User's Guide

GET1NCEP

Retrieve an NCEP water vapor image

Function:

Retrieve an NCEP water vapor image for the date of interest.

Parameters:

HOUR
Acquisition hour used to determine which NCEP model to retrieve:


HOUR          Z model
-------       --------
0-2             00
3-8             06
9-14            12
15-20           18
21-23           00 (next day's)

MONTH
Month of output image

DAY
Day of output image

YEAR
Four digit year of output image

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

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

WATERBASEDIR
Base water vapor directory (See User Note 1)

BACKDIR(--)
Backup water vapor directory (See User Note 4)

Examples:

  1. LAS> get1ncep hour=7 month=6 day=4 year=1998 out="jun04water" silobasedir="/avhrr/ncep_watervapor" waterbasedir="/sgs4/km1/adaps/images"

    The NCEP daily image for June 4, 1998 is retrieved. The standard ddr will be found in directory /sgs4/km1/adaps/images and the NCEP images on the silo in directory /avhrr/ncep_watervapor/1998. The output image name is jun04water.

Description/Algorithm:

The input parameters are combined to create image names of the daily images. The SILO is checked to see if the daily image exists. If the daily image exists, it is retrieved. If no NCEP image exists for the day in interest, an error status is returned. No climatology data exists for the NCEP dataset.

Nonfatal Error Messages:

    None.

Fatal Error Messages:

  1. [get1ncep-noob] Daily NCEP image not on SILO

    The daily NCEP image was not on the SILO. Consider using the TOVS dataset instead.

  2. [get1ncep-sread] Unable to read NCEP image (hour = XX) from SILO

    An error occurred while reading from the SILO. Ensure the system is operational, and try again.

User Notes:

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

    
       basedir \--- ncep_watervapor \--- 1979
                                    \--- 1980
                                    \--- ...
                                    \--- 2000
    
    

  2. The host directories on the SILO begin with /hsm/lta1, the uftp routines will not work without /hsm/lta1 so SILO adds this prefix if missing. However it is best if you include it.

  3. Temporary files are created (and eventually deleted) in the same directory as specified in the OUT parameter.
  4. 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.