Changes between Version 11 and Version 12 of PointObservationConventionsTwo


Ignore:
Timestamp:
10/22/10 09:42:43 (8 years ago)
Author:
caron
Comment:

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  • PointObservationConventionsTwo

    v11 v12  
    336336    :CF\:featureType = "timeSeries";
    337337}}}
    338 
    339 === 9.3.5 Flattened representation ===
    340 
    341 When factoring out the station information is not desired, one may use a 'flattened representation', in which the station information is repeated for each observation. This is similar to a 'denormalized' relational table. The station_id variable, which is required, is used to associate the observations into a time series.
    342 
    343 {{{
    344 dimensions:
    345   obs = UNLIMITED ;
    346 
    347 variables:
    348   float lon(obs) ;
    349     lon:long_name = "station longitude";
    350     lon:units = "degrees_east";
    351   float lat(obs) ;
    352     lat:long_name = "station latitude" ;
    353     lat:units = "degrees_north" ;
    354   float alt(obs) ;
    355     alt:long_name = "vertical distance above the surface" ;
    356     alt:standard_name = "height" ;
    357     alt:units = "m";
    358     alt:positive = "up";
    359     alt:axis = "Z";
    360   int station_id(obs) ;
    361     station_name:long_name = "station" ;
    362     station_name:standard_name = "station_id";
    363 
    364   double time(obs) ;
    365     time:long_name = "time of measurement" ;
    366     time:units = "days since 1970-01-01 00:00:00" ;
    367   float humidity(obs) ;
    368     humidity:long_name = "specific humidity" ;
    369     humidity:coordinates = "time lat lon alt" ;
    370     humidity:_FillValue = -999.9;
    371   float temp(obs) ;
    372     temp:long_name = "temperature" ;
    373     temp:units = "Celsius" ;
    374     temp:coordinates = "time lat lon alt" ;
    375     temp:_FillValue = -999.9;
    376 
    377 attributes:
    378     :CF\:featureType = "timeSeries";
    379 }}}
    380 
    381 The humidity(i) and temp(i) data are associated with the coordinate values time(i), lat(i), lon(i), and optionally alt(i). All samples with the same station_id are assumed to belong to the same timeSeries.
    382 
    383 In some observational networks, station location may change. However, for timeSeries feature types this should be infrequent and not overly consequential. In principle, a new station identifier should be assigned. In practice, occasional and small adjustments to station location may not matter for typical processing of data for visualization, and generic clients may not detect these changes, eg they may assume that the first location encountered is valid for all other observations at the same station. Specialized clients, of course, may be more careful in examining station location data, and nothing prevents data providers from using a factored representation as in 9.3.1, 9.3.2, and 9.3.3, and also putting location information into the observation record, as in the flattened representation in 9.3.5.
    384338
    385339