OPeNDAP software

DapperM
A Matlab interface to Dapper - an OPeNDAP in-situ data service

Dapper is a newly emerging, community-standard OPeNDAP server for in situ data. DapperM is a Matlab interface to data served by the Dapper OPeNDAP server. Matlab functions include an interactive lat/lon/depth/time data selection tool and functions for obtaining and using selected profile and time series datasets. The functions are described below, and an example is given. Documentation is built into Matlab for convenience of the user.

Regularly-updated Observing System datasets available through the PMEL dapper server include global Argo profiling floats, World Ocean Database 2005 profile data, TAO El Nino buoy data, Global Summary of the Day meteorological data, coastal buoy data from the National Data Buoy Center (NDBC), the Global Temperature-Salinity Profile Program (GTSPP) data, and PMEL time series and profile data.

Example

Argo data from near the Aleutian Islands is selected with the Dapper Wizard NdEdit function (Figure 1, below). NdEdit simplifies the process of limiting the data of interest to a time range of 2003-08-27 through 2003-12-14 (right hand window) and displaying the space time distribution of the selected datasets (left two windows).

Figure 1. Dapper Wizard NdEditfunction for lat/lon/depth/time selection of stations from a large data collection.
Click to enlarge.

Figure 2. Variable list

Once the data is selected it is returned to the DapperM interface. All variables that are available in the dataset are listed (Figure 2, right).

Pressing the “Save to Matlab” button will create the selection_1 CellArray in the users work area.

The data is now available to the user, as shown in the screen snapshot of the internal structure of the CellArray in Figure 3 (below).

Figure 3. Matlab Selection Cell Array containing data.

Metadata can be displayed for any station (Figure 4, below left), and and a single variable can be selected and a waterfall plot can be created to give a quick look at the selected profiles (Figure 5, below. right).

Figure 4. Viewing metadata for a selected station. Click to enlarge.

Figure 5. Waterfall plot made with DapperM (click to enlarge)

Matlab functions provided by DapperM:

• dpr_attributes. Returns a CellArray that contains the attribute names and values.
• dpr_date. Converts milliseconds since 1970 to the Matlab date values suitable for use with datestr() function.
• dpr_dimensions. Returns a CellArray of the dimension names, lengths, and unlimited dimension flag.
• dpr_variables. Returns a CellArray of variable names and a reference of the Variable Java object.
• dpr_wizard. Opens the DapperWizard and returns a data collection.
• dpr_profiles. Given a station, returns all the variables in a matrix that are profiles.
• dpr_variable_names. Returns a CellArray with the names and units of all independent variables.
• dpr_gui. Matlab GUI interface to the DapperM Java Wizard. This interface provides stand-alone access to the Dapper server and returns data as a CellArray. The CellArray is automatically named as selection_#, where # is a unique sequence number. Selection is a CellArray of dimensions {n,6} where n is the number of stations in the collection.
  • selection{n,1} = CellArray, variable data
  • var{m,1} = variable name
  • var{m,2} = data array, where m is the variable number
  • selection{n,2} = CellArray, station global attributes
  • attribute{j,1} = attribute name
  • attribute{j,2} = attribute value
  • selection{n,3} = longitude (0-360 degrees east)
  • selection{n,4} = latitude
  • selection{n,5} = time (MATLAB format)
  • selection{n,6} = time string

Downloads

DapperM V1.0 is available from anonymous ftp at ftp://ftp.pmel.noaa.gov/EPIC/java/DapperM.

A few Dapper Servers

• in-situ data collections from PMEL in Seattle (http://dapper.pmel.noaa.gov/dapper),
• in-situ data at the IPRC APDRC in Hawaii (http://apdrc.soest.hawaii.edu:9090/dapper/)
• gridded near-realtime ocean surface currents, derived from satellite altimeter and scatterometer data, for the Pacific Ocean, from the OSCAR project (http://www.epic.noaa.gov/dapper/oscar).

References & More Information