EPIC data selection terminology

Data selection procedure

Step 1. Choose Dataset(s)

  • After opening the data selection window, user must select the dataset(s) first. If you are using a browser that supports the Java Applet and JavaScripts features used in EPIC Web Browser, the location range will be drawn on the world map for the dataset you selected and the text fields (above the map) will be updated to show the time range and total number of data files avalible from the dataset(s) you selected.
  • Click on the next button on the dataset selection window go to the refine data selection window.

Step 2. Refine Data Selection

  • On refine data selection window, user can specify the location range by Mouse-Drag on map or enter values to text fields. User can also specify other desired selection criteria.
  • All the selection criteria are optional.
  • If you do not specify any selection criteria, then all data will be selected (potentially tens of thousands of data sets).
  • Click on the [Search] button or "next" button to start the searching process.

Step 3. Data Plotting, Listing and Downloading

  • The results of the search will be a scrolling list of data sets which met the selection criteria. From this scrolling list, you can select a data set for plotting, listing or downloading.

EPIC data selection terminology

Datasets - referrs to a collection of data, generally from a region. Generally, all data has been collected by PMEL scientists, unless otherwise noted. Data origin information is always included in the data file as metadata.

  • Pacific - data from the Pacific Ocean
  • non-PMEL - data obtained or collected by scientists at institutions outside PMEL
  • NODC - from the NODC World Ocean Atlas CD-ROM 1994 of bottle data.
    • S.Indian - South Indian Ocean
    • S.Pacific - South Pacific Ocean
    • S.Atlantic - South Atlantic Ocean
  • Reid - Reid and Mantyla bottle data for the whole globe is available - Courtesy of Dr. Alex Orsi, who formatted this data set for use in EPIC
  • FOCI - CARD FOCI data
  • WCOAST - Data from the West coast of the US
  • PUGET - Puget Sound data
  • ASIA - Data from Asia (China Sea, Sulu Sea)
  • Arctic - Data from the West Arctic
  • Vents - Data from the hydrothermal venting area in the mid-latitudes of the North Pacific Ocean
  • Alaska - data from the Gulf of Alaska and Bering Sea

EPIC data types fall into three categories:

  • Profile Data Types - One-dimensional data sets indexed by pressure or depth, specifically, data collected by CTD, XBT or from Bottles. We Profile data into these groups:
    • CTD
    • BOTTLE
    • XBT
  • Time Series Data Types - One dimensional data set indexed by time, such as that collected by instruments such as an anemometor, a current meter or a thermistor on a moored buoy. We devided time series data into these groups:
    • "Met" -- for Surface Meteorology data including Wind, Air Temperature, Relative Humidity, Shortwave Rediation, Barometric Pressure, etc.;
    • "Ocean" -- Ocean data including Ocean Temperature, Pressure, Salinity, Conductivity, etc.
    • "Drf" -- Drifter buoy data.
  • Track Data Types - Data collected along the track of a moving platform such as a ship or a drifting buoy. Examples are shipboard Acoustic Doppler Current Profiler (ADCP) data and drifting buoy data. Track data is one- or two-dimensional data, indexed by time and sometimes by pressure. For each time point, variables include latitude, longitude and any measurements made by instruments on the moving platform.
Select or locate data by specifying one or more of the following selection criteria. Any of the criteria can be ignored. If no criteria are specified, then all data in the database will be selected, potentially tens of thousands of data sets (not recommended).
  • Longitude range - to specify a range of of longitudes, enter the Westernmost and Easternmost longitudes as numbers between -180 and + 180. West is negative and East is positive.
    • e.g., -110.5 is 110.5 degress West longitude, near the West coast of South America, 137 is 137 degrees East longitude, near the East coast of Indonesia, both in the Pacific Ocean.
    Longitudes can also be entered with E or W to indicate the hemisphere.
    • e.g., 110W, 110w, 110 W, 110 w and -110 are equivalent ways of specifying 110W, and 137E, 137e, 137 E, 137 e, and 137 are equivalent ways of specifying 137 degrees East longitude.
  • Latitude range - to specify a range of latitudes, enter two latitudes as numbers between -90 and 90. South is negative and North is positive.
    • e.g., -10.5 is 10.5 degrees South latitude, and 10 is 10 degrees North latitude.
    Latitudes can also be entered with N or S to indicate hemisphere.
    • e.g., 10.5S, 10.5s, 10.5 S, 10.5 s, and -10.5 are equivalent ways of entering 10.5 degrees South latitude.
  • Date range - All data sets which contain some data inside the specified time range will be selected.
  • Depth range - Depths in the ocean are entered as positive numbers, increasing downwards towards the bottom of the ocean. The surface of the ocean is 0, and 6000 meters deep in the ocean is 6000.
    • For profile data (CTD, XBT, or Bottle data), this is the depth or pressure range which you REQUIRE the data to cover. For example, if you enter 0,1000, that means you will reject a CTD data file which only includes data from the surface to 500 meters depth, but will accept a CTD data file which includes data from the surface to 5000 meters depth.
    • For time series data, any time series from an instrument inside the specified depth range will be selected.
  • Month sub-range - If you have selected a multi-year date range, and you only want to choose data within certain months, i.e., the Northern hemisphere summer (Jun-Aug), then enter the subset of months to be searched.
  • Delta-t is the time interval between data points in Time-Series files. You can select min and max Delta-t, or leave it blank and all delta-t values will be considered in the search.
  • String(s) to locate in Filename - This search criteria is included for the convenience of scientists familiar with the EPIC data sets. File names often contain identifying information, such as Cruise identification for CTD data. This search criteria allows selection of data based on this identifying informaton. Enter one or more character strings, separated by spaces. Data with file names containing all the specified character strings will be selected.
Once data is selected, there are options for the individual casts or stations for profile data selection or for the individual time series, and other options for the entire set of selected data sets.
  • Cast options (profile data selection) - A cast referrs to profile data collected at a single location. A cast is sometimes called a station, and this data is stored in a single EPIC data file. Cast options are operations on an individual cast, such as making a property versus property plot or listing the data from a single profile.

  • Time-Series Options (time series data selection) - are operations on an individual time-series, such as making a plot or listing the data from a single time-series.

  • Variables (time series data selection ) - Most Time-Series Data Sub-Types have only a single variable, like Barometric Pressure, but some, like Wind include Zonal and Meridional wind.
  • Pointer file options - An EPIC pointer file is a list of data file names. Pointer file options are choices for different operations on a whole collection or list of data files, such as making a location plot, editing the pointer file, or downloading the pointer file to your local disk.

Criteria for a test of demonstration

For a test or demonstration of profile data selection, try the following selection criteria (Pacific CTD data in longitude range 96W to 94W and latitude range 3N to 5N):

  • Dataset: Pacific (CTD)
  • Longitude range: Westernmost = 96w and Easternmost = 94w
  • Latitude range: Northmost = 5N and Southmost = 5S
  • Time range: 1-30 April 1982
  • --> Try a MERIDIONAL Section Plot of temperature from 0-300 m
For a test or demonstration of time series data selection, try the following selection criteria (Alaska Current data in longitude range 120E to 120W and latitude range 45N to 80N):
  • Dataset: Alaska (Ocean)
  • Longitude range: Westernmost = 120E and Easternmost = 120W
  • Latitude range: Northmost = 80N and Southmost = 45N
  • Time range: Jan 1 1990 - Dec 31 1995
  • Click "Search" at the bottom of the page
  • Click "Go" at the bottom of the page
  • --> Select up to 6 variables and click "Go" to make a time series plot