The WMO Rolling Review of Requirements and the State of Wind Measurements in the Global Observing System (Invited Presentation)

For more than 60 years the WMO Global Observing System has successfully served as the observational backbone for most weather prediction activities undertaken by national weather services around the world. As part of its Rolling Review of Requirements (RRR) process, WMO routinely reviews and assesses the performance of the GOS against the evolving requirements of its Members and issues guidance on the adequacy of the GOS and its various individual components. A very important input to this guidance is provided by global NWP centers around the world, based on impact experiments (data addition and data denial), Forecast Sensitivity Observation Impact (FSOI) diagnostics, and Observing System Simulation Experiments (OSSEs). Current assessments of the GOS continue to show a system that is heavily skewed toward mass or temperature observations over many parts of the globe, in large part thanks to the very successful deployment of infrared and microwave sounders and GNSS radio-occultation instruments in space. In contrast, vertically resolved wind measurements are obtained primarily from radiosonde ascents and from commercial aircraft ascents and descents out of and into major international airports, and they are therefore still relatively sparse in space and time. In this presentation we will briefly introduce the RRR and the guidance it provides regarding the composition of the GOS, before discussing possible avenues toward improving the balance of observations in the future.