2012_CATALOGO_QR_SP-PORTUS-STP_AF

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Short Term Prediction Software Implementation / Product Code: SP-PORTUS-STP-XXX

Specications and appearance are given as guidelines and may change without notice.STP Software Specications / Document: SP-PORTUS-STP-XXX rev1.0

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Why a Short Term Prediction system?

HF coastal radars have evolved over the past 40 years into worldwide operational networks that

provide real-time data to a variety of end users. Over 450 such radars are operating today of whichabout 400 are CODAR SeaSondes. The primary data products are two-dimensional (2D) surfacecurrent vector maps, which require two or more radars with overlapping coverage. In addition

to surface currents, secondary outputs include wave parameters, tsunami detection and vesseldetection.

The fate of drifting objects in the sea surface, such as vessels adrift or oil spills are highly dependenton ocean surface currents. While the unique ability of HF Radar to provide surface current nowcast

over large areas in near real time is of great value, the ability to forecast the currents and, thus,the fate of drifting material is an even more important tool. It can play a critical role for tracking

and forecasting oil spills, for improving navigation safety and for helping in coastal and offshoreinfrastructure operations as well as for search and rescue (SAR) applications.

Figure: The sinking of the supertanker Prestige off the coast of Spain in November 2002 was one of the most devastating oil spills everworldwide. During the crisis most of the decisions had to be taken with limited information.

In 2002 the U.S. Coast Guard (USCG) began a program to evaluate SeaSonde data products

for use in search and rescue (SAR) operations incorporating radar-derived current elds into short-

term predictive systems (STPS) to improve SAR capability, efcacy, and reduce costs of searchoperations in the sea. The STPS methods employed in the USCG SAR relied on a long record (at leastone year) of surface current data to extract statistical information and predict the tidal and non-

tidal components (not including the local wind effects). After nearly a decade of such careful testand evaluation, these methods were incorporated into the U.S. Coast Guard operations.

The need of a long time record of surface current in the region of interest to obtain a prediction aswell as the non explicit use of local wind effects are certainly a restriction to new monitored areas, incases of emergency or under strong wind effects. The challenge, therefore, is to draw upon surface

current data collected during the last few hours and forecasted winds and be able, herewith, toinitialize an accurate STP forecast method for the next 24 hours.


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And exactly this is what the present PORTUS STP software package is intended to do: to obtain high

quality HF Radars-based forecasted current elds for the short term (24 hours) using data informationfrom the previous 24 to 48 hours .

Figure: High quality STP forecasted (2-D) surface current vector map.

Product description

Prior to the ingestion of any HF Radar derived data into a forecasting system, an optimal QC, a

good spatial coverage, as well as a good estimation of the spatial error distribution of the surfacecurrents is crucial. This is done by means of OMA processing methodologies as described in the

document SP-PORTUS-OMA-100.

The STP software module reilies on the assumption that surface currents forecast can be decomposed

in tidal plus non-tidal components. The tidal currents are predicted by tidal constituents derivedfrom a harmonic analysis and that the non tidal components are decomposed in seasonal, windinduced and low-frequency components (eddies and ocean fronts) .

Figure: Rationale behindthe PORTUS-STP short termprediction system.


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Figure: HF Radar currents

and OMA-STP forecastingalgorithms as principal inputto any oil spill, chemicalsubstance or object driftermodels.

The new and unique concept behind the present STP methodology is that it operates based on a

very short time (24 to 48 hours) history of measured, OMA-tted surface-current coefcients . Therationale is that most locations are dominated by semi-diurnal, diurnal, and inertial harmonics, aswell as constant and linear trend, a ~12, to 48-hour history set followed by a 12 to 24 hour forecast

has showed to be a reasonable goal for an accurate forecast (Barrick et al., 2011).

The strength of a STPS methodology based on OMA-based coefcients rather than on otherrepresentation of the surface currents relies on the fact that OMA modes, especially the lower-

order, most energetic ones, represent ocean structures with great kinetic energy. Therefore, theyshould have some reasonable degree of inertia, i.e., they are more noise free over short periods oftime such as an hour or two.

As a measure of the STP forecast skill what is normally done, as part of the STP implementationprocess in any project, is to compare trajectories of the virtual particles forced by the OMA nowcastcurrents and by the STP-derived currents in order to construct a metrics of the system performance.

Figure: Simulated trajectories in the NOFOrapid deployment (Norway) followed byvirtual particles (initial positions are the redpoints) being forced by actual OMA ttedcurrents (blue lines) and forecasted OMAcurrents (black lines)


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About QUALITAS

Created in 2002, QUALITAS has its main activity in providing technology and data

intensive solutions to the operational oceanography, offshore, search and rescue,navigation and marine renewable sector focused on:

Ocean Observing Technologies Information Management Systems

Decision Support Tools Customized Software Solutions

QUALITAS activity in providing systems and solutions is ISO 9001 and ISO 14001 certified.

Phone: +34 913 886 656 E-mail : info@qual itasremos.com

Fax: +34 913 885 782 www.qualitasremos.com


SP-PORTUS-STP-XXX includes:

Includes a single-use (locked toa particular SeaSonde System)software license for

one domain of radar coveragearea not including winds SP-PORTUS-

STP-100

one domain of radar coverage

area including winds SP-PORTUS-STP-200

Provided as a software enhancementto the PORTUS Marine Information

System

Implemented and validated by

CODAR and QUALITAS as part of thesoftware installation process

Processing Software Package

Features: Provides an accurate currents

forecast in the area of total vector

coverage in a forecast interval ofup to 24 hours

Integrated as an extension moduleof the basic PORTUS by QUALITASMarine Information System

2012_CATALOGO_QR_SP-PORTUS-STP_AF

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