Update to Precipitation Validation

Precipitation is a reasonable metric for evaluating reanalyses, because it is coupled to both the water and energy cycles and will be affected by the heating and water vapor increments, as well as variations in the dynamic response of the system to the data assimilation. Bosilovich et al (2008) evaluated precipitation among reanalyses, and also included results from the MERRA validation experiments. Below is an update of some of the Taylor diagrams presented there, now including both MERRA and ERA Interim reanalyses. See Bosilovich et al. (2008) for more explanaiton and the original citations for Taylor diagrams. These are showing that both MERRA and Interim precipitation are close in skill, and ahead of the previous generations of reanalyses. NCEP CFSR will be included in the next version of this evaluation. This was presented in part at the last AMS Annual Meeting (presentation at AMS).