`HYCOMGOMl0043D` Class

Represents a HYCOM GOMl0.04 3D variable as a Grid Dataset.

Module:	`GeoEco.DataProducts.HYCOM`
Intended use:	All properties and methods are recommended for external callers
COM:	Not exposed as a COM class
ArcGIS:	Some methods are exposed as ArcGIS geoprocessing tools

Constructor

class HYCOMGOMl0043D( variableName[, startYear[, endYear[, timeout[, maxRetryTime[, cacheDirectory]]]]]): Constructs a new HYCOMGOMl0043D instance.

Read-only properties

DisplayName: Informal name of this object.

ParentCollection: DatasetCollection that is the parent of this object (if any).

Instance methods

GetAllQueryableAttributes( ): Returns a list of all queryable attributes.

GetQueryableAttribute( name): Returns the queryable attribute with the specified name.

GetQueryableAttributeValue( name): Returns the value of the queryable attribute with the specified name.

GetQueryableAttributesWithDataType( typeMetadata): Returns a list queryable attributes having the specified data type.

GetSpatialReference( srType): Returns the spatial reference of this dataset.

SetSpatialReference( srType, sr): Sets the spatial reference of this dataset.

Classmethods

ConvertSpatialReference( srType, sr, outputSRType): Converts a spatial reference from one format to another, such as an OGC WKT string to a Proj4 string.

CreateArcGISRasters( variableName, outputWorkspace[, mode[, rasterNameExpressions[, rasterCatalog[, spatialExtent[, linearUnit[, startDate[, endDate[, timeout[, maxRetryTime[, cacheDirectory[, calculateStatistics[, buildPyramids]]]]]]]]]]]]): Creates rasters for a HYCOM GOMl0.04 3D variable.

CreateClimatologicalArcGISRasters( variableName, statistic, binType, outputWorkspace[, mode[, rasterNameExpressions[, binDuration[, startDayOfYear[, spatialExtent[, linearUnit[, startDate[, endDate[, timeout[, maxRetryTime[, cacheDirectory[, calculateStatistics[, buildPyramids]]]]]]]]]]]]]): Creates climatological rasters for a HYCOM GOMl0.04 3D variable

InterpolateAtArcGISPoints( variableNames, points, valueFields, tField[, method[, where[, noDataValue[, timeout[, maxRetryTime[, cacheDirectory[, orderByFields[, numBlocksToCacheInMemory[, xBlockSize[, yBlockSize[, tBlockSize]]]]]]]]]]]): Interpolates HYCOM GOMl0.04 3D variables at points.

TestCapability( capability): Tests whether a capability is supported by this class or an instance of it.

Remarks

At the time this class was developed, the HYCOM + NCODA Gulf of Mexico 1/25 Degree Analysis (GLMl0.04) consisted of two gridded datasets:

expt_20.1 - The 20.1 experiment running from 1 January 2003 through 30 June 2010.
expt_30.1 - The 30.1 experiment running from 1 July 2010 and running to the present day plus five days.

The datasets have identical spatiotemporal extents and resolutions and the same oceanographic variables. This class treats them as one continuous dataset and takes time slices prior to 1 July 2010 from expt_20.1 and on or after that date from expt_30.1. (On the HYCOM server, the datasets actually overlap slightly, with expt_20.1 ending slightly after 30 June 2010 and expt_30.1 starting slightly before 1 July 2010. The class ignores the overlapping time slices and switches from expt_20.1 to expt_30.1 on 1 July.)

The grids are in Mercator projection based on a sphere with radius 6371001 m, with square cells approximately 4.5 km on a side. The geographic extent is approximately 18 to 32 N, 98 to 76 W. The time step is 1 day, with time slices representing the instantaneous condition of the ocean estimated at 00:00 UTC on each day.

The HYCOM documentation states that HYCOM provides a five day forecast and five day hindcast from the current date, although we have observed netCDF files on their servers that suggested this window may extend seven days in both directions. HYCOM revises the data within this window daily, using the latest ocean observations assimilated from buoys, satellites, and other sensors. Use caution when working with time slices close to the current date, as it appears that time slices continue to be revised until they are 7 days older than the current date.

Occasionally, HYCOM fails to generate data for a time slice, presumably due to an outage or other problem in their data processing infrastructure. For example, in 2004, HYCOM failed to generate data for three of the 366 time slices of that year. Although HYCOM omits these time slices from their server, this class represents them as grids filled with the No Data value.

The datasets include both 3D variables (dimensions x, y, and time) and 4D variables (dimensions x, y, depth, and time). The 4D variables are estimated at 40 depth levels: 0, 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100, 125, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1750, 2000, 2500, 3000, 3500, 4000, 4500, 5000, and 5500 m.

This class accesses the HYCOM datasets using the OPeNDAP protocol, allowing data to be retrieved very efficiently. However, during periods of high load, the HYCOM OPeNDAP server often requires five to ten minutes to return the first slice of data. Please be patient; after the first one is returned, the rest will go much faster. During periods of extreme load, the tool may fail with a timeout error. If this happens, increase the timeout value and try again, or wait until later when the server is less busy.

References

Chassignet, E.P., Hurlburt, H.E., Metzger, E.J., Smedstad, O.M., Cummings, J.A., Halliwell, G.R., Bleck, R., Baraille, R., Wallcraft., A.J., Lozano, C., Tolman, H.L., Srinivasan, A., Hankin, S., Cornillon, P., Weisberg, R., Barth, A., He, R., Werner, F. and Wilkin, J. (2009). US GODAE: Global Ocean Prediction with the HYbrid Coordinate Ocean Model (HYCOM). Oceanography 22: 64-75.