Data Browsing/Mining in Sensor Observation Service (SOS) Servers
servers (see resource material below) have been established to allow the
user to connect directly to in-situ, active measurement devices (including
remotely placed instruments). This technology was designed within
the OGC family of functionalities with a view toward bridging the gap
between operational earth sciences and geospatial methods. Methods
to access and obtain data through known SOS sites are presented here.
Uncertainty surrounds the future of SOS, which is not being widely used
yet. Many initial test sites are apparently now inoperable.
Preliminary Reading (in
OceanTeacher, unless otherwise indicated):
Version: July 2013
|1. Install EDC
(latest version; and check back for new versions every time you use EDC)
edcconfig.xml file in your C:\EDC folder, and change <CLOSE_AFTER_PROCESSING>
|3. Run EDC.
|4. You'll find these 3 tabs
at the beginning:
- BROWSE - Locate and open a SOS server
- DATA VIEWER - Infrequently used by SOS; simple raster viewer
- LOG - Status of command operations
Select BROWSE > SENSOR OBS SERVICE
|5. At the bottom
of this exercise you'll find a small list of SOS servers; most are known to
be in operation now, but that is not guaranteed. The only "global"
source is the US National Data Buoy Center (NDBC) which is responsible for
many international site.
|6. Copy the NDBC link and
paste it into the space by SOS.
|7. Then click CONNECT (on the
|8. The LOG tab automatically
opens, and you'll see a message like this.
- VALID SENSORS - 838
- UNIQUE VARIABLES - 9
Keep watching until you see PROCESSING COMPLETE, or an error message.
08:32:06 Building Request
08:32:06 Reading SOS URL: http://sdf.ndbc.noaa.gov/sos/server.php?request=GetCapabilities&service=SOS&version=1.0.0
08:32:13 Fetched GetCapabilities in 6.984 seconds
08:32:13 Size of SOS capabilities request (mB)= ~1.70023
08:32:13 Parsing for Offerings...
08:32:15 Seconds to parse SOS capabilities: 1.531
08:32:15 Found 838 valid sensors.
08:32:15 Parsing out unique variables
08:32:15 Found 9 unique variables in 0.0 seconds
08:32:15 Adding sensors to map (this could take awhile)
08:32:15 Processing of SOS Server complete
|9. Now a new tab has appears,
SOS-SUBSET & PROCESS, and the page is filled with five new large items
|10. On the left are the
SENSORS, a list of all measurement sites covered by this SOS server.
You could look in this list for a desired location and check it.
|11. In the middle is a map,
currently in 3-D mode. Click on 2D just below it, and you'll see this
flat map of the 838 stations. You can also click directly on any
station dot to see information about it, and to select it for data download.
|12. On the right you'll find
this list of the nine available variables. [Beside each variable name
is a link to that term in the MMI Ontology Registry and Repository (ORR), a
web application through which you can create, update, access, and map
ontologies and their terms.]
Although it is not listed here, just about all these stations also have SEA
LEVEL. The author doesn't know why
has not picked this up, and has asked for clarification.
|13. In the lower-left corner
is a typical geographic location tool, where you could enter the coordinates
of an area of interest.
|14. Occupying most of the
bottom of the display is a calendar tool where you can select the times of
interest. This data collection goes back 23 years! The default
selection seems to be the last 10 days.
|15. Now, let's click the
SELECT BY BBOX tool, and drag a rectangle around some stations in the
eastern Indian Ocean.
|16. EDC automatically puts
checks by the station items in the left-hand list, so you don't have to do
|17. We'll accept the time
range of the last 10 days, and we'll request all the variables, so just
click SELECT ALL there.
|18. When TIMES, STATIONS and
VARIABLES have been selected, a GET OBSERVATIONS control appears.
|19. This page appears.
There's really nothing to do here but click START.
|20. The LOG page opens again,
and you can watch the progress of your request. The most important
parts are the final lines. They show that EDC results are saved in a
folder named EDC\OUTPUT. This is followed by:
- SOS Server Name - NDBC in this case
- Date and Time - Very similar to ISO format
- Filename.CSV - Where filename is the station ID; CSV means it
is an ASCII comma-separated variables format, very easy to read in most
This very organized method will let you always get back to these data
later on, without difficulty.
Loading DIF to ERSI CSV XSL Schema from
[long log text deleted for bravity]
|21. You can check on the
results, by examining the folders in Windows Explorer, as you see here.
Actually each CSV file has an XML file twin (contains the same data, but in
a rather awkward XML format).
Stations without any data can be recognized
immediately due to their size, 1 KB.
|22. What you do with these
data is up to you, but here's the first CSV file in the list, to show you
what you have. Notice that the only data item here is WATER LEVEL,
which is strangely not in the list of VARIABLES in Panel 12.
concludes this short exercise, provided in MDL just to show you a new
technology that doesn't offer a lot of data yet. The burden is on you
to monitor the situation and see if any projects of interest to you might
have SOS servers online. Then of course the further burden on you is
to find out what the data contain and how they can be used.
24. Selected SOS
Servers - Web searches for SOS
servers return dozens of site addresses, but most are not in