GEMPAK Listing Programs: SFLIST

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5.0 GEMPAK Listing Programs: SFLIST

SFLIST lists any parameters which can be derived from the data in a GEMPAK surface data file. SFLIST can also print the undecoded TEXT information for standard and special observations if that information was stored by the decoding program.

Let's start by using the surface listing program SFLIST.

Enter sflist to get the user interface. It should look something like this:

prompt% sflist

SFFILE          Surface data file               $GEMPAK/data/hrcbob.sfc
AREA            Data area                       WV 
DATTIM          Date/time                       LAST 
SFPARM          Surface parameter list          TMPF;DWPF;WTHR  
OUTPUT          Output device/filename          T       
IDNTYP          STNM or STID                    STID 
Parameters requested: SFILE, AREA ,DATTIM, SFPARM, OUTPUT, IDNTYP. 
GEMPAK-SFLIST>

If you weren't working through this tutorial and you didn't know much about SFLIST, you could read the on-line help file that describes this program, it's variables, how it works, and gives examples. To access this file: type phelp sflist at the GEMPAK-SFLIST> (or any) GEMPAK prompt. Here is the on-line help file for SFLIST. No need to thoroughly read it now, since we will learn about SFLIST here in the tutorial. Later, however, this feature may come in handy for learning about other programs.

Now, restore the defaults file. Remember, for SFLIST, you must type:

GEMPAK-SFLIST> restore defaults/sflist.nts

The user interface should now look like this:

GEMPAK-SFLIST>  display
SFFILE          Surface data file 
AREA            Data area 
DATTIM          Date/time 
SPARM           Surface parameter list 
OUTPUT          Output device/filename          t 
IDNTYP          STNM or STID                    stid 
Parameters requested: SFILE, AREA ,DATTIM, SFPARM, OUTPUT, IDNTYP. 
GEMPAK-SFLIST>

These are the variables that you have to set:

SFFILE
AREA
DATTIM
SFPARM

These variables have been set to default values, and you don't have to worry about them:

OUTPUT
IDNTYP

Variables

Note: You can see the GEMPAK help files on each of these variables by typing phelp name (where name is the name of the variable) at any GEMPAK prompt. For convenience in the tutorial, we've added a link to the help file for each variable below. ALSO, all the variables are described in the GEMPAK users manual in Chapter 3.

DATTIM - Date and Time.
- Entered as: YYMMDD/HHMM
  - YY = year
  - MM = month
  - DD = date
  - HH = hour
  - MM = minute
  For example:
  dattim=750301/1800
  means be March 1, 1975 at time 18:00 UTC (UTC, GMT, or Z is used as the standard meteorological time)
- Abbreviation:
  GEMPAK will look for the last date and time in the file.
  For example:
  dattim = /1200
  will look for the last date in the file and append the 1200 Z time to it.
- Ranges:
  dattim = 17/00-17/1200
- Lists:
  dattim=17/00;17/06;17/12
- Key Words:
```
list    Lists all the times in the file.
        Useful for when you don`t know
        the times when the data was 
        collected.  GEMPAK lets you choose 
        from the list of times.

last    GEMPAK uses the data from the
        last date/time in the file.

all     GEMPAK uses the data from every 
        date/time in the file. Useful for  
        comprehensive analyses.
```
SFFILE - Data file name (be sure to include the correct path)
- We'll be using Hurricane Bob data:
```
GEMPAK-SFLIST> $GEMPAK/data/hrcbob.sfc
```
AREA - Data area
There are many ways to specify area:
- Latitude/Longitude pairs to define the area:
Note: South and West are negative!
- Geographic Area
  The geographical areas are defined in the GEMPAK geography table $GEMTBL/stns/geog.tbl.
  For example:
```
AREA = US    AREA is defined as the region 
                around the United States. 
AREA = CO    AREA is defined as the region
                around Colorado.
```
- Station Area
  For example:
```
AREA = LAX   AREA is defined as the region 
                around Los Angeles.
```
- Full Data Set
```
AREA = DSET  AREA is defined as all stations         
                in the file.
```
- State, Province, Country
  You can specify AREA as any state or province abbreviation. In addition, abbreviations for the countries USA (US), Canada (CN), and Mexico (MX) can be used.
  For example:
```
AREA = QB    Quebec
AREA = CO    Colorado
AREA = MX    Mexico
```
- Country
  For countries other than US, CN, and MX, use the :C syntax.
  For example:
```
AREA = @AU:C    AREA is set to Australia
```
- Station List
  For when you know exactly which stations you want.
  For example:
```
AREA = @DEN;LAX;PDX     AREA is set to Denver
                        Los Angeles and Portland only.
```
- Integer Value
  Stations are selected if they fall into the range indicated.
  For Example:
```
AREA = SELV:0:2000   Selects stations with elevations
                        between 0 and 2000 meters.
AREA = SLAT:-45:45      Selects stations located between 45 
                        degrees south and 45 north.             
AREA = SLON:-45:45      Between 45 west and 45 east.
```
  Any station information can be used in this way: STID (Station ID-letters), STNM (Station Number), SLAT (Station Lat), SLON (Station Lon), STIM (Station Report Time).
- Key Symbols:
  Can be used with any of the geographical or station abbreviations.
- SFPARM - Surface Parameters
  - 4-Character parameter names
    For a complete list: phelp sfparm.
  - Separated by a semicolon
    sfparm = tmpc; pmsl; skyc
  - If necessary, GEMPAK will calculate parameters
    If the requested parameter is not present in the data set, GEMPAK will attempt to calculate it from other parameters that are available.
    For example:
    SFPARM = RELH
    If RELH (relative humidity) is not in the data set, GEMPAK will consult it's library of functional dependencies. GEMPAK finds:
    RELH=FUNC (TMPC;DWPT)
    Meaning, relative humidity (RELH) is a function of temperature (TMPC) and dew point (DWPT). GEMPAK can calculate RELH from the temperature and dew point as long as those parameters are in the data set. This is done automatically; all you have to do is ask for RELH.
  - Arithmetic functions
    You can manipulate the values of parameters using the following arithmetic functions:
    Multiply"*", Divide"/", Add"+", Subtract"-", Greater than">", Less than"<"
    For Example:
```
SFPARM = tmpc/2         Divides all temperatures by two.

SFPARM = pmsl>1000      Only includes mean sea level
                        pressures higher than 1000 mb.
```
  - Raw Hourly and Special reports (in addition to other parameters desired) if stored in the file
    SFPARM = text
    SFPARM = spcl
    SFPARM = text;spcl
    SFPARM = pmsl;tmpc;wthr;text
  Let's try it..

Exercises: Practice Exercises!!

List all measured data for the Rochester area from the last time in the Hurricane Bob surface data file.

Here's how to set the variables. Remember, you've already restored the defaults file earlier so the user interface should look like this:

 GEMPAK-SFLIST>display
 SFFILE    Surface data file                 
 AREA      Data area                         
 DATTIM    Date/time                         
 SFPARM    Surface parameter list            
 OUTPUT    Output device/filename            t
 IDNTYP    STNM or STID                      stid
 GEMPAK-SFLIST>

Now let's set the variables:

 GEMPAK-SFLIST>sffile=$GEMPAK/data/hrcbob.sfc
 GEMPAK-SFLIST>area=roc  
 GEMPAK-SFLIST>dattim=last
 GEMPAK-SFLIST>sfparm=dset

Redisplay the settings to be sure we've set everything properly:

GEMPAK-SFLIST>display
 SFFILE    Surface data file                 $GEMPAK/data/hrcbob.sfc
 AREA      Data area                         roc
 DATTIM    Date/time                         last
 SFPARM    Surface parameter list            dset
 OUTPUT    Output device (TPF)               T
 IDNTYP    STNM or STID                      STID
 GEMPAK-SFLIST>

Once all variables are defined, run the program.

GEMPAK-SFLIST>run

The list should look something like this (except quite a bit longer):

 GEMPAK-SFLIST>run
 PARM = PMSL;ALTI;TMPF;DWPF;SKNT;DRCT;GUST;WNUM;CHC1;CHC2;CHC3;VSBY;PT03;P03I;   
        HSUN;SNOW;TMPX;P24I
               
 
    STN  YYMMDD/HHMM      PMSL     ALTI     TMPF     DWPF     SKNT     DRCT
                          GUST     WNUM     CHC1     CHC2     CHC3     VSBY
                          PT03     P03I     HSUN     SNOW     TMPX     P24I
    ROC    910820/0600   1014.50    29.96    60.00    53.00     3.00    70.00
                      -9999.00     0.00   402.00 -9999.00 -9999.00    15.00
                          0.00 -9999.00 -9999.00 -9999.00    71.00 -9999.00
    ...

    YZE    910820/0600   1017.30    30.04    57.00    50.00     7.00    60.00
                      -9999.00     0.00     1.00 -9999.00 -9999.00    15.00
                      -9999.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
    YAM    910820/0600   1017.70    30.05    54.00    52.00     0.00     0.00
                      -9999.00     0.00     1.00 -9999.00 -9999.00    15.00
                      -9999.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
 Parameters requested: SFFILE,AREA,DATTIM,SFPARM,OUTPUT,IDNTYP.
 GEMPAK-SFLIST>

tip: Note: -9999.0 is the GEMPAK missing data value and indicates that no data was recorded.

Because this list was so overwhelmingly long, let's contract the data area. To do this we use the asterisk:

GEMPAK-SFLIST>area=roc**

This gives you a shorter list with data from only nine stations:

 GEMPAK-SFLIST>r
 PARM = PMSL;ALTI;TMPF;DWPF;SKNT;DRCT;GUST;WNUM;CHC1;CHC2;CHC3;VSBY;PT03;P03I;   
        HSUN;SNOW;TMPX;P24I                                                      
 
    STN  YYMMDD/HHMM      PMSL     ALTI     TMPF     DWPF     SKNT     DRCT
                          GUST     WNUM     CHC1     CHC2     CHC3     VSBY
                          PT03     P03I     HSUN     SNOW     TMPX     P24I
    ELM    910820/0600   1013.50    29.94    62.00    57.00     5.00    50.00
                      -9999.00     0.00   253.00   903.00  1104.00    10.00
                          0.00 -9999.00 -9999.00 -9999.00    79.00 -9999.00
    SYR    910820/0600   1013.40    29.93    61.00    56.00     6.00    10.00
                      -9999.00     0.00   302.00   802.00 -9999.00    10.00
                         -0.50 -9999.00 -9999.00 -9999.00    76.00 -9999.00
    JHW    910820/0600  -9999.00    29.92    60.00    51.00    11.00    90.00
                         14.00     0.00 -9999.00 -9999.00 -9999.00    10.00
                      -9999.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
    BUF    910820/0600   1014.20    29.96    62.00    57.00     6.00    90.00
                      -9999.00     0.00   852.00  1104.00 -9999.00    30.00
                         -0.20 -9999.00 -9999.00 -9999.00    76.00 -9999.00
    IAG    910820/0600   1013.60    29.94    61.00    54.00     6.00    90.00
                      -9999.00     0.00   352.00   803.00  2504.00    20.00
                          0.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
    ROC    910820/0600   1014.50    29.96    60.00    53.00     3.00    70.00
                      -9999.00     0.00   402.00 -9999.00 -9999.00    15.00
                          0.00 -9999.00 -9999.00 -9999.00    71.00 -9999.00
    ART    910820/0600   1014.60    29.96    49.00    48.00     4.00   130.00
                      -9999.00     0.00     1.00 -9999.00 -9999.00    15.00
                      -9999.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
    YTR    910820/0600   1014.70    29.96    59.00    52.00     2.00    90.00
                      -9999.00     0.00  2506.00 -9999.00 -9999.00    15.00
                      -9999.00 -9999.00 -9999.00 -9999.00 -9999.00 -9999.00
 Parameters requested: SFFILE,AREA,DATTIM,SFPARM,OUTPUT,IDNTYP.
 GEMPAK-SFLIST>

To leave the program, type exit.

GEMPAK-SFLIST>exit

GEMPAK Online Tutorial > GEMPAK Listing Programs

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Variables

Note: South and West are negative!