[gradsusr] TRMM data

Syed Ahsan Ali ahsanshah01 at gmail.com
Wed Jun 6 11:46:27 EDT 2012 

Dear Zhong

While working with the V6 data and referring to the page for conversion of
3-hourly (mm/hr)rainfall to total daily rainfall [
http://disc.sci.gsfc.nasa.gov/additional/faq/precipitation_faq.shtml#convert],
I concatinated the 3-hourly binary files first and then made a single daily
file and used the following command to display the data for a grid point in
grads.
 d sum(r*24,t=1,t=8) and it gives me the answer 96. But when I downloaded
and displayed the daily rainfall file from the ftp (which is accumulated
rainfall as per readme) for the same grid point and the same day it gives 0
answer. While the actual observed rainfall is 116mm. So, where could be the
problem.

Kind Regards
Ahsan

On Wed, Jun 6, 2012 at 8:37 PM, Zhong Liu <Zhong.Liu-1 at nasa.gov> wrote:

> Dear Ahsan,
>
> Glad to hear the info is useful.
>
> If you plan to do subsetting of the data, the GrADS way could
> be useful, especially with GDS and OPeNDAP. You could write a GrADS script
> to
> do that as well.
>
> Good luck!
>
> Regards,
>
> -Zhong
>
>
> On 6/6/2012 11:34 AM, Syed Ahsan Ali wrote:
>
> Dear Zhong
>
> Thanks alot for the email. This is great news that V7 is available.
> I have tried a simple thing that is concatenation of all files using CAT
> command in linux to make a single file. I'll also try the method which you
> have mentioned.
>
> Thank you
> Best Regards
> Ahsan
>
> On Wed, Jun 6, 2012 at 8:17 PM, Zhong Liu <Zhong.Liu-1 at nasa.gov> wrote:
>
>> Dear Ahsan,
>>
>> Dr. Lynnes forwarded your question to me.
>>
>> First, V7 TRMM 3B42 and its daily have just been released. Please use
>> them if possible,
>>
>> ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/3B42_V7 ( for 3 hourly)
>>
>> ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/Derived_Products/3B42_V7/Daily(daily)
>>
>> To aggregate files, I have an example below.
>>
>> Please note that the similar method can be applied to GDS, OPeNDAP, or
>> binary files (listed in the above
>> directories).
>>
>> Hope these help.
>>
>> Regards,
>>
>> -Zhong
>>
>> ga-> open 3b42_netcdf.ctl
>> Scanning description file:  3b42_netcdf.ctl
>> Data file 3B42.%y2%m2%d2.%h1.6A.nc <http://h1.6a.nc/> is open as file 1
>> LON set to 0 360
>> LAT set to -49.875 49.875
>> LEV set to 1000 1000
>> Time values set: 1998:1:1:0 1998:1:1:0
>> ga-> set time 18z1apr2010 0z2apr2010
>> Time values set: 2010:4:1:18 2010:4:2:0
>> ga-> define rtmp=r
>> Define memory allocation size = 6921600 bytes
>> ga-> set fwrite test.bin
>> FWrite file name = test.bin
>> FWwrite byte order is little_endian; format is stream
>> Fwrite replacing an existing file if it exist
>> ga-> set gxout fwrite
>> ga-> d rtmp
>> Wrote 576800 of 576800 elements to test.bin as Stream Little_Endian
>> Wrote 576800 of 576800 elements to test.bin as Stream Little_Endian
>> Wrote 576800 of 576800 elements to test.bin as Stream Little_Endian
>> Press enter to continue:::::
>> ga-> disable fwrite
>>
>> where 3b42_netcdf.ctl is,
>>
>> dset ^3B42.%y2%m2%d2.%h1.6A.nc <http://h1.6a.nc/>
>> dtype netcdf
>> options template
>> title TRMM 3B42 V6 three hourly TRMM rainfall
>> undef -9999.9
>> xdef 1440 linear -179.875 0.25000000
>> ydef 400  linear -49.8750000 0.25000000
>> zdef 1 levels 1000
>> tdef 41384 linear 00:00Z01jan1998 3hr
>> * end_time 21:00Z29feb2012 (this_is_comment_line)
>> vars 2
>> precipitation=>r      0  y,x Hourly Rain Rate (mm/hr)
>> relativeError=>err    0  y,x Error (mm/hr)
>> endvars
>>
>> and to test the output file, use this ctl,
>>
>> dset test.bin
>> title TRMM 3B42 V6 three hourly TRMM rainfall
>> undef -9999.9
>> xdef 1440 linear -179.875 0.25000000
>> ydef 400  linear -49.8750000 0.25000000
>> zdef 1 levels 1000
>> tdef 39432 linear 00:00Z01jan1998 3hr
>> * end_time 21:00Z30jun2011 (this_is_comment_line)
>> vars 1
>> r         0   99 Hourly Rain Rate (mm/hr)
>> endvars
>>
>>
>>
>>
>> On 6/5/2012 7:53 AM, Lynnes, Christopher S. (GSFC-6102) wrote:
>>
>>> On Jun 5, 2012, at 7:47 AM, Christopher Lynnes wrote:
>>>
>>> Is this something that can be solved by our GDS server for this user?
>>>>
>>> I'm thinking of: http://disc2.nascom.nasa.gov/dods/3B42RT.info
>>>
>>> But I don't know how to aggregate to a time series using GrADS.  It must
>>> be possible…
>>>
>>> Begin forwarded message:
>>>>
>>>> From: Syed Ahsan Ali<ahsanshah01 at gmail.com>
>>>>> Subject: Re: [gradsusr] TRMM data
>>>>> Date: June 5, 2012 3:53:14 AM EDT
>>>>> To: GrADS Users Forum<gradsusr at gradsusr.org>
>>>>> Reply-To: GrADS Users Forum<gradsusr at gradsusr.org>
>>>>>
>>>>>
>>>>> Dear  Jayakrishnan,
>>>>>  I have downloaded the 3-hourly nc files and also had a plan to
>>>>> concatenate all of them, but the problem was that there is no date
>>>>> information in the file so when I'll concatenate there would be a mess up.
>>>>> Thanks for the link. But I don't know how to combine these binary files.
>>>>> Any hint for this.
>>>>>
>>>>> Best Regards
>>>>> Ahsan
>>>>>
>>>>> On Tue, Jun 5, 2012 at 10:08 AM, Jayakrishnan P.R<
>>>>> prjayakrishnan at gmail.com>  wrote:
>>>>> Dear Ahsan,
>>>>>              I think you downloaded the single nc file from mirador
>>>>> search. It will contain only sinlgle time data in each 3 hour. To have a
>>>>> time series of data you will have to concatenate the data files. There is
>>>>> another simple site to download the binary files of TRMM three hourly as
>>>>> well as daily. You can download the data from this alternate site and
>>>>> combine the data files and write a corresponding ctl file.
>>>>>
>>>>> This is the link for TRMM data
>>>>>
>>>>> ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/3B42_V6 ( for 3 hourly)
>>>>>
>>>>> ftp://disc2.nascom.nasa.gov/data/TRMM/Gridded/Derived_Products/3B42_V6/Daily(daily)
>>>>>
>>>>>
>>>>> Best of luck.....
>>>>> --
>>>>> Sincerely
>>>>> ***********************************************
>>>>> Jayakrishnan.P.R
>>>>> CSIR-Senior Research Fellow
>>>>> Department of Atmospheric Sciences
>>>>> Cochin University of Science and Technology (CUSAT), Cochin-682 016
>>>>> Kerala, India.
>>>>> Mob: 09895417565
>>>>>
>>>>> ***********************************************
>>>>>
>>>>> _______________________________________________
>>>>> gradsusr mailing list
>>>>> gradsusr at gradsusr.org
>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> gradsusr mailing list
>>>>> gradsusr at gradsusr.org
>>>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>>>
>>>> --
>>>> Dr. Christopher Lynnes, NASA/GSFC, Code 610.2, 301-614-5185
>>>>
>>>> --
>>> Dr. Christopher Lynnes, NASA/GSFC, Code 610.2, 301-614-5185
>>>
>>>
>>
>> --
>> Zhong Liu, Ph.D.
>> Zhong.Liu-1 at nasa.gov
>> George Mason University and
>> NASA Goddard Earth Sciences Data and
>> Information Services Center
>> NASA/GSFC, Code 610.2
>> Greenbelt. MD. 20771  U.S.A.
>> (301) 614-5764 (voice)
>> (301) 614-5268 (fax)
>> http://disc.gsfc.nasa.gov
>> http://disc2.nascom.nasa.gov/Giovanni/tovas/
>> http://disc.sci.gsfc.nasa.gov/hurricane/trmm_quikscat_analysis.shtml
>> http://disc.sci.gsfc.nasa.gov/agriculture/ais_sup/current_conditions.shtml
>>
>>
>
>
> --
> Zhong Liu, Ph.D.Zhong.Liu-1 at nasa.gov
> George Mason University and
> NASA Goddard Earth Sciences Data and
> Information Services Center
> NASA/GSFC, Code 610.2
> Greenbelt. MD. 20771  U.S.A.
> (301) 614-5764 (voice)
> (301) 614-5268 (fax)http://disc.gsfc.nasa.govhttp://disc2.nascom.nasa.gov/Giovanni/tovas/http://disc.sci.gsfc.nasa.gov/hurricane/trmm_quikscat_analysis.shtmlhttp://disc.sci.gsfc.nasa.gov/agriculture/ais_sup/current_conditions.shtml
>
>


-- 
Syed Ahsan Ali Bokhari
Electronic Engineer (EE)

Research & Development Division
Pakistan Meteorological Department H-8/4, Islamabad.
Phone # off  +92518358714
Cell # +923155145014
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20120606/c52b4e2d/attachment-0003.html

More information about the gradsusr mailing list