Asian dust aerosol data to be displayed in GrADS

[Christopher Lynnes]

On Jan 20, 2010, at 3:27 AM, Jason Snyder wrote:

> I just need to find access to TOMS, MODIS, ACE data which shows dust/ 
> sulfate aerosols.  I do not care which data set it is.  I tried  
> using the GODDARD data and it would not display in GrADS becuase of  
> some time compatibility issue.  The website for this is:
>
> http://portal.nccs.nasa.gov/cgi-lats4d/webform.cgi?&i=GEOS-5/yotc/0.25_deg/assim/inst3_3d_aer_Nv
>
Jason,
    I can't speak to the portal.nccs.nasa.gov site, but there is  
another Goddard site, called Giovanni, that has *some* of the data you  
seem to be looking for.  That site is at: http://giovanni.gsfc.nasa.gov
   Giovanni has a number of different portals or "instances" as we  
call them.  I suggest you start with the Aerosol Daily instance:
http://gdata1.sci.gsfc.nasa.gov/daac-bin/G3/gui.cgi?instance_id=aerosol_daily
which includes MODIS Daily, OMI Daily, MISR Daily and GOCART models.   
GOCART includes specific parameters for dust and sulfate, but our  
holdings only go up to 2007.
   We have TOMS data in the TOMS instance, but it only goes up to  
2005.  However, there are more recent aerosols from the follow-on OMI  
instrument.  There is also MISR data.  We do not have any ACE data,  
however.

To obtain data downloads for  GrADS, select the "Lat-Lon map Time- 
averaged" Visualization.  If you want daily files, you will have to do  
this with single-day time slices in the Temporal window.  Run  
"Generate Visualization".  In the results screen, you will see a  
Download Data tab.  Click on that to see the Download Data screen.   
Then click the NCD box in the Two Dimensional Map Plot section, then  
click Download in Batch.  (Due to a bug, you have to use Download in  
Batch, even if you only want one file). This will give you a tar file  
of NetCDF files that are readable in GrADS using the sdfopen command.   
(However, they do not include a time coordinate so you will have set  
that yourself to compare with other datasets.)

Here is a an example of sdfopen on a Giovanni-downloaded data file.

ga-> sdfopen  
MOD08_D3 
.A2009003.005.2009011045601 
.pscs_000500347353.Optical_Depth_Land_And_Ocean_Mean.G3.gridSubsetter.nc
Scanning self-describing file:   
MOD08_D3 
.A2009003.005.2009011045601 
.pscs_000500347353.Optical_Depth_Land_And_Ocean_Mean.G3.gridSubsetter.nc
SDF file has no discernable time coordinate -- using default values.
SDF file  
MOD08_D3 
.A2009003.005.2009011045601 
.pscs_000500347353 
.Optical_Depth_Land_And_Ocean_Mean.G3.gridSubsetter.nc is open as file 1
LON set to 83.5 140.5
LAT set to 16.5 48.5
LEV set to 0 0
Time values set: 1:1:1:0 1:1:1:0
E set to 1 1
ga-> q file 1
File 1 :
   Descriptor:  
MOD08_D3 
.A2009003.005.2009011045601 
.pscs_000500347353.Optical_Depth_Land_And_Ocean_Mean.G3.gridSubsetter.nc
   Binary:  
MOD08_D3 
.A2009003.005.2009011045601 
.pscs_000500347353.Optical_Depth_Land_And_Ocean_Mean.G3.gridSubsetter.nc
   Type = Gridded
   Xsize = 58  Ysize = 33  Zsize = 1  Tsize = 1  Esize = 1
   Number of Variables = 1
      optical_depth_l  0  y,x  Aerosol Optical Thickness at 0.55  
microns for both Ocean (best) and Land (corrected): Mean
ga-> set gxout shaded
ga-> d optical_depth_lContouring: 0 to 3.5 interval 0.5

CAUTION:  Please be careful about comparing aerosol parameters with  
each other or with models.  Sometimes two apparently similar  
parameters measure very different things (e.g., AOD vs. UV Aerosol  
Index), or measure them at different times during the day, which can  
produce a significant sampling bias.
>
> What other data sets are available.  Unfortunately, I am running  
> grads from a Windows based PC and do not have much of any resources  
> to use in which to produce fortran programs for reformatting data  
> sets (I am trying to get linux configured on my computer) so I need  
> to access ready to use data in netcd format.  I am trying to display  
> this with NCEP data, which has time steps ending on 0 hours Z,  
> therefore, I need to aerosol data that way.  I currently have  
> aerosol data from the above website but unfortunately it ends on 3  
> hours z.  How am I able to modify this file given my computational  
> resources at the moment?  Is it possible to do so?  Anyway, please  
> help me out with this.  Anyway, help would really greatly be  
> appreciated, whether in the form of using the above website,  
> modifying the file I have, or accessing ready to use aerosol files.   
> Again I am trying to examine aerosol files from both Asia and also  
> southern California.
>
> Thanks,
>
> Jason
>

--
Christopher Lynnes             NASA/GSFC, Code 610.2          
301-614-5185

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