root/MGET/Trunk/PythonPackage/dist/TracOnlineDocumentation/Documentation/PythonReference/Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.InterpolateAtArcGISPoints.html @ 981

Revision 981, 31.4 KB (checked in by jjr8, 13 months ago)

Merged revision(s) 964-980 from MGET/Branches/Jason:
Added moon.py
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* Incremented build number
* Working on #542: Add a tool for calculating the moon phase
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Rebuilt ArcGIS 9.3 toolbox.
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Fixed #544: On ArcGIS 9.3, 9.3 SP1, and 9.3.1, various "Interpolate ... at Points" tools fail with RuntimeError?: Failed to set the value of the ... field of a point from ArcGIS FeatureClass? ... to None due to TypeError?: an integer is required
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Fixed #545: Fit GLM and Predict GLM From Rasters tools fail with RPy_Exception: could not find function "..."
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Fixed/implemented:
* #542: Add a tool for calculating the moon phase
* #543: Binary output from Predict GLM, Predict GAM, etc. should be NoData? where inputs are NoData?
* Added temporal periodicity analysis tool.
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Rebuilt ArcGIS 9.3 toolbox.
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* Rebuilt ArcGIS 9.3 toolbox.
* Renamed 'Spatial Analysis' toolset to 'Spatial And Temporal Analysis'
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* Fixed #488: Create Fishnet For Points tool does not work on ArcGIS 10
* Finished implementation of Periodicity.AnalyzeArcGISTable
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Rebuilt ArcGIS toolbox. Fixed build break.
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Rebuilt installation packages. This will be merged with the Trunk and released as MGET 0.8a40.
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6          </style></head><body><div class="navigation"><div><table align="center" width="100%" cellpadding="0" cellspacing="2"><tr><td class="online-navigation"><a title="CreateClimatologicalArcGISRasters Method" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.CreateClimatologicalArcGISRasters.html?format=raw"><img src="previous.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Previous Page" /></a></td><td class="online-navigation"><a title="HYCOMGLBa008Equatorial3D Class" href="Class_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.html?format=raw"><img src="up.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Up one Level" /></a></td><td class="online-navigation"><a title="TestCapability Method" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.TestCapability.html?format=raw"><img src="next.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Next Page" /></a></td><td align="center" width="100%">GeoEco Python Reference</td><td class="online-navigation"><a title="Table of Contents" href="TableOfContents.html?format=raw"><img src="contents.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Table of Contents" /></a></td><td class="online-navigation"><a title="Module Index" href="ModuleIndex.html?format=raw"><img src="modules.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Module Index" /></a></td><td class="online-navigation"><img src="blank.png?format=raw" border="0" align="bottom" height="32" width="32" alt="" /></td></tr></table><div class="online-navigation"><b class="navlabel">Previous:</b> <a class="sectref" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.CreateClimatologicalArcGISRasters.html?format=raw">CreateClimatologicalArcGISRasters Method</a> <b class="navlabel">Up:</b> <a class="sectref" href="Class_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.html?format=raw">HYCOMGLBa008Equatorial3D Class</a> <b class="navlabel">Next:</b> <a class="sectref" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.TestCapability.html?format=raw">TestCapability Method</a> </div><hr /></div></div><h1><tt class="member">InterpolateAtArcGISPoints</tt> Method</h1><p>Interpolates 3D variables of the equatorial (Mercator) region of the HYCOM GLBa0.08 dataset at points.</p><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td class="metadataTitle">Class:</td><td class="metadataValue"><tt class="class"><a href="Class_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.html?format=raw">HYCOMGLBa008Equatorial3D</a></tt></td></tr><tr valign="baseline"><td class="metadataTitle">Intended use:</td><td class="metadataValue">Recommended for external callers</td></tr><tr valign="baseline"><td class="metadataTitle">COM:</td><td class="metadataValue">Exposed as the <a style="font-family: verdana, sans serif; font-size: small;" href="../COMReference/Method_GeoEco.HYCOMGLBa008Equatorial3D.InterpolateAtArcGISPoints.html?format=raw">InterpolateAtArcGISPoints</a> method of COM class <a style="font-family: verdana, sans serif; font-size: small;" href="../COMReference/Class_GeoEco.HYCOMGLBa008Equatorial3D.html?format=raw">GeoEco.HYCOMGLBa008Equatorial3D</a></td></tr><tr valign="baseline"><td class="metadataTitle">ArcGIS:</td><td class="metadataValue">Exposed as the <a style="font-family: verdana, sans serif; font-size: small;" href="../ArcGISReference/HYCOMGLBa008Equatorial3D.InterpolateAtArcGISPoints.html?format=raw">Interpolate HYCOM GLBa0.08 Equatorial 3D Variables at Points</a> geoprocessing tool</td></tr><tr valign="baseline"><td class="metadataTitle">Method type:</td><td class="metadataValue">Classmethod</td></tr></table><h3>Usage</h3><table cellpadding="0" cellspacing="0"><tr valign="baseline"><td style="white-space: nowrap;"><var>updatedPoints</var> = <b><tt class="method">HYCOMGLBa008Equatorial3D.InterpolateAtArcGISPoints</tt></b>(</td><td><var>variableNames</var><var>, points</var><var>, valueFields</var><var>, tField</var><big>[</big><var>, method</var><big>[</big><var>, extendYExtent</var><big>[</big><var>, where</var><big>[</big><var>, noDataValue</var><big>[</big><var>, timeout</var><big>[</big><var>, maxRetryTime</var><big>[</big><var>, cacheDirectory</var><big>[</big><var>, orderByFields</var><big>[</big><var>, numBlocksToCacheInMemory</var><big>[</big><var>, xBlockSize</var><big>[</big><var>, yBlockSize</var><big>[</big><var>, tBlockSize</var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var><big>]</big><var></var>)</td></tr></table><h3>Arguments</h3><dl><dt><var>variableNames</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">list</tt> of <tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr></table><p>HYCOM 3D variables to interpolate:</p><ul><li>emp - Water flux into the ocean, in kg/m^2/s.</li><li>mld - Mixed layer thickness, in m, defined as the depth at which the
7temperature change from the surface temperature is 0.2 degrees C.</li><li>mlp - Mixed layer thickness, in m, defined as the depth at which the
8pressure change from the surface pressure is 0.03 kg/m^3.</li><li>qtot - Surface downward heat flux, in W/m^2.</li><li>ssh - Sea surface height, in m, above the HYCOM reference spheroid.</li><li>surface_salinity_trend - Surface salinity trend, in psu/day.</li><li>surface_temperature_trend - Surface temperature trend, in degrees
9C/day.</li></ul><p>Please see the HYCOM documentation for more information about these
10variables.</p><p>For each variable that you select, you must also specify a field of
11the points to receive the interpolated value.</p></dd></dl><dl><dt><var>points</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr><tr valign="baseline"><td class="metadataTitle">Maximum length:</td><td class="metadataValue">255</td></tr><tr valign="baseline"><td class="metadataTitle">Must exist:</td><td class="metadataValue">Yes</td></tr></table><p>Points at which values should be interpolated.</p><p>HYCOM uses a Mercator coordinate system based on a sphere with radius
126371001 m. It is recommended but not required that the points use the
13same coordinate system. If they do not, this tool will attempt to
14project the points to the HYCOM coordinate system prior to doing the
15interpolation. This may fail if a datum transformation is required, in
16which case you will have to manually project the points to the HYCOM
17coordinate system before using this tool.</p></dd></dl><dl><dt><var>valueFields</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">list</tt> of <tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">0</td></tr></table><p>Fields of the points to receive the interpolated values. You must
18specify one field for each HYCOM variable that you selected for
19interpolation.</p><p>Each field must have a floating-point or integer data type. If a field
20cannot represent the interpolated value at full precision, the closest
21approximation will be stored and a warning will be issued. Because all
22of the HYCOM variables use a floating-point data type, we strongly
23recommend you use floating-point fields.</p></dd></dl><dl><dt><var>tField</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr><tr valign="baseline"><td class="metadataTitle">Maximum length:</td><td class="metadataValue">255</td></tr><tr valign="baseline"><td class="metadataTitle">Must exist:</td><td class="metadataValue">Yes</td></tr></table><p>Field of the points that specifies the date and time of the point.</p><p>The field must have a date or datetime data type. If the field can
24only represent dates with no time component, the time will assumed to
25be 00:00:00.</p><p>HYCOM uses UTC time. It is assumed that this field also uses UTC
26time.</p></dd></dl><dl><dt><var>method</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>u'Nearest'</code></td></tr><tr valign="baseline"><td class="metadataTitle">Allowed values:</td><td class="metadataValue"><code>u'Nearest'</code>, <code>u'Linear'</code></td></tr></table><p>Interpolation method to use, one of:</p><ul><li>Nearest - nearest neighbor interpolation. The interpolated value
27will simply be the value of the cell that contains the point. This
28is the default.</li><li>Linear - linear interpolation (also known as trilinear
29interpolation). This method averages the values of the eight nearest
30cells in the x, y, and time dimensions, weighting the contribution
31of each cell by the area of it that would be covered by a
32hypothetical cell centered on the point being interpolated. If the
33cell containing the point contains NoData, the result is NoData. If
34any of the other seven cells contain NoData, they are omitted from
35the average, and the result is based on the weighted average of the
36cells that do contain data. This is the same algorithm implemented
37by the ArcGIS Spatial Analyst's Extract Values to Points tool.</li></ul></dd></dl><dl><dt><var>extendYExtent</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">bool</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>False</code></td></tr></table><p>If this option is enabled, the northern extent of the HYCOM data
38will be extended from 47 N to 60 N by interpolating values from the
39bi-polar portion of HYCOM's grid.</p><p>The northern extent of the Mercator region of HYCOM's grid is about 47
40N. Above this latitude, HYCOM uses a complicated bi-polar projection
41that cannot be represented by most GIS programs. Because of that, this
42tool does not provide direct access to the bi-polar data above 47 N.
43But if this option is enabled, the tool will extend the Mercator
44region up to 60 N by interpolating values above 47 N from the bi-polar
45region using the nearest neighbor algorithm. Under this scheme, the
46value of each Mercator cell above 47 N will be copied from the
47bi-polar cell that is closest in latitude and longitude. A nearest
48neighbor algorithm was used for its computational simplicity and
49efficiency and to preserve sharp gradients that would be smoothed out
50by alternative techniques.</p></dd></dl><dl><dt><var>where</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr></table><p>SQL WHERE clause expression that specifies the subset of points to
51use. If this parameter is not provided, all of the points will be
52used.</p><p>The exact syntax of this expression depends on the type of feature
53class you're using. ESRI recommends you reference fields using the
54following syntax:</p><ul><li>For shapefiles, ArcInfo coverages, or feature classes stored in file
55geodatabases, ArcSDE geodatabases, or ArcIMS, enclose field names in
56double quotes: "MY_FIELD"</li><li>For feature classes stored in personal geodatabases, enclose field
57names in square brackets: [MY_FIELD].</li></ul></dd></dl><dl><dt><var>noDataValue</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">float</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><tt class="class">None</tt></td></tr></table><p>Value to use when the interpolated value is NoData.</p><p>If a value is not provided for this parameter, a database NULL value
58will be stored in the field when the interpolated value is NoData. If
59the field cannot store NULL values, as is the case with shapefiles,
60the value -9999 will be used.</p></dd></dl><dl><dt><var>timeout</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>60</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>1</code></td></tr></table><p>Number of seconds to wait for the THREDDS or OPeNDAP server to
61respond before failing with a timeout error.</p><p>If you also provide a Maximum Retry Time and it is larger than the
62timeout value, the failed request will be retried automatically (with
63the same timout value) until it succeeds or the Maximum Retry Time has
64elapsed.</p><p>If you receive a timeout error you should investigate the server to
65determine if it is malfunctioning or just slow. Check the server's
66website to see if the operator has posted a notice about the problem,
67or contact the operator directly. If the server just slow, increase
68the timeout value to a larger number, to give the server more time to
69respond.</p></dd></dl><dl><dt><var>maxRetryTime</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>120</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>1</code></td></tr></table><p>Number of seconds to retry requests to the THREDDS or OPeNDAP
70server before giving up.</p><p>Use this parameter to cope with a server that experiences transient
71failures. For example, some servers are rebooted as part of nightly
72maintenance cycles. If you start a long running operation and want it
73to run overnight without failing, set the maximum retry time to a
74duration that is longer than the time that the server is offline
75during the maintenance cycle.</p><p>To maximize performance while minimizing load during failure
76situations, retries are scheduled with progressive delays:</p><ul><li>The first retry is issued immediately.</li><li>Then, so long as fewer than 10 seconds have elapsed since the
77original request was issued, retries are issued every second.</li><li>After that, retries are issued every 30 seconds until the maximum
78retry time is reached or the request succeeds.</li></ul></dd></dl><dl><dt><var>cacheDirectory</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr><tr valign="baseline"><td class="metadataTitle">Maximum length:</td><td class="metadataValue">255</td></tr><tr valign="baseline"><td class="metadataTitle">Must exist:</td><td class="metadataValue">No</td></tr></table><p>Directory to cache OPeNDAP datasets.</p><p>A cache directory can dramatically speed up scenarios that involve
79accessing the same subsets the HYCOM data over and over again. When
80OPeNDAP data is requested from the HYCOM server, the cache directory
81will be checked for data that was downloaded and cached during prior
82requests. If cached data exists that can fulfill part of the current
83request, the request will be serviced by reading from cache files
84rather than the OPeNDAP server. If the entire request can be serviced
85from the cache, the OPeNDAP server will not be accessed at all and the
86request will be completed extremely quickly. Any parts of the request
87that cannot be serviced from the cache will be downloaded from the
88OPeNDAP server and added to the cache, speeding up future requests for
89the same data.</p><p>If you use a cache directory, be aware of these common pitfalls:</p><ul><li>The HYCOM documentation states that HYCOM provides a five day forecast
90and five day hindcast from the current date, although we have
91observed netCDF files on their servers that suggested this window
92may extend seven days in both directions. HYCOM revises the data
93within this time window daily, using the latest ocean observations
94assimilated from buoys, satellites, and other sensors. We recommend
95you do not cache data in this time window. The caching algorithm
96cannot detect whether cached data should be replaced with revised
97versions available on the server.</li><li>The caching algorithm permits the cache to grow to infinite size and
98never deletes any cached data. If you access a large amount of data
99it will all be added to the cache. Be careful that you do not fill
100up your hard disk. To mitigate this, manually delete the entire
101cache or selected directories or files within it.</li><li>The caching algorithm stores data in uncompressed files, so that
102subsets of those files may be quickly accessed. To save space on
103your hard disk, you can enable compression of the cache directory
104using the operating system. On Windows, right click on the directory
105in Windows Explorer, select Properties, click Advanced, and enable
106"Compress contents to save disk space".</li></ul></dd></dl><dl><dt><var>orderByFields</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">list</tt> of <tt class="class">unicode</tt>, or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr></table><p>Fields for defining the order in which the points are processed.</p><p>The points may be processed faster if they are ordered
107spatiotemporally, such that points that are close in space and time
108are processed sequentially. Ordering the points this way increases the
109probability that the value of a given point can be interpolated from
110data that is cached in memory, rather than from data that must be read
111from the disk or network, which is much slower. Choose fields that
112faciliate this. For example, if your points represent the locations of
113animals tracked by satellite telemetry, order the processing first by
114the animal ID and then by the transmission date or number.</p><p>If you omit this parameter, the Date Field will be used automatically.</p><p>This parameter requires ArcGIS 9.2 or later.</p></dd></dl><dl><dt><var>numBlocksToCacheInMemory</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>128</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>0</code></td></tr></table><p>Maximum number of blocks of HYCOM data to cache in memory.</p><p>To minimize the number of times that the disk or network must be
115accessed, this tool employs a simple caching strategy, in addition to
116disk caching described by the Cache Directory parameter. When it
117processes the first point, it reads a square block of cells centered
118on that point and caches it in memory. When it processes the second
119and subsequent points, it first checks whether the cells needed for
120that point are contained by the block cached in memory. If so, it
121processes that point using the in-memory block, rather than reading
122from disk or the network again. If not, it reads another square block
123centered on that point and adds it to the cache.</p><p>The tool processes the remaining points, adding additional blocks to
124the cache, as needed. To prevent the cache from exhausing all memory,
125it is only permitted to grow to the size specified by this parameter.
126When the cache is full but a new block is needed, the oldest block is
127discarded to make room for the newest block.</p><p>The maximum size of the cache in bytes may be calculated by
128multiplying this parameter by 4 (the number of bytes required for one
129cell of data) and then by all of the block size parameters.</p><p>If this parameter is 0, no blocks will be cached in memory.</p></dd></dl><dl><dt><var>xBlockSize</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>16</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>0</code></td></tr></table><p>Size of the blocks of HYCOM data to cache in memory, in the x
130direction (longitude). The size is given as the number of cells.</p><p>If this parameter is 0, no blocks will be cached in memory.</p></dd></dl><dl><dt><var>yBlockSize</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>16</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>0</code></td></tr></table><p>Size of the blocks of HYCOM data to cache in memory, in the y
131direction (latitude). The size is given as the number of cells.</p><p>If this parameter is 0, no blocks will be cached in memory.</p></dd></dl><dl><dt><var>tBlockSize</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">int</tt> or <tt class="class">None</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Default value:</td><td class="metadataValue"><code>3</code></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum value:</td><td class="metadataValue"><code>0</code></td></tr></table><p>Size of the blocks of HYCOM data to cache in memory, in the t
132direction (time). The size is given as the number of cells.</p><p>If this parameter is 0, no blocks will be cached in memory.</p></dd></dl><h3>Returns</h3><dl><dt><var>updatedPoints</var></dt><dd><table cellpadding="0" cellspacing="0" style="margin-top: 1.0em;"><tr valign="baseline"><td class="metadataTitle">Python type:</td><td class="metadataValue"><tt class="class">unicode</tt></td></tr><tr valign="baseline"><td class="metadataTitle">Minimum length:</td><td class="metadataValue">1</td></tr><tr valign="baseline"><td class="metadataTitle">Maximum length:</td><td class="metadataValue">255</td></tr><tr valign="baseline"><td class="metadataTitle">Must exist:</td><td class="metadataValue">No</td></tr></table><p>Updated points.</p></dd></dl><h3>Remarks</h3><p>This tool accesses the "All Experiments (Aggregated)" dataset
133of the
134<a href="http://www.hycom.org/dataserver/glb-analysis/">HYCOM + NCODA Global 1/12 Degree Analysis (GLBa0.08)</a>
135using the <a href="http://opendap.org/">OPeNDAP</a> protocol.</p><p>The dataset consists of a collection of 3D and 4D gridded variables.
136The 3D variables represent conditions at the surface of the ocean and
137have dimensions of x, y, and time. The 4D variables represent
138conditions at depth and have dimensions of x, y, depth, and time.</p><p>HYCOM uses an unusual georeferencing scheme in which the Earth is
139represented by a grid that uses three different projections. The
140southern portion of the grid, encompassing approximately 66 S to 78 S,
141is in an equirectangular projection, with rectangular cells having the
142dimensions of 0.08 degrees longitude and 0.032 degrees latitude. The
143equatorial portion of the grid, encompassing approximately 47 N to 66
144S, is in a Mercator projection with square cells approximately 8.9 km
145on a side (equivalent to 0.08 degrees of longitude at the equator).
146The northern portion of the grid, encompassing approximately 90 N to
14747 N, is in a complicated "bi-polar" projection.</p><p>This tool accesses the equatorial (Mercator) portion of the HYCOM
148grid, and is therefore very appropriate if your region of interest is
149between 47 N and 66 S. This tool can optionally extend the northern
150extent of of the Mercator grid to 60 N by interpolating values from
151the bi-polar region. If your region of interest is between 47 N and 60
152N, enable that option but review the HYCOM data carefully to ensure
153the interpolated values appear to be reasonable for your application.
154Also be aware of the increasing map distortion caused by the Mercator
155projection as you approach high latitudes; at 60 degrees latitude, the
156cells are actually only one-half as wide (4.5 km) as the projection
157claims (8.9 km).</p><p>If your area of interest is north of 60 N or south of 66 S, do not use
158this tool because it cannot access HYCOM data for those regions.</p><p>For more information on HYCOM's georeferencing, please see the
159<a href="http://www.hycom.org/hycom/documentation">HYCOM User's Guide</a>,
160chapter 3: The HYCOM Grid, sections 2.3: I/O File Formats in HYCOM,
161and 5.1: File "regional.grid.[ab]".</p><p>The temporal extent of this dataset is 11 November 2003 to several
162days beyond the current date, with a time step of 1 day. The time
163slices represent the instantaneous condition of the ocean estimated at
16400:00 UTC on each day.</p><p>The HYCOM documentation states that HYCOM provides a five day forecast
165and five day hindcast from the current date, although we have
166regularly observed netCDF files on their servers that suggested this
167window actually extends seven days in both directions. HYCOM revises
168the data within this window daily, using the latest ocean observations
169assimilated from buoys, satellites, and other sensors. Use caution
170when working with time slices close to the current date, as it appears
171that time slices continue to be revised until they are 7 days older
172than the current date.</p><p>Occasionally, HYCOM fails to generate data for a time slice,
173presumably due to an outage or other problem in their data processing
174infrastructure. For example, in 2004, HYCOM failed to generate data
175for three of the 366 time slices of that year. Although HYCOM omits
176these time slices from their server, this tool represents them as
177grids filled with the No Data value.</p><p>The dataset's 4D variables are estimated at 33 depth levels: 0, 10,
17820, 30, 50, 75, 100, 125, 150, 200, 250, 300, 400, 500, 600, 700, 800,
179900, 1000, 1100, 1200, 1300, 1400, 1500, 1750, 2000, 2500, 3000, 3500,
1804000, 4500, 5000, and 5500 m.</p><p><strong>References</strong></p><p>Chassignet, E.P., Hurlburt, H.E., Metzger, E.J., Smedstad, O.M.,
181Cummings, J.A., Halliwell, G.R., Bleck, R., Baraille, R., Wallcraft.,
182A.J., Lozano, C., Tolman, H.L., Srinivasan, A., Hankin, S., Cornillon,
183P., Weisberg, R., Barth, A., He, R., Werner, F. and Wilkin, J. (2009).
184US GODAE: Global Ocean Prediction with the HYbrid Coordinate Ocean
185Model (HYCOM). Oceanography, 22, 64-75.</p><p>The HYCOM User's Guide and many other technical documents are
186available on the
187<a href="http://www.hycom.org/hycom/documentation">HYCOM web site</a>.</p><div class="navigation"><div class="online-navigation"><p></p><hr /><table align="center" width="100%" cellpadding="0" cellspacing="2"><tr><td class="online-navigation"><a title="CreateClimatologicalArcGISRasters Method" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.CreateClimatologicalArcGISRasters.html?format=raw"><img src="previous.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Previous Page" /></a></td><td class="online-navigation"><a title="HYCOMGLBa008Equatorial3D Class" href="Class_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.html?format=raw"><img src="up.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Up one Level" /></a></td><td class="online-navigation"><a title="TestCapability Method" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.TestCapability.html?format=raw"><img src="next.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Next Page" /></a></td><td align="center" width="100%">GeoEco Python Reference</td><td class="online-navigation"><a title="Table of Contents" href="TableOfContents.html?format=raw"><img src="contents.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Table of Contents" /></a></td><td class="online-navigation"><a title="Module Index" href="ModuleIndex.html?format=raw"><img src="modules.png?format=raw" border="0" align="bottom" height="32" width="32" alt="Module Index" /></a></td><td class="online-navigation"><img src="blank.png?format=raw" border="0" align="bottom" height="32" width="32" alt="" /></td></tr></table><div class="online-navigation"><b class="navlabel">Previous:</b> <a class="sectref" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.CreateClimatologicalArcGISRasters.html?format=raw">CreateClimatologicalArcGISRasters Method</a> <b class="navlabel">Up:</b> <a class="sectref" href="Class_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.html?format=raw">HYCOMGLBa008Equatorial3D Class</a> <b class="navlabel">Next:</b> <a class="sectref" href="Method_GeoEco.DataProducts.HYCOM.HYCOMGLBa008Equatorial3D.TestCapability.html?format=raw">TestCapability Method</a> </div><hr /><span class="release-info">Marine Geospatial Ecology Tools version 0.8</span></div></div></body></html>
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