ENSO-correlated fluctuations in ocean bottom pressure and wind-stress curl in the North Pacific College of Marine Science, University of South Florida, St. Petersburg, FL 33701, USA
25 Oct 2011
Received: 23 June 2011 – Published in Ocean Sci. Discuss.: 08 July 2011 Abstract. We examine the output of an ocean model forced by ECMWF winds to study the
theoretical relationship between wind-induced changes in ocean bottom
pressure in the North Pacific between 1992 until 2010 and ENSO. Our analysis
indicates that while there are significant fluctuations correlated with some
El Niño and La Niña events, the correlation is still relatively low.
Moreover, the ENSO-correlated variability explains only 50 % of the
non-seasonal, low-frequency variance. There are significant residual
fluctuations in both wind-stress curl and ocean bottom pressure in the
region with periods of 4-years and longer. One such fluctuation began in
late 2002 and has been observed by the Gravity Recovery and Climate
Experiment (GRACE). Even after accounting for possible ENSO-correlated
variations, there is a significant trend in ocean bottom pressure in the
region, equivalent to 0.7 ± 0.3 cm yr−1 of sea level from January
2003 until December 2008, which is confirmed with steric-corrected
altimetry. Although this low-frequency fluctuation does not appear in the
ocean model, we show that ECMWF winds have a significantly reduced trend
that is inconsistent with satellite observations over the same time period,
and so it appears that the difference is due to a forcing error in the model
and not an intrinsic error.
Revised: 11 October 2011 – Accepted: 13 October 2011 – Published: 25 October 2011
Citation: Chambers, D. P.: ENSO-correlated fluctuations in ocean bottom pressure and wind-stress curl in the North Pacific, Ocean Sci., 7, 685-692, doi:10.5194/os-7-685-2011, 2011.