1. OCEANOGRAFIA 1 Anno Accademico 2014-2015 Docente: Renzo Mosetti rmosetti@ogs.trieste.it

2. How is oceanography important in understanding future climate? Oceanography and Climate Climate changes occur on different space and time scales. TIME SPACE Seasonal  Interannual  Decadal  Millennial Regional  Basin Wide  Global

3. Thermoregulating effects (e.g. moist air of the Gulf Stream and Kuroshio Extensions) Oceanography and Climate - seasonal timescales

4. Oceanography and Climate - interannual timescales El Niño is the strongest signal of climate variability on interannual timescales. It is a coupled mechanism between the tropical ocean and atmosphere.

5. Thomson, R. E., and J. F. R. Gower, 1998: A basin-scale oceanic instability event in the Gulf of Alaska. J Geophys Res-Oceans, 103, 3033-3040. Oceanography and Climate - interannual timescales Ocean Vortices are one of the strongest mixing agent in the ocean, they are important for ocean circulation and biology. Their role in climate is still unknown! NORTH AMERICA Gulf of Alaska

6. Changes of ocean circulation affects fish distributions and abundance. Oceanography and Climate - decadal timescales Sardines/Anchovies synchronized alternations between sardines/anchovies over the entire Pacific Ocean?

7. Changes in the ocean/atmosphere affect the ice caps, and therefore Sea Level. Oceanography and Climate - longer timescales Sea level will rise 7 to 22” in the next century, if melting does not accelerate --IPCC AR4, 2007

8. Marine Ecosystem regulate the cycling of chemical species relevant to climate (e.g. Carbon, DMS) Chlorophyll Spring 2005 (MODIS Satellite) Oceanography and Climate - longer timescales

9. Oceanography and Climate - millenial timescales Vertical circulation of the ocean MOVIE: The Day After Tomorrow

10. 3. Length and time scales

11. e.g. The ocean has a very long memory. We will learn about this, and about the mechanisms of interaction between ocean-atmosphere-land- ecosystems. Oceanography and Climate Climate changes occur on different space and time scales. What makes it interesting is that processes happening on different temporal and spatial scales are not separable and interact with each other  A NONLINEAR SYSTEM  COMPLEXITY WHY?

12. La non-linearità dei sistemi e la molteplicità dei loro stati di equilibrio

13. Resources in the Ocean and Economy What aspects of ocean sciences are relevant to the economy? Geological Resources extraction of petroleum, gas, metals, carbon sequestration?, etc. Ecological Resources mainly food from fisheries and maricultures Energy Resources extraction of power from waves, tides, currents and heat content Chemical Resources e.g. development of new drugs, salts, etc. Recreational Resources of coastal areas, e.g. beaches and more Oceanographic studies helped discover these resources and help to manage them (e.g. coastal processes and beaches, and many more…)

14. Ocean Resources, Economy and Oceanography An example: The City of Venice, ITALY 1. Dump: rain and tides distribute it in the lagoon) 2. Factory: factories drained their liquid waste partly into the lagoon and partly into dumps. Currents and erosion continue to disperse pollutants. 3. Sea: Meteorological conditions can accentuate high tides. Bora, a cold northerly in the Adriatic Sea, and Sirocco, a hot, dust-laden wind from the Libyan desert, can trigger dangerously high tides. 4. River: the Republic of Venice diverted four rivers that originally flowed into the lagoon. The loss of the silt and sediment is transforming the delta environment into a marine one. 5. Farm: 53 percent of the phosphates and other pollutants that enter the lagoon come from these sources. 6. Town: About 1,400,000 people live in the basin, but when one considers the quantity of nutrients and organic matter generated, environmentalists say, it is as if 4,000,000 people lived there. Offshore GAS extraction platforms Adriatic Sea opening to sea

15. Ocean Resources, Economy and Oceanography An example: The City of Venice, ITALY using oceanography and ocean engeneering Adriatic Sea More at http://www.pbs.org/wgbh/nova/venice/ opening to sea Install Gates to control the tide

16. Humans impacts on the Ocean and Climate How can humans impact the ocean and climate? dying corals, poison fish, global warming cholera in India, changes in Mediterranean species city of venice was an example Alterations: chemical (e.g. mercury, aerosols, green house gases, oil) biological (e.g. introducing new faunas, phosphate from changes in land use, overfishing …) physical/geological (e.g. shoreline interventions …)

17. CNN : Asian Brown Cloud' poses global threat August 12, 2002 Posted: 10:43 PM EDT (0243 GMT) Humans impacts on the Ocean and Climate Satellite view  Aerosols change: radiation budget clouds concentration amount of rain in clouds

18. CNN : Asian Brown Cloud' poses global threat August 12, 2002 Posted: 10:43 PM EDT (0243 GMT) Humans impacts on the Ocean and Climate Where does it come from? The sources are changing fast

19. … aerosol pollution is only one piece of a more complex puzzle The Global Warming Issue 0.8 C from thermometers from paleo records What will happen in the (near) future? An important question discussed by scientists (IPCC)

20. QUICK TOUR THROUGH PHYSICAL OCEANOGRAPHIC PHENOMENA QUICK TOUR THROUGH PHYSICAL OCEANOGRAPHIC PHENOMENA

21. Small scale examples: Breaking surface waves and bubbles Routes to Breaking I Breaking at larger scales may result from dispersive focusing, geometric focusing, wave-wave and wave- current interactions without wind- forcing being directly involved: a,b. At sufficiently high winds and small wave scales, each wave may be breaking (c). Note also in (c) the foam streaks aligned with the wind. Melville (1996)

22. Bubbles Bubble-mediated gas transfer Bubbles generated by breaking waves enhance air-sea gas transfer by being carried to depth and transferring gas under the increased hydrostatic pressure and surface tension effects Bubble-generated noise The breakup of the entrained air into discrete bubbles is accompanied by oscillations of the bubbles as they relax back to their equilibrium spherical shape. In the absence of surface-tension effects the lowest resonant frequency is proportional to the radius -1. Lamarre (1993), Melville (1996)

23. Surface waves 100 m 150 m Reflected waves

24. Tides Tides (the main diurnal or daily component): amplitude and phase, rotating around the amphidromes. Time scale - order 1 day. Space scale - basin size

25. TALLEY Copyright © 2011 Elsevier Inc. All rights reserved Sumatra Tsunami (December 26, 2004). (a) Tsunami wave approaching the beach in Thailand. Source: From Rydevik (2004). (b) Simulated surface height two hours after earthquake. Source: From Smith et al. (2005). (c) Global reach: simulated maximum sea-surface height and arrival time (hours after earthquake) of wave front. Source: From Titov et al. (2005). Tsunamis: surface waves with very long wavelengths

26. Internal waves SIO - Lerczak/Hendershott et al: The Internal Waves on the Continental Margin (IWAVES) experiment was an oceanographic study of internal waves on the continental slope and shelf. Off of Mission Beach, California. The field work began in the summer of 1996 and continued through October 1997.

27. Internal waves II Depth Time (hrs) 1719 14 m Lerczak, SIO thesis

28. Mesocale motions (eddies) Franklin/Folger map of the Gulf Stream: mean flow Satellite SST (AVHRR) image of Gulf Stream - O. Brown, R. Evans and M. Carle, University of Miami RSMAS, Miami, FL - mesoscale (meanders and eddies) - time dependent, O(100 km) scale, O( 2 weeks - 1 month), from instabilities of mean

29. Eddies in the Kuroshio Paths of the Kuroshio (the North Pacific’s equivalent to the Gulf Stream), based on temperature observations - Again note the mesoscale meandering within the broader envelope

30. Mean and anomaly The next several slides show “anomalies”. ean: the average of a series of measurements (or model output) over a fixed time interval such as a week, a month, a year, etc, or over a specific spatial interval (square kilometer, a 1 degree square, a five degree square, etc.). Anomaly: the difference between an observation and the mean value, however the mean value is defined. Therefore, by definition, the observed value = mean + anomaly (“Observed”, or “instantaneous”, or “synoptic”)

31. Mesoscale motions in altimetry TOPEX/Poseidon SSH anomaly - Wunsch and Stammer (http://puddle.mit.edu/~cwunsch). Look at website for animation.

32. Eddies in surface drifter tracks Surface drifter tracks (satellite tracking) - note vigorous mesoscale

33. Mean flow from surface drifters Mean surface flow from those surface drifters (Flatau, Talley, Niiler, 2003).

34. El Nino/La Nina - interannual (3-7 year), basin-scale Sea surface height anomaly during 1997 El Nino and 1999 La Nina, from Topex/Poseidon altimetry. NASA webpage: http://topex- www.jpl.nasa.gov/science/ima ges/el-nino-la-nina.jpg Sea surface is anomalously high in eastern equatorial region during El Nino and opposite in La Nina

35. Contenuti del Corso Caratteristiche fisiche degli oceani; Caratteristiche fisiche degli oceani; Proprietà fisiche dell’acqua di mare; Proprietà fisiche dell’acqua di mare; L’influenza dell’atmosfera; L’influenza dell’atmosfera; Il bilancio termico degli oceani; Il bilancio termico degli oceani; Le equazioni del moto; Le equazioni del moto; Il concetto di vorticità; Il concetto di vorticità; Le correnti geostrofiche; Le correnti geostrofiche; Risposta dell’oceano superficiale al vento; Risposta dell’oceano superficiale al vento; La circolazione Oceanica indotta dal vento; La circolazione Oceanica indotta dal vento; Processi equatoriali: El Nino Processi equatoriali: El Nino Onde da vento e onde lunghe, Onde da vento e onde lunghe, Processi costieri e maree Processi costieri e maree Sistemi osservativi e analisi dei dati Sistemi osservativi e analisi dei dati

36. Testo di Base R. H. Steward: Introduction to Physical Oceanography R. H. Steward: Introduction to Physical Oceanography Scaricabile liberamente dal sito: Scaricabile liberamente dal sito: http://oceanworld.tamu.edu/resources/ocng_textbook/PDF_files/ book_pdf_files.html