From Ocean Teacher Library
Exchanging Ocean Data in Real-timeContents |
Background
The Introduction document provides a brief overview of the types of instrumentation or platforms used to collect ocean data. It also provides a brief review of reasons for exchanging data in real-time. This document will summarize the information to be found in subsections that deal only with the real-time aspects.
The documents speaking about moving data into real-time data distribution systems provide a number of specific links and contacts relating to specific points under discussion. However, the JCOMM Data Management Programme Area (DMPA) is focused on encouraging and managing real-time data exchange. If any questions arise about what to do with kinds of data that are collected, if the data appear to fit into a category that can be exchanged but something is missing from formats, or if the data do not appear to be handled in current formats, you are encouraged to contact the chair of the Data Management Co-ordination Group or any member of the group.
What is “Real-time”?
First of all, “real-time” in oceanographic circles is arbitrarily defined as any observation collected within 30 days of the present. This is a pragmatic definition, adopted many years ago. It recognizes the difficulty of getting data ashore from platforms at sea and the subsequent processing required in order to ensure some level of confidence in the observations collected. It also recognizes that the time scales of variability in the ocean are typically slower than in the atmosphere, for which “real-time” is defined by a much shorter time scale. Advances in satellite transmission technology has alleviated some of the difficulties of moving data from at sea platforms to the shore. Still, for some platforms, power is an important consideration that restricts how much data can be transmitted.
Organization of Information
Subsections of this document are organized by generic types of platforms or instrumentation. The subsections are overviewed in the Introduction. So, sections are found on data from lowered instruments, on profiling floats and gliders, on moored and drifting buoys, on towed and underway instruments, on subsurface drifters, on instruments that accumulate time series, and on animal tags.
Each of these sections provides information on what to do to provide data for real-time distribution. The sections identify people or organizations to contact if questions arise.
Data Quality
Because of the time constraints for distributing data in real-time, it is not possible to carry out all of the detailed quality checking that might be done on delayed mode data. In particular, calibrations are not usually possible, nor are the checks to look for instrument drifts, time errors and sometimes position errors. Never-the-less, before data are sent for real-time distribution, providers are encouraged to carry out at least basic quality control procedures. A number of the more well organized programmes, referred to in the Introduction and that will be noted in various subsections, do have both recommended and published procedures.
Data Formats
International access to the data generally relies on using the World Meteorological Organization's Global Telecommunications System (GTS). To use this system data have specific rules and formats that need to be adhered to. A subsection on formats will describe these in some detail.
Internationally accepted formats for all ocean data do not yet exist. Where they do, they will be referenced in appropriate subsections. Where they do not, that also will be noted. In this latter case, adoption of the WMO BUFR format permits the development of new formats for real-time data exchange if tit is warranted. BUFR is described in another OceanTeacher Digital Library document.
Some data are distributed through internet web sites (whether or not they can also be distributed with existing real-time data formats). While this can be an efficient way for an organization to provide access to data, each web site is likely to use their own data format, conventions for reporting data quality issues, naming conventions for variables, etc. This makes the process of assembling data more difficult for a user who wishes to combine data from different sites. Collectors of data who are willing to provide data in real-time are encouraged to use international systems rather than construct their own.
Additional Resources
None
Subsections of this Article
| Pagename | Short title | Description | |
|---|---|---|---|
| Data from Tagged Biota | Data from Tagged Biota | Data from Tagged Biota | Step-by-step instructions for getting such data on the GTS. |
| Drifting Buoy Data | Drifting Buoy Data | Drifting Buoy Data | This provides information about exchange of data acquired by drifting buoys. |
| Formats for Real-time Data Exchange | Formats for Real-time Data Exchange | Real-time Data Formats and Exchange | An overview of formats used and methods for reporting data in real-time. |
| Lowered Instrument Data | Lowered Instrument Data | Real-time Exchange of Lowered Instrument Data | Step-by-step instructions for getting such data on the GTS. |
| Moored Buoy Data | Moored Buoy Data | Moored Buoy Data | This provides information about exchange of data acquired by moored buoys. |
| Profiling Float and Glider Data | Profiling Float and Glider Data | Profiling Float Data | This provides information about exchange of data acquired by profiling floats and gliders. |
| Towed Instruments and Underway Data | Towed Instruments and Underway Data | Underway Instrument Data | Step-by-step instructions for getting data from towed instruments on the GTS. |
Information about this article
Short title: Real-time Data Exchange
Description: This provides summary information about real-time exchange of data.
Expertise level: beginner
Author: bob.keeley
Approval status: approved
Approved by: bob.keeley
Last change: 2012-2-9
Subsection of: Exchanging In-situ Ocean Data
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