Re: [thredds] Question about NARR-A Monthly Complete PoR Aggregation NetcdfSubset

Hello Cedric,
Myself or one of the NOMADS Team will reply to your questions soon- were
looking into it.
Glenn- @ NOMADS

On Thu, Nov 10, 2011 at 12:00 PM, Cédric David <cedric.david@xxxxxxxxxxxxxxx
> wrote:

> Dear THREDDS user group,****
>
> I’m unsure whether or not this is the right place to send these
> questions.  If not, I’d love some advice on who to direct them to.****
>
> I’ve been getting North American Regional Reanalysis (NARR) data from
> http://nomads.ncdc.noaa.gov/thredds/narr.html using the netCDFSubset
> tool.  I am running some analysis on these netCDF files with focus on
> Precipitation, Evaporation, Runoff, Vegetation and Surface Air
> Temperature.  I have therefore downloaded the following variables:****
>
> **·         **Evaporation (time, y, x)****
>
> **·         **Subsurface_runoff_baseflow (time, y, x) ****
>
> **·         **Surface_runoff_non-infiltrating (time, y, x) ****
>
> **·         **Total_precipitation (time, y, x)****
>
> **·         **Vegetation  (time1, y, x)****
>
> **·         **Temperature_height_above_ground (time1,
> height_above_ground, y, x)****
>
> ** **
>
> I’m interested in a 20-year average of these fields (from 1980-01-01-0000
> to 2000-12-31-2100) so I figured I’d use the “NARR-A Monthly Complete PoR
> Aggregation” and download monthly averages in one unique file which I’d
> then use to compute a 20-year average.  The process ran fine but I’m
> curious about the netCDF file that I was able to download.  The first four
> variables (Evaporation, Subsurface_runoff_baseflow,
> Surface_runoff_non-infiltrating and Total_precipitation) indeed have
> several monthly grids.  However the last two variables (Vegetation and
> Temperature_height_above_ground) only have one unique grid each.  ****
>
> ** **
>
> So I downloaded several 3-hourly NARR-A files from the NetcdfSubset tool
> that I picked randomly from the entire dataset:****
>
> **·         **narr-a_221_19790101_0000_000.grb.nc ****
>
> **·         **narr-a_221_19800101_0000_000.grb.nc****
>
> **·         **narr-a_221_20001231_2100_000.grb.nc****
>
> **·         **narr-a_221_20100101_0000_000.grb.nc****
>
> **·         **narr-a_221_20111031_2100_000.grb.nc****
>
> ** **
>
> I realized that the Vegetation variable had the same exact grid for all
> these files.  So it makes sense to only have one grid in the aggregation.
> However, the Temperature_height_above_ground grid varies with time.****
>
> ** **
>
> So here are my two questions:****
>
> **1)      **Is the NARR Vegetation variable static?****
>
> **2)      **How is the Temperature_height_above_ground grid in the NARR-A
> Monthly Complete PoR Aggregation computed?****
>
> ** **
>
> Any help and advice would be greatly appreciated!!!****
>
> Many thanks,****
>
> Cedric ****
>
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