9780470682104, 2011. a, b
Noer, G. and Lien, T.: Dates and Positions of Polar lows over the Nordic Seas
between 2000 and 2010, Norwegian Meteorological Institute, Oslo, Norway, report, 16, 1–7, 2010. a
Nordeng, T. E. and Rasmussen, E. A.: A most beautiful polar low. A case study
of a polar low development in the Bear Island region, Tellus A, 44, 81–99, https://doi.org/10.1034/j.1600-0870.1992.00001.x, 1992. a, b, c
Nygård, T., Graversen, R. G., Uotila, P., Naakka, T., and Vihma, T.: Strong
dependence of wintertime Arctic moisture and cloud distributions on
atmospheric large-scale circulation, J. Climate, 32, 8771–8790,
2019. a
Ooyama, K.: A dynamical model for the study of tropical cyclone development,
Geofis. Int., 4, 187–198, 1964. a
Rasmussen, E.: The polar low as an extratropical CISK disturbance, Q.
J. Roy. Meteor. Soc., 105, 531–549, 1979. a
Reed, R. J. and Blier, W.: A Case Study of Comma Cloud Development in the
Eastern Pacific, Mon. Weather Rev., 114, 1681–1695, 1986. a
Reed, R. J. and Duncan, C. N.: Baroclinic instability as a mechanism for the
serial development of polar lows: a case study, Tellus A, 39, 376–384, 1987. a
Renfrew, I.: SYNOPTIC METEOROLOGY, Polar Lows, in: Encyclopedia of Atmospheric
Sciences, edited by: North, G. R., Pyle, J., and Zhang, F.,
Academic Press, Oxford, UK, 379–385, 2015. a
Savitzky, A. and Golay, M. J.: Smoothing and differentiation of data by
simplified least squares procedures, Anal. Chem., 36, 1627–1639,
1964. a
Shapiro, M. A. and Keyser, D.: Fronts, jet streams and the tropopause, in:
Extratropical cyclones, Springer, Boston, USA, 167–191, https://doi.org/10.1007/978-1-944970-33-8_10, 1990. a, b
Stoelinga, M. T.: A potential vorticity-based study of the role of diabatic
heating and friction in a numerically simulated baroclinic cyclone, Mon. Weather Rev., 124, 849–874, 1996. a
Wehrens, R. and Buydens, L. M.: Self-and super-organizing maps in R: the
Kohonen package, J. Stat. Softw., 21, 1–19, 2007. a
Yanase, W., Fu, G., Niino, H., and Kato, T.: A polar low over the Japan Sea on
21 January 1997. Part II: A numerical study, Mon. Weather Rev., 132,
1552–1574, 2004. a
Short summary
Polar lows are intense meso-scale cyclones occurring at high latitudes. The research community has not agreed on a conceptual model to describe polar-low development. Here, we apply self-organising maps to identify the typical ambient sub-synoptic environments of polar lows and find that they can be described as moist-baroclinic cyclones that develop in four different environments characterised by the vertical wind shear.
Polar lows are intense meso-scale cyclones occurring at high latitudes. The research community...
