[gradsusr] Aqua_AIRS_Level3/AIRX3STD.005 using opendap

Fri Feb 1 14:16:38 EST 2013

Yes, the key to the sdfopen problem for AIRS data is that different variables have different lengths for the vertical dimension. You can only see variables for one vertical dimension using sdfopen (and I don't know how to select which dimension you get).

OTOH, it is possible to open a single variable from the AIRS via OPeNDAP with sdfopen by specifying an OPeNDAP "constraint", so long as you include the variables (e.g., H2OPrsLvlsU112, LatitudeU271,LongitudeU272) that make up the dimensions, e.g.:

sdfopen http://acdisc.gsfc.nasa.gov/opendap/Aqua_AIRS_Level3/AIRX3STD.005//2008/AIRS.2008.01.01.L3.RetStd001.v5.2.2.0.G08066120251.hdf?RelHumid_AU46[0:1:11][0:1:179][0:1:359],H2OPrsLvlsU112[0:1:11],LatitudeU271[0:1:179],LongitudeU272[0:1:359]

You could do this separately with each variable that you wanted to work with, but it is admittedly a bit unwieldy, unless you are scripting it.

On Feb 1, 2013, at 11:19 AM, Jennifer Adams wrote:

You will definitely need a descriptor file for this … either for xdfopen or open. The coordinate variables have non-standard names, and there are a lot of them:

netcdf AIRS.2008.06.30.L3.RetStd001.v5.2.2.0.G08184124505 {
dimensions:
        CH4_LayersU115 = 3 ;
        CH4_LayersU231 = 3 ;
        CH4_LayersU250 = 3 ;
        CH4_LayersU269 = 3 ;
        CO_LayersU114 = 7 ;
        CO_LayersU230 = 7 ;
        CO_LayersU249 = 7 ;
        CO_LayersU268 = 7 ;
        CoarseCldLyrsU113 = 3 ;
        CoarseCldLyrsU229 = 3 ;
        CoarseCldLyrsU248 = 3 ;
        CoarseCldLyrsU267 = 3 ;
        EmisLvlsU116 = 4 ;
        EmisLvlsU232 = 4 ;
        H2OPrsLvlsU112 = 12 ;
        H2OPrsLvlsU228 = 12 ;
        H2OPrsLvlsU247 = 12 ;
        H2OPrsLvlsU266 = 12 ;
        LatitudeU271 = 180 ;
        LongitudeU272 = 360 ;
        MWEmisLvlsU251 = 3 ;
        MWEmisLvlsU270 = 3 ;
        TempPrsLvlsU111 = 24 ;
        TempPrsLvlsU227 = 24 ;
        TempPrsLvlsU246 = 24 ;
        TempPrsLvlsU265 = 24 ;
variables:

If all those dimensions with the same size have different values, you'll need a separate descriptor for each set of coordinates. Variables that have the same coordinates can be grouped together in a single descriptor file.
--Jennifer

On Feb 1, 2013, at 10:43 AM, M.Mahakur wrote:

Respected All,

I tried to access the L3 AIRX3STD v5 of AQUA/AIRS data using opendap:

sdfopen http://acdisc.gsfc.nasa.gov/opendap/Aqua_AIRS_Level3/AIRX3STD.005//2008/AIRS.2008.01.01.L3.RetStd001.v5.2.2.0.G08066120251.hdf

It opened with the error: SDF file has no discernable time coordinate -- using default values.

Hence it printed a wrong value for time (as below):

SDF file http://acdisc.gsfc.nasa.gov/opendap/Aqua_AIRS_Level3/AIRX3STD.005//2008/AIRS.2008.06.30.L3.RetStd001.v5.2.2.0.G08184124505.hdf is open as file 1
LON set to 0 360
LAT set to -89.5 89.5
LEV set to 0 0
Time values set: 1:1:1:0 1:1:1:0
E set to 1 1
ga-> q file
File 1 :
 Descriptor: http://acdisc.gsfc.nasa.gov/opendap/Aqua_AIRS_Level3/AIRX3STD.005//2008/AIRS.2008.06.30.L3.RetStd001.v5.2.2.0.G08184124505.hdf
 Binary: http://acdisc.gsfc.nasa.gov/opendap/Aqua_AIRS_Level3/AIRX3STD.005//2008/AIRS.2008.06.30.L3.RetStd001.v5.2.2.0.G08184124505.hdf
 Type = Gridded
 Xsize = 360  Ysize = 180  Zsize = 24  Tsize = 1  Esize = 1
 Number of Variables = 137

The major problem is it does not show all varibles. The no. of varibales are much larger than 137! I tried with opengrads also, the same problem.

How can I solve this? I am sure lot of users are using this data ..

Regards and Thanks,

Mahakur
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IGES/COLA
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