Names: Lab Section: each group of 2 turns in one labGEOSCIENCE 001 OCEANOGRAPHY LABThis is a computer-based lab exercise in which we will use an incrediblecomputer resource to visually explore a huge quantity of oceanographic data in order to learn some fundamental things about the oceans.Background to Cover Before LabThe IRI Data Viewer is maintained by Columbia University’s Lamont Doherty Earth Observatory, which is one of the world’s largest researchcenters. They have collected and organized a vast range of data, including data on the world’s oceans. In this lab, we will be using a data set that shows the following parameters for the whole world ocean, in 3-D:Salinity, density (and potential density), temperature (and potential temperature), phosphate, phosphate*, nitrate, silicate, dissolved oxygen, chlorophyll, and a few others. The data are presented as annual averages, as monthly averages, and as seasonal averages, so you can see how these parameters vary over time too. There are numerous other data sets at this site; the whole range of them can be found at this page: http://iridl.ldeo.columbia.edu/docfind/databrief/cat-ocean.html First, get to know the Data Viewer program and how to manipulate it, by going to the site and working through the tutorial before coming to lab. The full tutorial is a lengthy affair, but if you work through the Visualizing Data section (http://iridl.ldeo.columbia.edu/dochelp/Tutorial/MVD/Visualization/ ), you should bein good shape — ignore the parts that deal with the expert mode. If you try to do the lab problems without going through the tutorial, you’ll be frustrated, sad, and you will run out of time.At a minimum, you need to be able to view the data at different scales,zoom in and out; change the depth; change the values plotted on the horizontal and vertical axes to either see a map view, or a cross-sectional view of the ocean; and change the values of the ends of the color bar to highlight the variability in some areas of the oceans. Note that when you make a cross-sectional view, where depth is along the vertical axis, the program default puts the surface at the bottom of thepage and the bottom of the ocean (where the depth is greatest) at thetop; you ought to reverse the values on this axis so that up is up (0 in the top box, 5500 in the bottom to see the whole ocean).It is also helpful to know how to make an animation, which can save you some time in making repeated views of the data — this is all explained in the tutorial. Just as an example, though, if you go to this data set: http://iridl.ldeo.columbia.edu/SOURCES/.LEVITUS94/.ANNUAL/.temp/ and click on the map view up near the top center of the screen. Then go tothe uppermost box in the center where you can set the depth, type 0 to 5750 and then hit redraw; you’ll see an animated map of the temperature going from the surface down to the bottom — pretty cool (at least at the bottom). Deep Water FormationAt present, the world’s oceans are thoroughly mixed on a timescale of just a few thousand years. The surface circulates and mixes due to theeffects of wind-generated currents, while the deep waters are mixed more sluggishly by a system of deep currents that form near the two poles. The deep currents effectively ventilate the world’s oceans, bringing oxygen (and CO2) into the deep parts of the oceans. This is part of the reason that the oceans have the capacity to hold a huge quantity of CO2. But how does this system work? What drives it? What determines where and when and how much deep water is formed? These are some the questions we’ll try to answer in this lab.Deep water formation is all about density, and density is a function of temperature and salinity, as shown in the diagram below. The curved lines represent lines of equal density and you can use this diagram to figure out the density of water knowing the temperature and salinity. You can also use this to predict how much the density will change if you change the salinity or temperature from some starting condition.To get surface waters to sink, their density (r) must exceed the density of the underlying waters, and much of the deeper waters of the oceansare around 1.028 g/cm3. This is not an easy thing to do, so there are very few places around the earth where deep water can form.A. Where does the deep water filling the world’s oceans form? We’ll look for some answers by using chemical tracers. There are many ways of doing this, but one of the best is to use a parameter called ‘phosphate-star’, which combines phosphate and oxygen concentrations in the following way: PO4*= PO4 + O2/175 − 1.95 μmol/kgThe thinking behind this is that the value of phosphate star is effectively established at the surface or the ocean and it should remainnearly constant if the water sinks and heads into the deep ocean. Phosphate is a nutrient for primary producers in the oceans and if they consume phosphate, they release at lot of oxygen, which is added to the water. When organisms die, their remains are consumed by microbes in a process that consumes oxygen and releases phosphate back into the water. So, either way, the phosphate star value stays thesame, making it a ‘conservative tracer’ that can be used to track different water masses moving around in the oceans. For this question, you will go to the LEVITUS94 data set, starting with the annual average data: http://iridl.ldeo.columbia.edu/SOURCES/.LEVITUS94/.ANNUAL/ .NOTE: for the following questions, your answers have to refer to actual data — you need to support your answers with facts, and thosefacts can take the form of a graphic, an image from the program, or a kind of numerical summary of what you see in the images generated by the program. So, for this first question, simply saying Antarctica or North Atlantic is not sufficient — you need to say, with some precision, what the basis is for choosing one or the other as the main source of the deep water.1. Where does most of the deep water come from — Antarctica or the North Atlantic? (along the way here, you need to answer the following: what is the PO4* value around Antarctica? What is the PO4* value around the North Atlantic, just north of Iceland? What are the deep ocean PO4* values as seen in cross-sections from north to south through the Pacific and Atlantic?) Be sure to read the above paragraph before answering this