r.stage3(1)	       Grass User's Manual	      r.stage3(1)



NNAAMMEE
       rr..ssttaaggee33 - NEXRAD weather radar input tool.

       _(_G_R_A_S_S _R_a_s_t_e_r _P_r_o_g_r_a_m_)

GGRRAASSSS VVEERRSSIIOONN
       4.x

SSYYNNOOPPSSIISS
       rr..ssttaaggee33 [--vv] iinnppuutt==_n_a_m_e [oouuttppuutt==_n_a_m_e]

DDEESSCCRRIIPPTTIIOONN
       A  Stage  III precipitation product is a mosaic of all the
       Stage II precipitation estimates  within  the  RFC  (River
       Forecast  Center)  area.   The Stage III products are pro-
       duced by merging radar precipitation estimates  (Stage  I)
       with  ground  truth  data  provided by rain gages.  In the
       Arkansas-red River Forecast Center (ABRFC)  this  includes
       15  88-D  radars and approximately 500 rain gages.  The 13
       RFC's within the United	States	will  eventually  produce
       Stage  III products.  As of 4-94 the ABRFC is the only RFC
       currently producing Stage III products.	 As  more  radars
       come on line other RFC's will begin producing this product
       as well.  The 88-D radars have difficulty  detecting  pre-
       cipitation  when  the raindrops are very small or when the
       precipitation is in the form of snow.  Under these  condi-
       tions  precipitation estimates tend to be under estimated.
       Large Hail within a storm causes the radar to  over  esti-
       mate precipitation amounts.  The grid cell size is approx-
       imately 4 km by 4 km.  The  NetCDF  files  containing  the
       precipitation  values  in  the units of 1/100 of mm can be
       obtained from ABRFC's  gopher  server.	_r_._s_t_a_g_e_3  program
       generates  the GRASS raster map layers only in the Lat/Lon
       coordinate system.  UTM is not utilized because	the  area
       being  referenced is too large for a UTM zone.  The region
       settings for the ABRFC's coverage area is:

	__________________________________________
	projection: 3 (Latitude-Longitude)
	zone:  0
	north: 41:16:06N
	south: 32:48:28N
	east:  90:53:28W
	west:  107:08:03W
	__________________________________________


       You may use the clark66 spheroid and  use  any  resolution
       that  may  be  suitable as far as your other data require-
       ments are concerned. (start with esres= nsres =	0:00:30).


       This  version  of  _r_._s_t_a_g_e_3 will work only on NetCDF files
       created after the 6th of April 1994.


       You will need the NetCDF libraries created by the  Unidata
       Program	Center.  The NetCDF libraries can be obtained via
       anonymous     ftp     from     unidata.ucar.edu	    under
       pub/netcdf/netcdf.tar.Z.  You will the need to compile the
       libraries.   _r_._s_t_a_g_e_3  can  be  only  run  within   GRASS.
       _r_._s_t_a_g_e_3  needs	both  the NetCDF libraries as well as the
       GRASS libraries.  If  you  have	all  the  libraries  then
       _r_._s_t_a_g_e_3  can  be  compiled simply by running "gmake" (For
       GRASS 4.2 it is gmake4.2) in this directory.


       In the above, if the output  parameter  is  not	specified
       then  a	mapname  with  the same name as that of the input
       parameter is created.  The rainbow colortable  is  created
       for  the resultant map.	The resulting maps have a resolu-
       tion of 0:02:59.


       A few sample NetCDF files and the corresponding GIF  files
       are  provided  in the sample directory.	The vector direc-
       tory contains the vector boundary output from the  command
       _v_._o_u_t_._a_s_c_i_i of the ABRFC basin.


       To  run _r_._s_t_a_g_e_3 on the sample files just go into the sam-
       ple directory and type:


       _r_._s_t_a_g_e_3 _-_v _i_n_=_0_4_0_5_9_4_1_8_._n_c


       This will create a raster map  by  the  name  04059418.nc.
       Similarly  _r_._s_t_a_g_e_3  can be run on other sample files. You
       can use the  corresponding  GIF	files  to  compare  them.
       Since  the GIF files are in a different projection system,
       there is some distortion in between the	raster	maps  and
       the  GIF file.  However the values in the raster are prop-
       erly georeferenced.

   OOPPTTIIOONNSS
   FFllaagg::
       --vv     Verbose


   PPaarraammeetteerrss::
       iinnppuutt == nnaammee
	      Name of the netcdf file to be converted.

       oouuttppuutt == nnaammee
	      Name of the resultant raster map.


AAUUTTHHOORRSS
       Nalneesh Gaur, Arkansas Red Basin River Forecast Center

       Norman L. Bingham, Arkansas Red Basin River Forecast  Cen-
       ter

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_4 _$



GRASS 5.0					      r.stage3(1)
