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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-3 Analytical Services

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-3 to create the output from the analytical service. Each step is linked to an Operation Technical Summary page which describes this operation in more detail.

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

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]

Lat-Lon Area Plot, time-averaged

To generate a time-averaged area plot, the data values for each grid cell (which may also be called a pixel) 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. Parameter weighting or pixel weighting may be used to produce the plot. Parameter weighting is used for the Aerosol Small Mode Fraction.

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. [Difference] ... 4. [Dimension Avg] ... 5. [Time-Series Plot]

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 overlain 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, Longitude-Pressure)

This service creates a 2D 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 End Time 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

The Curtain Plot 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 point for a given 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 (default is 3), along with error bars. Each vertical profile is represented by its own color.

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

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

 

5.2 Giovanni-3 Operations

The Global Change Master Directory (GCMD) contains SERFs (Service Entry Resource Format) summarizing each of the Giovanni-3 operations. They are linked in the table below. The third column provides a link to the corresponding Operation Technical Summary.

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
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
HDF Scaling G3_HDFScaling G3_operation_HDF_scaling
Difference, Time-Series G3_operation_difference_map
Dimension Averaging G3_operation_dimension_avg
Grid Subset G3_operation_grid_subset
Parameter Weighted Average G3_operation_parameter_weighting
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_SwathStrip
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
Vertical Feature Mask Extractor G3_operation_profile_VFM
Two-Dimensional Map Plot G3_operation_map_to_plot
Profile Renderer G3_ProfileRenderer G3_operation_profile_renderer



 

 



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  • Last updated: June 13, 2008 18:58:43 GMT