Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Importance of latent heat release in ascending air streams for atmospheric blocking


Atmospheric blocking is a key component of extratropical weather variability1 and can contribute to various types of extreme weather events2,3,4,5. Changes in blocking frequencies due to Arctic amplification and sea ice loss may enhance extreme events6,7, but the mechanisms potentially involved in such changes are under discussion8,9,10,11. Current theories for blocking are essentially based on dry dynamics and do not directly take moist processes into account12,13,14,15,16,17. Here we analyse a 21-year climatology of blocking from reanalysis data with a Lagrangian approach, to quantify the release of latent heat in clouds along the trajectories that enter the blocking systems. We show that 30 to 45% of the air masses involved in Northern Hemisphere blocking are heated by more than 2 K—with a median heating of more than 7 K—in the three days before their arrival in the blocking system. This number increases to 60 to 70% when considering a seven-day period. Our analysis reveals that, in addition to quasi-horizontal advection of air with low potential vorticity12,13,14,15, ascent from lower levels associated with latent heating in clouds is of first-order importance for the formation and maintenance of blocking. We suggest that this process should be accounted for when investigating future changes in atmospheric blocking.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Diabatic heating and PV anomalies along trajectories computed backwards from the blocking region.
Figure 2: Diabatic heating during blocking life cycle.
Figure 3: Properties of blocking trajectories.
Figure 4: Spatial distributions of blocking trajectories.

Similar content being viewed by others


  1. Rex, D. Blocking action in the middle troposphere and its effect on regional climate. I: An aerological study of blocking. Tellus 2, 169–211 (1950).

    Google Scholar 

  2. Carrera, M. L., Higgins, R. W. & Kousky, V. E. Downstream weather impacts associated with atmospheric blocking over the Northeast Pacific. J. Clim. 17, 4823–4839 (2004).

    Article  Google Scholar 

  3. Sillmann, J. & Croci-Maspoli, M. Present and future atmospheric blocking and its impact on European mean and extreme climate. Geophys. Res. Lett. 36, L10702 (2009).

    Article  Google Scholar 

  4. Pfahl, S. & Wernli, H. Quantifying the relevance of atmospheric blocking for co-located temperature extremes in the Northern Hemisphere on (sub-)daily time scales. Geophys. Res. Lett. 39, L12807 (2012).

    Article  Google Scholar 

  5. Pfahl, S. Characterising the relationship between weather extremes in Europe and synoptic circulation features. Nat. Hazards Earth Syst. Sci. 14, 1461–1475 (2014).

    Article  Google Scholar 

  6. Liu, J., Curry, J. A., Wang, H., Song, M. & Horton, R. M. Impact of declining Arctic sea ice on winter snowfall. Proc. Natl Acad. Sci. USA 109, 4074–4079 (2012).

    Article  Google Scholar 

  7. Francis, J. A. & Vavrus, S. J. Evidence linking Arctic amplification to extreme weather in mid-latitudes. Geophys. Res. Lett. 39, L06801 (2012).

    Article  Google Scholar 

  8. Screen, J. A. & Simmonds, I. Exploring links between Arctic amplification and mid-latitude weather. Geophys. Res. Lett. 40, 959–964 (2013).

    Article  Google Scholar 

  9. Barnes, E. A., Dunn-Sigouin, E., Masato, G. & Woolings, T. Exploring recent trends in Northern Hemisphere blocking. Geophys. Res. Lett. 41, 638–644 (2014).

    Article  Google Scholar 

  10. Hassanzadeh, P., Kuang, Z. & Farrell, B. F. Responses of midlatitude blocks and wave amplitude to changes in the meridional temperature gradient in an idealized dry GCM. Geophys. Res. Lett. 41, 5223–5232 (2014).

    Article  Google Scholar 

  11. Coumou, D., Petoukhov, V., Rahmstorf, S., Petri, S. & Schellnhuber, H. J. Quasi-resonant circulation regimes and hemispheric synchronization of extreme weather in boreal summer. Proc. Natl Acad. Sci. USA 111, 12331–12336 (2014).

    Article  Google Scholar 

  12. Shutts, G. J. The propagation of eddies in diffluent jetstreams: Eddy vorticity forcing of ‘blocking’ flow fields. Q. J. R. Meteorol. Soc. 109, 737–761 (1983).

    Google Scholar 

  13. Hoskins, B. J. & Sardeshmukh, P. D. A diagnostic study of the dynamics of the Northern Hemisphere winter of 1985–86. Q. J. R. Meteorol. Soc. 113, 759–778 (1987).

    Article  Google Scholar 

  14. Nakamura, H., Nakamura, M. & Anderson, J. L. The role of high- and low-frequency dynamics in blocking formation. Mon. Weath. Rev. 125, 2074–2093 (1997).

    Article  Google Scholar 

  15. Yamazaki, A. & Itoh, H. Vortex–vortex interactions for the maintenance of blocking. Part I: The selective absorption mechanism and a case study. J. Atmos. Sci. 70, 725–742 (2013).

    Article  Google Scholar 

  16. Masato, G., Hoskins, B. J. & Woolings, T. J. Wave-breaking characteristics of midlatitude blocking. Q. J. R. Meteorol. Soc. 138, 1285–1296 (2012).

    Article  Google Scholar 

  17. Tyrlis, E. & Hoskins, B. J. Aspects of a Northern Hemisphere atmospheric blocking climatology. J. Atmos. Sci. 65, 1638–1652 (2008).

    Article  Google Scholar 

  18. Barnes, E. A., Slingo, J. & Woolings, T. A methodology for the comparison of blocking climatologies across indices, models and climate scenarios. Clim. Dynam. 38, 2467–2481 (2012).

    Article  Google Scholar 

  19. Ferranti, L., Corti, S. & Janousek, M. Flow-dependent verification of the ECMWF ensemble over the Euro-Atlantic sector. Q. J. R. Meteorol. Soc. 141, 916–924 (2015).

    Article  Google Scholar 

  20. Tilly, D. E., Lupo, A. R., Melick, C. J. & Market, P. S. Calculated height tendencies in two Southern Hemisphere blocking and cyclone events: The contribution of diabatic heating to block intensification. Mon. Weath. Rev. 136, 3568–3578 (2008).

    Article  Google Scholar 

  21. Cheung, H. N. et al. Observational climatology and characteristics of wintertime atmospheric blocking over Ural-Siberia. Clim. Dynam. 41, 63–79 (2013).

    Article  Google Scholar 

  22. Schwierz, C. Interactions of Greenland-scale Orography and Extratropical Synoptic-Scale Flow PhD thesis, ETH Zurich (2001)

  23. Croci-Maspoli, M. & Davies, H. C. Key dynamical features of the 2005/06 European winter. Mon. Weath. Rev. 137, 664–678 (2009).

    Article  Google Scholar 

  24. Schwierz, C., Croci-Maspoli, M. & Davies, H. C. Perspicacious indicators of atmospheric blocking. Geophys. Res. Lett. 31, L06125 (2004).

    Article  Google Scholar 

  25. Croci-Maspoli, M., Schwierz, C. & Davies, H. C. A multifaceted climatology of atmospheric blocking and its recent linear trend. J. Clim. 20, 633–649 (2007).

    Article  Google Scholar 

  26. Wernli, H. & Davies, H. C. A Lagrangian-based analysis of extratropical cyclones. I: The method and some applications. Q. J. R. Meteorol. Soc. 123, 467–489 (1997).

    Article  Google Scholar 

  27. Scherrer, S. C., Croci-Maspoli, M., Schwierz, C. & Appenzeller, C. Two-dimensional indices of atmospheric blocking and their statistical relationship with winter climate patterns in the Euro-Atlantic region. Int. J. Climatol. 26, 233-249 (2006).

    Google Scholar 

  28. Madonna, E., Wernli, H., Joos, H. & Martius, O. Warm conveyor belts in the ERA-Interim data set (1979–2010). Part I: Climatology and potential vorticity evolution. J. Clim. 27, 3–26 (2014).

    Article  Google Scholar 

  29. Methven, J. Potential vorticity in warm conveyor belt outflow. Q. J. R. Meteorol. Soc. 141, 1065–1071 (2015).

    Article  Google Scholar 

  30. Gray, S. L., Dunning, C. M., Methven, J., Masato, G. & Chagnon, J. M. Systematic model forecast errors in Rossby wave structure. Geophys. Res. Lett. 41, 2979–2987 (2014).

    Article  Google Scholar 

  31. Dee, D. P. et al. The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).

    Article  Google Scholar 

  32. Tibaldi, S. & Molteni, F. On the operational predictability of blocking. Tellus A 42, 343–365 (1990).

    Article  Google Scholar 

Download references


We thank MeteoSwiss for providing access to ECMWF analysis data. Discussions with H. Davies have been very helpful in designing this study. C.M.G. acknowledges support from the Swiss National Science Foundation (Grant PZ00P2_148177/1).

Author information

Authors and Affiliations



All authors designed the study and discussed the results and manuscript. S.P. analysed the data. S.P. and H.W. wrote the manuscript.

Corresponding author

Correspondence to S. Pfahl.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1815 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Pfahl, S., Schwierz, C., Croci-Maspoli, M. et al. Importance of latent heat release in ascending air streams for atmospheric blocking. Nature Geosci 8, 610–614 (2015).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing