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13 Data File Access
In this document we describe what data files you should expect to find on your system and how you would find out what files you actually have on your system.

Table of Contents

What Data Should I Expect to be Accessible from My System?

How McIDAS Finds Files

What Data Can I Actually Access from My McIDAS Session?


What Data Should I Expect to be Accessible from My System

For the purpose of this discussion, we assume that you are ingesting only the data products in the Unidata-Wisconsin datastream. This means that you should only have satellite imagery.

The McIDAS data products that are contained in the Unidata-Wisconsin datastream are:

Source   Product                Resolution   Size       Broadcast Frequency
--------+----------------------+------------+----------+-------------------
CIMSS    Clour Top Pressure       11 km      320 x 960        hourly
CIMSS    Precipitable Water       11 km      320 x 752        hourly
CIMSS    Sea Surface Temp          4 km      360 x 720        daily 
CIMSS    Lifted Index             11 km      320 x 752        hourly
CIMSS    CAPE                     11 km      400 x 800        hourly
CIMSS    Ozone                    16 km      480 x 640        hourly
CIMSS    Wildfire ABBA - NA        5 km     1190 x 1172       hourly
CIMSS    Wildfire ABBA - SA        5 km     1700 x 1128       hourly
GOES-E   Visible       0.65 um     4 km     2726 x 1732  half hourly
GOES-E   Near Infrared  3.9 um     4 km     2726 x 1732  half hourly
GOES-E   Water Vapor    6.5 um     4 km     2726 x 1732  half hourly
GOES-E   Infrared      10.7 um     4 km     2726 x 1732  half hourly
GOES-E   CO2           13.3 um     4 km     2726 x 1732  half hourly
GOES-W   Visible       0.65 um     4 km     1400 x 1740  half hourly
GOES-W   Near Infrared  3.9 um     4 km     1400 x 1740  half hourly
GOES-W   Water Vapor    6.8 um     8 km      700 x 872   half hourly
GOES-W   Infrared      10.7 um     4 km     1400 x 1740  half hourly
GOES-W   Far Infrared  12.0 um     4 km     1400 x 1740  half hourly
GRID     MDR                       9 km      350 x 640        hourly
MULTI    Antarctic     10.7 um    21 km      512 x 512      3 hourly
MULTI    Mollweide WV   6.8 um    20 km      350 x 640      3 hourly
MULTI    Mollweide IR  10.7 um    20 km      350 x 640      3 hourly

A more detailed description of these products and examples of their areal coverage (where appropriate) can be found at:

http://www.unidata.ucar.edu/data/datastream.html


How McIDAS Finds Files

McIDAS uses a combination of two facilities to locate data and information files: MCPATH and file REDIRECTions.

MCPATH

MCPATH is a Unix environment variable that specifies a list of directories that McIDAS-X commands will search when they look for files. The MCPATH variable specifies, in order of precedence from left to right, the directories McIDAS-X routines search when looking for data, anciallary data (e.g., map outline files, enhancements, etc.) and help files. A colon (:) separates each directory defined in MCPATH.

For example, if MCPATH is set to:

/home/fred/mcidas/data:/home/mcidas/data:/home/mcidas/help

and McIDAS-X wants to read from a data file, it first looks for the file in /home/fred/mcidas/data. If the file is not found there, McIDAS-X checks for the file in /home/mcidas/data then /home/mcidas/help. If the file is not located in any of the directories, the system outputs a message saying that the file was not found.

Setting MCPATH

You can set MCPATH in two ways:

If you do not define MCPATH, the McIDAS-X startup script sets MCPATH to:

$HOME/mcidas/data:$HOME/mcidas/help:~mcidas/data:~mcidas/help

To change MCPATH's value, exit McIDAS-X, set MCPATH to the new value and restart McIDAS-X. If you use the Korn or Bourne shell, the Unix command to explicitly set MCPATH is similar to:

export MCPATH;MCPATH=$HOME/data:$HOME/mcidas/data:/home/mcidas/data:/home/mcidas/help

If you use the C shell, the command is similar to:

setenv MCPATH $HOME/data:$HOME/mcidas/data:/home/mcidas/data:/home/mcidas/help

To set the value of MCPATH each time you login to your account, add the command above to your shell-specific configuration file: .cshrc for the C and Tcsh shells, and .profile for the Bourne and Korn shells, .bash_profile for BASH, etc..

When you start McIDAS-X, a temporary directory is automatically created for you, and its full path is added to MCPATH. For example, $HOME/.mctmp/356052, is appended to the MCPATH value, whether the McIDAS-X start-up script set MCPATH or you set its value.

Writing Data

If you run a McIDAS-X command that writes data, the directory in which the data file is written will be put in the first MCPATH directory for which you have write permission.

If you run a command that writes data to a named file and there are files of the same name residing in one or more MCPATH directories, the command will output to the first writable directory in MCPATH.

For example, if a file named AREA0001 exists in the third and fourth MCPATH directories, the McIDAS-X command LWU POKE AREA0001 0 1 will attempt to write to the copy of AREA0001 in the third MCPATH directory. If you do not have write permissions for that file, you may get unexpected results; for example, the command stops due to write failure.

**CAUTION**

If you run a command that rewrites a file, and a file of the same name exists in more than one MCPATH directory, then you will most likely get unexpected results. The reason for this is that the process of rewriting a file is typically one of deleting the file followed by writing a new copy of it. The delete operation will attempt to remove the file from the first MCPATH directory it is found in. When the command goes to write the new copy of the file, it will again look through the MCPATH directories to see where it should be written. Upon finding a file of the name that it is trying to create, it will attempt to overwrite the existing file. If the write permission on that file is not set, then the write will fail.

File Redirection

File redirection is the specification of the directory in which a file or group of files will be found, read, and written by McIDAS applications. Files that are REDIRECTed with the McIDAS REDIRECT command will be used in precedence over files found in directories listed in MCPATH. This lets you explicitly set the location of a particular file or group of files represented by a file mask (regular expression).

For example, if MCPATH is set to:

/home/fred/mcidas/data:~mcidas/data:~mcidas/help
and each of these directories contains a file named AREA0001, the McIDAS command LWU LIST AREA0001 will use the file in /home/fred/mcidas/data if the file is not redirected to another directory.

However, if you have the redirection entry:

AREA00*  /home/dave/aircraft/data
the LWU command uses the file AREA0001 stored in /home/dave/aircraft/data instead of the one stored in /home/fred/mcidas/data.

Instructions for creating redirection files are contained in the Unidata McIDAS Users Guide.

Unidata provides a set of example redirects in the file EXAMPLE.NAM. This file is put in the user mcidas' data directory (~mcidas/data) by the McIDAS-X installation process.

EXAMPLE.NAM is intended to be copied to LOCAL.NAM and then edited by the McIDAS administrator. The editing changes needed are the setting of directories to match your site's McIDAS installation. The entries in EXAMPLE.NAM should be all that are necessary to insure access to McIDAS data files produced by ldm-mcidas decoders or by McIDAS-XCD.

What Data Can I Actually Access from My McIDAS Session?

SSEC began recasting McIDAS into a client-server model in early 1993. The Distributed Data Environment (DDE) allowed McIDAS-OS2 systems (now archaic) acting as clients to access data from McIDAS-MVS servers.

Over the years since 1993, the DDE has been transitioned into the Abstract Data Distribution Environment (ADDE) that is now an integral part of McIDAS-X.

In non-ADDE McIDAS commands, all image, grid and point source files are referenced by file numbers. If you don't know the the file numbers or don't understand the McIDAS file naming conventions, finding and using data could be difficult. ADDE commands, on the other hand, access information from named datasets. Dataset names are assigned to sets of files by the McIDAS system administrator on the machine that is running the ADDE server. End users then run ADDE client commands to interrogate these ADDE servers to find out what data is available to their sessions. They no longer need to be concerned about which files the data actually resides in.

The current ADDE implementation allows Unix workstations to act as clients that can access data from any other workstation, accessible over TCP/IP ethernet, on which McIDAS-X has been installed and on which the McIDAS remote ADDE server has been installed. ADDE servers do not have to only exist on remote machines, however. When ADDE clients make requests for data not served by ADDE remote servers, a local server is automatically started in the user's session to provide the data.

The concepts that form the basis for ADDE clients are discussed in detail in the ADDE section.

Instructions for installing an ADDE remote server are contained in Installing the McIDAS-X ADDE Remote Server.

McIDAS provides a variety of routines to list data available to your McIDAS session. Each data type (IMAGE or AREA, GRID, and POINT or MD) have utilities that list the datasets (ADDE) or files (non-ADDE) that are available for use. Which data are available for individual users is, however, dependent on how McIDAS was installed on their system and how their McIDAS environment is configured. For more information on configuring user's McIDAS sessions, please refer to: Customizing McIDAS-X Sessions.


Data Availability

ADDE Datasets

In the ADDE environment, one uses the DATALOC command to list dataset group names and the Internet name or IP address of the ADDE servers that can supply the data. This list is known as as the client routing table. Typically, the McIDAS site administrator defines the contents of a globally accessible (through MCPATH) client routing table for all users. Knowledgeable users can, however, use DATALOC to manage private client routing tables in addition to accessing the globally defined one.

In its simplest form, DATALOC is run as follows:

DATALOC
On a system that has not had client routing tables setup, this would result in a empty listing:

Group Name                    Server IP Address
--------------------         ----------------------------------------
DATALOC -- done
As one works through the Unidata McIDAS Learning Guide, their individual client routing table will be built so that the DATALOC listing will begin to look something like:

Group Name                    Server IP Address
--------------------         ----------------------------------------
AREAS                        <LOCAL-DATA>
BLIZZARD                     ADDE.UCAR.EDU
MYDATA                       <LOCAL-DATA>
RTGRIDS                      ADDE.UCAR.EDU
RTIMAGES                     ADDE.UCAR.EDU
RTPTSRC                      ADDE.UCAR.EDU
RTWXTEXT                     ADDE.UCAR.EDU
TEST                         <LOCAL-DATA>

<LOCAL-DATA> indicates that data will be accessed from the local data directory.
DATALOC -- done
This listing tells us that the dataset groups named AREAS, MYDATA, and TEST will be served by a local ADDE server while BLIZZARD, RTGRIDS, RTIMAGES, and RTPTSRC datasets will be serviced by a machine whose Internet name is ADDE.UCAR.EDU.

A local ADDE server will attempt to supply data from all datasets that are not named in the client routing table. It is our recommendation, however, that the McIDAS system administrator defines ALL datasets explicitly so that users will be able to easily see all datasets that exist by running DATALOC.

After running DATALOC, one only knows about the dataset group names that are accessible from servers. To see all of the types of data available that a particular group, you would run the DSINFO command.

The command syntax for DSINFO is:

SINFO type group
The choices for type are:

  IMAGE - imagery (e.g. satellite imagery)
  POINT - point source data (e.g. surface observations, profiler data, etc.)
  GRID  - gridded data (e.g. model output)
  TEXT  - textual data (e.g. raw observations)
  NAV   - navigation information (e.g. navigation codicils)
  ALL   - any of the above
The default data type to list is ALL.

To see what data types are included in the group BLIZZARD, you would run:

DSINFO X BLIZZARD

        Dataset Names of Type: IMAGE in Group: BLIZZARD                
                                                                       
Name         NumPos   Content                                          
------------ ------   --------------------------------------           
G7-IR-4K         3    Storm of the Century G7 IR                       
G7-VIS-1K        1    Storm of the Century G7 1K                       
G7-VIS-4K        3    Storm of the Century G7 Vis                      
G7-VIS-FD        1    Storm of the Century G7 16K                      
IMAGES          14    Storm of the Century Images                      
M3-IR            3    Storm of the Century M3 IR                       
M3-VIS           3    Storm of the Century M3 VIS          

        Dataset Names of Type: POINT in Group: BLIZZARD                
                                                                       
Name         NumPos   Content                                          
------------ ------   --------------------------------------           
PTSRCS           5    Storm of the Century Point Source Data           
SFCHOURLY        1    Storm of the Century Surface Observations        
SHIPBUOY         1    Storm of the Century Ship/Buoy Observations      
SYNOPTIC         1    Storm of the Century Synoptic Observations       
UPPERMAND        1    Storm of the Century Upper Air (Mandatory Levels)
UPPERSIG         1    Storm of the Century Upper Air (Significant Levels)

        Dataset Names of Type: GRID  in Group: BLIZZARD                
                                                                       
Name         NumPos   Content                                          
------------ ------   --------------------------------------           
GRIDS            5    Storm of the Century Grids                       

    No Datasets found of Type: TEXT  in Group: BLIZZARD
    No Datasets found of Type: NAV   in Group: BLIZZARD
DSINFO -- done
The entries listed under Name are generically referred to as descriptors. Descriptors are not data files; they are names that identify sets of data files. Descriptors are very flexible. Different descriptors within a group can point to the exact same collection of data, or to various subsets. For instance, the descriptor IMAGES was defined to point at all of the data in all of the other descriptors for group BLIZZARD.

McIDAS Data Files

McIDAS provides the DMAP command for listing out the location of any/all files accessible to McIDAS sessions. DMAP uses information defined in the user's file REDIRECTion table and in the directories defined in the users's MCPATH.

The McIDAS data file naming convention uses the following prefixes to identify particular data, and auxiliary types:

  AREA - imagery (e.g. satellite imagery)
  MDXX - point source data (e.g., surface observations, profiler data, etc.)
  GRID - gridded data (e.g., model output)
  TEXT - textual data (e.g., raw observations)
  VIRT - virtual graphics (e.g., map outlines)

DMAP invoked without file specification:

DMAP
will list out all files that are accessible to you McIDAS session. These are files that are be contained in the session's file redirection table and in the directories detailed in the session's MCPATH. **Caution** this listing could be extensive!

DMAP can be instructed to look for individual or sets of files that have similar names. DMAP uses the characters specified on the command line as a mask for the file names that it should list. For instance:

DMAP AREA
will list out the locations of all files whose names begin with AREA.

DMAP AREA01
will list out the locations of all files whose names begin with AREA01 and so on.

DMAP can also list files based on specified sufficies. For example:

DMAP *.IDX
will list out all files that have IDX as their suffix.

DMAP is the quickest way of finding out where one or more files is located on the system. DMAP does not, however, tell you anything about what is contained in the file. The McIDAS utilities for listing the contents of data files are presented below.


Satellite Imagery

ADDE Imagery Listings

After you ran DSINFO X BLIZZARD above, you saw that the dataset whose group name is BLIZZARD has a variety of imagery data in it. To list more detailed information about the contents of the various descriptors in group BLIZZARD, you would use the ADDE IMGLIST command.

The simpliest invocation syntax for IMGLIST is:

IMGLIST dataset epos 
Here dataset is the full dataset name (group name and descriptor separated by a /) to search and epos is the ending position in the dataset.

To get a short listing of the most recent image in the set of 4 km GOES-7 Infrared images in group BLIZZARD, you would run:

IMGLIST BLIZZARD/G7-IR-4K

Image file directory listing for:BLIZZARD/G7-IR-4K
 Pos Satellite/         Date       Time      Center   Band(s)
     sensor                                 Lat  Lon
 --- -------------  ------------  --------  ---- ---- ------------
   3  GOES-7 IR     13 MAR 93072  18:01:00    26   87 8
IMGLIST: done
To list out all of the images in the set defined by the descriptor G7-IR-4K, you would run:

IMGLIST BLIZZARD/G7-IR-4K.ALL

Image file directory listing for:BLIZZARD/G7-IR-4K
 Pos Satellite/         Date       Time      Center   Band(s)
     sensor                                 Lat  Lon
 --- -------------  ------------  --------  ---- ---- ------------
   1  GOES-7 IR     13 MAR 93072  17:01:00    26   87 8
   2  GOES-7 IR     13 MAR 93072  17:31:00    26   87 8
   3  GOES-7 IR     13 MAR 93072  18:01:00    26   87 8
IMGLIST: done
To list out all of the images in the group BLIZZARD you would run:

IMGLIST BLIZZARD/IMAGES.ALL
Image file directory listing for:BLIZZARD/IMAGES                       
 Pos Satellite/         Date       Time      Center   Band(s)          
     sensor                                 Lat  Lon                   
 --- -------------  ------------  --------  ---- ---- ------------     
   1  GOES-7        13 MAR 93072  17:01:00    26   87 1                
   2  GOES-7        13 MAR 93072  17:31:00    26   87 1                
   3  GOES-7        13 MAR 93072  18:01:00    26   87 1                
   4  GOES-7 IR     13 MAR 93072  17:01:00    26   87 8                
   5  GOES-7 IR     13 MAR 93072  17:31:00    26   87 8                
   6  GOES-7 IR     13 MAR 93072  18:01:00    26   87 8                
   7  GOES-7        13 MAR 93072  18:01:00     1  113 1                
   8  GOES-7        13 MAR 93072  18:01:00    34  102 1                
   9  METEOSAT3     13 MAR 93072  17:00:00    26   84 1                
  10  METEOSAT3     13 MAR 93072  17:30:00    26   84 1                
  11  METEOSAT3     13 MAR 93072  18:00:00    26   84 1                
  12  METEOSAT3     13 MAR 93072  17:00:00    26   84 8                
  13  METEOSAT3     13 MAR 93072  17:30:00    26   84 8                
  14  METEOSAT3     13 MAR 93072  18:00:00    26   84 8                
IMGLIST: done                                                          
IMGLIST will list out more detailed information if you tell it to:

IMGLIST BLIZZARD/G7-IR-4K FORM=EXP

Image file directory listing for:BLIZZARD/G7-IR-4K
 Pos Satellite/         Date       Time      Center      Res (km)   Image_Size
     sensor                                 Lat  Lon    Lat   Lon
 --- -------------  ------------  --------  ---- ----  ----- ----- ------------
   3  GOES-7 IR     13 MAR 93072  18:01:00    26   87
    Band: 8  11.2 um Night cloud detection, sfc temp     4.0   4.0  1337 x 1604
     proj:    0 created: 93208 192750  memo: AAA-MSI TO IR16-S   VIA ARCHIVE
     type:AAA      cal type:RAW
     offsets:  data= 1280 navigation=  256 calibration=  768 auxillary=    0
     doc length: 512   cal length: 116   lev length:   4 PREFIX= 636
     valcod: 1104213119 zcor:  1 avg-smp: N
     pdl: 87 87  3  0  0  0 8A 8A  0  0  0  0  0  0  0  0
           0  0  0  0  0  0 10  0  0 73  6 33 59  1 20 2C
     start yyddd:93072  start time:180105  start scan:   56
     lcor: 1123  ecor:  7606  bytes per pixel: 2  ss: 33
     Image Center Point Res (derived)  Lat:   4.34 (km)  Lon:   3.62 (km)

IMGLIST: done
It can also tell you more explicit information on the band that the image represents:

IMGLIST BLIZZARD/G7-IR-4K FORM=BAND
Image file directory listing for:BLIZZARD/G7-IR-4K
 Pos Satellite/         Date       Time      Center      Res (km)   Image_Size
     sensor                                 Lat  Lon    Lat   Lon
 --- -------------  ------------  --------  ---- ----  ----- ----- ------------
   3  GOES-7 IR     13 MAR 93072  18:01:00    26   87
    Band: 8  11.2 um Night cloud detection, sfc temp     4.0   4.0  1337 x 1604
IMGLIST: done


Grid Point Data

ADDE Grid Data Availability

In ADDE, there is a single command GRDLIST that is used for listing out the grid datasets members and the contents of these members.

To see what members exist in the BLIZZARD/GRIDS dataset, you would run:

GRDLIST BLIZZARD/GRIDS.ALL FORM=FILE

DATASET NAME: BLIZZARD/GRIDS
 Dataset Position  Creation Date Max Grids         Directory Title
 ----------------  ------------- --------- -------------------------------
        1              93070         159   12Z 93070 NMC NGM TRAINING GRID
        2              93071         159   00Z 93071 NMC NGM TRAINING GRID
        3              93071         159   12Z 93071 NMC NGM TRAINING GRID
        4              93072         159   00Z 93072 NMC NGM TRAINING GRID
        5              93072         159   12Z 93072 NMC NGM TRAINING GRID
GRDLIST - done
To list out the the first five grids from the first member of the BLIZZARD/GRIDS dataset, you would run:

GRDLIST BLIZZARD/GRIDS.1 FORM=SHORT GRID=1 5

Dataset position 1      Directory Title= 12Z 93070 NMC NGM TRAINING GRID
PARAM  LEVEL      DAY        TIME    SRC FHOUR     FDAY       FTIME   GRID  PRO
----- ------- ------------ -------- ---- ----- ------------ -------- ------ ----
Z     1000 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      1 MERC
T     1000 MB 11 MAR 93070 12:00:00  NGM     0 11 MAR 93070 12:00:00      2 MERC
U     1000 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      3 MERC
V     1000 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      4 MERC
Z      850 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      5 MERC
Number of grids listed = 5
GRDLIST - done
To list out the contents of the first member of the BLIZZARD/GRIDS dataset, you would run:

GRDLIST BLIZZARD/GRIDS.1 FORM=SHORT GRID=1 LAST
You can also list all grids that match search conditions that you specify. Suppose you would like to get a list of all 700 mb temperature grids for forecast hours 12 through 36 for the 12Z run on March 11 . To produce this list, you would run:

GRDLIST BLIZZARD/GRIDS NUM=ALL LEV=700 PARAM=T FRANGE=12 36 TIME=12 DAY=93070

Dataset position 1      Directory Title= 12Z 93070 NMC NGM TRAINING GRID
PARAM  LEVEL      DAY        TIME    SRC FHOUR     FDAY       FTIME   GRID  PRO
----- ------- ------------ -------- ---- ----- ------------ -------- ------ ----
T      700 MB 11 MAR 93070 12:00:00  NGM    12 12 MAR 93071 00:00:00     30 MERC
T      700 MB 11 MAR 93070 12:00:00  NGM    24 12 MAR 93071 12:00:00     50 MERC
T      700 MB 11 MAR 93070 12:00:00  NGM    36 13 MAR 93072 00:00:00     70 MERC
Number of grids listed = 3
GRDLIST - done


Point Source Data

ADDE Point Source Data Availability

McIDAS provides a single ADDE routine, PTLIST that can be used to list out the contents of "point source" (e.g. surface SAOs and METARs; upper air soundings; wind profiler reports; etc.) dataset holdings.

PTLIST can be used to list out general information on a dataset member:

PTLIST BLIZZARD/SFCHOURLY.ALL FORM=FILE

Pos      Description                        Schema  NRows NCols
------   --------------------------------   ------  ----- -----
     1   SURFACE HOURLY OBSERVATIONS        ISFC       72  3500
PTLIST: Done
Since BLIZZARD has a descriptor, OBS, that contains all of the point source data types, one can list out general information for all of the dataset members with a single command:

PTLIST BLIZZARD/OBS.ALL FORM=FILE

Pos      Description                        Schema  NRows NCols
------   --------------------------------   ------  ----- -----
     1   SURFACE HOURLY OBSERVATIONS        ISFC       72  3500
     2   INTL. RADIOSONDE OBS (UPPER AIR    IRAB        8  1500
     3   INTL. RADIOSONDE OBS--SIG LEVELS   IRSG       16  8000
     4   SHIP/BUOY OBSERVATIONS             ISHP       24  3000
     5   SURFACE SYNOPTICS                  SYN         8  6000
PTLIST: Done
PTLIST can also be used to list out the names of the data stored within the dataset member:

PTLIST BLIZZARD/SFCHOURLY.ALL FORM=PARAM

   PARAMETER UNIT        STORAGE TYPE     DEFAULT FORMAT
   --------- ----        ------------     --------------
   TYPE                  integer          I9
   DAY       SYD         integer          I9
   TIME      HMS         integer          I9
   NREC                  integer          I9
   ID                    character        A4
   LAT       DEG         real             F9.4
   LON       DEG         real             F9.4
   ZS        M           integer          I9
   ST                    character        A4
   CO                    character        A4
   MOD                   integer          I9
   HMS       HMS         integer          I9
   CIGC                  integer          I9
   CC1                   integer          I9
   CC2                   integer          I9
   CIGH      FT          real             F9
   ZCL1      FT          real             F9
   ZCL2      FT          real             F9
   VIS       MI          real             F9.1
   WX1                   character        A4
   WX2                   character        A4
   T         K           real             F9.2
   TD        K           real             F9.2
   DIR       DEG         integer          I9
   SPD       MPS         real             F9.1
   GUS       MPS         real             F9.1
   PSL       MB          real             F9.2
   PCP       IN          real             F9.2
   SNO       IN          integer          I9
   PRE       MB          real             F9.2
PTLIST: Done
This listing tells us not only the names of the data elements of the data set member, but also their units, how they are stored, and how their values will be printed by default for other PTLIST options.

You can also simply find out the values for all of the data for the first entry in a dataset member:

PTLIST BLIZZARD/SFCHOURLY.ALL FORM=DATA

Row :      1  Col :      2
TYPE        =         0             | DAY         =     93072 SYD         |
TIME        =         0 HMS         | NREC        =      1924             |
ID          =       OAR             | LAT         =   36.6833 DEG         |
LON         =  121.7666 DEG         | ZS          =        41 M           |
ST          =        CA             | CO          =        US             |
MOD         =         0             | HMS         =    235500 HMS         |
CIGC        =         2             | CC1         =         2             |
CC2         = _missing_             | CIGH        =    15000. FT          |
ZCL1        =    20000. FT          | ZCL2        = _missing_             |
VIS         =      25.0 MI          | WX1         = _missing_             |
WX2         = _missing_             | T           =    289.27 K           |
TD          =    284.83 K           | DIR         =       270 DEG         |
SPD         =       6.2 MPS         | GUS         = _missing_             |
PSL         =   1019.31 MB          | PCP         = _missing_             |
SNO         = _missing_             | PRE         = _missing_             |
---------------------------------------------------------------------------
Number of matches found = 1
PTLIST: Done
One can also selection criteria by which parameters are listed. For instance, if you want to list out the station ID, report TIME, and Temperature for all of the stations in South Carolina that are reporting temperatures between 45 and 70 F at 15 Z, you would run:

PTLIST BLIZZARD/SFCHOURLY.1 FORM=DATA NUM=ALL PARAM=ID TIME T[F] SELECT='ST SC;T[F] 45 70;TIME 15'

  ID TIME[HMS]      T[F]
---- --------- ---------
CHS     150000     55.00
NBC     150000     50.99
MMT     150000     50.00
FLO     150000     64.99
SSC     150000     53.01
MYR     150000     63.00
CRE     150000     61.99
MYR     150000     61.99
Number of matches found = 8
PTLIST: Done

 


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