Abstract
Abstract. An energy-conservative metric based on the discrete wavelet transform is applied to assess the relative energy distribution of extreme sea level events across different temporal scales. The metric is applied to coastal events at Key West and Pensacola Florida as a function of two Atlantic Multidecadal Oscillation (AMO) regimes. Under AMO warm conditions there is a small but significant redistribution of event energy from nearly static into more dynamic (shorter duration) timescales at Key West, while at Pensacola the AMO-dependent changes in temporal event behaviour are less pronounced. Extreme events with increased temporal dynamics might be consistent with an increase in total energy of event forcings which may be a reflection of more energetic storm events during AMO warm phases. As dynamical models mature to the point of providing regional climate index predictability, coastal planners may be able to consider such temporal change metrics in planning scenarios.
Highlights
Developing tactics and strategies to address changes in the secular and dynamic behaviour of rising sea level constitutes an important challenge for a significant portion of the global population, including the socio-economic viability of their ports and cities (Nicholls et al, 2008)
It is known that the extensively shallow bathymetry offshore Pensacola significantly modifies the amplitude and phase response of storm surges (Harris, 1963). This suggests that event energy changes at timescales less than one day can be suppressed by bathymetry controlled boundary conditions and bottom friction, consistent with historical surge behaviour
We have explored the temporal characteristics of these events at Key West and Pensacola by decomposing event non-tide residual (NTR) with a discrete wavelet transform (MODWT)
Summary
The IPCC report recognizes the sparsity of literature characterizing sea level extremes. We are concerned with further analysis of the link found between AMO and duration of extreme events at Key West and Pensacola by Park et al (2010). Investigations of sea level extremes suggest that longterm increases of extreme water levels are driven by mean sea level rise, not due to an emerging physical mechanism (Woodworth and Blackman, 2004). A recent analysis by Park et al (2010) found positive trends between both extreme sea level and event duration with respect to the Atlantic Multidecadal Oscillation (AMO) (Kerr, 2000) at Key West and Pensacola, Florida. One can suggest a link between the AWP/increased storm activity as a forcing mechanism and the extreme coastal water levels and durations as a response
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