Time Scales of Sea-Level Variability along the Alaskan Coast

Alaska's coastal waters exhibit a rich variety of sea-level fluctuations, driven by multiple processes and encompassing a wide range of timescales. Water level data from a set of stations along the Alaska coast are examined from different perspectives to isolate portions of the variability with different periods or subranges of timescales. The approach is exploratory, addressing selected aspects of total observed variability to illustrate regional differences and seasonal characteristics. Tides vary from macrotidal at Anchorage to microtidal at Nome. The variance in the observed data that is not accounted for by the predicted tides varies regionally as well, and is relatively large at Nome. The seasonal cycle of sea level, parameterized in terms of harmonic constituents, exhibits differences among the set of stations with respect to amplitude, phasing, and shape. Non-periodic fluctuations in water level are decomposed and distributed over timescales by wavelet analysis, and then reconstructed as multiple time series, each containing only the timescales falling in a specified band.