[gradsusr] Averaging Multiple Data sets with Different Temporal Resolutions

[Perry, Aaron]

Hi Jennifer!


So, if some of the datasets aren't available during averaging, what happens to those data? Are 0s used in the averaging?


Aaron D. Perry
Class of 2016
Lyndon State College
Lyndonville, VT 05851
Twitter: @arnpry<https://twitter.com/arnpry>
Email: Aaron.Perry at lyndonstate.edu<http://Aaron.Perry@lyndonstate.edu/>
________________________________
From: gradsusr <gradsusr-bounces at gradsusr.org> on behalf of Jennifer M Adams <jadams21 at gmu.edu>
Sent: Tuesday, January 23, 2018 7:13:25 AM
To: GrADS Users Forum
Subject: Re: [gradsusr] Averaging Multiple Data sets with Different Temporal Resolutions



> On Jan 22, 2018, at 7:49 PM, Jeff Duda <jeffduda319 at gmail.com> wrote:
>
>
> Your blend would become "missing data" and you would get no plot at all once even one of the input fields dropped out.
^^ This is incorrect.

As it calculates averages, GrADS keeps track of missing data and weights the average accordingly. You will get a missing value in the result only if *all* the values are missing. For the time steps where *some* of the models are missing, you will get an average of the available models.
—Jennifer

> On Fri, Jan 19, 2018 at 10:19 AM, Perry, Aaron <Aaron.Perry at lsc.vsc.edu> wrote:
> I have a hypothetical question...
>
> If you were to blend multiple data sets together with varying temporal resolutions, (and after lterp'ing them all to the same grid) what would happen with one of the data sets if it's data time ran out before the others did?
>
> Ex.
>
> ND = No Data
>
> TAU   0       6       12      18      24      30      36      42      48      54      60      66      72      78      84      90      96      102     108     114     120     126     132     138     144     150     156     162     168     174     180     186     192     198     204     210     216     222     228     234     240
> GFS   -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -
> CMC   -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -
> ECM   -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       -
> NAM3  -       -       -       -       -       -       -       -       -       -       -       ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND
> NAM12 -       -       -       -       -       -       -       -       -       -       -       -       -       -       -       ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND      ND
>
>
> 'define blend = (GFS+CMC+ECM+NAM3+NAM12)/5.0'
>
> Would the sudden data drop-out in the average result in 0s being introduced into the average? How would you keep the data (last valid timestep) that runs out included in the overall average?
>
> Cheers,
>
>
> Aaron D. Perry
> Class of 2016
> Lyndon State College
> Lyndonville, VT 05851
> Twitter: @arnpry
> Email: Aaron.Perry at lyndonstate.edu
>
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>
>
>
> --
> Jeff Duda
> Research Scientist
> Cooperative Institute for Research in Environmental Sciences at the University of Colorado
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--
Jennifer Miletta Adams
Center for Ocean-Land-Atmosphere Studies (COLA)
George Mason University




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