NOAA/NOS/OCS/Coast Survey Development Laboratory Lyon Lanerolle 1,2, Richard Patchen 1, Frank Aikman III 1 and James Herring 3 1 National Oceanic and Atmospheric Administration (NOAA) National Ocean Service/Office of Coast Survey/Coast Survey Development Laboratory 1315 East-West Highway, Silver Spring, MD Earth Resources Technology (ERT) Inc Guilford Road, Suite 105, Annapolis Junction, MD Dynalysis of Princeton, Princeton, NJ

NOAA/NOS/OCS/Coast Survey Development Laboratory Motivation and Objectives – I Support Known Requirements for the Region Marine Operations : Oil and gas platform and port facilities (Anchorage) Resource Management : AK departments of Fish and Game and Natural Resources Coastal Sciences : Climate change/ocean acidification/coastal ecology, Kasitsna laboratory, Kachemak Bay NERR, AOOS and Universities Oil Response : NOAA’s ORR, Coast Guard, Cook Inlet Regional Citizens Advisory Council (CIRCAC), local communities Renewable Energy : Proposed facilities in Kachemak Bay and Fire Island Recreation : Charter sportfish industry, marine ecotourism

NOAA/NOS/OCS/Coast Survey Development Laboratory Motivation and Objectives – II Develop Improved Navigational and Ecological Products Navigational Products : tidal water elevations and currents Physical Products : temperature and salinity and density/density anomalies for sound speed calculations and ecological considerations Ecological Products : Dissolved Oxygen, Nitrogen, Phosphorous, etc. as needed by users/customers Operational Forecast System (OFS) : routinely (e.g. 4 x daily) generate the above products and make them available (via web, GUI, etc.)

NOAA/NOS/OCS/Coast Survey Development Laboratory Modeling Overview and Objectives Model implementation – fully three-dimensional, baroclinic with water elevations, currents, T and S as outputs; if necessary, also run ecological model in-line or off-line Establish realistic model bathymetry to be contributed to the modeling community Describe available observations for model forcings (open ocean boundary, meteorological, river, etc.) and model skill assessment Ensure model veracity against NOS standards Provide pathway to an OFS Continue to participate in multidisciplinary efforts in the region

NOAA/NOS/OCS/Coast Survey Development Laboratory Model Design and Set-up Use Rutgers University’s structured ROMS model Extent : Shelikof Straits to north of Anchorage and Marmot Island to East Chugach Island Orthogonal, curvilinear horizontal grid with finest resolution in Knik Arm (Anchorage), 148 x 790 points; sigma grid in vertical with at least 20 levels model bathymetry from NOS soundings for entire model domain Include wetting-drying

NOAA/NOS/OCS/Coast Survey Development Laboratory Model Domain and Nests Nests

NOAA/NOS/OCS/Coast Survey Development Laboratory Model Grid Resolution - I

NOAA/NOS/OCS/Coast Survey Development Laboratory Model Grid Resolution - II

NOAA/NOS/OCS/Coast Survey Development Laboratory Model Grid Bathymetry

NOAA/NOS/OCS/Coast Survey Development Laboratory Vertical σ-Coordinate Grid

NOAA/NOS/OCS/Coast Survey Development Laboratory Observational Data Needs Three open ocean boundaries : Two opening up to the Gulf of Alaska and one to the South of Shelikof Straits [Need non-tidal/total water elevations, barotropic currents, T and S and possibly ecological variables] Twenty three rivers : [Need river volume discharge, river T and river S and any other ecological variables – e.g. Nitrogen, Dissolved Oxygen, Phosphorous, etc.] Surface/Meteorological : can force model in two ways – (i) with wind stresses and net heat flux or (ii) with a bulk flux formulation [Need wind speeds, air T, air P, RH, net SW flux and downward LW flux] In addition to above model forcing, also need water elevations, currents, T, S (and any ecological variables) for model calibration and validation purposes At open ocean boundaries, ROMS also needs barotropic currents and the reduced boundary conditions are not always consistent and stable Need data for both synoptic hindcast calibration/validation runs as well as for operational runs

NOAA/NOS/OCS/Coast Survey Development Laboratory Data Sources for Model Forcing (hindcast and operational) Open ocean boundary forcing : (i) hindcast water elevations and barotropic currents – enpac2003, NOAA/NOS/CO-OPS/CMIST stations, (ii) hindcast T/S – climatology e.g. WOA2001, 2005, (iii) operational water elevations and barotropic currents – predictions from enpac2003 augmented with a non-tidal component from ETSS or global/regional models such as NCOM (see later), (iv) operational T, S from global/regional model (e.g. NCOM) [Regional models preferred due to higher resolution and better data assimilative capabilities] River forcing : USGS discharges, temperatures and NOAA/NWS forecast products Surface/Meteorological forcing : NARR blended with observed time- series (e.g. NOAA/NDBC stations) and NAM forecast products. Expect to enact forcing via ROMS bulk flux formulation

NOAA/NOS/OCS/Coast Survey Development Laboratory Water Elevation and Currents Data Sources at Open Boundaries NOAA/NOS/CO-OPS CMIST stations Many CMIST stations contain both currents and water elevation Information. Currents can be vertically integrated due to adequate vertical resolution of the observations. Gulf of AK O.B. Shelikof Straits O.B.

NOAA/NOS/OCS/Coast Survey Development Laboratory Coupling with Regional-Scale Models Can get all of the necessary open boundary variables from a regional model Off-line coupling technology now relative mature Proven technology now available at NOAA/NOS/OCS/CSDL Coupling at CSDL applied to West Florida Shelf and Poplar Island (Chesapeake Bay) Extending to Cook Inlet domain should be straightforward

NOAA/NOS/OCS/Coast Survey Development Laboratory Pathway to Operations Tides, 3D with constant density and wetting-drying [Calibrate and validate the water elevations and currents] - Phase I Tides, 3D, synoptic hindcast with density (for a period with a comprehensive set of observations) [Calibrate and validate the water elevations, currents, T, S and any ecological variables] – Phase II Tides, 3D, operational testing of the nowcast/forecast system at the NOAA HPC center using operatonal model forcings. [Evaluate and validate above variables for a 3-month period before becoming fully operational] - Phase III

NOAA/NOS/OCS/Coast Survey Development Laboratory Present Modeling Status - I Presently in Phase I – constant density, 3D, Tidal forcing only (no river or surface/met. forcing) ∆t out =5s, ∆t out /∆t in =20, wetting-drying MPI acceleration with 64 processors; computational effort ratio is ~1:40 Three tidal forcings explored : (i) enpac2003 for w.e. only, (ii) enpac2003 for w.e. and barotropic currents, (iii) w.e. from observations and currents from geostrophy interpolated across open boundary As expected, ROMS unstable with (i) but (ii) and (iii) give comparable results Tidal amplitudes in upper Cook Inlet sensitive to bottom drag

NOAA/NOS/OCS/Coast Survey Development Laboratory Present Modeling Status - II Calibrate tides using M2 constituent only – later introduce all M2 amplitudes sensitive to bottom drag – specially in upper CI Vary prescription and strength on bottom drag to optimal results CMIST-COI0514 Nikiski Anchorage

NOAA/NOS/OCS/Coast Survey Development Laboratory Summary and Conclusions In order to support regional known requirements and improved navigational and possibly ecological forecast products, there is an interest in developing a Cook Inlet OFS Modeling requirements have been identified – a fully 3D baroclinic model with realistic bathymetry to be shared as needed with the community Model design is based on ROMS with a high resolution grid in the horizontal and vertical – especially in upper CI near Anchorage Model forcing needs various data sources including forecast products for an OFS; due to ROMS design at open boundaries in addition to water elevations, T and S, also need barotropic currents; some data sources identified A natural way to obtain open boundary conditions is via coupling to a regional- scale model and the coupling technology presently exists at CSDL Pathway to operations identified – Phases I, II and III Presently calibrating Phase I via M2 tide amplitude and various bottom drag prescriptions