GESLA Version 4: Further Enhancements to the Global Higher-Frequency Sea-Level Dataset

Abstract. This paper presents GESLA-4, the latest major update to the quasi-global, higher-frequency sea-level dataset known as GESLA (Global Extreme Sea Level Analysis). Since its first release in 2009, GESLA has become a widely used observational resource for investigating tides, storm surges, extreme sea levels, and other coastal and oceanographic processes, supporting numerous published studies and major national and international assessments, including assessment reports of the Intergovernmental Panel on Climate Change. GESLA-4 represents a substantial expansion of the dataset, containing 136,069 station-years of observations across 6,682 records obtained from 43 international, national, and regional data sources. This represents an increase of 45,048 station-years and 1,563 records relative to GESLA-3. In addition to extending existing records and incorporating new data sources, GESLA-4 includes improvements to data processing and consistency, including a systematic review of record time zones. Data accessibility has also been enhanced through programmatic access via an Environmental Research Division's Data Access Program (ERDDAP) server and direct download links for individual stations via Amazon Web Services. This paper describes the assembly, processing, format and accessibility of GESLA-4, and also examines how the dataset has evolved across its four releases since 2009, and reviews how its scientific use has grown and diversified. GESLA-4 provides an extensive and readily accessible observational resource for investigating coastal sea levels, their variability and extremes, and their response to a changing climate.