Incorporate Near Real Time Green Vegetation Fraction Products In The NAM System

Green vegetation fraction (GVF) is a very important parameter for representing the land surface interactions with the atmosphere.  Monthly mean values from 1985 to 1989 are currently used in the NAM system.  Obviously, this data cannot represent the current real situation.  Therefore, near real time satellite products at 1 km resolution are developed from VIIRS.  These new products have weekly values and are updated daily.  These new products have been tested in the NAM.  Total 72 runs were conducted with 3 GVF products: climatology GVF and two versions of near real time GVF of 2014.  The primary results show that the model (NAM) is sensitive to GVF changes, and model performance can be improved by using the near real time GVF products.   Replacing Climatology GVF changes not only GVF itself, but also the surface albedo as well as canopy resistance.  Therefore, it is critical to replace the current static multi-year datasets of GVF with a consistent suite of updated products.