1. GIE/EIG EUMETNET, Registered Number 0818.801.249 - RPM Bruxelles International Collaboration in the field of GNSS-Meteorology and Climate Monitoring Jonathan Jones 1, Guergana Guerova 2, Jan Dousa 3, Olivier Bock 4, Henrik Vedel 5, Eric Pottiaux 6, Galina Dick 5, Siebren de Haan 10, Rosa Pacione 9, Gunnar Elgered 11 1. Met Office, UK. 2. Sofia University, Bulgaria. 3. Royal Observatory of Belgium. 4. Geodetic Observatory Pecny, Czech Republic. 5. GFZ, Germany. 6. Danish Meteorological Institute. 7. Tallinn Univ. of Technology, Estonia. 8. IGN, France. 9. e-geos s.p.a ASI/CGS, Italy. 10. KNMI, Netherlands. 11. Chalmers Univ. of Technology, Sweden. Abstract Global Navigation Satellite Systems (GNSS) have revolutionised positioning, navigation and timing, becoming a common part of our everyday life. Aside from the more standard applications, GNSS has proved to be an accurate sensor of atmospheric water vapour, the most abundant greenhouse gas, accounting for 60-70% of warming, and of obvious importance in weather forecasting. Atmospheric humidity is one of the most important parameters for forecasting extreme weather events and monitoring climate change, but is under-sampled in current operational meteorological and climate observing systems. A new EU COST Action (ES1206): Advanced GNSS Tropospheric Products for Monitoring Extreme Weather Events and Climate (GNSS4SWEC) will address new and improved capabilities from concurrent developments in both GNSS and meteorological communities to improve (short-range) weather forecasting and climate projections. Multi-GNSS will be utilised to develop new, more advanced products, stimulating the full exploitation of GNSS-meteorology on a wide range of temporal and spatial scales. The Action will also promote the use of atmospheric data as an input to improve satellite-based navigation services. ES1206 will work in close collaboration with the wider international community, such as with the Global Climate Observing System Reference Upper Air Network (GRUAN) GNSS Precipitable Water Task Team (GNSS-PW TT). Ground-based GNSS-PW has been identified as a Priority 1 GRUAN observation, and the GNSS-PW TT’s goal is to develop explicit guidance on hardware, software and data management practices to obtain GNSS PW measurements of consistently high quality at all GRUAN sites. G11A-0901 Background At the present time, EIG EUMETNET supports the operational exploitation of more than 1,800 continuously operating GNSS receivers in the framework of the E-GVAP project (http://egvap.dmi.dk), delivering more than 13 Million Zenith Total Delay (ZTD) tropospheric estimates for assimilation into Numerical Weather Prediction (NWP) models. Recent advancements in NWP models however, require observations with improved timeliness and (spatial and temporal) resolution than are currently available. The potential of GNSS observations to meet these new requirements, and also for use in very short-range forecasting of severe weather, has improved considerably in the last few years due to improved GNSS raw data timeliness (real-time data streaming), improved GNSS network coverage and improved GNSS processing techniques (e.g. real-time data processing). Additionally, the synergy between GNSS and NWP is mutually beneficial: GNSS ZTD estimates are assimilated into NWP models, whilst at the same time it can be beneficial to use NWP data as an input into GNSS processing schemes to improve the modelling of atmospheric signal propagation. This could significantly improve future real-time positioning and navigation accuracy. Finally, inconsistencies in long-term GNSS time series makes climate trend analysis challenging. Ongoing reprocessing efforts using state-of-the- art models are underway which will provide consistent time series of tropospheric data, using 15+ years of GNSS observations from over 600 stations worldwide. These datasets will enable validation of systematic biases from a range of instrumentation, improve the knowledge of climatic trends of atmospheric water vapour, and benefit global and regional NWP reanalyses and climate model simulations (e.g. IPCC AR5) COST ES1206 – Organization The ES1206 Action Team consists of experts from 41 institutions in 28 countries. The Action will integrate a number of nationally funded research projects and directly collaborate with a number of international programmes and organisations (e.g. IGS, EUREF, E-GVAP and EUPOS) and will develop extensive links to others programmes such as Galileo, GEO, IPCC AR5, WMO-GRUAN, GMES, HYMEX and EPOS. ES1206 will be organized in three Working Groups (WGs): WG1: Advanced GNSS processing techniques WG2: GNSS for severe weather monitoring WG3: GNSS for climate monitoring Key Scientific Questions What are the additional benefits of multi-GNSS constellations on tropospheric products? Which new, more advanced, GNSS tropospheric products (slants, gradients etc) are suitable for operational nowcasting? How far can new, advanced GNSS tropospheric products improve the nowcasting of severe weather? What is the value of re-processed GNSS tropospheric products for climate research? How much can multi-GNSS tropospheric products improve climate analysis? Can atmospheric data improve real-time satellite-based positioning estimates? Benefits of COST ES1206 Coordinate international GNSS-meteorology R&D, improving cross-border data and knowledge transfer (data processing, meteorology and climate monitoring) Improve the understanding of atmospheric processes resulting in improved nowcasting of severe weather, leading to improved hazard management, lowering the risk to life and to national infrastructure. Promote the use of re-processed long-term GNSS tropospheric data in climate research. Promote the use of NWP data as an input to GNSS processing algorithms, leading to improved satellite-based products through improved signal propagation modelling. Develop new multi-GNSS processing techniques, using observations from all satellite constellations, leading to new, more advanced tropospheric products with improved accuracy and reliability. The Action will link to the activities of the tropospheric working groups of the International GNSS Service (IGS) and the International Association of Geodesy Reference Frame Sub- commission for Europe (EUREF) and work in support of the operational goals of E-GVAP. Coordinate the exploitation of GNSS and meteorological data for mutual benefit, leading to a consolidation of collaborating groups, resulting in more focused working practices and increasing the change of success with future research proposals. Figure 2 - GNSS slant delay schematic Contact - Jonathan.jones@metoffice.gov.uk Figure 1 - ES1206 project partners Figure 3 - Working Group 1 work plan Figure 4 - Working Group 2 work plan Figure 5 - Working Group 3 work plan Action Achievements Coordinate the development of new, multi-GNSS processing techniques and products Improve the understanding of short-term atmospheric processes Promote the use of, and determine the impact of, re-processed long-term GNSS tropospheric datasets for climate Link the Action activities to the IGS and EUREF, and work in support of E-GVAP Coordinate the exploitation of GNSS and meteorological data for mutual benefit Lead to a consolidation of collaborating groups