(GRASS Raster Program)
DESCRIPTION
r.ros generates the base ROS value, maximum ROS value, direction
of the maximum ROS, and optionally the maximum potential spotting distance
of a wildfire for each raster cell in the current geographic region. The
calculation of the two ROS values for each raster cell is based on the
Fortran code by Pat Andrews (1983) of the Northern Forest Fire Laboratory,
USDA Forest Service. The direction of the maximum ROS results from the
vector addition of the forward ROS in wind direction and that in upslope
direction. The spotting distance, if required, will be calculated by a
separate function, spot_dist(), which is based on Lathrop and Xu (in preparation),
Chase (1984) and Rothermel (1991). These three or four raster map layers
serve as inputs for another GRASS raster program r.spread. More information
on r.ros and r.spread can be found in Xu (1994).
moisture_1h=name Name of an existing raster map layer in the user's current mapset search path containing the 1-hour (<.25") fuel moisture (percentage content multiplied by 100).
moisture_10h=name Name of an existing raster map layer in the user's current mapset search path containing the 10-hour (.25-1") fuel moisture (percentage content multiplied by 100).
moisture_100h=name Name of an existing raster map layer in the user's current mapset search path containing the 100-hour (1-3") fuel moisture (percentage content multiplied by 100).
moisture_live=name Name of an existing raster map layer in the user's current mapset search path containing live (herbaceous) fuel fuel moisture (percentage content multiplied by 100).
velocity=name Name of an existing raster map layer in the user's current mapset search path containing wind velocities at half of the average flame height (feet/minute).
direction=name Name of an existing raster map layer in the user's current mapset search path containing wind direction, clockwise from north (degree).
slope=name Name of an existing raster map layer in the user's current mapset search path containing topographic slope (degree).
aspect=name Name of an existing raster map layer in the user's current mapset search path containing topographic aspect, counter-clockwise from east (GRASS convention) (degree).
elevation=name Name of an existing raster map layer in the user's current mapset search path containing elevation (meters).
output=name Prefix of new
raster map layers in the user's current mapset to contain
1) the base (perpendicular) ROS
(cm/minute);
2) the maximum (forward) ROS (cm/minute),
3) the direction of the maximum
ROS, clockwise from north (degree), and optionally
4) the maximum potential
spotting distance (meters).
If 'my_ros' is given as the output name, then r.ros automatically
assigns 'my_ros.base', 'my_ros.max', 'my_ros.maxdir', and optionally,
'my_ros.spotdist' as the names for the actual output map layers.
If the options moisture_1h=name, moisture_10h=name, and moisture_100h=name are partially given, the program will assign values to the missing option using the formula:
moisture_100h = moisture_10h + 1 = moisture_1h + 2.
However at least one of them should be given. Options velocity=name
and direction=name must be in pair, whether given or not. If none
is given, the program will assume a no-wind condition. Options slope=name
and aspect=name must be in pair, whether given or not. If none is
given, the program will assume a topographically flat condition. Option
elevation=name must be given if -s option is used.
r.ros -vs model=fire_model moisture_1h=1hour_moisture moisture_live=live_moisture
velocity=wind_speed direction=wind_direction
slope=slope aspect=aspect elevation=elevation output=my_ros