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Extracts eddy tracklines from the Chelton et al. (2011) mesoscale eddy database in SpatiaLite format.
In order to use this tool, you must first download the mesoscale eddy database netCDF file (usually available at http://cioss.coas.oregonstate.edu/eddies/) and convert it to a SpatiaLite database using the Convert Mesoscale Eddies NetCDF to SpatiaLite Database tool.
Each line represents the track of an eddy and includes attributes such as the start date, end date, duration, polarity, and various summary statistics. The track is constructed by connecting the eddy centroid points present in the database.
Because the database includes over 200,000 eddies, we recommend that you use the Where Clause parameter to limit the extraction to the eddies that occured in your region and time period of interest. If you do not specify the Where Clause, all 200,000 tracks will be extracted, which may take 30-45 minutes on a relatively fast computer and produce an output feature class that requires 50-100 MB of disk space.
References
Chelton, D.B., M.G. Schlax, and R.M. Samelson (2011). Global observations of nonlinear mesoscale eddies. Progress in Oceanography 91: 167-216.
Command line syntax| Expression | Explanation |
|---|---|
| <spatiaLiteDB> | Mesoscale eddies SpatiaLite database to read. This database is produced from the mesoscale eddy database netCDF file (usually available at http://cioss.coas.oregonstate.edu/eddies/) by the Convert Mesoscale Eddies NetCDF to SpatiaLite Database tool. |
| <outputFeatureClass> | Line feature class to create. Each line represents an eddy track. Longitude coordinates will range from 0 to 360. Tracks that cross the Prime Meridian will be split into multi-part lines. The lines will have the following attributes; data types are indicated in parentheses following the field name.
Please see Chelton et al. (2011) and http://cioss.coas.oregonstate.edu/eddies/ for more information about how these parameters were calculated. A spatial index will be created on the output feature class. |
| {tableName} | Name of the table to read from the SpatiaLite database. |
| {where} | SQL WHERE clause expression that specifies the eddy centroids that identify the eddy tracks to extract. If this parameter is not provided, all of the tracks will be extracted. The expression should reference the attributes of the centroids, not the tracks. Please see the documentation for the Convert Mesoscale Eddies NetCDF to SpatiaLite Database tool for a description of the centroid attributes. If this expression does not select all of the centroids that make up a track, the entire track will be extracted anyway. For example, if the expression specifies a geographic bounding box, complete tracks will be extracted for all eddies that had at least one centroid occur within the box. The expression is evaluated by the SQLite database engine that SpatiaLite is built upon. Please see the SQLite documentation for more information about the syntax of this expression. The following expression shows how to specify a geographic bounding box and time window to extract tracks that had at least one centroid occur in a region of the north Atlantic in the first three months of 2000. Note that longitude ranges from 0 to 360:
This example shows how to extract the tracks that had at least one centroid in the southern hemisphere, that had a duration of at least 16 weeks, and that had anticyclonic polarity:
You may use SpatiaLite's SQL functions in this expression to perform spatial comparisons. Please see the SpatiaLite documentation for more information. |
Scripting syntax| Expression | Explanation |
|---|---|
| Mesoscale eddies SpatiaLite database (Required) | Mesoscale eddies SpatiaLite database to read. This database is produced from the mesoscale eddy database netCDF file (usually available at http://cioss.coas.oregonstate.edu/eddies/) by the Convert Mesoscale Eddies NetCDF to SpatiaLite Database tool. |
| Output feature class (Required) | Line feature class to create. Each line represents an eddy track. Longitude coordinates will range from 0 to 360. Tracks that cross the Prime Meridian will be split into multi-part lines. The lines will have the following attributes; data types are indicated in parentheses following the field name.
Please see Chelton et al. (2011) and http://cioss.coas.oregonstate.edu/eddies/ for more information about how these parameters were calculated. A spatial index will be created on the output feature class. |
| SpatiaLite table name (Optional) | Name of the table to read from the SpatiaLite database. |
| Where clause (Optional) | SQL WHERE clause expression that specifies the eddy centroids that identify the eddy tracks to extract. If this parameter is not provided, all of the tracks will be extracted. The expression should reference the attributes of the centroids, not the tracks. Please see the documentation for the Convert Mesoscale Eddies NetCDF to SpatiaLite Database tool for a description of the centroid attributes. If this expression does not select all of the centroids that make up a track, the entire track will be extracted anyway. For example, if the expression specifies a geographic bounding box, complete tracks will be extracted for all eddies that had at least one centroid occur within the box. The expression is evaluated by the SQLite database engine that SpatiaLite is built upon. Please see the SQLite documentation for more information about the syntax of this expression. The following expression shows how to specify a geographic bounding box and time window to extract tracks that had at least one centroid occur in a region of the north Atlantic in the first three months of 2000. Note that longitude ranges from 0 to 360:
This example shows how to extract the tracks that had at least one centroid in the southern hemisphere, that had a duration of at least 16 weeks, and that had anticyclonic polarity:
You may use SpatiaLite's SQL functions in this expression to perform spatial comparisons. Please see the SpatiaLite documentation for more information. |