Re: NetCDF data files (fwd)

------- Forwarded Message

Date:    Tue, 20 Aug 2002 15:50:24 -0600
From:    Russ Rew <address@hidden>
To:      "Bui, Them" <address@hidden>
Subject: Re: NetCDF data files 

>To: "'address@hidden'" <address@hidden>
>From: "Bui, Them" <address@hidden>
>Subject: NetCDF data files
>Organization: NASA Marshall Space Flight Center
>Keywords: 200208201438.g7KEcFK11508

Them,

> I download a couple of the TIMED satellite images from the GUVI instrument.
> These are images from a satellite of the aurora (northern lights), airglow,
> and other atmospheric phenomenon and are gzipped netCDF format files.  The
> data is available at:
> 
> http://guvi.jhuapl.edu/levels/level1b/imaging/2002/007/
> 
> At this site, the AAreadme.txt indicate that these files are compressed
> binary NetCDF data files and can be decompressed with WinZip on a PC. The
> data file at this site file name
> GUVI_im_disk_v004r00_2002007_REV00452.L1B.gz (old name) and after I was
> using WinZip to decompress it, the file name is
> GUVI_im_disk_v004r00_2002007_REV00452.L1B.  
> Please let me know if you have any instruction and/or suggestion? 

I just tried downloading the file 

  
http://guvi.jhuapl.edu/levels/level1b/imaging/2002/007/GUVI_im_disk_v004r00_2002007_REV00459.L1B.gz

by right clicking on the directory entry in my Mozilla web browser,
and it stored the file as:

  GUVI_im_disk_v004r00_2002007_REV00459.L1B.gz

which was 2617776 bytes in size.

Then I unzipped this using the gunzip utility:

  $ gunzip GUVI_im_disk_v004r00_2002007_REV00459.L1B.gz

resulting in an uncompressed file named

  GUVI_im_disk_v004r00_2002007_REV00459.L1B

that was 18771864 bytes in size.

You were right, this is a netCDF file, even though it doesn't have the
".nc" extension.  I can tell by running the ncdump utility on it:

  $ ncdump -h GUVI_im_disk_v004r00_2002007_REV00459.L1B

which just prints out the structure of the data because I used the -h
("header info") option.  Without this option, ncdump would have also
printed out all the data.  I've appended the output I got with "ncdump
-h".  If you need the "ncdump" program, you can get it as part of the
netCDF package, which is downloadable in source form or in binaries
for various platforms from the netCDF web site at

  http://www.unidata.ucar.edu/packages/netcdf/faq.html#howtoget

--Russ

netcdf GUVI_im_disk_v004r00_2002007_REV00459 {
dimensions:
          NumScans = UNLIMITED ; // (159 currently)
          NumDarkCountPixels = 4 ;
          NumBackgroundCountPixels = 21 ;
          NumAcrossTrackPixels = 159 ;
          NumAlongTrackPixels = 14 ;
          NumColors = 5 ;
variables:
          int Time(NumScans) ;
                  Time:title = "Time since start of day" ;
                  Time:units = "Milliseconds" ;
          byte Detector(NumScans) ;
                  Detector:title = "Detector Number" ;
                  Detector:valid_range = 1s, 2s ;
          byte Slit(NumScans) ;
                  Slit:title = "Slit Position" ;
                  Slit:valid_range = 0s, 4s ;
          short DarkCountPixels(NumScans, NumDarkCountPixels) ;
                  DarkCountPixels:title = "Dark Count Pixels" ;
          short BackgroundPixels(NumScans, NumBackgroundCountPixels) ;
                  BackgroundPixels:title = "Background Count Pixels" ;
          float RadianceData(NumScans, NumAcrossTrackPixels, 
NumAlongTrackPixels, NumColors) ;
                  RadianceData:title = "Imaging Mode Disk Radiance Data" ;
                  RadianceData:units = "Rayleighs" ;
          byte DQI(NumScans, NumAcrossTrackPixels, NumAlongTrackPixels, 
NumColors) ;
                  DQI:title = "Data Quality Indicator" ;
          short CalibrationError(NumScans, NumAcrossTrackPixels, 
NumAlongTrackPixels, NumColors) ;
                  CalibrationError:title = "Calibration Error" ;
                  CalibrationError:units = "Percent" ;
                  CalibrationError:scale_factor = 10 ;
          short CountError(NumScans, NumAcrossTrackPixels, NumAlongTrackPixels, 
NumColors) ;
                  CountError:title = "Counting Statistical Error" ;
                  CountError:units = "Percent" ;
                  CountError:scale_factor = 10 ;
          float PiercePointLatitude(NumScans, NumAcrossTrackPixels, 
NumAlongTrackPixels) ;
                  PiercePointLatitude:title = "Latitude of Pierce Point" ;
                  PiercePointLatitude:units = "Geographic coordinates" ;
          float PiercePointLongitude(NumScans, NumAcrossTrackPixels, 
NumAlongTrackPixels) ;
                  PiercePointLongitude:title = "Longitude of Pierce Point" ;
                  PiercePointLongitude:units = "Geographic coordinates" ;

// global attributes:
                  :Title = "Level1B Imaging Disk Data" ;
                  :Data_Product_Type = "Level1B Imaging Disk Data" ;
                  :Source = "GUVI DP POC" ;
                  :Mission = "TIMED" ;
                  :Data_Product_Version = "004" ;
                  :Product_Format_Version = "00" ;
                  :Data_Product_Revision = "00" ;
                  :Software_Version = "2.4" ;
                  :Software_Name = "reformatter" ;
                  :Calibration_Version = "525.0" ;
                  :Description = "Level1B Imaging Disk Data" ;
                  :Comment = "" ;
                  :History = "" ;
                  :Filename = "GUVI_im_disk_v004r00_2002007_REV00459.L1B" ;
                  :Date_Generated = "2002136163032" ;
                  :Starting_Time = "2002007163822" ;
                  :Stopping_Time = "2002007181539" ;
                  :Starting_Orbit_Number = 459s ;
                  :Stopping_Orbit_Number = 0s ;
                  :Instrument_Mode = "IMAGING" ;
                  :Scan_Type = "DISK" ;
                  :Data_Region = "N/A" ;
                  :Grid_Size = 0s ;
                  :Used_Data_Product_Version_Number = "cal 5.0 color 2.0 
background 3.0 dark 4.0" ;
                  :Used_Data_Product_Revision_Number = "" ;
                  :Purpose = "Calibrated Imaging Disk Pixel Data" ;
                  :Intended_Recipient = "" ;
                  :File_Type = "NetCdf" ;
                  :81_Day_F10 = 0.f ;
                  :Daily_F10 = 182.4f ;
                  :F10_7_Source = "@" ;
                  :3_hour_Kp = 27 ;
                  :Daily_Kp = 2 ;
                  :Kp_Ap_Source = "Estimated" ;
                  :Daily_Ap = 7 ;
data:
}

------- End of Forwarded Message