THE EuroSITES E2M3A OBSERVATORY IN THE SOUTHERN ADRIATIC SEA:

A tool to monitor the dense water formation process

Vanessa CardinM. Bensi, M. Pacciaroni, G. Civitarese, M. Gacic

Istituto Nazionale di Oceanografia e di Geofisica Sperimentale – OGS Trieste - Italy

42nd International Liège Colloquium on Ocean Dynamics26 - 30 April, 2010 Liège - Belgium

Outline

�EuroSITES network

�Long-term variability

�Some conclusions

�Oceanographic results:

�Thermohaline properties

�Current data

�Mooring design – Scientific Payload

�Oceanography of the Adriatic Sea

The Adriatic Sea

•Complex Bathymetry

•Elongated shape

•Air-Sea Interaction

•Strong atmospheric forcing

•Interconnected with the Eastern Mediterranean through the Otranto Strait

Adriatic Circulation during the recent yearsLIW enter the otrantostrait and goes to thenorth

LIW saltier and warmer in the last years could have contributed to modify the new NAdDW

NAdDW flows southward and enrich the deep part of the South adriatic pit

NAdDWNAdDW

The dense waters which were since then formed, profoundlydiffer from waters of Adriatic origin observed in the regionpreviously: they are saltier and warmer than in the past

The E2M3A ObservatoryWhy this site?

•It is considered a major site of deep water formation and the origin of the semi-closed thermohaline cell in the Eastern Mediterranean.

•The dynamics of the area is dominated by the presence of a quasi-permanent cyclonic gyre that intensifies in the winter season creating the conditions for the production of dense and oxygenated waters

•Water is formed on the shelf; part of itflows into the Southern Adriatic Pit

•Adriatic Deep Water (ADW) is one ofthe main components of the EMDW

Since 2002: Joint project with the University of Bremen (2002-2003) Founded by projects like MFSTEP, Mersea, VECTORActually funded by EuroSITES (2008-2011)

E2-M3A

Trieste

Before EuroSITES 2006-

2008

Double Mors acoustic release

AANDERAA RCM11 @ 1186 m

Sediment trap @ 1174 m

CT SBE37 smp @1172m

6 vitrovex buoys

CT SBE37 smp @1014m

CT SBE37 smp @764m

CT SBE37 smp @564m

CT SBE37 smp @364m

Sediment trap @ 168 m

Underwater buoy ORE SS28’’ @ 162 m

Depth 1204 m

New Developments:

�Surface buoy with meteorological sensors

and CT + PCO2 at 15 m depth

� Acoustic Link between mooring lines

� CTD with O2 Sensor and trasmissometer

at 350 and 750m

�Reat time data transmission to land

station

�ADCP data transmitted in real-time

Disadvantages:

�Located 800 km away from OGS

�Difficult environment

�Not easy maintenance

�Request of ship-time

EuroSITES Network

9 existing deep ocean (> 1000m) observatories2 existing networks2 cable sites

AnimateM3A

EuroSITES Network

Convection Sites

Deep Water Formation- West vs East Mediterranean, biochemical cycled in the different ecosystem regimes of the Med

The E2M3A Observatory

Surface Buoy Measurements (RealTime)

Wind Speed and direction Young

Air Temperature Young

Air Pressure Young

Humidity Young

Solar Radiation Eppley

Mooring Line 1 (Principal)

Conductivity and temperature 15m CT SBE37 Yes

pCO2 – Pro 15m PRO-OCEANUS yes

pH sensor 15m SUNBURST yes

The E2M3A Observatory:

ParameterParameter Depth Depth Sensor name / Sensor name / ManufacturerManufacturer RR--TT

Mooring line 2 (secondary)

Acoustic Current profiler upward looking 360m ADCP RDI WH 150 kHz Yes

Conductivity, temperature, oxygen, particulate 364m CTD SBE16 Plus Yes

Conductivity, temperature 564m CT SBE37 No

Conductivity, temperature, oxygen, particulate 764m CTD SBE16 Plus Yes

Conductivity, temperature 1014m CT SBE37 No

Conductivity, temperature 1172m CT SBE37 No

temperature, conductivity, sea pressure, turbidity, dissolved Oxygen

1180mAANDERAA RCM11 No

Acoustic modems Linkqvest

Current parameters measurements

Webpage: http://nettuno.ogs.trieste.it/eurosites/Real_time.htmlhttp://www.ogs.trieste.it

300m

1250m

ThermohalineThermohaline propertiesproperties

�Mooring data has been validated with CTD profiles collected during cruises performed in the Southern Adriatic

� Complete absence of mixing during winter 2006-2007

� On the contrary the following winter (Jan-April 2008) intermediate-deep convection occurred down to 750-800m.

Nov 2006- Oct 2009

� The abrupt decrease in salinity occurred after May 2008 could be a consequence of an higher production of new dense water in the northern basin (fresher)

2006-2008

2002-2003Warming of the bottom layer at the E2M3A site?

� The increase of temperature and salinity at deep layers, that lead to a decrease in density at the bottom, should have reference to the increase of salt observed in the north basin till 2007

2002/03+2006/07

November to May

Where are we now and how the present situation fix in the long-term variability?

300m

CurrentCurrent datadata

08/09

� The flux in the South Adriatic Pit appears barotropicand characterized by the passage of many mesoscaleeddies both in the intermediate than in the bottom layer.

ADCP data recorded in the intermediate layer (between 80 and 300m) permit to study in detail the vertical mixing

300mCurrentCurrent datadata

1182m

� Current measurements at 1180m allow us to study the advection of North Adriatic Dense Water (NAdDW ) in the bottom layer of the South Adriatic

Conclusions�a�Important to have in-situ measurements together with mesoscalesurveys in a complex area

�High time resolution measurements provide value information of mesoscale features in the area

�The analysis of the thermohaline parameters of the 2006-2009 mesurements confirms the already pointed out by Rubino & Hainbucher (2007)

�A constant increase of temperature and salinity in the South Adriatic pit in the last 2 years and a weakness of the LIW in the intermediate layer

�Joint measurements of satellite imageries, mesoscale surveys and mooring sites give the right picture of the oceanographic conditionsin the area