The effect of the NAO on sea level and on mass changes in the Mediterranean Sea. Issue 2 (26th February 2013)

• Record Type: Journal Article
• Authors: Tsimplis, M. N.; Calafat, F. M.; Marcos, M.; Jordà, G.; Gomis, D.; Fenoglio‐Marc, L.; Struglia, M. V.; Josey, S. A.; Chambers, D.P.
• Is Part Of: Journal of geophysical research. Volume 118:Issue 2(2013:Feb.)
• Page Start: 944
• Page End: 952
• Publication Date: 2013-02-26
• Subjects: sea level -- North Atlantic Oscillation -- Mediterranean Sea -- mass addition; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/jgrc.20078
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract : [1] Sea level in the Mediterranean Sea over the period 1993–2011 is studied on the basis of altimetry, temperature, and salinity data and gravity measurements from Gravity Recovery and Climate Experiment (GRACE) (2002–2010). An observed increase in sea level corresponds to a linear sea level trend of 3.0 ± 0.5 mm/yr dominated by the increase in the oceanic mass in the basin. The increase in sea level does not, however, take place linearly but over two 2–3 year periods, each contributing 2–3 cm of sea level. Variability in the basin sea level and its mass component is dominated by the winter North Atlantic Oscillation (NAO). The NAO influence on sea level is primarily linked with atmospheric pressure changes and local wind field changes. However, neither the inverse barometer correction nor a barotropic sea level model forced by atmospheric pressure and wind can remove fully the NAO influence on the basin sea level. Thus, a third contributing mechanism linked with the NAO is suggested. During winter 2010, a low NAO index caused a basin sea level increase of 12 cm which was almost wholly due to mass changes and is evidenced by GRACE. About 8 cm of the observed sea level change can be accounted for as due to atmospheric pressure and wind changes. The residual 4 cm of sea level change is caused by the newly identified contribution. The physical mechanisms that may be responsible for this additional contribution are discussed. Key points: Updated sea level trends for the Mediterranean Sea are provided NAO contribution to atmospherically corrected sea level remains significant Mass component interannual variability determine by the NAO