The scope of Dr. Koike’s activities has been broad, crosscutting several aspects of Earth sciences over his extensive career. The importance of his contributions is seen in the influence he has had on the community in planning large-scale environmental experiments and new paradigms for integrating data and models to create hydrologic knowledge for decision-making and benefitting society. Dr. Koike’s research over the years has covered a wide range of hydroclimatological areas, including hydrologic modeling, satellite-based data assimilation, and large-scale field and process studies, especially the extended studies related to the hydroclimatology of the Asian summer monsoon and water balance on the Tibetan Plateau. Toshio is best known for his development of an integrated hydrological modeling system with emphasis on the biospheric elements, including energy and carbon dioxide fluxes and soil moisture distribution. Toshio’s scientific leadership has contributed significantly to research initiatives of the World Climate Research Programme’s (WCRP) Global Energy and Water Cycle Experiment (GEWEX). The initiation and implementation of the GEWEX-Asian Monsoon Experiment (GAME)-Tibet project is a great example of his leadership. The impact of GAME on the international scientific community is seen in the thousands of published scientific articles, referencing the use of data and knowledge from the GAME-Tibet program. In addition to his scientific contributions, Dr. Koike has been a leader in shaping several international programs. He was a leader in embedding science into the Sendai Framework for Action on Disaster Risk Reduction. He has been a key player in the intergovernmental Group on Earth Observations (GEO), which initiated the Global Earth Observation System of Systems. For his part, he led the contributions of Japan for integration of observations and model simulations of international programs (WCRP/GEO/Global Climate Observing System) by facilitating the University of Tokyo to serve as a data hub archive with mirror sites around the world. He was instrumental in establishing Asia-Oceania Group on Earth Observations in cooperation with the governments of China, Korea and Australia. Dr. Koike serves as a role model when it comes to training a new generation of scientists. As the executive director of the International Centre for Water Hazard and Risk Management, he has created a training program for young scientists and practitioners from many developing countries including Bangladesh, Pakistan, the Philippines and others. Professor Koike’s outstanding contributions exemplify the spirit of the Ambassador Award and AGU’s goal of recognizing individuals committed to “advancing discovery in Earth and space sciences and its benefit for humanity and the environment.” — Soroosh Sorooshian University of California, Irvine Irvine, California

I am truly honored to receive the AGU Ambassador Award. I would like to thank my nominators, Professors Soroosh Sorooshian, Gordon McBean and Jeff Dozier, and my supporters, Drs. Antonio Busalacchi, Kevin Trenberth and Ghassem Asrar. I have been working on integrating data and models, particularly satellite data assimilation, to create hydrologic knowledge for helping to make science-based decisions. As a professor at the Nagaoka University of Technology and the University of Tokyo and the executive director of the International Centre for Water Hazard and Risk Management (ICHARM), I have also been creating education and training programs for young scientists and practitioners from many developing countries. I am deeply grateful that these research and educational projects have given me many chances to bridge the gap between science and local actions and contribute to various policy- and decision-making processes. Today, water-related disasters intensified by climate change are affecting various aspects of society all over the world. The impacts have extended to the water-food-energy nexus and the quality of life. When these circumstances worsen, society will eventually be plagued with problems arising in such areas as gender, equality and peace to a great degree. Throughout the COVID-19 pandemic, which has led to serious damage directly to our health, the world has learned that complex, cascading and systemic risks that are usually implicit in social, economic and environmental systems can suddenly emerge and threaten humanity beyond boundaries in space and time. “How should humanity survive such risks and live with them in a sustainable way?” is a fundamental question. The science community should support society’s transformation into a resilient, sustainable and inclusive body by playing key roles in cross-sectoral decision-making. The Chair’s Summary, approved at the 4th Asia-Pacific Water Summit held in Kumamoto, Japan, in April 2022, clearly states the following three targets: Promote water cycle consilience by accelerating the open science policy, particularly focusing on observation, modeling and data integration.Foster "facilitators," that is, catalytic beings who can lead the way toward resolving problems by providing professional advice on site using a broad range of scientific and Indigenous knowledge. Work together beyond disciplines and sectors among different levels while taking an end-to-end approach. I have been blessed with so many great opportunities to address these three targets in collaboration with excellent, enthusiastic leaders and colleagues and young scientists and practitioners all over the world. I am delighted to receive the 2022 Ambassador Award on behalf of all these people. Thank you. —Toshio Koike International Centre for Water Hazard and Risk Management Tsukuba, Japan