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You are here: GES DISC Home Giovanni - Interactive Visualization and Analysis Additional Features Users Manual Giovanni-3 Online Users Manual: 5. Services and Operations

Giovanni-3 Online Users Manual: 5. Services and Operations


In the nomenclature of Giovanni, a service provides a data visualization or analytical result requested by the user. Giovanni operations are steps in the data processing sequence which are performed to produce the service output. 

5.1 Giovanni Analytical Services and Operations

 

In the table below, the data lineage appears below the description of the analytical service. Each step in the data lineage is an operation performed by Giovanni to create the output from the analytical service. Each step is linked to an Operation Technical Summary page that describes this operation in more detail.  

Some important operations may be included in several different services (and thus will appear in the visualization lineage) when invoked by user preference:    these types of operations are also included in the table.   The Parameter Masking operation is sometimes invoked by user preference and sometimes invoked by mandatory settings in Giovanni;    because it may not appear in a given lineage, it only appears in the Operations table.

 

Below the first table is a table listing the SERFs in the Global Change Master Directory (GCMD) and the corresponding Operation Technical Summary for each of the Giovanni-3 operations.

Analytical Service Description
Animation

The Animation output option creates a series of monthly area plots for the selected region and displays them sequentially. This option is useful for rapidly visualizing regions with seasonal variability and determining the most illustrative months for area plot output.

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [2-D Map Plot] ... 4. [Animation]

Anomaly

The Anomaly operation calculates the parameter anomaly for a selected time-period, based on the parameter climatology.   Anomaly values can be displayed as lat-lon maps or time-series.   Anomalies are useful for determining large differences from normal or "mean" conditions.   The anomaly operation can only be requested when a parameter climatology is available.

1.  [Anomaly]

Lat-Lon Area Plot, Time-averaged

To generate a time-averaged area plot, the data values for each grid cell in the user-specified area are averaged over the user-specified time range. The average value of the data parameter for each grid cell is plotted and displayed. Averaging in this case is a linear operation.

Parameter weighting or pixel weighting may be used to produce the plot.  Parameter weighting is currently only used for the Aerosol Small Mode Fraction data parameter.  If parameter weighting is employed, the averaging is nonlinear.

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset]... 3. [Time Avg] ... 4. [2-D Map Plot]

Lat-Lon Plot, Difference Map

This service creates an area plot of the difference between two parameters or two different data sets of the same parameter. The latter function is useful for generating anomalies utilizing data parameter climatologies.

Operation steps performed to generate this visualization:
1. [Data Fetching]
... 2. [Grid Subset] ...  3. [Dimension Avg] ... 4. [Difference Map]

Latitude-Time
Hovmöller Plot

Longitude-Time Hovmöller Plot

Latitude vs. time and longitude vs. time Hovmöller plots are plots of the selected parameter as either longitudinal variation versus time (latiitude-averaged) or latitudinal variation versus time (longitude-average).   These plots allow a two-dimensional representation of changes occurring in a given region spanning a selected time period. 

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Dimension Avg] ...
4. [2-D Map Plot]

Correlation Plot

This service creates a plot of the correlation coefficient for two parameters over a specified time period.

Operation steps performed to generate this visualization:
1. [Data Fetching] ...2. [Grid Subset] ... 3. [Correlation Map] ...
4. [2-D Map Plot]

Comparison Plot

This service creates an area plot with two parameters. The values of the first parameter are represented with a color palette, and the values of the second parameter are represented with labeled contour lines overlaid on the color plot of the first parameter.

Operation steps performed to generate this visualization:
1. [Data Fetching]
... 2. [Grid Subset] ... 3. [Time Avg] ... 4. [Comparison Plot]

Cross-Map Plot (Latitude-Pressure)

Cross-Map Plot(Longitude-Pressure)

This service creates a two-dimensional representation of data parameter values plotted in pressure or altitude (in the vertical dimension) vs. latitude or longitude (in the horizontal dimension). The data parameter values in the Cross-Section Plot are interpolated and displayed in log-scale.

  • For Latitude-Pressure, the data are averaged over longitude, and the service will generate a profile rather than a cross-section if a single latitude value is selected.
  • For Longitude-Pressure, the data are averaged over latitude, and the service will generate a profile rather than a cross-section if a single longitude value is selected.

Operation steps performed to generate this visualization:

1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Time Avg] ... 4. [Dimension Avg] ... 5. [Cross Section and Vertical Profile Rendering]

Cross-Map Plot (Time-Pressure)

This service creates a two-dimensional representation of data parameter values plotted in pressure or altitude (in the vertical dimension) vs. time (in the horizontal dimension). The data parameter values in the Cross-Section Plot are interpolated and displayed in log-scale.

  • The data are averaged over longitude and latitude and will generate a profile rather than cross-section if the Begin Time and EndTime are the same.

Operation steps performed to generate this visualization:

1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Dimension Avg] ... 4. [Cross Section and Vertical Profile Rendering]

Scatter Plot

Scatter Plot, Time-averaged

A scatter plot is a two-dimensional (X-Y) plot of two selected parameters. The user specifies the time range, and each grid cell (pixel) provides one average X value and one average Y value calculated over this time range. The X and Y values are plotted and a least squares line is fitted to the distribution.

Operation steps performed to generate this visualization:

Scatter Plot:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Time Stitch] ... 4. [Scatter Plot]

Scatter Plot, Time-Averaged:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Time Avg] ...
4. [Scatter Plot Time Avg]

Curtain Plot

This service creates a two-dimensional representation of data parameter values plotted against pressure or altitude (in the vertical dimension) and distance along the satellite ground track (in the horizontal dimension). The data parameter values in the Curtain Plot are displayed using a color palette.

Operation steps performed to generate this visualization: (documentation of these steps is currently in progress)

1.[Data Fetching] ... 2. [Swath Pressure] ... 3. [Swath Stitch] ...
4. [Across-Track Swath Subset] ... 5. [Along-Track Swath Subset] ...
6. [Profile VFM] ... 7. [HDF Scaling]... 8.[Swath Strip] ...
9. [Swath Center Pixel] ... 10. [Curtain Plot]

Time Series, Area-averaged

The area-averaged time-series service calculates a single average data parameter value for the entire user-specified area for each time element in the user-specified time range. Each average value is plotted against the time units to create the time-series output.Parameter weighting or pixel weighting may be used to produce the plot. Parameter weighting is used for the Aerosol Small Mode Fraction. This time-series service should be utilized for multi-parameter overlay plots.

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Dimension Avg] ...
4. [Time-Series Plot]

Time-Series Difference

This service creates a time-series plot of the difference between two parameters at each time step in a specified time period. One application of this service is for examining anomalies, computed by generating the differences of a parameter during a specific time period in comparisoin to mean values calculated over a much longer time period (climatologies).

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Dimension Avg] ...
4. [Difference]
... 5. [Time-Series Plot]

Time-Series, Area Statistics

This operation generates statistics to accompany a time-series plot. The statistics included are the weighted mean, pixel count, weighted standard deviation, maximum, and minimum. This service is recommended for single parameter analysis.

Operation steps performed to generate this visualization:
1. [Data Fetching] ... 2. [Grid Subset] ... 3. [Dimension Avg] ...
4. [Time-Series Statistics]

Regridding

The regridding operation (g3Regrid) has been implemented for services which require datasets with the same resolution. This step will be especially useful for data intercomparison services (such as Correlation Maps, Lat-Lon map of time averaged differences, etc.) where the data are provided by different instruments. Because the regridding step will only appear in the lineage when it is invoked by the user, it is given a separate description here.

1. [Regridding]

Vertical Profile

The Vertical Profile operation displays the nearest vertical profiles to a selected pointfor agiven date. The vertical profiles are displayed as an X-Y plot, with the X-axis as the geophysical value and the Y-axis as altitude in pressure units. Users may display from 1 to 6 profiles (the default is 3) along with error bars. Each vertical profile is represented by its own color.

Operation steps performed to generate this visualization:

1. [Data Fetching] ... 2. [Swath Stitch] ...
3.[Swath Center Pixel] ... 4. [Along-Track Swath Subset] ...
5. [HDF Scaling] ... 6. [Profile Renderer]

Zonal Mean

The Zonal Mean over a given area is the sequence of data generated by taking the average over a range of longitudes for each latitude. The Zonal Mean calculation only works with data in a single atmospheric layer (defined by pressure in hPA), such as 300 hPA as an example. The zonal mean cannot be calculated for a pressure range, i.e., for the range 300-400 hPA.

  • The zonal mean operation works by exporting the data from the dataset and then averaging along the longitude axis for each latitude point.

Operation steps performed to generate this visualization: (documentation of these steps is currently in progress)

1.  [Data Fetching]...   2.  [Grid Subset]...   3. [Time Avg]...              4.  [Dimension Avg]...  6.  [Zonal Mean]

Histogram

Histogram, Area-Averaged

Histogram, Time-Averaged

The Histogram service constructs a histogram (frequency distribution) for:  spatial data values in a single time interval (Histogram);   spatial data values averaged over multiple time intervals (Histogram, Area-Averaged);  and time-series data for a selected area (Histogram, Time-Averaged).

Operation steps performed to generate this visualization:

Histogram

1. [Data Fetching ] ... 2. [Preprocessor ] ... 3. [Parameter Masking ] ... 4. [Grid Subsetter ] ... 5. [Anomaly ] ... 6. [ Time Stitch ] ... 7. [Histogram Rendering ]

Histogram, Area-Averaged

1. [Data Fetching ] ... 2. [Preprocessor ] ... 3. [Parameter Masking ] ... 4. [Grid Subsetter ] ... 5. [Anomaly ] ... 6. [Dimension Averaging ] ... 7. [Time Stitch ] ... 8. [Histogram Rendering ]

Histogram, Time-Averaged

1. [Data Fetching ] ... 2. [Preprocessor ] ... 3. [Parameter Masking ] ... 4. [Grid Subsetter ] ... 5. [Anomaly ] ... 6. [Time Averaging ] ... 7. [Histogram Rendering

 

5.2 Giovanni-3 Operations

The Global Change Master Directory (GCMD) contains SERFs (Service Entry Resource Format) summarizing each of the Giovanni operations. They are linked in the table below. The third column provides a link to the corresponding Operation Technical Summary.

G3 appears in these names for consistency, as they were created for Giovanni during the Giovanni-3 development and implementation stage.    [More information]

GCMD SERF Name SERF Link Operation Technical Summary Link
A-Train Across Track Subset G3_operation_swath_subset
Along Track Swath Subsetter G3_operation_swath_track_trim
Altitude Pressure Conversion G3_operation_swath_pressure
Animation Rendering G3_operation_animation_plot
Anomaly G3_Anomaly G3_operation_anomaly
Comparison Plot G3_operation_comparison_plot
Correlation Map G3_operation_correlation_map
Curtain Plot Renderer G3_operation_curtain_plot
Data Fetching G3_operation_data_fetching
Difference, Area Map G3_operation_difference_map
Difference, Time-Series G3_operation_difference_map
Dimension Averaging G3_operation_dimension_avg
Dimension Collapsing G3_DimCollapse G3_operation_dimension_collapse
Grid Subset G3_operation_grid_subset
HDF Scaling G3_HDFScaling G3_operation_HDF_scaling
Histogram G3_Histogram G3_operation_histogram_plot
Parameter Masking G3_MapMask G3_operation_parameter_masking
Parameter Weighted Average G3_operation_parameter_weighting
Preprocessing G3_Preprocess G3_operation_preprocessing
Profile Renderer G3_ProfileRenderer G3_operation_profile_renderer
Regridding G3_Regridding G3_operation_regridding
Scatter Plot G3_operation_scatter_plot
Scatter Plot, Time-Averaged G3_operation_scatter_plot_time_avg
Swath Center Pixel Extractor G3_operation_swath_center_pixel
Swath Preparation G3_operation_swath_prep
Swath Stitcher G3_operation_swath_stitch
Swath Strip G3_operation_swath_strip
Time Averaging G3_operation_time_avg
Time Series Rendering G3_operation_time_series
Time Series Statistics G3_operation_time_series_stats
Time Stitch G3_operation_time_stitch
Two-Dimensional Map Plot G3_operation_map_to_plot
Vertical Feature Mask Extractor G3_operation_profile_VFM
Zonal Mean G3_ZonalMean G3_Zonal_Mean

 


 

 

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