HiOOS P.I. - B. Taylor Waves and Water Levels Component M. Merrifield & D. Luther - Co-PIs

HiOOS P.I. - B. Taylor Waves and Water Levels Component M. Merrifield & D. Luther - Co-PIs

Waves and Water Levels Objectives Inundation Product: Warning of extreme high sea levels at least a day in advance around Oahu (in collaboration with Coastal Inundation component of HiOOS). Harbor Conditions Products (Nowcast & Forecast): Providing real-time information & forecasts of tides, sea/swell, seiches and currents at two high-use, vulnerable harbors: Barber’s Pt., Oahu, and Kaumalapau, Lana’i.

Inundation Problem High Tide + High Winter Surf (Setup) = North Shore Coastline Flooding (property damage & road overtopping)

Inundation Problem High Tide + A Little Extra (due to an eddy) = Low-Land Flooding (property damage & business disruption) CRAIG T. KOJIMA / CKOJIMA@STARBULLETIN.COM Charles Memminger kayaks at the intersection of Ahua and Kilihau streets in Mapunapuna, which often floods at high tide. July 30, 2006.

Inundation Problem: High Tide + A Little Extra (due to an eddy) = Beach Flooding (increased erosion & tourist discontent) Ala Moana Park Honolulu

Inundation Product Requires: • accurate tides along Oahu shorelines (spring tide range ~ 1.2m ) • provided by G. Carter (SOEST/UH) model validated by NOAA station SL • sea/swell setup prediction (often reaches 0.5m ) • provided by model validated with near-shore wave/SL data funded under HiOOS • mesoscale eddy SL prediction (range each year ~ 0.3m ) • provided by HiOOS modeling component • SSH annual cycle estimate (Sep-Oct max; often has a range of 0.3m ) • provided by HiOOS modeling component • long-term SL rise estimate (at Honolulu, currently ~ 0.003m/yr) • provided by analyses of NOAA SL gauge data • storm surge prediction (during hurricane, easily over 2.0m ) • defer to NWS • tsunami (depending on location, expect up to 2.0m ) • defer to PTWC

Inundation Product: Sea/swell setup based on HiOOS models of wave amplitude & setup, validated with HiOOS & other NOAA wave & SL obs. Wave setup at Mokuleia, N. Shore Oahu

Inundation Product: Sea/swell setup varies significantly along shoreline. Where barrier reef is wide, coastal water level unrelated to outside wave activity. Makapu’u Oahu

Global WaveWatch 3 Regional WaveWatch3 Inundation Product: Nested models (K-F Cheung, SOEST/HiOOS) bring wave predictions into shallow water (validated with HiOOS & NOAA obs). Local Boussinesq Model SWAN – Littoral Wave Model

High Event Inundation Product: Mesoscale eddies originate east of the islands and propagate to the islands, often amplifying along the way. Honolulu Sea Level Satellite SSH Y. Firing, M. Merrifield, Oceanography

Inundation Product: Eddy heights along the shores of Oahu will be determined by high-resolution models validated by NOAA SL gauges & altimetry. • Ocean circulation model comparisons for • 17 Sep. 2007. Note: • Coastline resolution • Channel resolution • Open-ocean and near-shore currents • - Enhanced resolution model captures eddies. • - Model output must be evaluated with SL obs.

Harbor Conditions Problem: SL amplitudes of seiches (3-40 minute periods) in some harbors often reach 10’s of cm’s, with concomitant disruptive currents. Kahului, Maui SL - Jan. 28-29, 1998 Sea Level (m) Sea Level (m) 40 cm changes in 20 minutes Time (day of year - 1998) Time (day of year - 1998)

Harbor Conditions Product: For best results, directional wave buoys are deployed outside target harbors: sea/swell monitoring & seiche prediction. Kaumalapau Hbr. Lana’i J. Aucan, M. Merrifield, Oceanography ACE, CDIP

Harbor Conditions Product: mock-up of a real-time product that we have on-line for Kaumalapau: tides & seiche surge from our harbor gauge; gravity wave height from our wave buoy.

Harbor Conditions Product: similar product under construction for Barber’s Pt. Hbr., Oahu, but will also have currents in channel per request of pilots. M. Merrifield, D. Luther, J. Aucan - Oceanography

Important In Situ Assets • All HiOOS W&WL sensors feed into the usual national and international data repositories for SL and surface wave data, e.g., • CDIP • NOAA CO-OPS • IOC SL Facility

Underway Development Work: • Inundation Product: • refine near-shore sea/swell wave modeling • establish accuracy of eddy SL in regional ocean circulation models • Harbor Conditions Products: • deploy current meter off Barber’s Pt. Harbor • deploy real-time harbor conditions product for Barber’s Pt. Hbr. • establish prediction capability for harbor seiche/surge

Future Expansion: • Hawaii: • acquire SL data from more locations around Oahu to refine wave • setup model in terms of reef dimensions • - need to acquire and deploy more temporary sea level gauges • expand inundation product to other vulnerable (low-lying) Hawaii • coastlines, such as west Maui • - need to evaluate specific contributors to inundation through • deployment of wave and SL gauges • establish harbor conditions products at other vulnerable Hawaiian • harbors, e.g., Kahului & Hilo • - need to deploy directional wave buoys, sea level sensors and • current meters both inside and outside of harbors (some • temporary; some permanent)

Future Expansion: • Pacific Islands: • expand/export our wave & water level products and monitoring systems • to other islands in the PacIOOS RA • - currently have a directional wave buoy deployed off Guam • - NOS & UHSLC network of sea level gauges on Pacific Is. gives • us a jump start on evaluating inundation characteristics at • many Pacific Is. • - need to evaluate/confirm specific contributors to inundation through • deployment of wave and SL gauges • - need to deploy directional wave buoys, sea level sensors and • current meters both inside and outside of harbors (some • temporary; some permanent) • need to expand high resolution wave and ocean circulation modeling • to target islands

December 2008 Flooding at Majuro

HiOOS P.I. - B. Taylor Waves and Water Levels Component M. Merrifield & D. Luther - Co-PIs