Changes between Version 7 and Version 8 of PointObservationConventions
 Timestamp:
 10/26/09 10:30:29 (9 years ago)
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PointObservationConventions
v7 v8 18 18 You 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. 19 19 20 All point data must have lat, lon and time coordinate or auxiliary coordinate variables, which are identified according to section 4of this document. Some feature types allow the vertical coordinate to be optional, and some require it.20 All 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. 21 21 22 22 There are two main ways to represent point data in the classic netCDF model: … … 30 30 31 31 * 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 Chapter532 * coordinates are identified with the "coordinates" attribute on the data variables, as specified in sections 4 and 5 33 33 * coordinates may use missing values, but must do so in a consistent way 34 34 * index numbering, if used, is always 0 based … … 38 38 == 9.2 Point Data == 39 39 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.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. 41 41 42 42 {{{ … … 76 76 == 9.3 Time series of Station Data == 77 77 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: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 stationTimeSeries features. 79 80 Some assumption are common to all stationTimeSeries representations: 81 81 82 82 * The outer dimension of the latitude and longitude coordinates (which must agree) is the 'station dimension'. … … 88 88 === 9.3.1 Multidimensional representation === 89 89 90 When the number of observations at each station is the same, one can use the multidimensional representation.90 When the numbers of observations at each station are the same, one can use the multidimensional representation: 91 91 92 92 {{{ … … 193 193 }}} 194 194 195 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 .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, and must be type integer. 196 196 197 197 The 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. … … 242 242 }}} 243 243 244 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 .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, and must be type integer. 245 245 246 246 The 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. … … 248 248 === 9.3.4 Single station === 249 249 250 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 itmust be a scalar (or 1D char).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, and must be a scalar (or 1D char). 251 251 252 252 {{{ … … 393 393 === 9.4.2 Single Trajectory === 394 394 395 When a single trajectory is stored in a file, one can use a variation of the Multidimensional representationwhich removes the trajectory dimension:395 When a single trajectory is stored in a file, one can use a variation of 9.4.1 which removes the trajectory dimension: 396 396 397 397 {{{ … … 433 433 The 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. 434 434 435 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.435 Note 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. 436 436 437 437 Note that this is the same as Example 5.5. … … 440 440 === 9.4.3 Ragged array (contiguous) representation === 441 441 442 When the number of observations for each trajectory varies, one can use the contiguous ragged array representation. One stores the set of observationfor 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;442 When 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 {{{ 445 dimensions: 446 obs = 3443; 447 447 trajectory = 77 ; 448 448 … … 485 485 The 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. 486 486 487 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. 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. The observations are associated wit the trajectory using the same algorithm as in 9.3.2. 488 488 489 489 === 9.4.4 Ragged array (indexed) representation === … … 601 601 === 9.5.2 Single Profile === 602 602 603 When a single profile is stored in a file, one can use a variation of the Multidimensional representationwhich removes the profile dimension:603 When a single profile is stored in a file, one can use a variation of the 9.5.1 which removes the profile dimension: 604 604 605 605 {{{