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Trends in Ship-Reported Oceanic Precipitation Frequency from 1958 through 2014
  • Grant Petty
Grant Petty
University of Wisconsin-Madison

Corresponding Author:[email protected]

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57 years of qualitative ship-board weather reports are used to assess apparent trends in precipitation occurrence over the global oceans. Positive trends of up to ~15% per decade, relative to the long term mean precipitation frequency at a location, are found over most tropical and temperate ocean areas, with negative trends of up to ~5% per decade being found principally at higher latitudes. While it cannot be ruled out that the observed trends are an artifact of gradual changes in shipboard weather reporting habits or procedures over time, no specific candidate for such a change has been identified that could explain the existence of robust positive and negative trends and their apparent geographic coherence.