Pregled istraživanja na SCOOL projektu o termohalinim promjenama i dinamic i

1. Pregled istraživanja na SCOOL projektu o termohalinim promjenama i dinamici Ivica Vilibić Institut za oceanografiju i ribarstvo, Split

2. SCOOL Abstract: Climate change is a growing environmental, scientific as well as economic issue. However, although we are aware of certain changes our understanding of their origin and consequences is still very limited. Long-term data series are a key to this understanding and hard structures of marine organisms, including bivalve shells, present an important archive of environmental data potentially extending decades or even centuries into the past. Sclerochronology is an emerging interdisciplinary field that enables obtaining of marine environmental data from bivalve shell structural elements as well as their geochemical composition. These data are of great importance for understanding of the marine ecosystem-level process and responses to climate variability. Our motivation for the project is, by applying modern sclerochronological methods, to construct chronologies for three relatively long-lived bivalve species (longevity about half-century), living in the eastern Adriatic Sea. Target organisms include dog cockles Glycymerisglycymeris and G. bimaculata, and a smooth clam Callistachione. These chronologies will be analysed in parallel with long-term in situ and climate model oceanographic data, in order to quantify environmental effect on the bivalve growth. Further on, the oceanographic data will be used for portraying of ocean dynamics and processes that occur over interannual and decadal timescales in the Adriatic-Ionian basin and are important for growth of all marine organisms. The project will grow from two relatively independent topics, sclerochronology and ocean physical (environmental) sciences, merging them in an interdisciplinary manner in the later stage of the project execution. The project is highly interdisciplinary, while the project team is transnational.

3. D2.1 Baza podataka oceanografskih podataka sakupljenih tijekom eksperimenta u sjevernom Jadranu (m6) D9.4 Rad o dugoročnim promjenama oceanografskih svojstava Jadrana na recenziji (m6) D9.5 Rad o analizama klimatskih simulacija u Jadranu na recenziji (m18) D9.6 Rad o primjeni novih metoda (SOM) na analizu međugodišnjih i dekadskih varijacija Jadrana na recenziji (m24) D9.7 Prvi rad o geokemijskom sastavu analiziranih ljuštura na recenziji (m30) D9.8 Rad o sposobnosti klimatskih modela da reproduciraju značajne dinamičke procese u Jadranu na recenziji (m36) D9.9 Rad o kronologiji jedne vrste na recenziji (m40) D9.10 Drugi rad o geokemijskom sastavu analiziranih ljuštura na recenziji (m44) D9.11 Rad o master kronologiji na recenziji (m46) D9.12 Rad koji povezuje analizu okolišnih parametara načinjenih iz analiza ljuštura te dugoročnih nizova na recenziji (m48)

4. We analyzed long-term time series of temperature, salinity, and dissolved oxygen (DO) concentrationscollected along the Palagruza Sill transect (middle Adriatic) between 1952 and 2010. The data havebeen mostly collected on seasonal basis, allowing for extraction of seasonal signal from the series. By applyingSelf-Organizing Maps (SOM) method, a kind of unsupervised neural network method, the processes ona decadal time scale emerged as the most relevant for changes of oceanographic properties in the middleAdriatic area. Sensitivity studies revealed that oceanographic patterns obtained by SOM were not sensitiveto shortening of time series, to removal of data from one station or to removal of DO from the analysis.Simultaneous SOM-based mapping of sea surface heights in the northern Ionian Sea, with these heightsserving as a proxy for the Adriatic-Ionian Bimodal Oscillating System (BiOS), revealed asymmetry betweenanticyclonic and cyclonic BiOS patterns and correlated the decadal oscillations in the middle Adriatic withthe reversals in the BiOS circulation regimes. These reversals are found to either rapidly change oceanographicproperties in the middle Adriatic (e.g., during the Eastern Mediterranean Transient) or to changethem with a time lag of 2–3 years. The mapped connections may be used for a short-time (a few years) forecastingof the Adriatic oceanographic properties or for mapping future climate decadal oscillations as seenby ocean climate models.

5. Figure 7. (a) Absolute dynamic topography (ADT) 2 x 3 SOM patterns derived for the central Mediterranean (January 1993 to April 2014) and sorted by altimetry difference between blue and red rectangles, (b) the respective BMU time series, and (c) the BMU time series for the SOM patterns computed from temperature and salinity data at the Palagruza Sill transect between 1952 and 2013

6. This paper aims to document salinity and temperature regimes in the middle and south Adriatic Sea by applyingthe Self-Organizing Maps (SOM) method to the available long-term temperature and salinity series. The datawere collected on a seasonal basis between 1963 and 2011 in two dense water collecting depressions, Jabuka Pitand Southern Adriatic Pit, and over the Palagruža Sill. Seasonality was removed prior to the analyses. Salinityregimes have been found to oscillate rapidly between low-salinity and high-salinity SOM solutions, ascribed tothe advection of Western and Eastern Mediterranean waters, respectively. Transient salinity regimes normallylasted less than a season, while temperature transient regimes lasted longer. Salinity regimes prolonged their durationafter the major basin-wide event, the Eastern Mediterranean Transient, in the early 1990s. A qualitativerelationship between high-salinity regimes and dense water formation and dynamics has been documented. TheSOM-based analyses have a large capacity for classifying the oscillating ocean regimes in a basin, which, in thecase of the Adriatic Sea, beside climate forcing, is an important driver of biogeochemical changes that impactstrophic relations, appearance and abundance of alien organisms, and fisheries, etc.

7. Fig. 6. Connectivity diagrams for S- and S+ salinity regimes, with percentages of connections between different BMU. 2D representation of spatial distribution of sea temperature anomaly for BMUs classified to anomaly intensity into three classes (T-, T° and T+). Relativeappearance of each neuronis written on left bottom corner of each picture.

8. The paper investigates wintertime dynamics of the coastal northeastern Adriatic Sea, and is based on numerical modelling and in situ data collected through field campaigns executed during the winter and spring of 2015. The data have been collected by a variety of instruments and platforms (ADCPs, CTDs, glider, profiling float), and have been accompanied with a one-way coupled ALADIN/ROMS modelling effort. Research focus has been put on dense water formation (DWF), thermal changes and circulation, and water exchange between the coastal and open Adriatic. According to both observations and modelling results, dense waters are formed in the northeastern coastal Adriatic during cold bora outbreaks, even during milder-than-average winters (as was the winter of 2015). However, dense water formed in this coastal region has, due to lower salinities, lower densities than dense water formed at the open Adriatic. Since the sea is deeper in the coastal area than at the open Adriatic, dense waters from the open Adriatic occasionally enter the coastal area near the bottom of the connecting passages, while the surface flow is mostly outward from the coastal area. Median residence time of the coastal area is estimated to about 1-2 months, indicating that the coastal area may be relatively quickly renewed by the open Adriatic waters. The model significantly underestimates currents and transports in connecting channels, which may be a result of a too coarse resolution of atmospheric forcing, misrepresentation of bathymetry or absence of the air-sea feedback in the model. Obtained data represents a comprehensive marine dataset, pointing to a number of interesting phenomena to be investigated in the future.

9. Geographical position and bathymetry of the coastal northeastern Adriatic, with indicated measurements conductedthrough the NAdEx 2015 experiment: stations A1 to A9 (black circles) where ADCP/SBE911 were moored at the 5 bottom, stations 1to 19 (black diamonds) where CTD probe profiling has been executed, Arvor-C profiling (orange stars) and glider profiling (yellowstars).

10. Temperature, salinity and PDA valuesmeasured at the Kvarnerić transect during (a) Leg 1 cruise between 3 and 6December 2014, and (b) Leg 2 cruise between 26 and 29 May 2015.

11. Temperature, salinity and density values measured between 19 February and 5 March 2015 by Arvor-C profiling float inthe Kvarner Bay.

12. Observation-to-model (a, b, c) Q-Q plots and (d, e, f) Box-Whiskers plots of (a, d) current speed, and (b, e) temperatureand (c, f) salinity measured at stations A1 to A9. Dash-dot lines represent the Q-Q slope of a particular dataset in respect to the idealdistribution line (full line).

13. This study aims to document the effects of imposing differentriver runoff forcing and tidal forcing to the dense water formation (DWF)rates and dynamics in a semi-enclosed sea. An extreme DWF episode thatoccurred in the winter of 2012 in the shallow northern Adriatic Seaduring a prolonged cold bora wind outbreak event has been reproducedusing a one-way coupled atmosphere-ocean modelling system comprised ofthe atmospheric Aladin/HR mesoscale model and ocean ROMS model. Threedifferent river runoff forcing and tides/no tides scenarios were imposedon the model. The introduction of tides and river climatology instead ofreal rivers did not substantially change the modelled DWF transports andvolumes, whereas the simulation using the old Raicich climatologyresulted in a substantial freshening of the entire Adriatic that reducedor prevented the DWF at sites in the northern and northeastern Adriatic.The necessity of using an up-to-date river runoff climatology to properlyreproduce the DWF in semi-enclosed seas is emphasized.

14. Daily bottom (a) temperature, (b) practical salinity and (c) PDA fields modelled on 14 February 2012 by the REAL model run (1st column), and the differences between REAL and TIDE (2nd column), REAL and CLIM (3rd column), and REAL and RAICICH (4th column) model runs.

15. A performance analysis of the NEMOMED8ocean regional circulation model was undertaken for theAdriatic Sea during the period of 1961–2012, focusingon two mechanisms, dense water formation (DWF) andthe Adriatic–Ionian Bimodal Oscillating System (BiOS),which drive interannual and decadal variability in thebasin. The model was verified based on sea surface temperatureand sea surface height satellite measurements andlong-term in situ observations from several key areas. Themodel qualitatively reproduces basin-scale processes: thermohaline-driven cyclonic circulation and freshwater surfaceoutflow along the western Adriatic coast, dense waterdynamics, and the inflow of Ionian and Levantine watersto the Adriatic. Positive temperature and salinity biases arereported; the latter are particularly large along the easternpart of the basin, presumably because of the inappropriateintroduction of eastern Adriatic rivers into the model. Thehighest warm temperature biases in the vertical directionwere found in dense-water-collecting depressions in theAdriatic, indicating either an inappropriate quantification ofDWF processes or temperature overestimation of modelleddense water. The decadal variability in the thermohalineproperties is reproduced better than interannual variability,which is considerably underestimated. The DWF rates arequalitatively well reproduced by the model, being largerwhen preconditioned by higher basin-wide salinities. Anticycloniccirculation in the northern Ionian Sea was modelledonly during the Eastern Mediterranean Transient. Noother reversals of circulation that could be linked to BiOS-drivenchanges were modelled.

16. Temperature (left), salinity (middle) and PDA (right) profilesat the Palagruža Sill transect: a modelled mean values, b modelledvariances, c bias with respect to the measurements, d RMSE/STDratios with respect to the measurements, and e modelled-versus-measuredvariance ratios.

17. Vertical profiles of temperature and salinity bias and RMSE values a at station JP between 1961 and 1989 and b at station D1200between 1966 and 2009.

18. Difference between sea surface height 2 × 3 SOM fieldscomputed over NEMOMED8 and AVISO series over the same period(1993–2012). Mean values are removed from both series prior to theanalysis. The position of the BiOS-driven Northern Ionian Gyre isindicated by the dashed circle.

19. --- in preparation Modelling interannual changes in dense water formation on the northern Adriatic shelf Hrvoje Mihanović, Ivica Janeković, Ivica Vilibić, Vedrana Kovačević, Manuel Bensi Abstract The paper aims to document wintertime thermohaline properties and dense water formation (DWF) dynamics, rates and transports in the northern Adriatic between 2008 and 2015. The focus has also been directed to the year-to-year difference between two known DWF sites, at the shelf and in the eastern coastal region. The estimates are based on high-resolution interannual simulation by ROMS, one-way forced by Aladin/HR operational mesoscale model, with new river climatology imposed particularly at the eastern Adriatic coast. Substantial interannual variability in wintertime bottom densities has been found, varying for more than 1.0 kg/m3 between years. The variations are largely associated with the January-February heat losses, while atmospheric preconditioning in November-December has a little effect to the DWF rates. By contrast, salinity is preconditioning the DWF in the eastern coastal site, which has been found relevant for DWF rates during extraordinary winter of 2012. Contribution of coastal DWF site to the overall DWF rates in other years has not been substantial. Saw-tooth pattern in thermohaline series has been observed and reproduced at the bottom of the middle Adriatic depressions, not previously documented for such a shallow region.

20. Maximum bottom PDA values over a year between 2008 and 2015.

21. Wintertime (NDJF) cumulative net heat fluxes over the northern Adriatic between 2008/09 and 2014/15.

22. Kuda dalje: • Termohaline promjene i dinamika: • Analize jadranskih procesa i pojava u klimatskim modelima i klimatskim projekcijama (Natalija doktorat) – Clim Dyn • Analize mjerenja iz sjevernog i srednjeg Jadrana, povezivanje svih jadranskih dugih nizova s BIOS indeksom (u slučaju da dobijemo podatke CIM-a Rovinj) - GRL • Povezivanje kronologije i okolišnih parametara: • Kronologija u sjevernom Jadranu i kvantifciranje veze sa raznim meteo-hidro-ocean parametrima  je li sjeverni Jadran dominatno pod utjecajem lokalnih procesa ili procesa u cijelom Jadranu – Sci Rep • Povezivanje svih kronologija pojedine vrste/svih vrsta sa BIOS indeksom i drugim okolišnim parametrima – GRL • Povezivanje kronologija sa podacima biogeokemijskih modela