User's Guide

GETTOVS

Create a complete water vapor image

Function:

Create a water vapor image for the input date by combining data from the daily observation and climatological data. Also create a QC image that indicates the origin of the water vapor values.

Parameters:

MONTH
Month of output image

DAY
Day of output image

YEAR
Four digit year of output image

SATID
Satellite ID. The one- or two-digit satellite ID, for example: if satellite is NOAA-14 use 14 for SATID.

OUT
Filled water vapor output image. A 1-band image of water vapor values.

QC
Quality Control output image. A 1-band image containing QC values which indicate the origin of water vapor values. (See User Note 3)

SILOBASEDIR
Base SILO directory (See User Notes 1 and 2)

WATERBASEDIR
Base water vapor directory (See User Note 1)

TIMEFLAG("PM")
Time of day flag. Indicates whether the water vapor should come from the morning or afternoon observation.

BACKDIR(--)
Backup water vapor directory (See User Note 5)

Examples:

  1. LAS> gettovs month=6 day=4 year=1998 satid=14 out="jun04water" qc="jun04qc" silobasedir="/avhrr/" waterbasedir="/sgs4/km1/adaps/images" timeflag="pm"

    The TOVS daily observation for the afternoon of June 4, 1998 from NOAA 14 is filled with daily climatologies for June 4th pm. The daily climatologies will be found in directory /sgs4/km1/adaps/images/tovs/dailyfillpm and the daily observation on the silo in directory /avhrr/tovs_watervapor/1998. The images created are jun04water and jun04qc.

Description/Algorithm:

The input parameters are combined to create image names of the daily observation and climatology images. The SILO is checked to see if the daily observation exists. If the daily observation doesn't exist or there is an error copying from the SILO, a backup image without any valid data is used in its place. A monthly climatology is created for the month and day of the observation. The daily observation is filled first with daily then with monthly climatology data and a QC image is created. The monthly and daily observation images are deleted.

Nonfatal Error Messages:

  1. [gettovs-warn] Daily observation not on SILO, using backup image

    The daily observation image was not on the SILO. A backup image with no water vapor data is copied and filled with climatological data.

Fatal Error Messages:

    None

User Notes:

  1. All TOVS water vapor images are stored in directory structures with a base directory under which directories for daily climatologies and daily observations by year are contained. The daily observation directories (e.g. 1999) are only stored on the SILO.

    
       basedir ----- dailyfillam
       	    \--- dailyfillpm
                \--- 1979
    	    \--- 1980
    	    \--- ...
    	    \--- 2000
    
    

  2. The host directories on the SILO begin with /dmf/edc, the routines used to access the SILO, such as SILO-READ, will not work if the /dmf/edc is not included in WATERBASEDIR.

  3. The QC band contains values that indicate the origin of the water vapor value for the pixel in the corresponding output image. The values are:

        0 - pixel value from daily observation
        1 - pixel value from daily climatology
        2 - pixel value from monthly climatology
        3 - pixel value was interpolated in monthly climatology
        5 - pixel value from daily NCEP model (closest hour)
        6 - pixel value from NCEP model ( + 6 hours)
        7 - pixel value from NCEP model ( - 6 hours)
    

  4. Temporary files are created in the same directory as specified in the OUT parameter.
  5. The backup directory parameter has been added to allow users to work around silo problems. If water vapor images are not available on the silo or the silo is down, users can place image files in the backup directory and specify this directory in the parameter BACKDIR. When invoked the silo will be checked first and, if the file cannot be retrieved, the backup directory will be used.

    The backup directory is only a backup for the silo and as such only the img files are copied. There are cd's in the archive containing all TOVS and NCEP images except the current year. Current years images are archived in January of the following year. The CD's are stored as code 049; project AVHRR greeness; and description: TOVS/NCEP water vapor YYYY. The ADAPS software person should have an online backup of current year images available.