[ncl-talk] Data conversion

[Alan Brammer]

Forgot the offset, which is mentioned in the link Kevin sent. 


ir_u = byte2flt( fbindirread (file_name_read ,0, (/2,3298,9896/),"ubyte")) +75.
ir_u at _FillValue= 255+75.

"Each record is a 9896 x 3298 Fortran array of IR brightness temperatures that have been scaled to fit into 1-byte by subtracting "75" from each datum.  Therefore it is necessary for the user to add a value of "75" to each data value when using the data."


> On 4 Feb 2016, at 13:30, Alan Brammer <abrammer at albany.edu> wrote:
> 
> ok, wow. Don’t send the same message 3 times, if the first answers weren’t complete at least expand and attempt something not just copy paste the same lines again.  
> 
> as said before .Z means it’s compressed.  gunzip merg_2016020123_4km-pixel.Z  will uncompress it. Then you have a binary file as a small amount of googling would have told you.  
> The same search would have linked you to various messages on here and various scripts where other people have included simple examples of this file type (myself included). Here is an example of reading and making a simple plot.  There are plenty of examples on how to write netcdf on the NCL website so you should develop code from there.  Most simple example at bottom of script below. 
> https://www.ncl.ucar.edu/Applications/o-netcdf.shtml <https://www.ncl.ucar.edu/Applications/o-netcdf.shtml>
> 
> Read the documentation on the below functions and understand what is occurring .
> 
> 
> begin
> file_name_read = "merg_2016020123_4km-pixel"
> 
> ir_u = byte2flt( fbindirread (file_name_read ,0, (/2,3298,9896/),"ubyte")) 
> 
> 
> lon_g = fspan(0.0182,360,9896)
> lat_g = fspan(59.982,59.982-0.036383683*3298,3298)
>  
> lon_g at units      = "degrees_east"
> lon_g at long_name  = "longitude"
> lon_g at short_name = "longitude"
> lon_g!0 = "lon"
> lon_g&lon = lon_g
> 
> lat_g at units      = "degrees_north"
> lat_g at long_name  = "latitude"
> lat_g at short_name = "latitude"
> lat_g!0 = "lat"
> lat_g&lat = lat_g
> 
> 
> ir_u!0      = "time"
> ir_u!1      = "lat"
> ir_u!2      = "lon"
> 
> ir_u&lat    = lat_g
> ir_u&lon    = lon_g
> 
> ir_u at _FillValue= 255
> 
> 
> wks = gsn_open_wks("X11","")
> res = True
> res at cnFillOn = True
> res at cnFillMode = "RasterFill"
> res at cnLinesOn = False
> plot = gsn_csm_contour_map(wks, ir_u(0,:,:), res)
> 
> ncout = addfile(file_name_read+”.nc”,”c”)
> ncout->ir_data = ir_u
> 
> end
> 
> 
> 
> 
> 
>> On 4 Feb 2016, at 13:04, Benjamin Alabi <alabibenjamin2 at gmail.com <mailto:alabibenjamin2 at gmail.com>> wrote:
>> 
>> Thanks for your assistance sir. I've tried the cdo to get general information on the data, but it didn't work
>> I need help from someone that can guide me to convert this data format - 'merg_2012091000_4km-pixel.Z' to netcdf format.
>> I download Gobally-merged (60N-60S) pixel-resolution IR brightness temperature data (equivalent blackbody temps), merged from all available geostationary satellites (GOES-8/10, METEOSAT-7/5)
>> This is the link:
>> http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=Global-merged%20IR%20Brightness%20Temperature%20Data&project=TRMM&dataGroup=Ancillary&version=001&CGISESSID=25c6337b80163b3743e8bea85d015558 <http://mirador.gsfc.nasa.gov/cgi-bin/mirador/presentNavigation.pl?tree=project&dataset=Global-merged%20IR%20Brightness%20Temperature%20Data&project=TRMM&dataGroup=Ancillary&version=001&CGISESSID=25c6337b80163b3743e8bea85d015558>.
>> I really want it to be in netcdf format.
>> 
>> Regard
>> 
>> 
>> 
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