[gradsusr] Averaging Multiple Data sets with Different Temporal Resolutions

[Jennifer M Adams]

> 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