OceanDIVA - Ocean Data Inter-comparison and Visualization Application

Introduction

   OceanDIVA was developed as a model-data comparison and validation tool for oceanography that can be used with standards-compliant datasets across the internet.

   OceanDIVA is a Java web application developed by, and hosted at the Reading e-Science Centre, within the Environmental Systems Science Centre at the University of Reading.
It produces data on the misfit between in-situ ocean observation profiles and gridded model output. The in-situ data and the model data must be in NetCDF format, and can be located either locally at Reading, or read in remotely via the OPeNDAP protocol. Output can take two forms - either KMZ (zipped KML) for viewing in Google Earth, or a series of png images of Probability Density Functions (PDFs) of model-observations misfits in selected ocean regions.
   KMZ output allows the user to view the geospatial distribution of the data and misfits [screenshot], whereas the PDF output allows the user to get more statistical information about the distribution of misfits within a given region(s) [screenshot].

How to use OceanDIVA

   Within the OceanDIVA interface, instructions are provided about each option in the right hand panel.

   There are a number of choices on the interface which must be made by the user, as well as some which are optional. Simply make the choices by selecting from the drop-down menus etc, and then click the 'Go' button at the bottom of the page.
Choice of Observation and Model datasets
   The two most important choices, are to pick an observations dataset and a model dataset from the two drop-down menus at the top of the page. A number of OPeNDAP sites are listed, but beware that links may be dropped if URLs change.
Choice of vertical coordinate
   There is a drop-down menu to select whether the vertical coordinate will be depth (default) or temperature (for example salinity may be calculated on T-surfaces). The choices of data to be plotted on these levels change dynamically in response.
Choice of output
   One must opt for either KMZ (default) or PDF output from a drop-down menu. A description of these options is provided in the 'introduction' box above.
Choice of regions
   By clicking on the '+' symbol at the Regions choice, one can expand a list of default ocean regions, along with the option to define new regions. If KMZ output has been selected, then ticking the box next to a region(s) results in a) the outline of this region being drawn on Google Earth and b) the ability to click on a button at the NW corner of the region to reveal the region name, number of profiles, and the mean RMS error of the chosen data. If PDF output is selected, then any region which has been selected here will be included in the PDF output (i.e. probability density functions of the misfits in this region will be produced).
Choice of name
   The text entered into the 'Name' box will be used as the name of the dataset displayed in Google Earth if KMZ output has been selected. It also forms the basis of the filename for either KMZ, or any PDFs produced.
Choice of label
   This option is not available for PDF output. The user can tick any combination of boxes to request that data be included in labels for the profiles in Google Earth. Note that Google Earth only displays labels when the view is zoomed in below a certain height.
Choice of variables to be plotted
   This option is not available for PDF output. The variables available here change dynamically in response to the choice of vertical coordinate. Two actions can be taken here. Firstly, one may select or deselect a given variable via the tick box. Secondly, one may alter the values of the variable which act as delimiters for the colour-coding of the profiles in Google Earth. This is done by changing the numbers in the small text boxes between the coloured squares. For example, by changing the number to the left/right of the orange square, one sets the lower/upper limit for colouring a profile orange.
Choice of how to colour profiles
   This option is not available for PDF output. By selecting from this drop-down menu, the user can select a data type - e.g. salinity, and a vertical coordinate range (including the option of the entire profile) over which to calculate the RMS misfit values to colour-code the profiles by. For example one may opt to colour-code the profiles according to the salinity RMS misfit between observed and model data between 0m and 300m depth. One can choose to define a new vertical coordinate inverval if desired (see below).
Choice of user-defined vertical coordinate range
   This option is not available for PDF output. Here one can define a new range for the choice of vertical coordinate - e.g. between the 5 degree and 15 degree isotherms. Data on the RMS misfit within this range will be shown in the profile pop-up bubble in Google Earth when a profile is clicked. Additionally, the user may choose to colour-code all profiles by the RMS misfit over the range defined here (see above).