# Changes between Version 5 and Version 6 of udg/ecoms/dataserver/web

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Timestamp:
Feb 26, 2014 10:56:29 AM (8 years ago)
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 v5 [[Image(openDAPwindow.png,align=center,width=520px,title=Detail of the OPeNDAP dataset access form for a particular dataset.)]] Note that, as explained before, the variables provided by the data portal (e.g. minimum temperature) are stored as gridsets. Thus, in addition to these variables, also auxiliary coordinate variables (lat, lon, run, time, member) should be handled for geo-temporal data referencing ([attachment:openDAPwindow.png see Figure]). Moreover, three time coordinates are included as referece for different grid variables because they are defined for different forecast times (one extra time for precipitation and different temporal resolution for mean sea level pressure). Note that this highly complicates the direct analysis of the data and, hence, this options is only recommend for data exploration. In the following we show how to use this service to explore the structure of the datasets and to obtain simple pieces of information in ASCII format. Note that the variables provided (e.g. minimum temperature) are stored as gridsets. Thus, in addition to these variables, also auxiliary coordinate variables (lat, lon, run, time, member) should be handled for geo-temporal data referencing. Moreover, three time coordinates are included as referece for different grid variables because they are defined for different forecast times (one extra time for precipitation and different temporal resolution for mean sea level pressure). Note that this highly complicates the direct analysis of the data and, hence, this options is only recommend for data exploration. By default, if no specifications are given in the different subsetting boxes of the OpenDAP form, the whole data on the whole spatio/temporal and member ranges of the dataset would be accessed. However, this option will raise an error due to the large size of the request (the maximum size of a single request has been set to 100 Mbytes in the ''SPECS-EUPORIAS data portal'' for the sake of multi-connection efficiency). The basic steps to retrieve subsets of data are the following: In the following we show how to use this service to explore the structure of the datasets and to obtain simple pieces of information in ASCII format. 1. To select a variable click on the checkbox to its left. 1. To constrain the variable, edit the information that appears in the text boxes below the variable. This is a   vector of integers indicating index positions of length three, with the following order: [start:stride:end]. By default, if no specifications are given in the different subsetting boxes of the OpenDAP form, the whole data on the whole spatio/temporal and member ranges of the dataset would be accessed. However, this option will raise an error due to the large size of the request (the maximum size of a single request has been set to 100 Mbytes for the sake of multi-connection efficiency). The basic steps to retrieve subsets of data are the following: 1. Select a variable click on the checkbox to its left. 1. Constrain the variable: Edit the information that appears in the text boxes below the variable. This is a   vector of integers indicating index positions of length three, with the following order: [start:stride:end]. 1. To get ''ASCII'' or ''binary'' values for the selected variables, click on the ''Get ASCII'' or ''Get Binary'' buttons of the ''Action'' field. Note that the URL displayed in the ''Data URL'' field is updated as you select and/or constrain variables. The URL in this field can be cut and pasted in various OPeNDAP clients. [[Image(opendapquery.png,align=center,width=520px,title=Detail of the query from the OPeNDAP dataset access form to retrieve a subset (a time series for a single gridbox) of minimum temperature.)]] Note that the indexes selected for the run coordinate correspond to the December initializations (index positions 11, 23,..., and that indexes start in 0) and for the time coordinate correspond to January (positions, 31 to 62, in days after the run time). The proper use of this service requires a full understanding of the data structure and, therefore, it is only advised for data exploration.