The color of sea level: Importance of spatial variations in spectral shape for assessing the significance of trends

Author
Keywords
Abstract
We investigate spatial variations in the shape of the spectrum of sea level variability based on a homogeneously sampled 12 year gridded altimeter data set. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a fifth-order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times of what would be calculated assuming \textquotedblleftwhite\textquotedblright noise and that the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes over this period.
Year of Publication
2010
Journal
Journal of Geophysical Research (Oceans)
Volume
115
Number of Pages
10048
Date Published
10/2010
URL
http://adsabs.harvard.edu/abs/2010JGRC..11510048H
DOI
10.1029/2010JC006102