CHARACTERIZATION OF HURRICANES USING SATELLITE METOCEAN MEASUREMENTS : THE GUADELOUPE CASE

Demonstration Case Study (Ref: 342509)

I Name:

CHARACTERIZATION OF HURRICANES USING SATELLITE METOCEAN MEASUREMENTS : THE GUADELOUPE CASE

II Keywords:

Primary Keywords: Hurricanes, Oceanography, Sea-state

Secondary Keywords: Extreme conditions, Waves, Datawell, Wavedir, Wind

III Summary:

BCEOM organism whished an estimation of some hurricanes sea-states parameters offshore the Guadeloupe. In order to answer to the technical specifications MétéoMer implemented an operational procedure based upon the use of satellite sea-state measurements. The dense, homogeneous and world-wide coverage of these satellite data enable the achievement of such studies anywhere on the ocean, with significantly lowered investments and delays.

IV Description:

1 Customer Need:

BCEOM organism wished a quick and reliable estimate of some hurricanes sea-states parameters - heights, periods and directions - , offshore Guadeloupe. The operational characterization of such particular events is critical with the sole use of classical data sources - metocean hindcast through models, field measurements - due to the high intensities and /or to the variability of such particular phenomena

2 Method:

In order to answer to both BCEOM technical specifications and operational time constraints ( a two weeks delay for providing the results ), MeteoMer implemented an operational procedure, here based upon the determinant use of the following satellite sea-state measurements :

• Altimeter significant wave heights ( Hs ), provided by Geosat ( from Sept.86 to Nov.89 ), ERS1( from Dec.91 ) and Topex-Poseidon ( from April 92 ). Correction formula and qualification processes are applied on these data, in order to provide information which quality and confidence ranges are similar to those of field measurements,
• Sea-state directional wave height spectra, from the combined use of ERS1 SAR in wave mode measurement ( for the swell component ) and ERS1 scatterometer wind measurement ( for the wind-sea component ). These directional spectra represent a tremendous contribution to metocean studies since they bring most of the engineering required sea-state parameters : heights, periods and directions.

These measurements, as well as all satellite wind ones, are already stored in MeteoMer, on a world-wide scale. They are immediately accessible for metocean studies needs, through an internal dedicated archiving and interrogation system. The achieved study included the following steps :

• Definition of an area offshore the eastern coast of Guadeloupe, further used for the detection of hurricanes tracks,
• Search of hurricanes having crossed this area during the satellite sea-state measurements period. These hurricanes tracks in the offshore area and during this period were detected and identified through the use of Internet and MeteoMer own stored information,
• Deprocessing of MeteoMer elaborated sea-state world-wide satellite database, on the aforementioned offshore area, and for specific hurricanes crossing dates and locations,

For every identified hurricane within the offshore area, provision of corresponding sea-state Hs, peak periods and directions, after a final thorough analysis by MeteoMer engineers.

3 Result:

In this study, we have to determined the sea-states generated by the main hurricanes in the NE Guadeloupe area. At the end of this two weeks study, BCEOM was provided with a final report including a brief description of methods and satellite measurements used, and with its required determination of hurricanes - tracks on the offshore area and corresponding heights, periods and directions, -. These results were provided in numerical synthesis tables and colour computer graphics showed hurricanes tracks and corresponding satellite measurements.

Satellite tracks over the Hurricane Luis :

Luis was one of the studied hurricane for the 1995's tropical season and this figure shows several altimeter tracks of Topex-Poseidon on the area.
One of them comes through the hurricane trajectory at the same time as the phenomenon and it gives the associated altimeter significant wave height and wind speed.

4 Deliverables:

MeteoMer provides to the BCEOM two tables :

• The first containing the main characteristics of these hurricanes : Name, dates, maximum registered wind speed, minimum pressure,
• The second containing the precise dates of these hurricanes at the closest position of the NE of the Guadeloupe, the position (Lat, Lon) of the corresponding satellite measurement, the distance to the NE of the Guadeloupe of this measurement, the wind speed and the maximum significant wave height of this measurement.

We also provide the different tracks of the satellite measurements concerning these hurricanes.

5 Customer Opinion:

With this study, BCEOM benefited from three dramatic new aspects of metocean studies brought by the basic use of satellite measurements :

• On a technical hand, once applied some high-level analyses processing, satellite now offer reliable wind and sea-state measurements, with a world-wide, homogeneous and dense coverage of oceans. Here, satellite brought direct reliable measurements of these particular hurricanes events, otherwise difficult to represent either through the only use of models ( high intensities and variabilities ) or through field measurements, which generally can't stand such severe conditions,
• On an operational hand, MeteoMer developed some satellite measurements handling procedures, allowing the provision of elaborated engineering metocean parameters in accordance with operational time constraints (here, with a 2 weeks delay),
• On a financial hand, satellite measurements instantaneously offered to BCEOM the equivalent of a several years duration field measurement campaign.

6 Cost / Benefit:

The total cost of this study was 7.7 kecu (for 16 studied hurricanes), VAT excluded, including data and report. As a remark, this achieved study is only a first level one, corresponding with a direct provision, though thoroughly analysed, of satellite measurements corresponding with hurricanes crossing dates and locations in an area. MeteoMer can implement more elaborated procedures, concerning the hindcast of metocean events, be they common ones ( typical conditions or classical storms ) or particular ( typhoons, hurricanes,..). For instance, satellite measurements and metocean models can be combined in order to provide time series of offshore and nearshore directional wave height spectra, including the event paroxysm, on your very precise location. Such elaborated specific hindcasts range from 1 to 5 Kecu, VAT excluded, according to the analysed phenomena.
The combined use of satellite measurements and of metocean offshore and coastal models, offers an efficient and reliable characterization of specific events, through a whole range of operational procedures covering the various engineering needs and delays constraints. Furthermore, the dense, homogeneous and world-wide coverage of satellite measurements enables the achievement of such studies for many otherwise poorly investigated locations anywhere on the oceans, with significantly lowered investments and delays, and improved ( results guarantee / cost ) ratio. Thus, MeteoMer already achieved many similar studies of specific events hindcasts, from the Mediterranean to the Asian areas, for insurance, oil or harbours customers.

V References:

1. Customer References

   Customer

   Name: Mr Piallat

   Company: BCEOM

   Address: 259 Av. de Melgueil - BP 21 - 34280 La Grande Motte - France

2. Provider References

   Name: Mr Lasnier

   Company: MeteoMer

   Address: Quartier les Barestes - RN7 - 83480 Puget sur Argens - France

   Tel: +33 (0)4 94 45 66 11

   Fax: +33 (0)4 94 45 68 23

   E-mail: 4meteomer@meteomer.fr

   Web: www.meteomer.fr www.meteomer.com

3. Scientific References

   Name: Mr Lasnier

   Company: MeteoMer

   Address: Quartier les Barestes - RN7 - 83480 Puget sur Argens - France

   Tel: +33 (0)4 94 45 66 11

   Fax: +33 (0)4 94 45 68 23

   E-mail: 4meteomer@meteomer.fr

   Web: www.meteomer.fr www.meteomer.com