Inconsistencies between Long-Term Trends in Storminess Derived from the 20CR Reanalysis and Observations

Journal Article · Wed Feb 06 00:00:00 EST 2013 · Journal of Climate

DOI:https://doi.org/10.1175/jcli-d-12-00309.1· OSTI ID:1565087

Krueger, Oliver ^[1]; Schenk, Frederik ^[1]; Feser, Frauke ^[1]; Weisse, Ralf ^[1]

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1. Helmholtz-Zentrum Geesthacht (Germany)

Global atmospheric reanalyses have become a common tool for both validation of climate models and diagnostic studies, such as assessing climate variability and long-term trends. Currently, the Twentieth Century Reanalysis (20CR), which assimilates only surface pressure reports, sea ice, and sea surface temperature distributions, represents the longest global reanalysis dataset available covering the period from 1871 to the present. Currently the 20CR dataset is extensively used for the assessment of climate variability and trends. In this work, the authors compare the variability and long-term trends in northeast Atlantic storminess derived from 20CR and from observations. A well-established storm index derived from pressure observations over a relatively densely monitored marine area is used. It is believed that both variability and long-term trends derived from 20CR and from observations are inconsistent. Specifically, both time series show opposing trends during the first half of the twentieth century: both storm indices share a similar behavior only for the more recent periods. While the variability and long-term trend derived from the observations are supported by a number of independent data and analyses, the behavior shown by 20CR is quite different, indicating substantial inhomogeneities in the reanalysis, most likely caused by the increasing number of observations assimilated into 20CR over time. The latter makes 20CR likely unsuitable for the identification of trends in storminess in the earlier part of the record, at least over the northeast Atlantic. The results imply and reconfirm previous findings that care is needed in general when global reanalyses are used to assess long-term changes.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 1565087
• Journal Information: Journal of Climate, Vol. 26, Issue 3; ISSN 0894-8755
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Extratropical cyclones
Climate change
Surface observations
Reanalysis data
Decadal variability
Trends