McIDAS-X Learning Guide
Version 2020

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Grids and Grid Files - Listing Grids and Grid Files

1. Start a McIDAS session.

   At the Unix prompt:

   Type:    mcidas

   Your session should still be set for twenty frames from the last time you changed the Configuration GUI. If not, set it for twenty frames, as described in Getting Started.

2. Add the RTGRIDS dataset and list the grid datasets in the RTGRIDS group.

   Type:    DATALOC ADD RTGRIDS ADDE.SSEC.WISC.EDU;DSINFO GRID RTGRIDS

3. List the grid file directory for the GFS data.

   Type:    GRDLIST RTGRIDS/GFS.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 in the partial listing.

   DATASET NAME: RTGRIDS/GFS Dataset Position Creation Date Max Grids Directory Title ---------------- ------------- --------- ------------------------------- 9 2020139 20000 ALL 00Z GFS 0 HR<=VT<=24 HR 10 2020140 20000 ALL 00Z GFS 0 HR<=VT<=24 HR 19 2020139 20000 ALL 00Z GFS 24 HR< VT<=48 HR 20 2020140 20000 ALL 00Z GFS 24 HR< VT<=48 HR 29 2020139 20000 ALL 00Z GFS 48 HR< VT<=72 HR 30 2020140 20000 ALL 00Z GFS 48 HR< VT<=72 HR

4. Setup a local dataset that accesses a local grib file and list the first ten grids in the first grid file in the dataset. Download the grib files from a FTP site. For this example, it is assumed the data has been placed in the directory <local-path>/Data/Grid directory.

5. Download the files from ftp.ssec.wisc.edu.

   ftp ftp.ssec.wisc.edu
   login anonymous
   prompt
   binary
   cd pub/mug/Data/Grid
   mget GFS*

6. Example file name:

   GFS_CONUS_80km_20190903_1200.grib1

7. Run the DSSERVE command to access the grib file.

   Type:    DSSERVE ADD GRIB/GFS GRIB TYPE=GRID DIRFILE='<local-path>/Data/Grid/GFS_CONUS*'

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

   Type:    GRDLIST GRIB/GFS.1 NUM=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= /GFS_CONUS_80km_20190903_1200.gr PAR LEVEL DAY TIME SRC FHR FDAY FTIME GRID PRO ---- ---------- ------------ -------- ---- ---- ------------ -------- ----- ---- Z 850 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 1 LAMB Z 1000 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 2 LAMB Z 750 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 3 LAMB Z 900 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 4 LAMB Z 700 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 5 LAMB Z 875 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 6 LAMB Z 625 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 7 LAMB Z 950 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 8 LAMB Z 925 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 9 LAMB Z 550 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 10 LAMB Number of grids listed = 10

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

   Type:    GRDLIST GRIB/GFS.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= /GFS_CONUS_80km_20190903_1200.gr PAR LEVEL DAY TIME SRC FHR FDAY FTIME GRID PRO ---- ---------- ------------ -------- ---- ---- ------------ -------- ----- ---- Z 850 MB 03 SEP 19246 12:00:00 GFS 0 03 SEP 19246 12:00:00 1 LAMB Total pts= 6045 Num rows= 65 Num columns= 93 received: 2020141 013638Z Geopotential height GRIB ID numbers: Geographic = 211; PAR = 7; Model ID = 81; Level type =100 Units of gridded variable are GPM Scale of variable is: 2 Lambert Conformal Tangent Cone Projection Row num of pole= -113.34 Col num of pole= 53.00 Col spacing (m)= 81270.0 Standard Latitudes= 25.00 25.00 Standard Longitude= 95.00 Number of grids listed = 1

10. List all the 500 mb height (Z) grids in the grib file.

    Type:    GRDLIST GRIB/GFS LEVEL=500 PARAM=Z NUM=ALL

    The forecast grids for this level and parameter are listed.

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

    Type:    GRDINFO GRIB/GFS 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.

12. 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 GRIB/GFS HIST LEVEL=500 PARAM=Z FHOUR=12 BINSIZE=120 FORMAT=I5

13. 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 GRIB/GFS 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 925 MB from GFS Grid is at 120000 UTC on 2019246 from dataset: GRIB/GFS Row Col Latitude Longitude Value Units Level Param 34 64 39.721 84.897 76.3 % 925 MB RH 35 64 39.016 84.965 91.2 % 925 MB RH 34 65 39.666 83.982 85.7 % 925 MB RH 35 65 38.961 84.056 97.8 % 925 MB RH 36 65 38.254 84.129 76.2 % 925 MB RH 37 65 37.544 84.201 59.9 % 925 MB RH 38 65 36.833 84.272 56.5 % 925 MB RH 39 65 36.119 84.342 58.3 % 925 MB RH 40 65 35.404 84.412 55.2 % 925 MB RH 34 66 39.606 83.069 95.2 % 925 MB RH 35 66 38.902 83.149 87.0 % 925 MB RH 36 66 38.195 83.228 64.7 % 925 MB RH 37 66 37.485 83.306 58.8 % 925 MB RH 38 66 36.774 83.383 57.1 % 925 MB RH 39 66 36.061 83.458 55.2 % 925 MB RH 40 66 35.346 83.533 86.2 % 925 MB RH 34 67 39.542 82.156 96.1 % 925 MB RH 35 67 38.837 82.242 79.4 % 925 MB RH 36 67 38.131 82.327 66.1 % 925 MB RH 37 67 37.422 82.411 55.7 % 925 MB RH 38 67 36.711 82.494 63.6 % 925 MB RH 39 67 35.998 82.575 77.9 % 925 MB RH 40 67 35.283 82.656 79.9 % 925 MB RH 34 68 39.473 81.245 91.7 % 925 MB RH 35 68 38.768 81.337 72.2 % 925 MB RH 36 68 38.062 81.428 58.7 % 925 MB RH 37 68 37.353 81.518 62.6 % 925 MB RH 38 68 36.642 81.606 77.9 % 925 MB RH 39 68 35.930 81.693 72.4 % 925 MB RH 40 68 35.215 81.780 76.5 % 925 MB RH 34 69 39.399 80.335 77.9 % 925 MB RH 35 69 38.695 80.433 64.7 % 925 MB RH 36 69 37.988 80.530 72.1 % 925 MB RH 37 69 37.280 80.625 71.9 % 925 MB RH 38 69 36.569 80.719 68.0 % 925 MB RH 39 69 35.857 80.813 76.7 % 925 MB RH 40 69 35.143 80.904 72.3 % 925 MB RH 40 70 35.066 80.030 72.1 % 925 MB RH GRDINFO Done, Number of grids listed=1

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