Strong, low frequency (decadal) environmental fluctuations during the 20th century in the North Pacific Ocean, on the Washington coast, and in Puget Sound

At decadal period (10-20 years), dynamic linkage was evident between atmospheric low pressure systems over the North Pacific Ocean and circulation in a Pacific Northwest fjord (Puget Sound). As the Aleutian low pressure center shifts, storms arriving from the North Pacific Ocean deposit varying amounts of precipitation in the mountains draining into the estuarine system; in turn, the fluctuating addition of fresh water changes the density distribution near the fjord basin entrance sill, thereby constraining the fjord's vertical velocity structure. This linkage was examined using time series of 21 environmental parameters from 1899 to 1987. Covariation in the time series was evident because of the strong decadal cycles compared with long-term averages, interannual variability, and seasonal cycles.

Inferences from tree rings on low frequency variations in runoff in the interior western United States

EXTRACT (SEE PDF FOR FULL ABSTRACT): Low frequency variations in runoff, AD 1700-1964, in the interior western United States are inferred from smoothed tree-ring series averaged over north, central, and south regions. ... Relative locations of peaks and troughs in streamflow, precipitation, temperature, and tree-ring series suggest that annual precipitation and warm season evapotranspiration variations may both be important to low frequency fluctuations in tree growth and in streamflow.