New Zealand Journal of Marine and Freshwater Research abstracts
El Niño and decadal effects on sea-level variability in northern New
Zealand: a wavelet analysis
DEREK G. GORING
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 8602
Christchurch, New Zealand
email: d.goring@niwa.cri.nz
ROBERT G. BELL
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 11 115
Hamilton, New Zealand
Abstract Sea-level data from two sites in northern New
Zealand, along with the Southern Oscillation Index (SOI), are analysed for
interannual and decadal variability using wavelets. The analysis shows, using
statistically significant wavelet power, there is a significant relationship
between mean sea level (MSL) and SOI. However, the relationship is highly
variable, both in magnitude and in the range of time-scales over which it
occurs. This non-stationarity necessitates the use of techniques such as
wavelets for analysis. An interdecadal response in MSL around northern New
Zealand has been isolated, with shifts occurring in 1950 and the late 1970s.
This behaviour in MSL appears to coincide with shifts in the Pacific Decadal
Oscillation, thought previously to be largely centred in the North Pacific. A
strong correlation between SOI and sea surface temperature (SST) is also
demonstrated. This relationship appears to be stable in magnitude (a large
change in SOI produces a large change in SST) and to occur over the same range
of time-scales. More SST and MSL data are required for other parts of New
Zealand to determine whether these findings apply elsewhere.
Keywords wavelets; El Niño; ENSO; mean sea level;
decadal timescales; Pacific Decadal Oscillation
M98076
Received 13 October 1998; accepted 15 March 1999
PDF file of entire paper: medium quality (2353K); (scanned from paper original: notes about this process)
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