Seminar Abstract

Harold Mofjeld

Tuesday, April 21, 2009


Patterns in time of extreme tides and sea level rise over the 21st century: Puget Sound and the other marine waters of Washington State


Understanding and planning for the effects of sea level rise (SLR) in Washington's marine waters requires a detailed knowledge of how the tides will vary over the 21st Century. This is because the tides play a fundamental role in the ecosystem of Washington's marine waters and largely determine when shore-side development is vulnerable to coastal flooding. By adding predicted tides at reference tide stations to SLR based on the Mote et al. (2008) scenarios, the extreme high and low water patterns are identified for four regions: Puget Sound, Eastern Straits, NW Olympic Peninsula, and the outer coast including its large embayments. The 18.6-yr nodal cycle in the extreme tides form a repeating pattern that tends to alternately mimic the effects of rapid SLR on total water level and then reverse them through each cycle. During the present and next decade, there are therefore opportunities to measure SLR effects and model associated with extreme water levels that will occur much later in the Century due to SLR only.

Speaker bio:

Harold Mofjeld is a JISAO Senior Fellow and UW/Oceanography Affiliate Professor. Harold has done research and community outreach on tides, tsunamis, and sea level variations in Puget Sound and other marine waters of Washington State for the past 30 years. During the late 1970's and early 1980's the tidal research was in support of the environmental MESA Program to understand the transport and fate of contaminants in Puget Sound. The work then shifted to tsunami forecasting, mapping and preparedness for Washington and other states, including outreach programs to county and local agencies while serving as the scientific advisor on tsunamis to the WA Emergency Management Division and member of the Washington State/Local Tsunami Workgroup. The work also included instrument development and planning associated with the improved U.S. tsunami warning system for the Pacific and Atlantic Oceans. Besides the tides and tsunamis, much of the research has focused on subtidal, seasonal, interannual and decadal variations in coastal sea level. Other research interests are theoretical wave dynamics, statistical modeling, and climate variability.