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An assessment of deep steric height variability over the global ocean
Author(s) -
Ponte Rui M.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2011gl050681
Subject(s) - deep sea , climatology , ocean heat content , environmental science , geology , deep water , sea surface height , oceanography , ocean current , sea surface temperature
An ocean state estimate constrained by most available data is explored to assess characteristics of variability in deep steric height—a 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 “unobserved” deep ocean (below ∼1700 m). Excluding linear trends, variability in deep steric height is typically 10–20% 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° scales would allow for best determination of deep variability and long term trends.