GrADS command quick list

GrADS command list :


A detail of GrADS commands can be found here :



$  grads     # start GraDS

ga->  ! ls  -ltr        # use ! to send command to shell.

ga->  open model.ctl    # open param description file

ga->  query file    # see what is in this file

ga->  d ps     # display

ga->  clear           clears the display
ga->  c

ga->  set lon -90     sets longitude to 90 degrees West
ga->  set lat 40      sets latitude to 40 degrees North
ga->  set lev 500     sets level to 500 mb
ga->  set t 1         sets time to first time step

ga->  set lon -180 0     X is now a varying dimension
ga->  set lat 0 90

Note: from now on, "ga->  " is omitted. 

c
set t 1 5

display (tsfc-273.16)*9/5+32

d sqrt(u*u+v*v)   # conversion

d mag(u,v)        # built-in function mag: magnitude of the wind

d ave(hgt,t=1,t=5)     # built-in function ave :

d hgt-ave(hgt,x=1,x=72)   # take means over longitude to remove the zonal mean:

d hgt(t=2) - hgt(t=1)     # perform time differencing


The complete specification of a variable name is:       name.file(dim +|-|= value, ...)

ga-> q   files                # check how many files are open.
File 1 : gfs.t12z.pgrb2.0p25.anl
  Descriptor: gfs.t12z.pgrb2.0p25.anl.ctl
  Binary: gfs.t12z.pgrb2.0p25.anl
File 2 : gfs.t12z.pgrb2.0p25.f000
  Descriptor: gfs.t12z.pgrb2.0p25.f000.ctl
  Binary: gfs.t12z.pgrb2.0p25.f000
ga-> set   dfile  1           # set default file to file 1.
Default file set to: gfs.t12z.pgrb2.0p25.anl
ga-> q    file           # check to see what is in file 1.

display hgt.2 - hgt.1

d hcurl(u,v)      # horizontal relative vorticity via finite differencing

d vint(ps,q,275)  # a mass weighted vertical integral

set cint 30     # contour interval
set ccolor 3    # contour color 
set csmooth on     # apply a cubic smoother

# gxout : graphics output
set gxout shaded     # alternate ways of displaying the data  .
set gxout contour
draw title 500mb Heights and Vorticity    # annotate title

set gxout vector    # view wind vector
d u;v

home decoration sample

water pipe

Water pressure: 80 psi

The most common source of excessive water pressure is the municipal water supplier. The water company sets the pressure to meet their own needs, such as delivering water to fire hydrants, high elevation buildings (or tall ones), and other reasons. This water pressure is often well over 100 psi, and too often over 150 psi. However, the maximum recommended pressure for a residence is 80 psi.

Copper pipe:

½ L : 1,200 psi

1/2 L :  1,000 psi

¾ M : 700 psi

½ ,3/8, ¾ Coil : 360 psi

Plastic coil pipe:

100 psi   ,

Usage: Landscape and agricultural irrigation, residential and commercial water service, well/pump water systems

CPVC pipe:  

100 psi

Usage: CPVC Ultra-Pure is used for hot and cold water systems

Temp: [ 33F, 180F]  or   [ 0c, 80c]

Size : measure OD ( outside diameter )

Advantage : as durable as copper  and stand up high temperature and pressure.

Used to transition from metal piping systems to CPVC

Used to transition from metal male pipe threads to CPVC.

PVC pipe:

280 psi

Size : measure ID ( inside diameter)

Usage: Pressure and drain, waste and vent

Schedule 40 : The most common Schedules are 40, 80 and 120, with Schedule 40 being the most readily available and commonly used. As the schedule gets larger the pipe wall gets thicker from the outside in, so the inside hole (bore) of the pipe gets smaller.

Adapter from copper to CPVC.

        

         

Use Compression Fittings on copper and PEX tubes.  

     

     

   

 

Use Compression Fittings on copper tubes

     

 

Prevent nail from drilling thru. pipe

 

Use PEX in bathroom remodel 

                                                                 

PEX pipe:

160 psi

30F < temp < 200F

Its pressure rating is even higher than CPVC, therefore it’s more suitable to replace copper pipe in bathroom or kitchen remodel projects.

Advantage: it’s more flexible.  Use clip ring can easily clip into shower header, etc. 
$30 / 1/2inch 100 ft  pex pipe
50C / crimp ring
80C / coupling fitting

      

Home basics

Home is all about how to take care of Water & fire/electricity. Once these two things are well taken care of, then the house should be in a good shape.

So it’s very important to know these basic information about water-related and electrical components used in your home.

Home =  water + electricity


1.  water pipe  
2.   todo

GRIB2

GRIB:  GRIdded Binary

          data in the form of grid-point values expressed in binary form

GRIB1 v.s. GRIB2

1. GRIB1 Product Definition Section into the GRIB2 Identification, Product Definition, and Data Representation Sections.
2. Option for iterating the Sections and expansion of the concept of templates.

A single GRIB2 message structure:

Definition of A field in a GRIB2 message:

     a grid ,    for example, ht@500mb for fhr 12.

eg: If there are 500 hPa height field forecasts on a Northern Hemisphere polar

stereographic grid produced by a particular numerical model at forecast hours 12, 24, 36, and 48, then we have 4 fields, which can be saved in one single GRIB2 message.

EG: 500 hPa height field forecasts produced at forecast 24 hours on

four different grid projections.

GrADS and GRIB2

 
wgrib : for GRIB1 
wgrib2 : for GRIB2

 
Relationship (Data descriptor : *.ctl files) between GRIB2 and GrADS: 
# ctl name don't matter, but better use cmd below.
$ g2ctl.pl gfs.t00z.pgrb2.0p25.f000 > abc.ctl
$ g2ctl.pl gfs.t00z.pgrb2.0p25.f000 > gfs.t00z.pgrb2.0p25.f000.ctl

 

Explanation of "PRES 0 1, 102,0 Pressure[Pa]" :
1) space deliminator, so it's four parts: PRES / 0 / 1,102,0 / Presssure[Pa]
2)
PRES: name of parameter
0 : 1 level on surface
1,102,0 : parameter description, see below ( VV, LTYPE, LEVEL,TRI)
Pressure[Pa]: unit

Eg of VV, LTYPE, (LEVEL), (TRI):
1, 102, 0 n/a
33, 100 n/a n/a
34, 100 n/a n/a

VV:
1 : pressure
33: wind u component
34: wind v component
LTYPE:
100 : pressure level
102 : mean sea level
(LEVEL)
0 : mean sea level

(TRI)
n/a

Explanation: 
1, 102, 0 : mean sea level pressure

 
Index file (.idx) : tell where fields in GRIB2 are located.
$ gribmap -v -i gfs.t00z.pgrb2.0p25.f000.ctl > grib2_field_vs_grads_var

Note : 1) binary file "gfs.t00z.pgrb2.0p25.f000.idx" will be generated. 
2) Input GRIB2 file "gfs.t00z.pgrb2.0p25.f000" must be present.