Requirements for Surface Marine
Observations in Support of Wind and Wave
Forecasting and Hindcasting
V.R. Swail
Climate Research Division
Environment Canada
Toronto, Ontario
WMO/IOC JCOMM Expert Team on
Wind Waves and Storm Surges
Selected Resource Documents
GCOS International Meeting of Experts. Asheville NC 1995
CLIMAR99 Workshop Vancouver, BC 1999*
OceanObs99 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 21st Century”
† †available on OOPC web site
© available from www.oceanweather.com/waveworkshop
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
• Platform Operations – disconnecting, discontinuing operation,
• 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
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
– Development and validation of wave hindcasts and reanalyses 
offshore design criteria
– Climatological summaries
– Legal cases
• 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.
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
• 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.
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…..
• 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
• The serious decline in number of VOS ships continues.
Neville Smith
Vincent Cardone
Peter Janssen
Gerbrand Komen
Val Swail
Wind Wave Observations
“+” : 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 SaR, 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
Wind Wave Observations
“+” : 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 DaS 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
wave spectrum and wind data series12
Waves are hard to measure. Why?
• Define what you want to measure (and why)
– for engineering design; cf models, satellite
– Hs, Hm, Hc, Tp, T0, 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
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 – 3m, 10m, 12m, NOMAD, TriAxys, WR
TOGA/TAO, PIRATA buoys – taut moorings
Drifting buoys
ARGO floats
Ocean Sites
Shipboard systems:
Radar systems (WAMOS, MIROS)
Tucker instruments
Downward looking lasers
• Issues – power budgets, message length, response characteristics
Holliday et al., 2006. Were extreme waves in the Rockall Trough the largest
ever recorded?, Geophys. Res. Lett., 33, L05613
Holliday et al., 2006. Were extreme waves in the Rockall Trough the largest
ever recorded?, Geophys. Res. Lett., 33, L05613
Holliday et al., 2006. Were extreme waves in the Rockall Trough the largest
ever recorded?, Geophys. Res. Lett., 33, L05613
Holliday et al., 2006. Were extreme waves in the Rockall Trough the largest
ever recorded?, Geophys. Res. Lett., 33, L05613
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, L05613,
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
Better linkages of JCOMM ETWS, ETMC, OCG (DBCP, SOT); OOPC;
9th International Workshop on Wave Hindcasting and Forecasting
Victoria, B.C.
24-29 September 2006
Theme: Extreme Storm Seas