Ocean Sciences Atlantic Canada’s Real-Time Water Level System Observations, Predictions, Forecasts and Datums on the Web Authors: Phillip MacAulay (CHS) Charles O’Reilly (CHS) Keith Thompson (Dalhousie) + forecast 3D Continuous datums PWLN Dalcoast II observe, collect, predict WebTide LAT wrt MWL zero phase shift, multi band pass, recursive filter zero phase shift, multi band pass, recursive filter RTWL System

Ocean Sciences CHS Atlantic’s Permanent Water Level Network 16 tide gauges, 000’s kms of coastline Long Term Sea Level (GLOSS) Tsunami Gauges Storm Surge Gauges Presentation Subtext: Socio-economic and Hydrographic motivations for maintaining coastal water level monitoring programs and networks Presentation Subtext: Socio-economic and Hydrographic motivations for maintaining coastal water level monitoring programs and networks

Ocean Sciences New Versatile Sutron XPert Dataloggers Backup Communications GOES Satellite Systems (need 10 min permission) High Frequency Water Level Measurements and Gauge Polling 1 minute averaged sampling, 10 minute gauge polling, average 5 min data latency Sutron XConnect real time data collection software Redundant Sensors Primary Rotary Encoder (Stable, Accurate, Reliable) Secondary Bubbler (Stable, Secondary Backup) Tertiary Pressure sensor (Extreme Water Levels, Fast Response Wells, Tertiary Backup) Laser sensor (Stable, Highly Accurate, Direct Independent Measurement Testing for GLOSS sites) New Versatile Sutron XPert Dataloggers Backup Communications GOES Satellite Systems (need 10 min permission) High Frequency Water Level Measurements and Gauge Polling 1 minute averaged sampling, 10 minute gauge polling, average 5 min data latency Sutron XConnect real time data collection software Redundant Sensors Primary Rotary Encoder (Stable, Accurate, Reliable) Secondary Bubbler (Stable, Secondary Backup) Tertiary Pressure sensor (Extreme Water Levels, Fast Response Wells, Tertiary Backup) Laser sensor (Stable, Highly Accurate, Direct Independent Measurement Testing for GLOSS sites) P atm 1) Legacy Sensor: Continuous chain float and pulley with optical encoder and tungsten weight, specific gravity =18 2) Secondary Sensor: Continuous fast response bubbler 3) Backup Sensor: Submersible pressure sensor 4) Laser sensor: 0 00 o o o o pump P=  w gh h o PWLN Equipment and Operational Upgrades Who is Crazy?

Ocean Sciences Schematic of the Atlantic RTWL System A Collaborative Effort Data Acquisition PC (XConnect) Water Level Clients PWLN Tide Gauges DFO Science (Matlab, Modeling) RTWLOracle Dbase ISDM XConnect Backup Archival Data CHS XP Network (XConnect) DFO web server, RTWL web pages Real time data Data Backup GOES Satellite link GOES Satellite Download Archival Data CHS DFO Science ISDM Dalhousie Clients Dalhousie Dalcoast II

Ocean Sciences RTWL Web Pages Kohila Thana, Science Informatics

Ocean Sciences Examples of other Real or Quasi-Real Time Systems National Oceanographic and Atmospheric Administration’s (NOAA) Tides and Currents web site ----Physical Oceanographic Real-Time System (PORTS) European Sea Level Service (ESEAS) Monitoring Network System for Systematic Sea Level Measurements in the Mediterranean and Black Sea (MedGLOSS) UK National Tidal and Sea Level Facility (NTSLF) National Oceanographic and Atmospheric Administration’s (NOAA) Tides and Currents web site ----Physical Oceanographic Real-Time System (PORTS) European Sea Level Service (ESEAS) Monitoring Network System for Systematic Sea Level Measurements in the Mediterranean and Black Sea (MedGLOSS) UK National Tidal and Sea Level Facility (NTSLF)

Ocean Sciences Observations, Constituent Predictions, The Residual Weather (storm surges, positive and negative) Departures at tidal frequencies (variations in the tidal constituents) Everything else affecting water level variations (infra-gravity waves, harbour seiches, tsunamis, shelf waves …) Weather (storm surges, positive and negative) Departures at tidal frequencies (variations in the tidal constituents) Everything else affecting water level variations (infra-gravity waves, harbour seiches, tsunamis, shelf waves …) The Residual: Observations – Predictions (non-tidal behavior) Timescales (minutes to months) Reason for continued monitoring of coastal water levels (Presentation Subtext) Immediate impact on coastal environments, populations, and infra-structure Danger to navigation Validate storm surge models Timescales (minutes to months) Reason for continued monitoring of coastal water levels (Presentation Subtext) Immediate impact on coastal environments, populations, and infra-structure Danger to navigation Validate storm surge models North Sydney, NS St. Lawrence, NFLD

Ocean Sciences Forecasting the Residual Effects of weather Dalcoast II -- 2D, barotropic, non-linear, lateral diffusion, 1/12 o, forced by EC 3hr winds and pressure (48hr surge forecast, once per day) Everything else Spectral-nudging Kalman Filter (Thompson etal., 2006) -- zero phase shift, multi band pass, recursive filter Effects of weather Dalcoast II -- 2D, barotropic, non-linear, lateral diffusion, 1/12 o, forced by EC 3hr winds and pressure (48hr surge forecast, once per day) Everything else Spectral-nudging Kalman Filter (Thompson etal., 2006) -- zero phase shift, multi band pass, recursive filter Bobanovic and Thompson, 2001 s t denote an auxiliary state vector x 1, x 2, ….,x t equispaced scalar values to be filtered Build Term Decay Term Proto-Forecast = Constituent Predictions + timeseries of 0-24 hr surge hr surge Forecast model residual error = Observations (up to last) – (Proto-Forecast) Residual error Nowcast = Filter (forecast model residual error), *Nowcast mode, build/modify state vector energy Residual error forecast = Filter, *Forecast mode, project existing state vector energy into the future (no decay) Final forecast = Proto-forecast + residual error nowcast and forecast Proto-Forecast = Constituent Predictions + timeseries of 0-24 hr surge hr surge Forecast model residual error = Observations (up to last) – (Proto-Forecast) Residual error Nowcast = Filter (forecast model residual error), *Nowcast mode, build/modify state vector energy Residual error forecast = Filter, *Forecast mode, project existing state vector energy into the future (no decay) Final forecast = Proto-forecast + residual error nowcast and forecast. Filter band pass width, gain, (spin up period) -1 Filter band pass width, gain, (spin up period) -1 Filtered values Filtered values Forecast Nowcast Tide gauge locations Bias term Band Pass Frequencies

Ocean Sciences Selection of Filter Frequencies and Gains From Theory: Diurnal O 1, Semidiurnal M 2 gain/filter band widths wide enough to capture other diurnal and semidiurnals From Recent Observations (analysis of forecast model residual error timeseries): Upper Tidal and Seiche Frequencies, gain/decay timescales ~ 1.5 to 2 wave periods From Theory: Diurnal O 1, Semidiurnal M 2 gain/filter band widths wide enough to capture other diurnal and semidiurnals From Recent Observations (analysis of forecast model residual error timeseries): Upper Tidal and Seiche Frequencies, gain/decay timescales ~ 1.5 to 2 wave periods Forecast model residual error Seiche content Seiche energy/frequencies Residual tidal energy/frequencies

Ocean Sciences Example Forecast Past Future Datums Operational code under testing, Available on RTWL web pages soon Operational code under testing, Available on RTWL web pages soon

Ocean Sciences Continuous Datums for Atlantic Canada Discrete Calculation Gridded Surfaces Dynamical Modeling What are they? Where are we starting from? Why do we need them? Where are we in Atlantic Canada? How should we now best proceed? Planning, Development Stage Although in principal prototypical versions have already used Labrador route survey Webtide 07 Northumberland Strait Survey Webtide 07 Fundy Survey Webtide, Omnistar What are they? Where are we starting from? Why do we need them? Where are we in Atlantic Canada? How should we now best proceed? Planning, Development Stage Although in principal prototypical versions have already used Labrador route survey Webtide 07 Northumberland Strait Survey Webtide 07 Fundy Survey Webtide, Omnistar

Ocean Sciences Sea bed Spatially variable tidal properties 2D Simplification Ellipsoid Long Timescale WL Monitoring Vertical Control Datum Management Hydrographic reason to maintain a minimal, effective water level monitoring network/program, maintain/track tidal datums wrt relative sea level rise (Presentation Subtext) Present and past approach, What are continuous Datums? Constant Datum Transform Assumption (CDTA) Hydrographic reason to maintain a minimal, effective water level monitoring network/program, maintain/track tidal datums wrt relative sea level rise (Presentation Subtext) Present and past approach, What are continuous Datums? Constant Datum Transform Assumption (CDTA) + BM + CD (xxxx) + + Stn 0491 Lat, Long DEV (xxxx) MWL (xxxx) Transforms Discrete Vertical Control, Tide stations datum targetambiguity Growing systematic errors Continuous Surface Honoring Discrete Control mwl Tidal range Hat Lat Geodetic + <30 cm

Ocean Sciences Why do we need them? With GPS based vertical positioning, RTK or modeled (Omnistar), errors introduced to charts by the CDTA can become significant part of vertical error. CDTA can be inappropriate some activities: – route surveys – surveys where tidal target surfaces change significantly over survey scale (estuaries, Bay of Fundy) – Flood mapping of large areas – RTK solutions and Anywhere, anytime water level applications (WebTide), Continuous applications need continuous datums With GPS based vertical positioning, RTK or modeled (Omnistar), errors introduced to charts by the CDTA can become significant part of vertical error. CDTA can be inappropriate some activities: – route surveys – surveys where tidal target surfaces change significantly over survey scale (estuaries, Bay of Fundy) – Flood mapping of large areas – RTK solutions and Anywhere, anytime water level applications (WebTide), Continuous applications need continuous datums WebTide Constituents derived from a Hydrodynamic Barotropic Ocean Model Assimilating Topex Posieden Altimeter data Constituents derived from a Hydrodynamic Barotropic Ocean Model Assimilating Topex Posieden Altimeter data Dupont, F., C.G. Hannah, D.A. Greenberg, J.Y. Cherniawsky and C.E. Naimie Modelling system for tides for the North-west Atlantic coastal ocean. [online]. [Accessed 21 April, 2008]. Available from World Wide Web: Dupont, F., C.G. Hannah, D.A. Greenberg, J.Y. Cherniawsky and C.E. Naimie Modelling system for tides for the North-west Atlantic coastal ocean. [online]. [Accessed 21 April, 2008]. Available from World Wide Web: Multi-constiuent, anywhere tidal prediction

Ocean Sciences Distance weighted datum transform MWL to CD (Discrete calculation) Exponent p determines local flatness and width of transition zone Exponent p determines local flatness and width of transition zone Webtide provides anytime, anywhere tidal prediction wrt to a floating MWL We want tidal prediction wrt CD, need anywhere transform between MWL and CD Webtide provides anytime, anywhere tidal prediction wrt to a floating MWL We want tidal prediction wrt CD, need anywhere transform between MWL and CD Used in: Labrador Northumberland 07 Fundy 07 Used in: Labrador Northumberland 07 Fundy 07 j j j j i coastline Coastal datum control points dist j far=max(dist j ) T i – transform at i t j – transform at j w j – weight for t j Location transform required Herman Varma

Ocean Sciences How should we best proceed? Closely examine the programs and methods employed by others, NOAA/NOS, UK (Excellent Workshop Monday) Develop plans of approach (brainstorm, communicate needs/requirements Discuss options with Datum clients Develop project outlines/proposals Acquire necessary resources and get on with it Closely examine the programs and methods employed by others, NOAA/NOS, UK (Excellent Workshop Monday) Develop plans of approach (brainstorm, communicate needs/requirements Discuss options with Datum clients Develop project outlines/proposals Acquire necessary resources and get on with it

Ocean Sciences How should we best proceed? Concept outline for an Atlantic Plan 1. Develop an initial theoretical target surface example: LAT as Sum of WebTide constituent amplitudes 1. Develop an initial theoretical target surface example: LAT as Sum of WebTide constituent amplitudes WebTide is based around a floating MWL, thus a surface computed from it must then be referenced to observed mean water levels. MWL is better known at some shore based locations than others. Away from the coast we must rely on either satellite altimetry or Geodetic models.

Ocean Sciences How should we best proceed? Concept outline for an Atlantic Plan 2. Compare existing shore-based Datum reference points to theoretical target surface. There will be misfit. Find and identify poor reference control, iteratively adjust target surface to more closely honor high quality shore- based reference control. Iterations between steps 1 and 2 may be necessary. 2. Compare existing shore-based Datum reference points to theoretical target surface. There will be misfit. Find and identify poor reference control, iteratively adjust target surface to more closely honor high quality shore- based reference control. Iterations between steps 1 and 2 may be necessary.

Ocean Sciences How should we best proceed? Concept outline for an Atlantic Plan 3. Adjust or supersede the target surface where good surrounding shore-based reference Datums permit independent surface estimation. Sequester inshore areas requiring further data or modeling. (NULL datum concept) 4. Calculate the seamless Datum surface grid. Grid spacing could be variable based on the local rate of change of the Datum surface. 5. Agree on standardized methods for interpolation between datum surface grid points and thus calculation of all Datum transformations. 6. Transform Dissemination tools? For Hydrographic work? Public? (VDatum?) 7. Border transitions? regional (Atlantic/Quebec), international (Atlantic/US) 3. Adjust or supersede the target surface where good surrounding shore-based reference Datums permit independent surface estimation. Sequester inshore areas requiring further data or modeling. (NULL datum concept) 4. Calculate the seamless Datum surface grid. Grid spacing could be variable based on the local rate of change of the Datum surface. 5. Agree on standardized methods for interpolation between datum surface grid points and thus calculation of all Datum transformations. 6. Transform Dissemination tools? For Hydrographic work? Public? (VDatum?) 7. Border transitions? regional (Atlantic/Quebec), international (Atlantic/US) Combination of the 3D Datum surfaces with WebTide will yield an anytime, anywhere, on Datum water level prediction/sounding reduction tool.

Ocean Sciences Savi Narayanan, CHS directorate, direction and funding John Loder, expertise on tsunami gauge locations John O’Neill and Kohila Thana, system and web design Mike Ruxton, Craig Wright, Larry Norton, Mark McCracken, James Hanway, CHS Geomatics Steve Parsons, Herman Varma, Chris Coolen, Fred Carmichael, CHS Atlantic CHS Quebec, Pacific and Central and Arctic Carmen Reid, Canadian Coast Guard Savi Narayanan, CHS directorate, direction and funding John Loder, expertise on tsunami gauge locations John O’Neill and Kohila Thana, system and web design Mike Ruxton, Craig Wright, Larry Norton, Mark McCracken, James Hanway, CHS Geomatics Steve Parsons, Herman Varma, Chris Coolen, Fred Carmichael, CHS Atlantic CHS Quebec, Pacific and Central and Arctic Carmen Reid, Canadian Coast Guard Acknowledgements

Ocean Sciences Higher High Water High Water Lower Low Water Low Water MHHW NOS Generation of Tidal Datum Fields MHW tidal datum fields (as well as MHHW, MLW, MLLW, MSL, MTL, DTL) from calibrated hydrodynamic models Analysis of model-produced time series, then adjusted to provide a best fit to datums at NOS gauges.

Ocean Sciences Vertical Datum Transformations in VDatum Orthometric Datums NAVD 88 North American Vertical Datum 1988 NGVD 29 National Geodetic Vertical Datum of D/Ellipsoid Datums NAD 83 (NSRS)North American Datum 1983 WGS 84(G873)World Geodetic System 1984 (G873) WGS 84(G730)World Geodetic System 1984 (G730) WGS 84(orig)World Geodetic System 1984 (original system ) WGS 72World Geodetic System 1972 ITRFInternational Terrestrial Reference Frame , , 2000 SIO/MIT 92Scripps Institution of Oceanography / Mass. Inst. of Tech NEOS 90National Earth Orientation Service 1990 PNEOS 90Preliminary Nat’l Earth Orientation Service 1990 Tidal Datums MLLWMean Lower Low Water MLWMean Low Water LMSLLocal Mean Sea Level MTLMean Tide Level DTLDiurnal Tide Level MHWMean High Water MHHWMean Higher High Water

Ocean Sciences Conversion value at any location is determined by interpolation using surrounding values. For geodetic grids, set of nine points are used with bi-quadratic interpolation. For points in tidal grid, two methods are used. If four surrounding VDatum points are non-null, bilinear interpolation is used. If 1-3 points are null value, inverse-distance-squared weighting is used for non-null values. VDatum Interpolation to the User Input Location

Ocean Sciences RTWL Initiatives 2006/07 Link Matlab to RTWL database and web pages ─ Employ Matlab’s powerful computational engine for RTQC ─ Interactive web content using Matlab Real time quality control (RTQC), tsunami detection, and water level forecasting ─ Reliability of Nowcast data on the web ─ Identification of tsunami signals ─ Water level forecasts (storm surge model) Observation-based tsunami detection and warning enhancement (Sable/Hibernia) ─ Early detection/verification ─ Landfall wave height estimation, Zhigang Xu (IML) Link Matlab to RTWL database and web pages ─ Employ Matlab’s powerful computational engine for RTQC ─ Interactive web content using Matlab Real time quality control (RTQC), tsunami detection, and water level forecasting ─ Reliability of Nowcast data on the web ─ Identification of tsunami signals ─ Water level forecasts (storm surge model) Observation-based tsunami detection and warning enhancement (Sable/Hibernia) ─ Early detection/verification ─ Landfall wave height estimation, Zhigang Xu (IML) Sable Hibernia

Ocean Sciences Storm Surges ~1 meter storm surges during spring tides, Feb/01/2006 Potential Flooding ~1 meter storm surges during spring tides, Feb/01/2006 Potential Flooding

Ocean Sciences Simulated Tsunami Arrival Simulated tsunami signal, Zhigang Xu (IML)