What is in databases
    Click here for data description
    SPIDR Installation Guide
    SPIDR User's Guide
    SPIDR Web-services Guide
How to work with data
    New SPIDR user
    Advanced SPIDR user
How to use the pages
    Select data set
    Data query
    Time series plot
    User data basket
    Time interval & sampling
    DMSP orbits search
    DMSP orbits viewer

SPIDR Time Interval and Sampling


    The "Time Interval and Sampling" page is used to select the date interval and time step for the SPIDR data queries.

    Usage basics

    When visiting SPIDR for the first time, the date interval and time step are set as "Undefined", and the system follows data-centric workflow. It means that all the datasets will be presented to user regardless their availability at any given time period. To use the time-centric workflow, the system needs the time interval and sampling to be specified by user. In that case the lists of datasets, stations and available data will be filtered by SPIDR before presenting them to user based on the data availability for the given time interval

    To set up (or change) the date interval and time step in SPIDR the user has to select year, month, day and hour for the beginning and end of the date interval as well as the time step to be used for data sampling within the interval. For fast selection of the time intervals such as "last day", "last week" or "last month", the corresponding buttons below the time interval form can be used. Then the user has to confirm the choice by selecting the action "Update time settings" with the button "GO".

    On the next visit the "Time Interval and Sampling" page will show the previously selected time interval and sampling settings. For the registered SPIDR users the time settings are persistent in the user data basket and restored to previously set values on next sessions.

    To unset the date interval and time step, the use has to select "Clear Time Settings" action and to confirm it with the button "GO". After that the SPIDR time settings will return to the "Undefined" state.

    Time step (data sampling interval) is set by the user together with the date interval in the corresponding selection list. The default time step is "minimal for the data type". That means that each data set will be plotted and exported to user with its own time step. For example, Kp index will be used with the 3 hours sampling, and the Dst index will have 1 hour time step. If user selects specific time step, say 30 min, then all time series the user works with will be re-sampled (step-wise interpolated or downsampled) to confirm this specific time step. When downloaded from SPIDR in ASCII or Matlab-friendly export formats, the "interpolated" flag will be set by system for each observation in the dataset.

    Time step is a property of the SPIDR date interval and both are changing and handled by system in the same way.

    The date interval and time step, defined at the "Time Interval and Sampling" page by user, are transparently used through the system for all actions requiring the time settings. For example, the same time settings will be used for plots, data basket export or for the system usage statistics display if they are requested in the same user session. The time settings for the current session are shown at the left menu of the SPIDR page.

    The selected time interval and sampling will affect display of the station maps and list of the data sets available for the given time interval. The "availability" filter for data sets can be turned off by a check box above the datasets listing. To draw station maps with all stations the user has first to unset the time interval. The data export from user basket is also based on the time interval and sampling settings.

    The user can change the time interval and sampling settings at any moment during the SPIDR session. It is possible to get to the time settings page:
      -    from the top menu item "Time interval";
      -    from the left menu link "Change" near either the date interval or time step values;
      -    by selecting "Change time interval" action in the "Next action" list at the bottom of the page (if available);
      -    automatically re-directed by the system workflow if the time settings are needed by the next system action
           and they are were not set before by the user.

    If the SPIDR system workflow requires the time interval and sampling to be set before the next action, the workflow will be interrupted, the user will be redirected to the time setting page, and after that the workflow will resume to the next action with new time settings.