Recent studies on the Adriatic long-term oceanographic changes

Ivica VilibićIvica VilibićInstitute of Oceanography and Fisheries,Institute of Oceanography and Fisheries,

Split, Croatia, vilibic@izor.hrSplit, Croatia, vilibic@izor.hr

Papers:

Vilibić, I., Matijević, S., Šepić, J., Kušpilić, G., 2012. Changes in the Adriatic oceanographic properties induced by the Eastern Mediterranean Transient. Biogeosciences, 9, 2085-2097.

Vilibić, I., Šepić, J., Proust, N., 2013. Weakening of thermohaline circulation in the Adriatic Sea. Climate Research, 55, 217–225.

Vilibić, I., Pištalo, D., Šepić, J., 2015. Long-term variability and trends of relative geostrophic currents in the middle Adriatic. Continental Shelf Research, 93, 70-80.

Vilibić, I., Čikeš Keč, V., Zorica, B., Šepić, J., Matijević, S., Džoić, T., 2015. Hydrographic conditions driving sardine and anchovy populations in a land-locked sea. Marine Mediterranean Science, in press, doi: 10.12681/mms.1120.

Vilibić, I., Mihanović, H., Ivčević, A., Kušpilić, G., Milun, V., 2015. Mapping of oceanographic properties along a middle Adriatic transect by using Self-Organising Maps. Estuarine Coastal and Shelf Science, in press.

Mihanović, H., Vilibić, I., Dunić, N., Šepić, J., 2015. Mapping of decadal middle Adriatic oceanographic variability and its relation to the BiOS regime. Journal of Geophysical Research, under review.

Palagruža Sill

Data:Data:- Palagruža transectPalagruža transect- Stations P1 (528), P2 (529), P3 (216), Stations P1 (528), P2 (529), P3 (216), P4 (206), P5 (199) – number of vertical P4 (206), P5 (199) – number of vertical profiles in bracketsprofiles in brackets- 1952-20101952-2010- temperature, salinity, DO, TIN, HPOtemperature, salinity, DO, TIN, HPO44

2-2-

Vilibić et al. (BG, 2012)EMTEMT

A strong footprint of A strong footprint of EMT in all physical and EMT in all physical and chemical parameterschemical parameters

Vilibić et al. (BG, 2012)

Different TIN/HPO4 ratio during the EMT period indicate different Different TIN/HPO4 ratio during the EMT period indicate different origin of the intermediate water masses in the Adriatic Seaorigin of the intermediate water masses in the Adriatic Sea

T, S, T, S, tt, DO trends 1952-2010, DO trends 1952-2010• • significant at 95%significant at 95%oo insignificant insignificantItalyItalyCroatiaCroatia

Vilibić et al. (CR, 2013)

Trends in the last 60 years indicate Trends in the last 60 years indicate a weakening of the Adriatic THCa weakening of the Adriatic THC

Vilibić et al. (CSR, 2015) NEMOMED8 RegCM trendsNEMOMED8 RegCM trends

RegCM do not reproduce RegCM do not reproduce weakening of the Adriatic THCweakening of the Adriatic THC

Vilibić et al. (MMS, 2015)

FFluctuations of sardine and anchovy luctuations of sardine and anchovy parameters are dependant oparameters are dependant onn fluctuations of the Adriatic hydrography.fluctuations of the Adriatic hydrography.

Mihanović et al. (JGR, 2015)

SOM setup:SOM setup:• batch training algorithmbatch training algorithm (efficient training) (efficient training)• a 4x3 SOM grida 4x3 SOM grid (good compromise between (good compromise between

details and graphic presentation)details and graphic presentation)• rrectangular lattice structureectangular lattice structure (preferable for (preferable for

small size SOMs)small size SOMs)• llinear initialization of unit weightsinear initialization of unit weights (EOF (EOF

decomposition and linear interpolation of decomposition and linear interpolation of the first two leading EOFs – saves time with the first two leading EOFs – saves time with complex data sets)complex data sets)

• ““eepp”” neighborhood function neighborhood function (gives the least (gives the least smoothing to the SOM units)smoothing to the SOM units)

The data:The data:• T, S, DO at the Palagruža Sill, 1952-2010T, S, DO at the Palagruža Sill, 1952-2010

Application of a novel method, Self-Organizing Application of a novel method, Self-Organizing Maps (SOM), to the Adriatic long-term Maps (SOM), to the Adriatic long-term thermohaline series.thermohaline series.

Motivation:Motivation: To objectively map the characteristic To objectively map the characteristic thermohaline patterns over the Palagruža Sill.thermohaline patterns over the Palagruža Sill.

Mihanović et al. (JGR, 2015)

The data:The data:• T, S, DO at the T, S, DO at the Palagruža Sill, 1952-2010Palagruža Sill, 1952-2010

Bad data exampleBad data example

Mihanović et al. (JGR, 2015)

Objectively extracted Objectively extracted patterns at the transectpatterns at the transect SOM patterns (BMUs) SOM patterns (BMUs) stand for different circulation stand for different circulation modes of the Adriatic, modes of the Adriatic, reflecting in water mass and reflecting in water mass and primary production dynamicsprimary production dynamics

Mihanović et al. (JGR, 2015)

Changing the length of the dataset and the number of Changing the length of the dataset and the number of stations used does not change largely SOM patternsstations used does not change largely SOM patterns BIOS is the dominant generator of the Adriatic variabilityBIOS is the dominant generator of the Adriatic variability

All data, gapsAll data, gaps

1975-2010, without P41975-2010, without P4

1994-2010, no gaps1994-2010, no gaps

Mihanović et al. (JGR, 2015)

SOM patterns of the SOM patterns of the Absolute Dynamic Absolute Dynamic Topography (ADT) in Topography (ADT) in northern Ionian Sea show a northern Ionian Sea show a strong resemblance with T-S strong resemblance with T-S changes along the Palagruža changes along the Palagruža SillSill Assymetric ADT patterns Assymetric ADT patterns in the northern Ionian Seain the northern Ionian Sea BiOS reversals may be BiOS reversals may be rapid (within a year) or slow rapid (within a year) or slow (2-3 years), resulting in a (2-3 years), resulting in a rapid or a slow changes in rapid or a slow changes in the Adriatic propertiesthe Adriatic properties

Some SCOOL perpectives ...Data:Data:- There are other long-term stations which may There are other long-term stations which may be investigated for long-term changes be investigated for long-term changes e.g. in e.g. in coastal region coming from Pag-Konavle coastal region coming from Pag-Konavle monitoring programme, D1200, ...monitoring programme, D1200, ...- ... to be used for assessment of changes in ... to be used for assessment of changes in eastern coastal areaeastern coastal area

Research topics:Research topics:- Connecting Adriatic changes to the Ionian Connecting Adriatic changes to the Ionian circulationcirculation- Analysing climate hindcast and projections for Analysing climate hindcast and projections for the Adriatic decadal changes and processes the Adriatic decadal changes and processes (DWF, BiOS)(DWF, BiOS)- Constructing a simple BiOS-based indexConstructing a simple BiOS-based index- Reconstructing oceanographic conditions Reconstructing oceanographic conditions from chronologiesfrom chronologies- Connecting chronologies with long-term data Connecting chronologies with long-term data measurementsmeasurements