`HYCOMGLBa008Equatorial3D` Class

Represents a 3D variable of the equatorial (Mercator) region of HYCOM GLBa0.08 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 HYCOMGLBa008Equatorial3D( variableName[, extendYExtent[, timeout[, maxRetryTime[, cacheDirectory]]]]): Constructs a new HYCOMGLBa008Equatorial3D 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[, rotationOffset[, extendYExtent[, spatialExtent[, linearUnit[, startDate[, endDate[, timeout[, maxRetryTime[, cacheDirectory[, calculateStatistics[, buildPyramids]]]]]]]]]]]]]]): Creates rasters for a 3D variable of the equatorial (Mercator) region of the HYCOM GLBa0.08 dataset.

CreateClimatologicalArcGISRasters( variableName, statistic, binType, outputWorkspace[, mode[, rasterNameExpressions[, binDuration[, startDayOfYear[, rotationOffset[, extendYExtent[, spatialExtent[, linearUnit[, startDate[, endDate[, timeout[, maxRetryTime[, cacheDirectory[, calculateStatistics[, buildPyramids]]]]]]]]]]]]]]]): Creates climatological rasters for a 3D variable of the equatorial (Mercator) region of the HYCOM GLBa0.08 dataset

InterpolateAtArcGISPoints( variableNames, points, valueFields, tField[, method[, extendYExtent[, where[, noDataValue[, timeout[, maxRetryTime[, cacheDirectory[, orderByFields[, numBlocksToCacheInMemory[, xBlockSize[, yBlockSize[, tBlockSize]]]]]]]]]]]]): Interpolates 3D variables of the equatorial (Mercator) region of the HYCOM GLBa0.08 dataset at points.

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

Remarks

This class accesses the "All Experiments (Aggregated)" dataset of the HYCOM + NCODA Global 1/12 Degree Analysis (GLBa0.08) using the OPeNDAP protocol.

The dataset consists of a collection of 3D and 4D gridded variables. The 3D variables represent conditions at the surface of the ocean and have dimensions of x, y, and time. The 4D variables represent conditions at depth and have dimensions of x, y, depth, and time.

HYCOM uses an unusual georeferencing scheme in which the Earth is represented by a grid that uses three different projections. The southern portion of the grid, encompassing approximately 66 S to 78 S, is in an equirectangular projection, with rectangular cells having the dimensions of 0.08 degrees longitude and 0.032 degrees latitude. The equatorial portion of the grid, encompassing approximately 47 N to 66 S, is in a Mercator projection with square cells approximately 8.9 km on a side (equivalent to 0.08 degrees of longitude at the equator). The northern portion of the grid, encompassing approximately 90 N to 47 N, is in a complicated "bi-polar" projection.

This class accesses the equatorial (Mercator) portion of the HYCOM grid, and is therefore very appropriate if your region of interest is between 47 N and 66 S. This tool can optionally extend the northern extent of of the Mercator grid to 60 N by interpolating values from the bi-polar region. If your region of interest is between 47 N and 60 N, enable that option but review the HYCOM data carefully to ensure the interpolated values appear to be reasonable for your application. Also be aware of the increasing map distortion caused by the Mercator projection as you approach high latitudes; at 60 degrees latitude, the cells are actually only one-half as wide (4.5 km) as the projection claims (8.9 km).

If your area of interest is north of 60 N or south of 66 S, do not use this class because it cannot access HYCOM data for those regions.

For more information on HYCOM's georeferencing, please see the HYCOM User's Guide, chapter 3: The HYCOM Grid, sections 2.3: I/O File Formats in HYCOM, and 5.1: File "regional.grid.[ab]".

The temporal extent of this dataset is 11 November 2003 to several days beyond the current date, with a time step of 1 day. The time slices represent 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 regularly observed netCDF files on their servers that suggested this window actually extends 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 dataset's 4D variables are estimated at 33 depth levels: 0, 10, 20, 30, 50, 75, 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.

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.