This aggregation is nothing more than a TDS software aggregation
of the narrmon-a_221_* files.
The Vegetation Type parameter is a static fixed field:
http://nomads.ncdc.noaa.gov/thredds/catalog/narr/catalog.html?dataset=narr/AWIP32-fixed.grb
I do not know why it would even appear in the narrmon-a files.
ALL fields in the narrmon fields and files are averages of the
<days_in_month>*8
fields in that month. Even for fields where avg() doesn't make sense,
such as precipitation rate or anything with time in the denominator of
the unit
- which are typically more useful as a sum() statistical operation.
-Dan
On Tue, Nov 15, 2011 at 2:08 PM, Glenn Rutledge <glenn.rutledge@xxxxxxxx>wrote:
> 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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>> thredds@xxxxxxxxxxxxxxxx
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>>
>
>
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--
=======================================
Dan Swank
STG, Incorporated - Government Contractor
NCDC-NOMADS Project: Software & Data Management
Data Access Branch
National Climatic Data Center
Veach-Baley Federal Building
151 Patton Avenue
Asheville, NC 28801-5001
Email: Dan.Swank@xxxxxxxx
Phone: 828-271-4007
=======================================
