Requirements for Surface Marine Observations in Support of

Requirements for Surface Marine Observations in Support of Wind and Wave Forecasting and Hindcasting V. R. Swail Climate Research Division Environment Canada Toronto, Ontario Chair WMO/IOC JCOMM Expert Team on Wind Waves and Storm Surges 1

Selected Resource Documents • • • GCOS International Meeting of Experts. Asheville NC 1995 CLIMAR 99 Workshop Vancouver, BC 1999* Ocean. Obs 99 Workshop St. Raphael France 1999† MARCDAT-I Workshop Boulder CO 2002** JCOMM ETWS-I Meeting Halifax, NS 2003* OOPC-8 Meeting Ottawa ON 2003 † † CLIMAR-II Workshop Brussels, Belgium 2003*, ** MARCDAT-II Workshop Exeter UK 2005** Marine Multi-Hazard Warning Systems Meeting Geneva 2006* International Workshops on Wave Hindcasting and Forecasting© *available on JCOMM web site **available on ICOADS web site †Swail et al. , in “Observing the Oceans in the 21 st Century” † †available on OOPC web site © available from www. oceanweather. com/waveworkshop 2

Waves are important. Why? • Loads on structures, vessels failure – Ocean Ranger, Draupner, “Perfect Storm” “QE-II storm” • Ship Operating conditions – schedules, fuel usage, damage, loss of cargo • Platform Operations – disconnecting, discontinuing operation, evacuation • Coastal impacts especially when combined with storm surge – erosion, inundation, structural damage • Bottom scour – pipelines, bottom-mounted facilities • Effects on weather and climate (roughness, albedo, fluxes) • In the absence of ice, waves produce the dominant loads on structures 3

Wave measurements are important. Why? • Real time wave (and wind) measurements – Wind and wave forecasting operations • Data assimilation into numerical models • Subjective assimilation into wave forecasting – Guidance to weather sensitive operations – Ship routing services – Marine (multi-hazard) warnings • Archive of real time and delayed mode wave measurements – Wind and wave model validation studies – Operational forecast verification – Calibration and validation of satellite (and ship radar) wave estimates – Development and validation of wave hindcasts and reanalyses offshore design criteria – Climatological summaries – Legal cases 4

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ETWS-I EXCERPTS • 7. 3. 2 The meeting urged that the network of in situ wave observations from moored buoys be enhanced, particularly for offshore locations and in the tropics and southern ocean, in order to provide more balanced geographical coverage and therefore more representative statistics in the validation of wave model output and calibration of satellite sensors. 6

ETWS-I EXCERPTS (2) A. 3 Ship wave observations • Much of the wave information used in climatological studies and in operational forecasting is acquired as visual observations from shipping (especially from vessels in the VOS system). The use of such data requires caution as they exhibit considerable variability in quality. Seeking more uniform observing practices through training and providing guidance material can enhance quality of these data. Automation of wave observations from merchant shipping remains a distant goal but this possibility should not be abandoned. • Consider the feasibility of automation of wave observations from shipping, e. g. though the use of ship bow-mounted sensors (in cooperation with the OCG & OOPC). • Improved wave measurements from VOS would be of great benefit in wave analysis and forecasting, for assimilation into models, and verification of forecast output. The ETWS requests that the OCG document existing automated wave measurements from ships, and consider the implementation of appropriate systems in the VOSClim programme. The ETWS will participate in the evaluation of present and future automated wave measurement systems. 7

ETWS-I EXCERPTS (3) A. 4 Rescue of wave …. . data and facilitating access to it • Further development of wind wave ……. requires access to historic wave data. Not all sources of such data are yet known and not always is the data storage reliable enough to guarantee that a future user will be able to access the data. To some extent this is also related to the lack of corresponding metadata. Therefore JCOMM should continue attempts to identify existing public and private sources of surface wind, wave, and storm surge measurement data with the objective to ensure its safe storage and, if possible, open access to the data and metadata and its incorporation into an international data exchange system…. . 8

MARCDAT–II EXCERPTS • The need for the broad spatial sampling provided by traditional VOS, including manual observations of clouds and waves, was noted…. . . Automatic Weather Systems (AWS) on ships provide large data volumes, useful for many purposes, but do not provide a wide spatial coverage. Often the parts of the report requiring manual input are missing from AWS observations • Wave summaries should be included in ICOADS. The need for a subset of very high quality data was discussed. The importance of metadata was stressed; the errors are thought to mainly arise from how the measurements are taken. • New type of wave information may come from VOS based estimates of directional wave spectra (with low accuracy, but high frequency - e. g. every second). Every ship has a radar (usually 2) and this can be used to extract wave spectra. A further source of information may come from laser range finders installed on some oil platforms. • A high quality subset of wave information should be developed. • The usefulness of a variety of new sources of wave information should be investigated. • The serious decline in number of VOS ships continues. 9

Neville Smith Vincent Cardone Peter Janssen Ma r ylo Ta rtin ter WIND WAVES AND Pe Ho lt Gerbrand Komen Jea n. B nin i yab idl ir R ot im ad Vl Val Swail 10

Wind Wave Observations Visual “+” : sometimes the only observations available, the longest term data base, basis for current climatologies (consistent when used as ensemble but for mean conditions only), mariners’ feedback to services, useful in services such as Sa. R, useful in development of statistical forecasting techniques, in subjective corrections to wind OA (Cardone, private communication), used in legal cases. “-” : subjective, insufficiently accurate for use in data assimilation schemes, considerable scatter of individual observations, hard to automate for VOS, possible fair-weather bias. VSOP-NA results - no waves Automation of Observations, Message Compilation, Transmission, and Archival 11

Wind Wave Observations PIRATA Instrumented “+” : objective, precise, spectral (1 -D or 2 -D), represent off-shore industry feedback, useful for verification, as ground truth for remote sensing (some!), for local climate purposes. “-” : impact on Da. S usually short-lived, insufficient amount of spectral data, particularly directional spectra. More spectral, better 2 -D, data needed, encourage the exchange of measured wave data over the GTS, inclusion of in situ wave data on operational moored buoys, need for co-locations of i) satellite and moored buoy wave heights ii) 2 -D 1 wave spectrum and wind data series 2

Waves are hard to measure. Why? • Define what you want to measure (and why) – for engineering design; cf models, satellite – Hs, Hm, Hc, Tp, T 0, Tm, 1 -D, 2 -D spectra • Buoy Response issues – Slack moorings, taut moorings, hull response, sensor orientation, wave breaking, peak avoidance (around or through) • Ship response issues – vessel characteristics, underway, hove to • Radar backscatter properties – waves incoming, outgoing • Where do you put wave sensors on ship? – holes in hull, (too) exposed sensors, interference • On board processing versus transmission time 13

Proposals for possible new wave measurement systems/deployments • Payloads – Heave sensors, 1 -D accelerometers, 3 -D motion packages, GPS, pressure sensors, acoustic Doppler • • • Moored buoys – 3 m, 10 m, 12 m, NOMAD, Tri. Axys, WR TOGA/TAO, PIRATA buoys – taut moorings Drifting buoys ARGO floats Ocean Sites Shipboard systems: – – Radar systems (WAMOS, MIROS) Tucker instruments Downward looking lasers ADCP • Issues – power budgets, message length, response characteristics 14

Holliday et al. , 2006. Were extreme waves in the Rockall Trough the largest ever recorded? , Geophys. Res. Lett. , 33, L 05613 15

Holliday et al. , 2006. Were extreme waves in the Rockall Trough the largest ever recorded? , Geophys. Res. Lett. , 33, L 05613 16

Holliday et al. , 2006. Were extreme waves in the Rockall Trough the largest ever recorded? , Geophys. Res. Lett. , 33, L 05613 17

Holliday et al. , 2006. Were extreme waves in the Rockall Trough the largest ever recorded? , Geophys. Res. Lett. , 33, L 05613 18

JCOMM EXTREME WAVE DATA BASE Motivation: JCOMM Expert Team on Wind Waves and Storm Surges noted the need for high quality measured wave data sets in areas of open ocean away from continental margins for use in model validation, forecast verification, satellite calibration and validation as well as climatology Catalyst: Rockall Trough storm of February 8, 2000 measured 18. 5 m SWH, the largest known reliably measured wave height, off Scotland Proposal: JCOMM supported the development of a JCOMM-label data base of wave measurements in “extreme storm seas”, SWH ≥ 14 m Requirement: Contributions of high quality wave measurements of extreme storm seas with appropriate documentation and metadata to the JCOMM data base – to be hosted – where? Holliday, N. P. , M. J. Yelland, R. Pascal, V. R. Swail, P. K. Taylor, C. R. Griffiths, and E. Kent, 2006: Were extreme waves in the Rockall Trough the largest ever recorded? , Geophys. Res. Lett. , 33, L 05613, doi: 10. 1029/2005 GL 025238. 19

What do we need with respect to Waves? More measured wave data anywhere, anytime, real time, delayed mode, Hs 2 -D spectra More open ocean wave measurements in Southern Ocean, tropics More high quality automated wind measurements More high quality research vessel wave data (e. g. Rockall Trough) More development of (automated) ship wave measurement systems More development of other (e. g. buoy) wave measurement systems Development of JCOMM extreme measured wave data base Inclusion of more wave measurements in existing marine data bases, e. g. ICOADS Development of wave products in ICOADS – coordinate with JCOMM TT OPD Better linkages of JCOMM ETWS, ETMC, OCG (DBCP, SOT); OOPC; SAMOS; GOSUD 20

9 th International Workshop on Wave Hindcasting and Forecasting Victoria, B. C. 24 -29 September 2006 Theme: Extreme Storm Seas 21

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