ICOS-CH Phase 4

ICOS-CH Phase 4 (2025 to 2028), the Swiss contribution to ICOS RI and continuation of ICOS-CH Phases 1 to 3 (2013 to 2025), provides high-quality greenhouse gas (GHG) concentration and flux data, complemented with meteorology, tree ecophysiology, and forest carbon stocks. Such data are relevant for a mechanistic understanding of carbon sinks and sources for different land use types, and for evidence-based policy- and decision-making to develop strategies to combat climate change and its consequences. Three unique stations are the backbone of ICOS-CH: a Class 1 Eco-system station (Davos, CH-Dav), a Class 1 Atmosphere station (Jungfraujoch, JFJ), and an Associ-ated urban station (Basel Klingelbergstrasse, CH-BaK; labelling ongoing). Thus, the overarching goal of Phase 4 is to maintain the CH-Dav and JFJ stations at Class 1 level (highest standards) and the CH-BaK station at Associated level.

In Subproject A, ICOS-CH is coordinated and ICOS-CH contributions to ICOS RI activities at national and international levels managed. This will allow continuous improvement and optimisation of integra-tion and communication of ICOS-CH, infrastructure-enabled research, and services offered. Continued services include free infrastructure access, open data and data products, participation in training schools, open exchange of experiences, publications, and media products for different target groups. Subproject B Davos, Subproject C Jungfraujoch, and Subproject D Basel will fulfil ICOS RI require-ments in terms of station operation, maintenance, calibration, response time in case of instrument failure, upgrade as well as data handling, transfer and data analyses. In addition, new instrumentation will be installed and tested, necessary flask sampling, biomass and soil carbon inventories carried out. With colleagues from ICOS RI, protocols for non-CO2 ecosystem flux calculations and for urban flux and observations and site characterisation will be developed. As from its very beginning in 2013, ICOS-CH data strategy will fully comply with open research data principles.

Based on these efforts, but also on past experiences and highly successful collaborations, ICOS-CH provides fundamental data and support for a growing number of users from a wide range of user communities (i.e., students, scientists, institutions, governmental agencies, general public) nationally and internationally. Based on open science principles, ICOS-CH enables research by users, either in situ, using excellent infrastructures, or in silico, using high-quality, long-term but also near-real time data, and will offer outstanding opportunities for national and international collaborations, ranging from long-term global monitoring networks to short-term research projects. Co-location of com-plementary measurements and observations from other long-term programmes leverage synergies and increase the value of the individual networks. Continuing past activities, ICOS-CH will provide first-rate support for capacity building and promote education of students and early-career scientists as well as outreach to society. ICOS-CH is highly valued by ICOS RI, strongly supported by all member institutions and by the State Secretariat for Education, Research and Innovation (SERI).