Workshop Motivation: Deoxygenation occurred in open and coastal ocean regions during the mid-20th to early 21st centuries, influencing marine ecosystems through changes in marine habitats, nitrogen cycling, and trace metal cycling. However, detecting O2 trends against uncertainty remains a challenge based on historical observations. Thus, this workshop aims to bring together experts worldwide to discuss issues in historical ocean oxygen observations, investigate techniques for estimating oxygen changes, including their uncertainties, and pave the way for better quantification and understanding of ocean deoxygenation.

Key Topics to be discussed: Oxygen Data Quality Control; Bias Assessment and Correction; O2 observation system; Reconstruction; Uncertainty; Oxygen Time Series: Oxygen Trend and Variability.

Expected Participants: 20~30 experts in person

Financial Support: Local organizers can support several participants outside of China for international travel and accomodation. Please apply through the regis- tration form and the organizers will contact you within Aug.10~24.

Meeting form: hybrid (in-person and online)

Please fill in the following form for registration: https://forms.gle/i48CD6thMvcQbRT3A

Registration deadline: August 10th, 2025

Contacts:

Juan Du (Institute of Atmospheric Physics, Chinese Academy of Sciences)-dujuan10@mail.iap.ac.cn

Lijing Cheng (Institute of Atmospheric Physics, Chinese Academy of Sciences) -chenglij@mail.iap.ac.cn