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AirNOW time zones -- KBenedict May 10, 2007

In the AirNOW dataset that is accessible through DataFed, what is the time zone for the stations data?

Re: AirNOW time zones -- Rhusar May 11, 2007 12:14 PM

Hey Sean, I know Tim may be out roaming the world, so I need a small favor. Would you check with the AirNow cast in your office what is the time zone on the OBS files that we are accessing for the Airnow data. We need to fix the DataFed WCS service so the times are properly encoded with the time zone for each station. Thanks in advance,

Re: Re: AirNOW time zones -- SRaffuse May 11, 2007 12:30 PM

Rudy, According to the AIRNow folks here, the time zone depends on the OBS file and is specified in the header (TZONE). The example you linked below is in EDT.

Re: Re: Re: AirNOW time zones -- Rhusar May 11, 2007 12:54 PM

Ok, is the TZone for a station changing with time or is it the same for a specific station?

Re: Re: Re: Re: AirNOW time zones -- SRaffuse May 11, 2007 12:58 PM

I believe that it can change with time at the whim of the agency delivering the data. For example, they may switch to and from daylight savings time. I have cc’d the AIRNow data management center folks and they can correct me if I am incorrect.

Re: Re: Re: Re: AirNOW time zones -- KBenedict May 11, 2007 1:31 PM

Quite impressive instant gratification. I'm amazed. Is there anything we can do to help at this point? I'm not sure that normalization to UTC is absolutely required (though probably useful). As long as the UTC offsets are included in the timestamps, probably using the ISO standard, that should provide sufficient data for retrieval using unambiguous time specifications. That being said, a question ... How does the OGC WMS/WCS time specification support Time Zone elements in time parameter requests? It seems that this is a likely area of potential confusion in different implementations of the OGC specifications. Just thinking about some of the implementation variations that you mentioned yesterday...

Why is my favorite AirNOW station missing? -- RPoriot 12:14, 15 June 2007 (CDT)

The Burlington, VT site has been monitoring PM2.5, but the data for that site are not accessible through the DataFed browser. Why?

Re: Why is my favorite AirNOW station missing? -- Rhusar 12:19, 15 June 2007 (CDT)

The AirNOW dataset accessible through the DataFed browser is delivered from a data cache that is maintained locally in the DataFed server. The cached version allows fast data access, spatial and temporal browsing and rapid data aggregation. The problem is that when a new station is added to the network, it does not immediately show up in the cached version since we don't automatically check for new sites. We recognize that this update anomaly should be remedied in the future.

AirNow Gridding and Access through Giovanni -- GLeptoukh 1 August 2007 (EDT)

I am back to work, so I've started to look into some things we've discussed. On PM2.5 gridding - still can't see any options under WCS or any other services associated with this product. Can you please point me to the right page? Cheers, -Greg

Re: AirNow Gridding and Access through Giovanni -- Rhusar 14:17, 1 August 2007 (EDT)

See Datafed wiki for Point to Grid Procedure

Re: Re: AirNow Gridding and Access through Giovanni-- APrados 14:17, 8 August 2007 (EDT)

Thanks for sending the info below. We tried it and it works fine, that is changing the needed parameters we can view the PM2.5 on the MODIS grid. We could not find the needed data files with the newly gridded data under WCS, but I see in your email below that there is a URL for a netCDF. Is that how we access the data files ?

Re: Re: Re: AirNow Gridding and Access through Giovanni -- KHoijarvi 9 August 2007

The access to the netCDF file is for Giovanni is: It is produced as:

  • click on "service program"
  • click on "InterpolateWeightedAverage" service in the diagram
  • click "service output" radiobutton (Just above "save and update

browser button")

  • select format "NetCDF n-dim cube"
  • Export URL's are in the table. Right click the "View" to get the

above url.

Re: Re: Re: Re: AirNow Gridding and Access through Giovanni -- APrados 15 August 2007

I was wondering if we could obtain a few more details from you on the code that does the Interpolation/weighted averaging to produce the gridded pm2.5 fields. Also, what EPA dataset you are bringing over (there are several as I have discovered) so I would be interested in talking to you or someone else in your group about which one you are using (some are corrected to a reference method, some are not, etc.)

Re: Re: Re: Re: Re: AirNow Gridding and Access through Giovanni -- Rhusar 1 October 2007

AirNow is one of the datasets in the data Catalog on the ESIP wiki. Each registered dataset has a 'DataSpace' wiki page, e.g. for AirNow. where the structured and the unstructured metadata about the dataset is aggregated. The DataSpace page for each dataset also has a companion Discussion page ( e.g. AirNow Discussion) where other dataset-relevant communication takes place. Both the metadata and discussion pages are open for reading and partially open for writing by the participating community.

OK, in a nutshell, that's the plan. Sound impressive, huh? Well, we are not really too far along. However, the current interaction between our two groups is a good opportunity to move another step toward this plan. I fact, I was hoping to use the AirNow dataset as a use case for a well-populated DataSpace page.

So, the first step is to transfer the essence of our email communication to the wiki, so it can become communal activity.

=Re: Re: Re: Re: Re: Re: AirNow Gridding and Access through Giovanni -- Ana Prados (Prados) 18:51, 1 October 2007 (EDT)=

Thanks Rudy. Additional information about PM2.5 data would be useful. EPA has several numeric codes to identify their data sets depending on whether they have been validated or not with respect to reference monitors. It may be useful for the user community to know which data set (code) is being displayed.