###### Abstract  
Visualization contributes to an in-depth understanding of ocean variables and phenomena, and a web-based three-dimensional visualization of ocean data has gained significant attention in oceanographic research. However, many challenges remain to be addressed while performing a real-time interactive visualization of large-volume heterogeneous scalar datasets in a web environment. In this study, we propose a WebGPU-based volume rendering framework for an interactive visualization of ocean scalar data. The ray casting algorithm, optimized with early ray termination and adaptive sampling methods, is adopted as the core volume rendering algorithm to visualize three-dimensional gridded data preprocessed from regular and irregular gridded volume datasets generated by ocean numerical modeling, utilizing the Babylon.js rendering engine and WebGPU technology. Moreover, the framework integrates a set of interactive visual analysis tools, providing functionalities such as volume cutting, value-based spatial data filtering, and time-series animation playback, enabling users to effectively display, navigate, and explore multidimensional datasets. Finally, we conducted several experiments to evaluate the visual effects and performance of the framework. The results suggest that the proposed WebGPU-based volume rendering framework is a feasible web-based solution for visualizing and analyzing large-scale gridded ocean scalar data. v 2025 18 January 2025 18 February 2025 18 January 2025 18 February 2025 18 January 2025 18 February 2025 18 February 2025  
visualization approaches [2; 3; 4; 5; 6], as more advanced techniques, can address these limitations by intuitively representing the geospatial characteristics of large-volume ocean spatiotemporal datasets, contributing to an in-depth understanding of ocean water masses and dynamic changes within ocean environmental phenomena. Therefore, this study focuses on developing a visualization framework for large-scale three-dimensional ocean scalar data on both regular and irregular grids, providing efficient data representation and interactive visual analysis capabilities for oceanographers and stakeholders. Ocean data visualization approaches are commonly categorized into two-dimensional and three-dimensional techniques [7]. Traditional two-dimensional data visualization techniques, typically based on Geographic Information Systems (GISs) in the form of 2D maps, have been widely adopted to depict and analyze ocean variables [8; 9; 10]. However, using 2D thematic maps to visualize complex data with three-dimensional spatial characteristics presents limitations. In contrast to two-dimensional visualization techniques, three-dimensional visualization techniques can better show the entire structure information of water masses and display the scattered features as a whole in three-dimensional space, enabling researchers to explore and comprehend water masses from multiple perspectives efficiently, thus supporting research in the field of ocean data analysis [11; 12]. Driven by the fast-paced advancements in computer graphics, the scope and sophistication of ocean data visualization research are continuously evolving, with an increasing focus on three-dimensional visualization techniques due to their ability to reveal spatiotemporal variability and complex characteristics of water masses in recent years. Three-dimensional data visualization encompasses various techniques, among which volume rendering is regarded as one of the most valuable. The primary techniques of volume rendering include indirect and direct volume rendering [13]. Indirect volume rendering, also known as iso-surfacing [14], includes algorithms like marching cubes and marching tetrahedra, which typically display three-dimensional data as constant-value contour surfaces. These algorithms can effectively capture and represent contour information of multidimensional volume data while providing advantages in computational efficiency and resource consumption.