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You are here: GES DISC Home Giovanni - Interactive Visualization and Analysis Giovanni Operation Technical Summary:   Anomaly

Giovanni Operation Technical Summary:   Anomaly

Anomaly

The Giovanni anomaly operation performs the required calculation in the following manner:

 

Monthly anomaly of the selected parameter(s):

    Xa ( i ) = X (i ) - Xm ( i )

where:

• i denotes month (1, 2, ... , 12)

• Xa(i) represents the anomaly data for the month i

• X(i) is the original data of the month i

• Xm(i) is the monthly climatology data for the month i


Note:  Temporal or spatial averaging can be performed on the anomaly data. For example, when time averaging is performed over periods longer than a month, such as for the Lat-Lon map, Time-averaged service, Giovanni calculates the monthly anomaly first, and averages the monthly anomalies for each grid point over the selected time period.  Similarly, when spatial averaging is requested, such as for the Time Series service,  Giovanni calculates the monthly anomalies first, and then performs spatial averaging for each monthly anomaly. 

 

How to use the Anomaly operation:

  • Select the Climatology Information check box:  the Climatology Information column will be displayed in the parameter selection window for those products with climatology data products available in the Giovanni system.

  • Select Only Parameters with Climatology check box:  only the parameters with climatology data will be displayed in the parameter selection window — the other parameters lacking climatology data will be hidden.

  • Select an Analysis OptionParameter, Climatology, or Anomaly:

    • If the Parameter radio button is selected, analysis and visualization services will apply to normal parameters.

    • If the Climatology radio button is selected, analysis and visualization services will apply to climatology data of selected parameters.

    • If the Anomaly radio button is selected, analysis and visualization services will apply to anomaly data of selected parameters.

Analysis Steps

  • Select one or more parameters.
  • Select a climatology parameter (if the Climatology or Anomaly radio button has been selected and there is more than one climatology data products available for a selected parameter).
  • Select Temporal Range
    • If Climatology radio button has been selected:
      • Climatology Information column will be displayed in the parameter selection window.
      • Only "Begin Month" and "End Month" are available in "Temporal" selection section, "Beign Year" and "End year" are hidden to avoid confusion.
      • By selecting "Begin Month" and "End Month" as a time range, any seasonal Climatology can be generated and visualized. For example, a selected month range of December-February will generate meteorological winter climatology (also referred as DJF) and a selected month range of June-August will generate meteorological summer climatology (also referred as JJA).
     
    • If Anomaly radio button has been selected:
      • Climatology Information column will be displayed in parameter selection window.
      • By selecting "Begin Date" and "End Date" as the time range, any seasonal anomaly can be generated and visualized. For example, a selected month range of 2007 December to 2008 February will generate meteorological winter (2007 DJF) anomaly, and a selected month range of 2008 June to 2008 August will generate meteorological summer (2008 JJA) anomaly.
  •  
  • Select Visualization Type.
  • Select Generate Visualization to submit.

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Last updated: Sep 09, 2009 02:27 PM ET
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