An assessment of deep steric height variability over the global ocean

Author
Keywords
Abstract
An ocean state estimate constrained by most available data is explored to assess characteristics of variability in deep steric height\textemdasha mostly unobserved quantity, yet important for understanding the relation between sea level, heat content and other ocean climate parameters. Results are based on monthly-averaged steric height anomalies, vertically integrated over the \textquotedblleftunobserved\textquotedblright deep ocean (below \~1700 m). Excluding linear trends, variability in deep steric height is typically 10\textendash20\% of that in the upper ocean, with larger values seen in extensive regions. Enhanced deep variability, at monthly to interannual time scales, occurs in areas of strong eddy energy. Deep signals are mostly thermosteric in nature, with halosteric contributions tightly correlated and generally compensating in the Atlantic and Indian oceans and adding in the Pacific. Potential inference of deep signals from knowledge of the upper ocean is hampered by poor correlations, and regressions based on upper ocean steric height fail to represent the estimated deep variability. Monthly sampling at \~2\textdegree scales would allow for best determination of deep variability and long term trends.
Year of Publication
2012
Journal
Geophysical Research Letters
Volume
39
Date Published
02/2012
ISSN Number
0094-8276
DOI
10.1029/2011GL050681