VIC Forcings Files

The VIC Classic Driver requires subdaily forcings (meteorological or other). Forcing timestep must be the same as snow model timestep, which is specified by the SNOW_STEPS_PER_DAY parameter in the Global Parameter File. The required forcing variables and units are listed below and must also be specified in the Global Parameter File

Meteorological Forcings, Required in all simulations:

Variable Description Units
AIR_TEMP Average air temperature C
PREC Total precipitation (rain and snow) mm
PRESSURE Atmospheric pressure kPa
SWDOWN Incoming shortwave radiation W/m2
LWDOWN Incoming longwave radiation W/m2
VP Vapor pressure kPa
WIND Wind speed m/s

Vegetation Timeseries Forcings (Optional):

Variable Description Units
ALBEDO Surface Albedo fraction (between 0 and 1)
LAI Leaf Area Index m2/m2
FCANOPY Partial veg cover fraction ( = 1 - canopy gap fraction ) fraction (between 0 and 1)

Lake Forcings, Required when LAKES is TRUE:

Variable Description Units
CHANNEL_IN Incoming channel flow (total volume over the time step) m3

Carbon Cycle Forcings, Required when CARBON is TRUE:

Variable Description Units
CATM Atmospheric CO2 mixing ratio ppm
FDIR Fraction of incoming shortwave that is direct fraction
PAR Photosynthetically active radiation W/m2

As of October 2015, work is currently underway to develop a next generation meteorological forcing generator. This work, in part, will support the development of VIC forcings. Follow or contribute to the development of these tools by visiting