WRF_ELEC Files

###########
## INTRO ##
###########

This is a first release in WRF of a basic electrification for the NSSL microphysics scheme. 
The electrification parameterizations are based out of past work in modeling. The basics of the
charge separation schemes comes from Mansell et al. (2005). Their use in the NSSL 2-moment microphysics
is shown in Mansell et al. 2010 and Mansell and Ziegler (2013). First implementation into WRF is
described by Fierro et al. (2013), which includes details of the basic discharge scheme (cylindrical
discharge regions centered on lightning initiation points).

Mansell et al. 2005: Charge structure and lightning sensitivity in a simulated 
   multicell thunderstorm. J. Geophys. Res., 110, D12101, doi:10.1029/2004JD005287

Mansell, E. R., C. L. Ziegler, and E. C. Bruning, 2010: Simulated electrification of a small 
   thunderstorm with two-moment bulk microphysics. J. Atmos. Sci., 67, 171-194, doi:10. 1175/2009JAS2965.1.

Fierro, A. O., E.R. Mansell, C. Ziegler and D. R. MacGorman 2013: The
  implementation of an explicit charging and discharge lightning scheme
  within the WRF-ARW model: Benchmark simulations of a continental squall line, a
  tropical cyclone and a winter storm. Monthly Weather Review, Volume 141, 2390-2415 


##############
## CONTACTS ##
##############

If you have trouble with this option please contact the developers directly (i.e., not wrf_help):

    Ted Mansell (Ted.Mansell _at_ noaa.gov)
    Alexandre Fierro (Alex.Fierro _at_ noaa.gov) 

###########
## SETUP ##
###########

# Obtain WRF-ELEC code #

Similar to WRF-CHEM, necessary files are provided externally at

https://sourceforge.net/projects/wrfelec

Files are available as an archive:

    WRFV37_ELEC.tgz (for use with unmodified WRF-3.7.0
    WRF_ELEC.tgz (only the 'elec' subdirectory for WRF-3.7.1 and later)
    
or as individual files in the "elec-3.x" directories.

First expand the archive in the top level of your WRF 3.7 directory and install BoxMG (below)
before running 'configure'.


# BoxMG #

The BoxMG elliptic equation solver is required for WRF-ELEC to calculate the 3D electric
potential. This library is distributed at the moment as a source code archive at

http://sourceforge.net/projects/boxmg4wrf/

It is also available via svn at the same site. Note that the code has only been compiled for Intel/AMD
(non-Itanium) architecture under Linux and OS X. (Not attempted on Cray or other platforms -- if you
succeed on other platforms, please let us know at <ted.mansell@noaa.gov>)

BoxMG needs to be installed before configuring WRF. Unpack the archive where you want the 
libraries to be and then follow the instructions in the INSTALL document.


# Configure/compile WRF #

To configure WRF, two environment variables must be set: WRF_ELEC and BOXMG

For tcsh:

setenv WRF_ELEC 1
setenv BOXMGLIBDIR [path to boxmg directory]

For bash:

export WRF_ELEC=1
export BOXMGLIBDIR=[path to boxmg directory]

For example, if the boxmg library directory is /opt/local/boxmg/lib, then (for tcsh)

  setenv BOXMGLIBDIR /opt/local/boxmg

Then run 'configure' in the WRF main directory and select an option for 'dmpar' (distributed
memory parallel). The code is set up only to use the MPI parallel solver from BoxMG, so do
not compile for serial mode. (It can still be run on a single processor, however.)


#############
## OPTIONS ##
#############

Specific namelist.input options are given below, along with a list of output fields.


Electrification only works with the NSSL 2-moment options (with hail):

 mp_physics(max_dom)
                                     = 17, NSSL 2-moment 4-ice scheme (steady background CCN)
                                     = 18, NSSL 2-moment 4-ice scheme with predicted CCN (better for idealized than real cases)
                                       ; to set a global CCN value, use
                                       
Other variables in the &physics namelist:

 elec_physics                        = 0, electrification (and charge arrays) turned off (DEFAULT)
                                     = 1, electrification turned on with "1D" lightning scheme based on Ziegler and MacGorman (1994, JAS) (only works with mp_physics = 17 or 18, i.e., 2-moment NSSL schemes)

 nssl_ipelec (max_dom)     ! NOTE: only set this to a nonzero value on the innermost domain
                                     = 0, charging turned off (DEFAULT)
                                     = 2, non-inductive charging only
                                     = 3, non-inductive + inductive charging
                                     = 1, not used (reserved for future use)

 nssl_idischarge                     = 0, no discharge
                                     = 1, discharge turned on (DEFAULT)

 nssl_iscreen                        = 0, no screening layer (DEFAULT)
                                     = 1, screening layer scheme of Ziegler et al. (1991, JGR)
                                     = 2, screening layer only applied at cloud top (seems to be better for storm complexes and large storms)

 nssl_ibrkd                          = breakdown electric field profile to initiate lightning
                                     = 1, constant profile with height with value set by nssl_ecrit
                                     = 2 to 5, variants of vertical Ecrit profile of Dwyer (2003, GRL) - '4' is recommended (DEFAULT is 4).

 nssl_isaund                         = Calls the appropriate version of the UMIST (e.g., Saunders et al. 1991 scheme)
                                     = -5 : Saunders etal 1991 (following Helsdon et al. 2001, but use normal charging instead of 'anomalous' zones)
                                     = 0 : Saunders 1991 (modified as in Wojcik 1994)
                                     = 2 : RR scheme ( no extra factor ) (Mansell et al. 2005, JGR)
                                     = 4 : Saunders and Peck Scheme ( no extra factor ) (Mansell et al. 2005, JGR)
                                     = 9 : Saunders and Peck Scheme ( no extra factor, cutoff at -32.47 as orig eq. from sp98 ) (Mansell et al. 2010, JAS)
                                     = 10 : Brooks et al. RARcrit for T > -15 using saund2 (otherwise same as isaund=2) (set rarfac to negative in saund2)
                                     = 11 : Brooks et al. RARcrit for T > -15 using saund6 (otherwise same as isaund=4)
                                     = 12 : Brooks et al. RARcrit for T > -15 using saund6 (otherwise same as isaund=9) (DEFAULT)

 nssl_lightrad                       = 12000, radius (m) of discharge cylinder for 1-D discharge scheme

 nssl_disfrac                        = 0.3, nominal fraction of charge removed per discharge

 nssl_ecrit                          = 120000, breakdown electric field (Volts/m) to initiate lightning (i.e., constant value with height). (for nssl_ibrkd=1)


###################
## OUTPUT FIELDS ##
###################

2D, time-dependent:

  LIGHT      : Sum of lightning initations in the column
  LIGHTDENS  : Flash extent density (sum of the number of flashes that extend into the grid column)
  LIGHTDIS   : A kind of "source point" density that adds up the number of points in a column that have lightning
               charge magnitude greater than 0.1*chgthr (effectively 0.01 nC/m^3 or more)

3D, time-dependent:

  POT         : Electric potential (Volts)
  ELECMAG     : Electric field magnitude
  ELECX       : x-component of E
  ELECY       : y-component of E
  ELECZ       : z-component of E
  INDUC       : Inductive charge separation rate
  NONINDUC    : Net noninductive charge separation rate
  SCW         : Charge density carried by cloud droplets
  SCR         : Charge density carried by rain
  SCI         : Charge density carried by cloud ice
  SCS         : Charge density carried by snow
  SCH         : Charge density carried by graupel
  SCHL        : Charge density carried by hail
  SCTOT       : Net charge density
  SCIONA      : Residual charge from lightning and evaporating hydrometeors that has not been reattached to another species