Using Daylight saving settings (APPLY_DLS) in sitecmp utility in POST for CMAQ v5.2.1


#1

Should i change APPLY_DLS setting to Y (as in default run script i see it is set to N), when i am generating model vs observation comparison csv, for any period between March 9-10 to Nov 2-3 which is the typical Daylight saving time period, say for example June-July 2013?
I am using CMAQ v5.2.1 just FYI


#2

No, the setting of APPLY_DLS should not be changed to Y unless the observations you are matching the model output against are reported in local time rather than local standard time. All the networks for which pre-packaged observational datasets are distributed through the CMAS data download page report data in standard time without any adjustments for daylight savings time.


#3

Thanks, so i will be keeping APPLY_DLS as N as far as i am using the pre-packaged 2000-14 obs datasets.
Just to point out, in v5.2.1 package in ‘Readme.txt’ in sitecmp/scripts; for CSN run script species definition i see it has “88370_val-blank” this gives error: cannot find [blank] species.

I changed it to “88370adj_val” and it works now, i used it from v5.2.1 package, but wanted to make sure i did the right thing and what does it (adj_val) means?
ALSO, why doe run_CSN.sitecmp uses “AQS_sites.txt”, when i see a “CSN_sites.txt” available. Readme.txt prescribes to use AQS_sites.txt even for CSN networks, is it a typo?


#4

Also, to be sure, the output csv from sitecmp has modeled and obs values at GMT or in LST? I thought sitecmp has time stamps in GMT/UTC and not in LST


#5

I’ll answer your second question first. The timestamp on the sitecmp output csv files is LST, but this is really determined by the timezone offset for each site that specified in the network specific site file. Site compare does a conversion of the input model data from GMT to LST using the timezone offset values in the site files. If no timezone offset is found in the files, sitecmp uses a simple 15 degree longitude method to estimate the timezone offset for a site. If you were to set the timezone offset value to zero for every site, your output from site compare would be in GMT, since it would end up applying a zero value for the timezone offset to the model data.

Most standard networks (e.g. AQS, CSN, IMPROVE) report observations in LST, which is why the site files for the networks included in AMET have non-zero timezone offset values for each site. If you happened to obtain an observation data set that was in GMT, you would need to set the timezone offsets in the site file to zero to get site compare to output in GMT.

As for first question, 88370adj is a blank adjusted version of the 88370 OC value from CSN. Depending on the year, that adjustment is either a constant 0.5 or 0.4 ug/m3, with 0.4 being more recent. Starting with 2015 and beyond, the 88370 value will be replaced with the 88320 value, which is an already adjusted version of OC. This will be consistent with the IMPROVE network data that already uses 88320.

Regarding the CSN_sites.txt file, all the CSN sites are contained in the master AQS_sites.txt list. So, I decided that instead of maintaining a separate CSN_sites.txt list, I would just use the AQS site list for CSN. In the end, the result is the same, I’ve just eliminated the need to update another file. Note that in the latest version of site compare, the program has the ability to read the site metadata files (csv) files that are typically released with AMET. I have stopped updating the text site lists and moved onto just updating the site metadata files. Again, this reduces the number of files I need to update.


#6

Also regarding difference in AERO_n species list for SEARCH sites between 2006-10 and 2011 or later. I notice, for 2011 and later the AERO_n species listed in README.txt are fewer and do not include aerosol species like OC, EC, SO4IJ, NO3IJ etc and only included gaseous species, any reason for that? I wanted to compare OC (and other OA species) for SOAS 2013; so can i go ahead and add the additional AERO_n species like OC, EC, SO4IJ, NO3IJ and their PM2.5 cut-offs (which are listed for SEARCH 2006-2010 hourly comparisons in README.txt)?
Do you recommend any other data besides SEARCH which contains OA measurements or Isoprene and Monoterpene measurements for SOAS 2013. I only saw ISOP (ppb) measurements in AQS for the CMAQ pre-processed 2000-14 data


#7

Sorry for the delay in replying. Both IMPROVE and CSN measure EC, OC, SO4, etc. There may be limited sites available in the SOAS region, but there should be at least some measurements available from those networks.

Also, I assume you have accessed the measurements made during the SOAS campaign itself. If not, there should be additional non-standard network measurements of OA available from SOAS. I’ve not used those data directly, but I know they are available. I may actually have some of those data in an AMET ready format. If you don’t already have them, I’d be happy to see what I have available.

Hope that helps.