A study on river discharge and salinity variability in the Middle Atlantic Bight and Long Island Sound

摘要

This study quantitatively characterizes annual, interannual, and decadal variability of Middle Atlantic Bight (MAB) river discharges, MAB surface salinities, Long Island Sound (LIS) surface salinities, and LIS salinity stratification via wavelet analysis. Links among rivers, salinities, and standard climate indices are investigated through correlation analysis of the complete data records and low-pass time series (including periods greater than 1.5 years). All rivers and salinities analyzed have strong annual cycles that are distinguishable from random noise. All records have interannual power, but this variability is indistinguishable from the noise background. Some MAB rivers have significant multi-decadal power (near either 18-year or 26-year periods). Correlations are strong among MAB rivers, salinities at different shelf sections, and salinities at LIS stations. Negative correlations between MAB rivers and surface salinities account for a significant part of the observed variance: up to 29% for shelf salinities and 46% for LIS salinities. Shelf and estuary salinities are positively correlated; accounting for at most 61% of the variance. LIS salinity stratification is positively correlated with river discharge (up to 36% of the variance). Interannual variability exhibits similar statistical relationships with higher correlations. Average annual cycles indicate a 1-2-month sequential lag between peak river discharge, minimum estuary salinity, and minimum shelf salinity. Weak but significant correlations indicate a tendency for high discharge, low LIS salinity, and high LIS stratification to coincide with positive intervals of the North Atlantic Oscillation Index.