ODV HowTo Ocean Data View HowTo Version 4.
Version 4.5 License Agreement By downloading or using this Software, you agree to be bound by the following legal agreement between you and the Alfred-Wegener-Institute for Polar and Marine Research (AWI). If you do not agree to the terms of this Agreement, do not download or use the Software. 1. SCIENTIFIC USE AND TEACHING Ocean Data View can be used free of charge for non-commercial, non-military research and teaching purposes.
ODV HowTo Contents 1 INTRODUCTION .......................................................................................1 2 COLLECTIONS........................................................................................1 2.1 3 ADDING OR DELETING META- AND COLLECTION VARIABLES ...................................... 1 STATION MAPS.......................................................................................1 3.1 3.2 3.3 3.4 4 MAKING CRUISE MAPS ..........................................
ODV HowTo 1 Introduction This document contains in-depth descriptions on how to perform frequently occurring tasks with ODV. 2 Collections 2.1 Adding or Deleting Meta- and Collection Variables The sets of meta- and collection variables in a given ODV data collection are defined when the collection is created.
Version 4.5 • In an empty directory on your disk create an ASCII file that contains the longitude, latitude coordinates of the stations or way-points of your track. This file should have a descriptive name (e.g., CruiseTrack_xxx.txt, where xxx represents the name of your cruise) and it should comply with the generic ODV spreadsheet format specifications.
ODV HowTo The latitude/longitude coordinates of the coastline or depth contour are stored in individual polygon segments (see Figure below). The first nS nodes of a segment represent a part of the actual coastline or bathymetry contour. This part of the segment is stroked when the outline of the contour is requested. In addition, each segment can have an optional, second part which will not be stroked but is only used to properly close the segment.
Version 4.5 1. In the directory containing the .coa files create a file coa2cdt.inp and enter the names of the .coa files to be processed. Put one file name per line and omit the .coa extension. 2. In a DOS box change to the respective directory and execute coa2cdt.exe. Make sure the coa2cdt.exe executable is in your path or in the .coa directory. Also make sure that the .coa files satisfy the .coa format, as described above. The .cdt files created by coa2cdt.
ODV HowTo SouthLatitude = 47.5 WestLongitude = -5. [Resolution] LatitudeRes = 0.015 LongitudeRes = 0.015 ridian have negative WestLongitude but positive EastLongitude. Resolution is given as decimal degrees. Using New Files To use the newly installed files in ODV maps do the following: Invoke the map Display Options dialog box (e.g., right-click the mouse while over the map and choose Display Options) and select the Layers tab. • Choose the newly installed series name (e.g.
Version 4.5 (2) for construction of the gridding domains and sub-domains when using DIVA gridding in maps. While the resolution of the bathymetric data in GEBCO1.nc is sufficient for long sections and for basin-wide gridding domains, this is no longer the case when dealing with short sections or small gridding domains.
ODV HowTo 3.4 Custom Section Bathymetry By default the bathymetry polygon of sections is constructed using the Bot. Depth metadata of the stations. Alternatively, you can also use gridded bathymetric data from the /include/GEBCO1.nc file or your own custom bathymetry (see previous section). As a third (and preferred) option you can construct the bathymetry polygon using along-track shipboard bathymetric data and provide the bathymetry polygon as .gob ODV graphics object file.
Version 4.5 • First X First Y The Huge Y of the closure points (9500 m in the example above) should exceed the maximum depth in the section plots. The maximum number of nodes nPts of the polygon is 1500. You may have to subsample the shipboard bathymetry data to stay within this limit. Once created you use the .gob bathymetry file for the section bathymetry polygon by choosing the file under Bathymetry>File on the Section Properties dialog. 4 Data Windows 4.
ODV HowTo ties > General page is checked this procedure has to be repeated after every redraw of the data window. You can avoid this by creating copies of the axis labels (Ctrl-C with the mouse over the respective label), unchecking the Automatic axis titles option and properly placing the axis labels ones and for all. Note that the station labels along the top margin are implemented as ODV graphics objects.
Version 4.5 the data window). Pressing the Gridding Misfits button will create a misfit plot similar to the one shown in the lower part of Figure 3-2 below. ODV also allows exporting the x, y, z data values as well as the gridding misfits at the data locations using the Extras > Clipboard Copy option of the respective window context menu (obtained by right-clicking on the window). You may also simply press Ctrl-C while the mouse is over the respective window.
ODV HowTo You can obtain further statistical information via the Extras > Statistics option or by pressing F4 while the mouse is over the misfit window. 4.4 Visualizing Property Differences between two Layers Plotting the distribution of some tracer on given depth or density surfaces is a standard procedure in ODV involving the definition of appropriate isosurface variables and use of these as Z-variable of SURFACE scope data windows.
Version 4.5 Figure 4-3: Phosphate concentrations at 10 and 250 m as well as the difference between the two layers. .
ODV HowTo 5 Overlay Windows 5.1 Contour Lines on top of a Shaded Field It is often useful to create section or isosurface plots where the distribution of one property (color shaded and/or contoured) is overlaid with contour lines of another property. Useful applications, of this technique are, for instance, density contours on top of any property section or depth contours on isosurface or isopycnal distributions. Example images are shown in Figures 4-1 and 4-2 below.
Version 4.5 Figure 5-2: Map showing isopycnals on top of color shaded phosphate distribution. 5.2 Arrows on top of a Shaded Field It is often useful to create maps where the distribution of one property (color shaded and/or contoured) is overlaid with arrows of another vector property, such as ocean current velocities or atmospheric winds (see Figure 4-3 below).
ODV HowTo Figure 5-3: Map showing wind arrows on top of color shaded distribution. To produce such plots, follow these steps: • • • • • • Switch to window layout mode via View>Window Layout. Setup the window for the underlying distribution (window a: define size and position; select a Z-variable for that window (property A), specify the display style, and possibly create some contour lines using the Properties option).
Version 4.5 • property A. If satisfied, save the view for later use (View>Save View As). Note that the only way to access and modify the properties of a data window entirely overlain by another window (such as window a), is via the main menu View>Window Properties option. 6 Data Quality Control ODV facilitates quality control of multi-parameter datasets by providing a range of automatic and visual checks for easy identification and flagging of outliers and suspicious data.
ODV HowTo Figure 6-1: Identification of outliers for a zonal section in the North Atlantic 7 Importing XYZ Data Irregularly spaced or gridded data for some quantity Z at given X and Y coordinates are commonly provided in files using three-columns for the X, Y and Z values, respectively.
Version 4.5 click on Use Default and specify the default depth value (use 0, if in doubt). ODV will import the data from the XYZ file, and lets you operate on the data in the usual way. To create a page with a map of the Z-variable create a data window with SURFACE scope. Modify the data window’s properties as usual, if this is necessary.
ODV HowTo 9 Using ODV Graphics ODV graphics files of the entire canvas or individual data windows can easily be included in print documents, posters or on Web pages. To create GIF, PNG, JPG or TIFF files of the entire canvas or of individual plots press Ctrl-S while the mouse is over the canvas or the respective plot window and choose GIF, PNG, JPG or TIFF as output type.
