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Precipitation Events in Northern New England, USA
Reference
Douglas, E.M. and Fairbank, C.A. 2011. Is precipitation in northern New England becoming more extreme? Statistical analysis of extreme rainfall in Massachusetts, New Hampshire, and Maine and updated estimates of the 100-year storm. Journal of Hydrologic Engineering 16: 203-217.

What was done
Concerned with the oft-heard contention that "the climate is changing across North America," and that precipitation events "have been occurring more frequently and with much greater intensity in the last few decades than has been seen in the past" -- to which view Douglas and Fairbank also subscribe -- the two researchers had as their objective "to investigate the presence of trends in extreme precipitation (denoted MAXP and defined as the annual maximum daily precipitation depth) time series for coastal northern New England," and to also do the same for the frequency of extreme precipitation events.

What was learned
Working with MAXP depths from 48 recording stations with long, continuous records in Maine, New Hampshire and Massachusetts (USA), the two researchers did indeed determine there was "a strong increase in the magnitude of extreme precipitation events over the last three decades," and they also determined that "the frequency of extreme rainfall events appears to be increasing." But over the much longer 51-year period of 1954-2005, they found that the trend in MAXP was "amazingly stationary." And working with seven stations having records stretching all the way back to 1893, they also found that "annual maximum precipitation in northern New England was relatively stationary up through 2005."

What it means
As is the case with almost all types of extreme meteorological phenomena that have been found to have been increasing in magnitude and frequency over the past few decades, Douglas and Fairbank discovered that when one looks still further back in time, equally extreme occurrences of the phenomena are typically found to have occurred, indicative of the fact that there is nothing unusual, unnatural or unprecedented about the recent trends in these sometimes dangerous weather events.

Reviewed 13 April 2011