Impact of land-surface initial conditions spin-up on warm season predictability simulated by the NCEP GFS coupled with the Noah LSM

The summer-time seasonal hindcasts for 2003 were discussed using the NCEP Global Forecast System (GFS). Two versions of GFS were used, one was based on the operational version that coupled with the OSU land surface model (LSM) and the other was an experimental version coupled with the Noah LSM. The use of Noah cycled global data assimilation system (GDAS) to enhance seasonal forecast skill was found to be self consistent with the experimental version of GFS. The impact of land state spin-up was evident for soil wetness at deep layers, while the impact on other fields was less evident.