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8.1 Grids and Grid Files - Listing Grids and Grid Files
In this exercise, you will list the grid files in the BLIZZARD dataset, list the grids in one of the grid files, and list information about the values in a grid.

  1. Start a McIDAS session.

    At the Unix prompt:

    Type: mcidas

    Your session should still be set for six frames from the last time you edited your .mcidasrc file. If not, set it for six frames, as described in Getting Started.

  2. Log on and initialize the workstation.

    Type: LOGON   initials   project#   I

  3. List the grid files in the BLIZZARD dataset.

    Type: DSINFO GRID BLIZZARD

  4. List the grid file directory for these grid files.

    Type: GRDLIST BLIZZARD/GRIDS.ALL FORM=FILE

    Each grid file has a dataset position, date the grid file was created, maximum number of grids the grid file can store, and a file description, as shown below.

    DATASET NAME: BLIZZARD/GRIDS                                                    
     Dataset Position  Creation Date Max Grids         Directory Title              
     ----------------  ------------- --------- -------------------------------      
            1             1993070         159   12Z 93070 NMC NGM TRAINING GRID 
            2             1993071         159   00Z 93071 NMC NGM TRAINING GRID
            3             1993071         159   12Z 93071 NMC NGM TRAINING GRID
            4             1993072         159   00Z 93072 NMC NGM TRAINING GRID 
            5             1993072         159   12Z 93072 NMC NGM TRAINING GRID
    

  5. List the first ten grids in the first grid file in the dataset.

    Type: GRDLIST BLIZZARD/GRIDS.1 GRID=1 10

    The first ten grids are listed in the Text and Command Window, which shows the dataset position, grid file description, parameter type, level, Julian date of the data, time of the data, source type, forecast hour, valid day/time, grid number, and projection.

    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
    T      850 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      6 MERC
    U      850 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      7 MERC
    V      850 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      8 MERC
    Z      700 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00      9 MERC
    T      700 MB 11 MAR 93070 12:00:00  ROI     0 11 MAR 93070 12:00:00     10 MERC
    Number of grids listed = 10                                                     
    

  6. Get the expanded listing of the first grid in this dataset.

    Type: GRDLIST BLIZZARD/GRIDS.1 FORM=ALL

    The expanded listing includes information about the total points, the number or rows and columns, the time the grid was received, units of the parameter, scaling factor, lat/lon extents and increments.

    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
    Total pts= 1188  Num rows=  33  Num columns=  36    received:      0 000000Z
    No GRIB number information  
    Units of gridded variable are GPM  Scale of variable is:   2              
    Mercator Projection                                                      
    Min Lat=  20.00  Max Lat=  60.00  Min Lon=  52.50  Max Lon= 140.00      
    Latitude Increment= 1.2500  Longitude Increment= 2.5000                
    Number of grids listed = 1                                            
    
  7. List all the 500 mb height (Z) grids in the grid file in dataset position 5.

    Type: GRDLIST BLIZZARD/GRIDS.5 LEVEL=500 PARAM=Z NUM=ALL

    The 0, 12, 24, 36, and 48 hour forecast grids for this level and parameter are listed.

  8. List the statistical information for the 12 hour 500 mb height grid in this dataset.

    Type: GRDINFO BLIZZARD/GRIDS.5 STAT LEVEL=500 PARAM=Z FHOUR=12

    Information about the maximum and minimum values, the mean and standard deviation of the values in the grid are listed.

  9. List a histogram of the values for this same grid. Bin the values in 120 m segments and format the values as integers.

    Type: GRDINFO BLIZZARD/GRIDS.5 HIST LEVEL=500 PARAM=Z FHOUR=12 BINSIZE=120 FORMAT=I5

  10. List the 24 hour Relative Humidity grid point values between 35° and 40° N and 80° and 85° W from this dataset. Format the data as a real value with one decimal place.

    Type: GRDINFO BLIZZARD/GRIDS.5 LIST PARAM=RH FHOUR=24 LAT=35 40 LON=80 85 FORMAT=F4.1

    Row, column, latitude, longitude, and values are listed for each grid point falling in this geographical region:

    Listing data from  24-hour forecast RH   Grid at 850 MB   from NGM              
    Grid is at 120000 UTC on 1993072 from dataset: BLIZZARD/GRIDS 
        Row    Col    Latitude    Longitude    Value         Units    Level  Param
        17      23      40.000      85.000    90.2                   850  MB   RH
        18      23      38.750      85.000    86.2                   850  MB   RH  
        19      23      37.500      85.000    77.2                   850  MB   RH 
        20      23      36.250      85.000    74.7                   850  MB   RH
        21      23      35.000      85.000    80.7                   850  MB   RH  
        17      24      40.000      82.500    96.7                   850  MB   RH 
        18      24      38.750      82.500    98.7                   850  MB   RH
        19      24      37.500      82.500    98.7                   850  MB   RH  
        20      24      36.250      82.500    98.2                   850  MB   RH 
        21      24      35.000      82.500    97.2                   850  MB   RH
        17      25      40.000      80.000    99.7                   850  MB   RH  
        18      25      38.750      80.000    99.7                   850  MB   RH 
        19      25      37.500      80.000    98.7                   850  MB   RH
        20      25      36.250      80.000    97.7                   850  MB   RH  
        21      25      35.000      80.000    98.7                   850  MB   RH 
    GRDINFO Done, Number of grids listed=1                                          
    

 


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