8.3    Sensitivities of Spectral Nudging Toward Moisture

Otte, Tanya L., U.S. Environmental Protection Agency, Martin J. Otte, U.S. EPA, Jared H. Bowden, University of North Carolina, and Christopher G. Nolte, U.S. EPA

Several studies with WRF and other models have shown that spectral nudging can improve predictions of 2-m temperature and large-scale fields for regional climate modeling.  However, compared to analysis nudging, precipitation predictions with spectral nudging are inferior for both means and extremes (Bowden et al. 2012; Otte et al. 2012).  In this work, we implemented spectral nudging toward moisture and performed several multi-decadal sensitivity runs with WRF.  We show that careful and conservative use of spectral nudging toward moisture (specific humidity) improves the prediction of precipitation without compromising other thermodynamic fields.