2012_CATALOGO_QR_SP-PORTUS-OMA_AF

8/2/2019 2012_CATALOGO_QR_SP-PORTUS-OMA_AF

1/4

Specications and appearance are given as guidelines and may change without notice.Open Mode Analysis Software Specications/ Document: SP-PORTUS-OMA-100 rev1.0

Open Mode Analysis Software Implementation | Product Code: SP-PORTUS-OMA-100

1

Why Open Mode Analysis Software

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 unique ability of HF radar systems to map in near real-time surface currents over large areasof the coastal ocean can play a critical role for tracking and forecasting oil spills, for improving

navigation safety and for helping in coastal and offshore infrastructure operations.

Radar detects target echoes against a background of unwanted noise. When wanting to monitor2D surface current vector maps by means of oceanographic HF radars, desired echoes are therst-order Bragg scatter from which currents information are obtained. CODAR SeaSondes world

leading HF Radar technology integrates effective methods to deal with this unwanted backgroundinterference which consist in ship echoes, reection of long distance signals at the ionosphericlayer, signals from other radio communication and broadcasting stations, etc. but nevertheless,

oscillations in coverage of any HF Radar network are a well known situation.

For pure geometrical reasons, surface current total vectors generation from HF Radars requires that

any patch of the ocean surface is directly viewed by at least two stations forming an angle toanother that is wider than, at least, 20 degrees. This is not always possible due to coastline geometry

in the stretch in between two radar stations or in the line between two stations.

Figure: Examples of occasional gaps in the (2-D) surface current vector map coverage of Long Range 5 MHz and High Resolution 40

MHz SeaSonde systems in Galicia (Spain) due to external interference and coastline geometry.


2/4

Figure: High quality OMA surface current vector map (right) andstandard surface current map (left).



2

Prior to the use of 2D surface currents inany decision support tool, an optimal dataquality control needs to be performed.

Spatial gaps can occur due to geometricinstabilities along the baseline between

sites, shadowing from local coastlinegeometry, ship echoes, Radio Frequencyinterferences, or antenna interaction with

the neareld environment. Therefore, llingspatial gaps is necessary when calculating

particle drifting trajectories. A widecontinuous good spatial coverage, as well

as information closer as possible to coast,is crucial to take the most out of HF radarobservations. This is what the PORTUS OMA

software package is intended for: furtherimprove the quality of SeaSondes surface

current maps.

Product description

The observed standard surface velocity map from two coastal radar stations in gure (left) althoughcovering a wide area, does not provide observations close to shore, or has spatial gaps due todifferent reasons (e.g. Radio Frequency noise interference, coastline geometry)

Figure: OMA boundariesas implemented inthe open ocean or anenclosed bay.

The PORTUS-OMA real-time processing tool relies on the widely proven technique of Open-boundarymodal analysis implemented by Lekien et al., (2004), and further optimized by Kaplan and Lekien

(2007).


3/4



3

Not only does the OMA make it possible to ll spatial gaps for a given geometry, but also the resulting

gridded currents eld has optimal properties for lagrangian applications. Open Mode Analysis OMAis a robust method for lling gaps, to extrapolate vector coverage in a predened domain, to

low-pass spatially ltering the surface currents data and also guarantees the ow is tangent to thecoastline preventing ow into the coastline. It is mathematically based on a vorticity-free (u) anda divergency-free (u) decomposition of any given surface velocity:

u= u + u

The modes (,) are computed solving two laplacian eigenvalue problems on the domain with

Dirichlet and Neumann conditions on the closed boundaries and adding boundary modes toaccount for ow through the open boundary.

Figure: Principal OMA modes as implemented in Ra de Vigo inside the PORTUS.


4/4

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


The enhanced real-time surface current vector map generation OMA software is implemented asan integrated module of the SeaSonde focused Portus Marine Information System. As part of thesoftware implementation process to any HF Radar system, OMA nowcasted elds are compared

against total surface vectors obtained by the conventional least-square (LS) local interpolationmethod (Lipa and Barrick, 1983) which, being a reliable combining method, is not gap-free and has

no kinematic constraints to prevent normal ow through the shoreline.

SP-PORTUS-OMA-100 includes:

Provided as a software enhancement to

the PORTUS marine information system

Implemented and validated by CODAR

and QUALITAS as part of the softwareinstallation process

Processing Software Package Features:

Extends area of total vector coverage from

standard backscatter geometry

Reduces occasional current vector outliers

and prevents ow through the coast

Is an extension module of the basic PORTUS

by QUALITAS rmware

Outputs les in standard ASCII, NetCDF,WMS or other customer formats

Outputs real-time data through ftp andhistoric data through OpenDAP

Documents

2012_CATALOGO_QR_SP-PORTUS-OMA_AF