Year-long measurement of surface currents in the Malta-Sicily Channel:

Lessons learned and implications

Malta, August 29th, 2013

Simone CosoliIstituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste

Year-long measurement of surface currents in the Malta-Sicily Channel:

Lessons learned and implications

Malta, August 29th, 2013

Simone CosoliIstituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste

Motivations-1: Marine traffic in the Malta – Sicily Channel

Oil spill density map (source: Policy research Corporation,JJoint Research Centre, European

Commission: http://serac.jrc.it

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Motivations-2: Fishing activities in the Malta – Sicily Channel

(1) Direzione generale delle politiche interne dell’unione Unita’ tematica B Politiche strutturali e di coesione – Pesca: la pesca in Sicilia – Parlamento Europeo

(2) GENERAL FISHERIES COMMISSION FOR THE MEDITERRANEAN

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Some numbers and facts(1,2):

-greatest fishing fleet in Italy as for :- number of boats (3323 boats - 24.4% national fleet @2010), - size of boats (19.3 tons avg – 14tons avg in Italy) - boat power (86.6 KW avg – 83.8 avg in Italy)

-fishing fleet:- 12-24m boats operating on a short-distance basis

(1 to 2 days trips)- >24m boats employed on long fishing trips

(3–4 weeks) in offshore waters

Motivations-2: Fishing activities in the Malta – Sicily Channel

Some numbers and facts(1,2):

-43 301 tons of captures in 2008:- 69% pelagic fishes: small-sized

big-sized

- 10% mollusc

- 21% crustacean

large amount of targeted species and over-fishing problems(1) Direzione generale delle politiche interne dell’unione Unita’ tematica B Politiche strutturali e di coesione – Pesca: la pesca in Sicilia – Parlamento Europeo(2) GENERAL FISHERIES COMMISSION FOR THE MEDITERRANEAN

Engraulis encrasicolus Sardina pilchardus

Xiphias gladius

Thunnus thynnus

Todarodes sagittatus Sepia officinalis

Parapenaeus longirostris Aristeus antennatus Nephrops norvegicus

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Motivations (yes, more): currents – ocean structures impact fish distribution and fishing activity

A conceptual model for Sardine in the Sicily Channel

(*)Lafuente et al., Influence of the surface circulation in the spawning strategy of the Sicilian Channel anchovy, ICES 2000 Annual Science Conference

Remote Ocean Sensing Workshop ROS 2013 March 13 – 14, 2013

Engraulis encrasicolus

Modification in AIS path: along-shore

transport of fish-larvae (depletion and

enrichment)

Offshore advection from AIS branches – upwelling or

northern winds – ageostrophic processesincrease mortality risks

Larvae entrapment in persistent vortices favors

fish growth

Background

ABV = Adventure Bank VortexMCC = Maltese Channel CrestISV = Ionian Shelfbreak Vortex

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Background

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Background

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Drifter tracks in the Sicily Channel (1992 – 2010)

Why not simple buoys?

Problems: Sub-optimal temporal and

spatial coverage in certain areas – oversampling in other areasCALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Why not models?Circulation Models:

3-D momentum eqtn.

continuity eqtn.

eqtn. of state

Problems:Complicated set of Differential Equations – not easy to solve

Tuning required – not always possible die to lack of data

Cannot account for ALL processes: Parametrisation of fine-scale physical processes often needed

No matter what or how complicated one makes it….some process will be missing (always)…

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

Combned TX-RX element

2 orthogonal crossed-loops

>180˚ coverage

combined TX-RX antennaintegrated in the support

mast

Why HF radars?

Italy

Compact, non invasive systems

Safe for population (avg.TX Pw. 35W)

Working continuously independently of weather conditions and sea-state

Unique spatial-temporal high-resolution not achievable with conventional instrumentation

CALYPSO Project Final Meeting, August 29, 2013, University of Malta, Valletta Campus, Valletta

TunisiaAlgeria

Libya

Sicily

Grecia

Albania

France

Italy

HF radar coverage

HF radar maps: how do they look like?

Seasonal variability in the AI-Stream as for position and extension Persistent gyre moves and stretches in time, predominant in winter

August 2012September 2012October 2012

Surface current regimes in the Malta Channel

December 2012

Persistent channel-wide cyclonic gyre (R~30 km) and less-evident anti-cyclonic gyre (R~10 km): impacts DEPEND on release location

16-12-2012

18-01-2013 20-02-2013

Persistent channel-wide cyclonic gyre (R~30 km) and less-evident anti-cyclonic gyre (R~10 km): impacts DEPEND on release location

Persistent channel-wide cyclonic gyre (R~30 km) and less-evident anti-cyclonic gyre (R~10 km): impacts DEPEND on release location

Importance for SAR activities

Importance for spill tracking

Periodic increase of NF levels @13MHz Strongest activity at afternoon-night

Lasting several hours

Affecting 1st order Bragg region interferences with radar currentsCommon problem @13MHz HF radar in the Med.Sea

RFI – removal algorithms exist – actually testing some @OGS

Filtering? Identification required first

ITU rules: HF radars can exist, but with a secondary license --license

Theoretical Noise Level (~-130dBm)

Up to 20-30 dBm fluctuations due to ?

Importance of measuring reliable current data: periodic RFI issue

Thanks for your attention!

Importance for SAR activities