Changes between Version 7 and Version 8 of PointObservationConventions


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Timestamp:
10/26/09 10:30:29 (10 years ago)
Author:
caron
Comment:

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  • PointObservationConventions

    v7 v8  
    1818You cannot mix multiple types of data in the same file. A global attribute CF:featureType indicates the feature type used in a particular file, and its value must be one of the above names in order to be correctly processed as point observation data.
    1919
    20 All point data must have lat, lon and time coordinate or auxiliary coordinate variables, which are identified according to section 4 of this document. Some feature types allow the vertical coordinate to be optional, and some require it.
     20All point data must have lat, lon and time coordinate or auxiliary coordinate variables, which are identified according to sections 4 and 5 of this document. Some feature types allow the vertical coordinate to be optional, and some require it.
    2121
    2222There are two main ways to represent point data in the classic netCDF model:
     
    3030 
    3131    * the lat, lon and time coordinates must always exist; a vertical coordinate may exist
    32     * coordinates are identified with the "coordinates" attribute on the data variables, as specified in Chapter 5
     32    * coordinates are identified with the "coordinates" attribute on the data variables, as specified in sections 4 and 5
    3333    * coordinates may use missing values, but must do so in a consistent way
    3434    * index numbering, if used, is always 0 based
     
    3838== 9.2 Point Data ==
    3939
    40 To represent data at scattered, unconnected points, both data and coordinates use the same, single dimension. The 'coordinates' attribute is used on the data variables to unambiguously identify the time, lat, lon and vertical auxiliary coordinate variables.
     40To represent data at scattered, unconnected points, both data and coordinates use the same, single dimension. The 'coordinates' attribute is used on the data variables to unambiguously identify the time, lat, lon, and vertical auxiliary coordinate variables.
    4141
    4242{{{
     
    7676== 9.3 Time series of Station Data ==
    7777
    78 Point data may be taken at a set of named locations called stations. The set of observations at a particular station, if ordered by time, is a time series, and the file contains a collection of time series data at named locations called stations.
    79 
    80 Some assumption are common to all station representations:
     78Point data may be taken at a set of named locations called stations. The set of observations at a particular station, if ordered by time, is a time series, and the file contains a collection of stationTimeSeries features.
     79
     80Some assumption are common to all stationTimeSeries representations:
    8181
    8282   * The outer dimension of the latitude and longitude coordinates (which must agree) is the 'station dimension'.
     
    8888=== 9.3.1 Multidimensional representation ===
    8989
    90 When the number of observations at each station is the same, one can use the multidimensional representation.
     90When the numbers of observations at each station are the same, one can use the multidimensional representation:
    9191
    9292{{{
     
    193193}}}
    194194
    195 The rowSize variable contains the number of observations for each station, and is identified by having a standard_name of "'''ragged_rowSize'''". It must have the station dimension as its single dimension.
     195The rowSize variable contains the number of observations for each station, and is identified by having a standard_name of "'''ragged_rowSize'''". It must have the station dimension as its single dimension, and must be type integer.
    196196
    197197The single dimension of the time coordinate is the obs dimension. All variables having the obs dimension as their outer dimension are observation variables. The obs dimension may use the unlimited dimension or not.
     
    242242}}}
    243243
    244 The humidity(i) and temp(i) data are associated with the coordinate values time(i), lat(s), lon(s), and optionally alt(s), where s = stationIndex(i). The stationIndex variable is identified by having a standard_name of "'''ragged_parentIndex'''".  It must have the obs dimension as its single dimension.
     244The humidity(i) and temp(i) data are associated with the coordinate values time(i), lat(s), lon(s), and optionally alt(s), where s = stationIndex(i). The stationIndex variable is identified by having a standard_name of "'''ragged_parentIndex'''".  It must have the obs dimension as its single dimension, and must be type integer.
    245245
    246246The single dimension of the time coordinate is the obs dimension. All variables having the obs dimension as their outer dimension are observation variables. The obs dimension may use the unlimited dimension or not.
     
    248248=== 9.3.4 Single station ===
    249249
    250 When there is a single station in the file, one can can use the multidimensional representation with number of stations = 1. One can also use scalar coordinates. This case is identified when the lat and lon coordinates are scalar. In this case, no connecting variable between station and observations is required, since they all belong to the same station. However, the station_id variable is still required; in this case it must be a scalar (or 1D char).
     250When there is a single station in the file, one can can use the multidimensional representation with number of stations = 1. One can also use scalar coordinates. This case is identified when the lat and lon coordinates are scalar. In this case, no connecting variable between station and observations is required, since they all belong to the same station. However, the station_id variable is still required, and must be a scalar (or 1D char).
    251251
    252252{{{
     
    393393=== 9.4.2 Single Trajectory ===
    394394
    395 When a single trajectory is stored in a file, one can use a variation of the Multidimensional representation which removes the trajectory dimension:
     395When a single trajectory is stored in a file, one can use a variation of 9.4.1 which removes the trajectory dimension:
    396396
    397397{{{
     
    433433The NO3(n) and O3(n) data is associated with the coordinate values time(n), z(n), lat(n), and lon(n). When the time coordinate is ordered, it is appropriate to use a coordinate variable for time, i.e. time(time). The time dimension may be unlimited or not.
    434434
    435 Note that structurally this looks like unconnected point data as in example 5.8.1. The presence of the CF:featureType = "trajectory" global attribute indicates that in fact the points are connected along a trajectory.
     435Note that structurally this looks like unconnected point data as in example 9.2.1. The presence of the CF:featureType = "trajectory" global attribute indicates that in fact the points are connected along a trajectory.
    436436
    437437Note that this is the same as Example 5.5.
     
    440440=== 9.4.3 Ragged array (contiguous) representation ===
    441441
    442 When the number of observations for each trajectory varies, one can use the contiguous ragged array representation. One stores the set of observation for each trajectory contiguously along the obs dimension, and adds a rowSize variable specifying the number of observations for each trajectory:
    443 
    444 {{{
    445 dimensions:
    446   obs = UNLIMITED ;
     442When the number of observations for each trajectory varies, and one can control the order of writing, one can use the contiguous ragged array representation. One stores the set of observations for each trajectory contiguously along the obs dimension, and adds a rowSize variable specifying the number of observations for each trajectory:
     443
     444{{{
     445dimensions:
     446  obs = 3443;
    447447  trajectory = 77 ;
    448448
     
    485485The O3(i) and NO3(i) data are associated with the coordinate values time(i), lat(i), lon(i), and alt(i). All observations for one trajectory are contiguous along the obs dimension, and should be time ordered. All variables that have trajectory as their single dimension are considered to be information about that trajectory. The obs dimension may use the unlimited dimension or not.
    486486
    487 The rowSize variable contains the number of observations for each trajectory, and is identified by having a standard_name of "ragged_rowSize". It must have the trajectory dimension as its single dimension.
     487The rowSize variable contains the number of observations for each trajectory, and is identified by having a standard_name of "ragged_rowSize". It must have the trajectory dimension as its single dimension. The observations are associated wit the trajectory using the same algorithm as in 9.3.2.
    488488
    489489=== 9.4.4 Ragged array (indexed) representation ===
     
    601601=== 9.5.2 Single Profile ===
    602602
    603 When a single profile is stored in a file, one can use a variation of the Multidimensional representation which removes the profile dimension:
     603When a single profile is stored in a file, one can use a variation of the 9.5.1 which removes the profile dimension:
    604604
    605605{{{