Storms and Storm Surges - Development of the storm climate

How is storm climate variability linked to hemispheric temperature variations?

The link between decadal and centennial variations of mean temperature and storminess has hardly been studied because of the lack of sufficient data. However, climate models exposed to variable solar, volcanic and greenhouse gas forcing provide good data, to study such links. This was done by Fischer-Bruns et al. (2002, 2005), who counted for each model's grid box the annual frequency of gales in a simulation beginning in 1550 and extending to 2100 (using the IPCC A2 scenario for 2000-2100). They found no obvious link between hemispheric mean temperatures for historical times; only during the anthropogenic climate change in the 21st century a parallel development of storminess and temperature is simulated, which is associated mainly with a spatial displacement of the storm track to the Northeast and not a major intensification.

The lack of a link between mean temperatures and the level of storminess during historical times is demonstrated by Figure 4, which shows the spatial pattern of the difference of temperature and of storm frequency (given as number of gales per year and grid box) during the Late Maunder Minimum (1675-1710) and the pre-industrial period of the simulation (1550-1800). The Late Maunder Minimum was the coldest period of the Little Ice Age, at least in Europe, and the model simulation indicates that this cooling was of almost global extent, affecting all of the Northern Hemisphere. This period was, at least in the model, not associated with a reduced level of storminess in the North Atlantic or in the North Pacific.

Thus, neither the admittedly very limited empirical evidence nor the modelling study by Fischer-Bruns et al. (2002, 2005) support the hypothesis that a general warming would lead via increased availability of humidity to a roughened storm climate.

Figure 4: Simulated differences in winter between the 'Late Maunder Minimum' (LMM, 1675-1710) and the pre-industrial time (1550-1800) – in terms of air temperature (top, K) and in terms of number of gale days (wind speed 8 Beaufort and more). Note that the LMM is portrayed by the model as particularly cold, but the storm activity shows little changes. Courtesy: Irene Fischer-Bruns.

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References

Fischer-Bruns, I., U. Cubasch, H. von Storch, E. Zorita, J. F. Gonzáles-Rouco and J. Luterbacher, 2002: Modelling the Late Maunder Minimum with a 3-dimensional OAGCM, CLIVAR exchanges 7, 59-61

Fischer-Bruns, I., H. von Storch, F. González-Rouco and E. Zorita, 2005: Modelling the variability of midlatitude storm activity on decadal to century time scales. Clim. Dyn. 25: 461-476, DOI 10.1007/s00382-005-0036-1