Climate Dynamics

, Volume 40, Issue 11, pp 2775–2800

Trends and low frequency variability of extra-tropical cyclone activity in the ensemble of twentieth century reanalysis

Authors

    • Climate Research DivisionScience and Technology Branch, Environment Canada
  • Y. Feng
    • Climate Research DivisionScience and Technology Branch, Environment Canada
  • G. P. Compo
    • CIRES, Climate Diagnostics CenterUniversity of Colorado
    • Physical Sciences DivisionNOAA Earth System Research Laboratory
  • V. R. Swail
    • Climate Research DivisionScience and Technology Branch, Environment Canada
  • F. W. Zwiers
    • Pacific Climate Impacts ConsortiumUniversity of Victoria
  • R. J. Allan
    • Hadley Centre, Met Office
  • P. D. Sardeshmukh
    • CIRES, Climate Diagnostics CenterUniversity of Colorado
    • Physical Sciences DivisionNOAA Earth System Research Laboratory
Article

DOI: 10.1007/s00382-012-1450-9

Cite this article as:
Wang, X.L., Feng, Y., Compo, G.P. et al. Clim Dyn (2013) 40: 2775. doi:10.1007/s00382-012-1450-9

Abstract

An objective cyclone tracking algorithm is applied to twentieth century reanalysis (20CR) 6-hourly mean sea level pressure fields for the period 1871–2010 to infer historical trends and variability in extra-tropical cyclone activity. The tracking algorithm is applied both to the ensemble-mean analyses and to each of the 56 ensemble members individually. The ensemble-mean analyses are found to be unsuitable for accurately determining cyclone statistics. However, pooled cyclone statistics obtained by averaging statistics from individual members generally agree well with statistics from the NCEP-NCAR reanalyses for 1951–2010, although 20CR shows somewhat weaker cyclone activity over land and stronger activity over oceans. Both reanalyses show similar cyclone trend patterns in the northern hemisphere (NH) over 1951–2010. Homogenized pooled cyclone statistics are analyzed for trends and variability. Conclusions account for identified inhomogeneities, which occurred before 1949 in the NH and between 1951 and 1985 in the southern hemisphere (SH). Cyclone activity is estimated to have increased slightly over the period 1871–2010 in the NH. More substantial increases are seen in the SH. Notable regional and seasonal variations in trends are evident, as is profound decadal or longer scale variability. For example, the NH increases occur mainly in the mid-latitude Pacific and high-latitude Atlantic regions. For the North Atlantic-European region and southeast Australia, the 20CR cyclone trends are in agreement with trends in geostrophic wind extremes derived from in-situ surface pressure observations. European trends are also consistent with trends in the mean duration of wet spells derived from rain gauge data in Europe.

Keywords

Reanalysis dataExtra-tropical cyclonesCyclone trackingData homogeneity testsData homogenizationTrends and low frequency variability

Supplementary material

382_2012_1450_MOESM1_ESM.pdf (741 kb)
PDF (1351 KB)

Copyright information

© Her Majesty the Queen in the Right of Canada as represented by the Minister of the Environment 2012