RE: [las_users] How to create Virtual Variable in LAS

["Sumagaysay, Rosanna M (3880-Affiliate)" <Rosanna.M.Sumagaysay@xxxxxxxxxxxx>]

Great Thank you for the information.

I'll try that out let you know of my results.

All the best,

Rosanna.

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From: Ansley Manke [ansley.b.manke@xxxxxxxx]
Sent: Thursday, October 25, 2012 5:13 PM
To: Sumagaysay, Rosanna M (3880-Affiliate)
Cc: las_users@xxxxxxxx
Subject: Re: [las_users] How to create Virtual Variable in LAS

Hi Rosanna,
Yes, you can do this in LAS.  The documentation you want is here,
http://ferret.pmel.noaa.gov/LAS/documentation/installer-documentation/advanced-dataset-configuration/

in the section about Using F-TDS to add virtual variables to datasets.  It should work fine with data from two different datsets.  The Ferret script you'll want is something like this:


! Open the datasets containing SST and the Quality flag
use "http://opendap.jpl.nasa.gov:80/opendap/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.s04m3pfv50-sst-16b.hdf"
use "http://opendap.jpl.nasa.gov:80/opendap/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.m04m3pfv50-qual.hdf"

! Define best_sst.  Add a /TITLE qualifer too if you wish
let/d=1/units="`sst[d=1],return=units`" best_sst = if qual[d=2] eq 7 then  sst[d=1]

! Now dataset 1 has SST and the defined-variable best_sst
set data 1


Try it from the Ferret command line and then work through the instructions for adding this virtual dataset to your LAS.

Ansley

On 10/25/2012 4:05 PM, Sumagaysay, Rosanna M (3880-Affiliate) wrote:

Hello,

This is an update to my first email.

I have two data files with the same spatial resolution and grid structure.  Example below.  (Please note that I'm working on creating my dataset aggregations via THREDDS.  Just wanted to point out here of the 2 different data sources).

File 1: (Sea surface temperature)
OPENDAP: http://opendap.jpl.nasa.gov/opendap/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.s04m3pfv50-sst-16b.hdf.html
or
FTP: ftp://podaac-ftp.jpl.nasa.gov/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.s04m3pfv50-sst-16b.hdf

File 2: (Quality Flag)
OPENDAP: http://opendap.jpl.nasa.gov/opendap/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.m04m3pfv50-qual.hdf.html
or
FTP: ftp://podaac-ftp.jpl.nasa.gov/OceanTemperature/avhrr/L3/pathfinder_v5/monthly/day/04km/2000/07/200007.m04m3pfv50-qual.hdf


Is there a way in LAS to provide the data users option to extracting SST data from "SST variable" based on a the highest Quality Flag value from the "Quality Flag variable" and creating a new Virtual Variable called "Best SST".

I've read the FAQ on "Serving Virtual Variables" but it looks like this is for an older version of LAS server. Is there a solution for doing this in LAS 7.3

http://ferret.pmel.noaa.gov/FERRET_17sep07/LAS/FAQ/virtual_variables.html


Thanks,
Rosanna.
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Rosanna Sumagaysay-Aouda
Physical Oceanography DAAC
http://podaac.jpl.nasa.gov/
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