What Is the Relative Importance of Different Types of Observations for Forecast Skill? Report from the Sixth WMO Impact Workshop in Shanghai, May 2016 (Invited Presentation)

It is well known that it is impossible to do numerical weather prediction (NWP) without adequate observational information to help determine the initial conditions. But what, exactly, is “adequate information”, and how do we know if the Global Observing System of the World Weather Watch, on which all NWP centers rely for observations, actually delivers that? Since 1997 WMO has organized a series of workshops at which representatives from all major NWP centers have presented and discussed their individual assessments of the respective contributions to skill of all the major elements of the GOS, using both data denial and data addition experiments, various types of modern sensitivity diagnostics and Observing System Simulation Experiments. The most recent of these events, the Sixth WMO Workshop on the Impact of Various Observing Systems on NWP was held in Shanghai in May 2012 and was attended by 80 participants from 14 countries. The Workshop resulted in a report that provides a consolidated assessment of the GOS from an NWP perspective as well as a number of recommendations addressed at developers and operators of both space-based and conventional observing system. The main workshop results and recommendation will be summarized in this presentation.