question about DATEM format

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lida
Posts: 5
Joined: April 16th, 2019, 11:02 pm
Registered HYSPLIT User: No

question about DATEM format

Post by lida » May 7th, 2020, 8:41 pm

Hi developers,

In sample data file , it says Duration is “Four digit hour-minutes for duration of the sample” in I5 format.
My question is if the duration is more than 99 hours, how to process sample data if using hysplit post-processing?
I think it would be more practical if duration format can be in yyyymmddhhmm.
Thank u!

Regards,

Da Li

alicec
Posts: 234
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: question about DATEM format

Post by alicec » May 13th, 2020, 5:27 pm

The duration in HHMM format refers to the duration of the sampling time.
For instance if the sampler took 3 hour samples over a five day time period the duration would be 0300.
The sample start time is defined in other columns and there would be one entry for each of
of the 3 hour samples over the 5 day time period for a total of 40 entries.

See for more details.
https://www.arl.noaa.gov/wp_arl/wp-cont ... /datem.pdf
COLUMNS in datem file
Year I4 Four digit year for sample start
Month I3 Two digit month for sample start
Day I3 Two digit day for sample start
Hour-Minutes I5 Four digit hour-minutes for sample start
Duration I5 Four digit hour-minutes for duration of the sample
Latitude F6.2 Latitude of the sampling point (Positive is north)
Longitude F8.2 Longitude of the sampling point (Positive is east)
Concentration F8.1 Average air concentration in (pico) mass units per cubic meter
Site Name A8 Character string for site identification

lida
Posts: 5
Joined: April 16th, 2019, 11:02 pm
Registered HYSPLIT User: No

Re: question about DATEM format

Post by lida » May 18th, 2020, 1:56 am

Hi alicec,

Thank you for your reply.
I had read the document, but our data is a continuous observation, just having start time and end time, and the delta-T is more than 99 hours.
For example

Location "Measured Value (mBq/m3)" Latitude Longitude Start Sampling [UTC] End Sampling [UTC]
NPP Bohunice 3 9.8 48.4944 17.6819 27/09/2017 00:00 04/10/2017 00:00

in this case, how i can use datem format?

regards,

Da Li

alicec
Posts: 234
Joined: February 8th, 2016, 12:56 pm
Registered HYSPLIT User: Yes

Re: question about DATEM format

Post by alicec » May 18th, 2020, 8:20 am

The HYSPLIT sampling time interval has the same format HH MM and cannot be longer than 99 hours.
https://ready.arl.noaa.gov/hysplitusersguide/S313.htm

I suppose you can always average output from multiple time periods from the HYSPLIT output.
How you proceed really depends on the details of what you are doing.
How many of these data points do you have?
Are you using the c2datem program to extract the model data from the concentration grid?
Are you comparing to HYSPLIT model output or some other model?

lida
Posts: 5
Joined: April 16th, 2019, 11:02 pm
Registered HYSPLIT User: No

Re: question about DATEM format

Post by lida » May 18th, 2020, 9:37 pm

Hi alicec,

In my sample data, most of them are more than 99 hours.
What i want to do is find the release location, I suppose c2datem is a must.
If you could leave a email , so i can send you the sample data.

Regards,

Da Li

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