Changing Characteristics of Precipitation and Drought in the Northeast U.S.

Map Type
Season
Time Period
Time Period
Time Period
Time Period
Snow Depth
Season
Year
Year
Year
Threshold
Year

Symbology


Upward-pointed triangles indicate statistically significant increasing of the variable in question over time at the station location being analyzed. Likewise, downward-pointed triangles indicate statistically significant decreasing in the variable in question over time at the station location being analyzed. A circle indicates that the trend was not deemed to be statistically significant using the Mann-Kendall trend test (see “Statistical Tests” below). The shading of the triangles and circles shows the magnitude of the Theil-Sen slope estimate at that station (see below), with blue hues indicating an wetting trend and red hues indicating a drying trend.

Statistical Tests


Statistical significance of time series trends was evaluated using the Mann-Kendall test for monotonic trend. For more information on the Mann-Kendall test, please refer to the bottom section of the documentation from NDMC’s Drought Risk Atlas, and to this 1998 paper by authors Hamed and Rao. The Theil-Sen slope estimator was used to detect linear slopes in most time series. Please see the Theil 1950 paper for information on this slope estimator.