Apologies from Raymond Nerzic who was unable to attend.
MEETING NOTES 23/03/99 Please advise me of any inaccuracies.
All received by Lund, apart from Bureau Veritas
Georg will generate new version of Technical Annex for "redefined" project, based on format of original. He will pass to David Cotton to make necessary additions.
We are again without an officer for our programme, as the officer recently assigned to us has just resigned.
A copy of Cees Leenaar's draft outline for a possible COMKISS II (under Framework V) was passed to Georg. All COMKISS partners should now have a copy.
Marc Prevosto advised that he and Raymond Nerzic will hold a meeting with Meteo France (at Aix en Provence) in the near future.
Data for "Beatrice" buoy of Ouessant Marc requested for altimeter wave data close to the Meteo France "Beatrice" buoy.
a) Guy Parmentier, Please ensure Lund have a cost statement as soon as possible!
b) Georg to Generate first version of revised project and pass to David
c) ALL - comments on Cees' COMKISS II proposal
d) Marc to advise David Cotton of times and location of altimeter data requirement for "Beatrice".
e) David to extract "Beatrice" altimeter time series data and place on ftp site for easy access.
The most important route for WP3100 is Trieste to Rotterdam (and from Rotterdam to Boston). The aim is to look at a particular ship where unusually early failure (development of crack) was experienced. The ship has been in almost continuous operation (85% of time) on the Trieste-Rotterdam return route, with the occasional extra leg to Boston, since July 1989. Each one way trip (Trieste-Rotterdam) takes approximately 15 days. Guy believes the ship leaves regardless of local conditions, at all times of year.
"Global Wave Statistics" are used as the data base to assess ocean wave conditions (by season). Significant wave height and average wave period are taken from data base, a general wave direction is assumed for each ocean region. The BV procedure generates a wave spectrum which it inputs to a fatigue calculation model. The only measurements available from the ship are from the ship inspection (once every five years) which revealed the crack.
The Trieste-Rotterdam and Rotterdam-Boston legs should be treated differently. SOS will first provide data definition, including retrieval cost, and wait for agreement from project team, before extracting the data. a) Trieste-Rotterdam SOS will assess best technique for dividing this leg into regions for subsequent extraction of archived altimeter data (Hs, wind speed and wave period estimate) along route. Will provide time ordered TOPEX data in a series of regions along the ship route. b) Rotterdam-Boston (N Atlantic Sector) SOS will divide this leg into larger regions, based on multiples of 2 x 2 degree grid squares, and extract data into individual data sets for each region. Once extracted these data will be placed on an ftp site, for subsequent analysis by U. Lund/IFREMER
a) Generate month by month time history of sea conditions along the route.
b) Compare altimeter data with data available from Global Wave Statistics (GWS) . Identify differences.
c) If differences exist, BV to rerun fatigue calculation models, and investigate for any significant differences in results.
a) Guy: Provide information on ship inspections. By 30 March
b) Guy Provide David with definition of Rotterdam to Boston Route in 2 x 2 degree grid squares. By 30 March
c) SOS: Generate data definition, with extraction costs. By 7 April
d) SOS: If approved, extract data (start on receipt of approval, complete by end April).
e) Lund/BV: Locate/extract appropriate data from GWS Data Base. (April)
f) Lund: Process altimeter and GWS data, compare (May-June)
g) Lund/BV: Rerun fatigue calculations (July-August)
h) All: review at COMKISS progress meeting (need for direction information, more satellites, etc).
Guy wishes to develop a new procedure to input a sequence of severe sea states into a crack propagation model, to assess chances of the propagation of a crack to a certain limit over 15 days. At the moment, BV do not have a procedure to analyse this problem. Guy defines three trial sets of conditions, requiring values every three hours for 15 days. These three sets of time series data would be provided for each season/quarter year. (i) The 15 day period starting with maximum ever recorded significant wave height. (ii) The 15 day period ending with maximum ever recorded significant wave height. (iii) The 15 day period with the maximum record mean value of (Hs**3)^1/3.
This is a difficult task! Clearly satellites alone cannot provide 3 hourly measurements along the ship route. Discussion suggested two possible approaches, using the satellite data base to develop estimates of persistence at points along the North Atlantic route, or identifying the intervals at which altimeter crosses over the ship track and investigating how these measurements can be best interpolated onto the surface representing the passage of the ship along the route. We agreed to start with a sampling study, investigating the latter approach, which should provide an indication of what sort of satellite sampling would be necessary to provide enough information. Further data analysis would only follow once a feasible procedure had been identified.
BV should write a summary note indicating the value of this study, and what problems exist with using existing data sources. Once a possible scheme has been devised, the extracted and processed satellite based information can be compared to existing sources of time series sea state information (hindcasts, nowcasts).
a) Guy: provide note indicating importance of this study to BV.
b) Guy: Route definition (see above) By 30 March.
c) Lund/IFREMER: - Literature study for investigation of sea state time and space scales in joint distributions.
d) David: - Provide times/intervals/locations of satellite crossings of N Atlantic part of Rotterdam-Boston route during example 15 day period. (early April)
e) Lund - Investigate possible schemes to interpolate altimeter data onto track line. (April/May)
f) Lund - If suitable technique identified, request data from SOS. (?June)
g) ALL: Revisit WP status in June - Agree future actions The Lund contingent had to leave at this point.
4.1.1 Definition of routes
Corsica Ferry routes Nice-Bastia, Nice-Calvi, Savona-Bastia, Civitavecchia-Golfo Aranci
4.1.2 Operational criteria (max permissible sea state):
Two levels, Hs < 4m and Hs < 6m.
4.1.3 Satellite Data Requirements:
High resolution required in time and space. As first step we agreed SOS would extract data along (?5) TOPEX tracks in the region of Corsica. These data would be extracted from a data base interpolated onto a fixed grid along the mean TOPEX track.
4.1.4 Methodology for analysing data base
The altimeter data to be first analysed to find variability of exceedance of thresholds at different locations on the satellite tracks. If necessary interpolation techniques could be attempted to propagate information to important locations. Altimeter derived estimates to be compared to those derived from available information (Meteo France hindcasts?). We would then aim to provide an assessment of the satellite sampling required to derived useful information for Corsica Ferry operations.
4.1.5 WP4100a ACTIONS.
a) SOS: Altimeter data definition and cost estimate.
b) SOS: Extract data on TOPEX tracks.
c) IFREMER: Contact Meteo France regarding access to their sea state wave data.
d) IFREMER: Analyse extracted alt data to derive threshold exceedance statistics.
The aim of this work package is to run ship response models over a satellite derived wave climate data base for the ferry routes to Corsica. The models will assess how often (by season) critical stresses are exceeded on each route. The occurrence of these exceedances can then be compared to the operational sea state threshold exceedance rates. This WP is a continuation of WP3300 (High Speed Craft Trials off Marseilles Nice). Before we can start on this work package, the response models need to be calibrated within WP3300. Thus this work package will only commence after August COMKISS meeting.
Dr. David Cotton Satellite Observing Systems 15, Church Street Godalming Surrey GU7 1EL UK ph +44 (0)1483 421213 fax +44 (0)1483 428691