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| You are here: NODC Home > Access Data > NODC Ocean Archive System > Ocean Archive Help |
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Linked index to information below: - General Help Introduction - The first page that you see is a selection critera selection page. This page allows you to select the fields that you wish to use when you search for data collections. You may select as few as one field (e.g. the Accession number, if you know the Accession Number of the collection that you desire), or you can select all fields. You do not have to use all of the fields that you choose. When selecting some fields however, you must be careful that the default selection critera do not cause your search to be limited to the point that records that you would like to see are excluded. For instance, Current status's default value is "New" and disposition's is "Online"; these criteria can be set to blank (no effect) using the relevent drop down menu. There are four types of selection critera specifications used: Text Box, you type in a value according to the format specified; Pull Down Menu, a menu appears when you click on the little arrow beside the box (the Boolean operators are all Pull Down Menus); Selection Box, a scrollable list of predetermined values (some allow a single value to be selected, others are multiple choice); Check Box, one or more selections can be made by clicking on the little boxes; Buttons, a place to click to make something happen (Continue, Reset, Clear or Search). Select multiple parameters in a selection box by using the normal convention
of holding down the control key and clicking additional values (or holding
down the control key and clicking to deselect a value). You can select
a range of values by selecting a value and then holding down the shift
key while clicking on a value above, or below the selected value. In addition to allowing you to select the fields to be used in your search, the page offers a link to the Parameter Utilities feature where you can search the Authority Tables to locate search criteria. There are authority tables for: Persons; Projects; Institutions; Platforms; Seanames; Data Types; Instrument Types; and Observation Types. These table lookups can be very useful when you are not sure how NODC identifies the criteria that you need to use in your search. The page has a Reset button that will change the selected fields back to the default selections; namely: Start date; End date; Datatypes; and the geographic bounding box fields. You can turn off the tips that are displayed on the search page by unchecking the "Show brief tips" box. Most of the tips explain the formats that are acceptable as selection criteria. Once a user becomes proficient with the system, they can turn off the tips, thereby using less real estate on the selection page. You can also set the number of data collection descriptions that will be displayed on the results page. The default is 10 items. The last item on the preferences page is the "Continue" button. Clicking on Continue will take you to the selection page, populated with the fields that you checked on the previous page. The material below gives a description of each of the fields that you can use to specify your selection criteria. General search behavior: within a field multiple values are or'ed; between fields the criteria are and'ed. - NODC Accession Number - Text box - integer up to 7 digits Accession Numbers are assigned by NODC to identify individual data shipments. Accession Number is a seven-digit field. Up until 1999 accession numbers were the two-digit year followed by a five-digit sequence number. For example, Accession Number 8300203 denotes the 203rd data shipment received in 1983. This practice was terminated in January 2000, and now accession numbers are simply an integer and have no intrinsic meaning. Sample Retrieval: Single Number: 8800123 selects information about this specific Accession Number. - Date Received - Text Box - date format Date received is the date on which NODC actually received the data from a particular source. This is not to be confused with the date on which data was collected or the starting date for a cruise. - Start Date - (earliest observation date) - Text Box - date format Start date is the date of the first or earliest observation within the data collection. This should not be confused with the date when NODC received the data (the Date received). Searching on Start date = 19990415 would identify all data sets where the earliest observation in the collection was April 15, 1999. This field is frequently used in conjunction with End date to form a range search. - End date - (latest observation date) - Text Box - date format End date is the date of the last or latest observation within the data collection. This should not be confused with the date when NODC received the data (the Date received). Searching on End date = 20010430 would identify all data sets where the latest observation in the collection was April 30, 2001. This field is frequently used in conjunction with Start date to form a range search. - Availability date - Text Box - date format Availability date is the date when NODC made the data collection available to the public. [Note: when entering dates please check for leap years and make sure the day you have specified actually exists. For instance specifying the date as 19920431 or a date as 19890229 will result in zero records returned]. - Size in Megabytes - Text Box - positive decimal number The size of the data collection (the sum of the sizes of all files in
the collection) in millions of bytes. Useful when trying to limit the
size of the collection desired to some threshold. - Submitted by - Selection Box - single choice The name of the scientist who submitted the data collection to NODC. The selection criteria is a drop down menu and the "=" operator is the only one that makes sense. Only one name can be selected for a search. If you decide that you do not want to use this criteria, you can select the blank (first) line in the list. - Geographical - Text Box - decimal degrees There are four fields associated with the geographic search: West boundary; East boundary; North boundary; South boundary. These are used to define a box with the West and North boundaries representing the upper left hand limit and the East and South boundaries representing the lower right hand limit. By specifying search criteria as greater than the West boundary and less than the East boundary and greater than the North boundary and Less than the South boundary, you will select all data collections whose boundaries define a box that when overlayed on the search box have some portion of the box inside the search box. Remember the records describe a collection of data (data sets) and not an individual point. Therefore geographic retrievals in this system are a box searching a box. The records that are selected are those where any portion of the record box is inside the selection box. Consequently, the search usually returns data sets that cover a much larger region than what most users would expect. - West Boundary - Text Box - decimal degrees - East boundary - Text Box - decimal degrees - North Boundary - Text Box - decimal degrees - South Boundary - Text Box - decimal degrees - Datatypes - Selection Box - multiple choice The Datatypes are the parameters that are contained in the collection. Since the assignment of data types to a data collection are based on the data format, sometimes even though the format contains a place to record an observation, the parameter may not have been sampled during that data collection effort. The selection criteria is in a drop down menu and you may select multiple parameters that will be or'ed together by using the normal convention of holding down the control key and clicking additional values (or holding down the control key and clicking to deselect a value). You can select a range of values by selecting a value and then holding down the shift key while clicking on a value above or below the selected value. - Observation types - Selection Box - multiple choice The Observation types describe how the data observations were collected. The values run the gambit from aerial photography through water chemistry, with time series and tows along the way. See the selection box on the search page. - Instrument types - Selection Box - multiple choice The Instrument types describe the intstrumentation that was used to collect the data. There are many values from accelerometer through YSI, handheld multi-parameter instruments with bathythermograph, XBTs and thermistors. See the selection box on the search page. - Sea areas - Selection Box - multiple choice The Sea areas are based on the International Hydrographic Bureau's Limits of Oceans and Seas. At present, only a fraction of the records contain entries for Sea area. If you search on Sea area and do not get a hit, it may be that the data you desire does not yet have the appropriate entry in the Sea area field. It does not mean that we don't have any data for that area. NODC is working to incorporate Sea area values in as many records as possible. Therefore, you may want to use Sea area in conjunction with latitude/longitude boundary searches to obtain all data from a certain geographical area. Sample Sea Areas retrieval - Contributing projects - Selection Box - multiple choice Contributing projects are the names of the projects that were associated with the collection of the data. Some names are spelled out but some are entered as acronyms. You can use the Parameter Utilities, Projects Vocabulary link to look up the acronym based on a search of the project name. Take you answer from that page and then use it in the Archive Search page. - Submitting Institution - Selection Box - single choice Submitting Institution is the institution that submitted the data collection to NODC. The Submitting Institution is not necessarily the institution that collected the data. Sometimes international organizations like the IOC will gather data from several sources and submit it to NODC. Most names are spelled out, but if you want to find the name that NODC uses for an acronym, use the Parameter Utilities, Institutions Vocabulary to look up the name based on the acronym. Sample retrieval for Institution. - Collecting Institution - Selection Box - multiple choice The Collecting Institutions are the institution(s) who were responsible for collecting the data. Most names are spelled out, if you want to find the name that NODC uses for an acronym, use the Parameter Utilities, Institutions Vocabulary to look up the name based on the acronym. Sample retrieval for Institution. - Platforms - Selection Box - multiple choice The Platforms are the names of the platforms that were used when collecting the data. If you cannot find a particular platform, you might try searching the platform table using the Parameter Utilities, Platforms Vocabulary. Then in the Search Preferences set it to use the NODC codes as one of your search criteria. You can then search on the code to see how the name is specified in the NODC Platforms list. - Title - Text Box - character string The Title is the title of the FGDC record for a data collection. Selection is usually done using a character string with the LIKE operator. - Current status - Selection Box - single choice Current status is one of four choices: New; Revision; Archived; Null (blank). New means that the data in the collection has not yet finished the archiving process, but it is available as is (possibly without complete identification or documentation). Archived means that the data collection is part of the NODC archive and has completed the process. Revision means that the data collection has a new version and the explaination should be available in the documentation. Null is used to turn off this search criteria without having to go back to the search criteria selection page to uncheck its box. - Disposition - Selection Box - single choice Disposition has four choices: Online; Offline; Mixed; Null (blank). Online means that you can download the data from this system. Offline means that you would need to make a request to the NODC User Services Group to obtain a copy of the data. Mixed means that some files are available online, and to obtain the remainder you would need to make a request to the NODC User Services Group. Null is used to turn off this search criteria without having to go back to the search criteria selection page to uncheck its box. |
| Last modified: Fri, 7-Sep-2007 17:28 UTC | NODC.Webmaster@noaa.gov | ||
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