OFViser: An Interactive Visual System for Spatiotemporal Analysis of Ocean Front

The ocean temperature front is a narrow transition zone where the temperature changes dramatically, which can be described by gradient of temperature. The temporal and spatial variations and the patterns of ocean fronts are of great concern to researchers by tedious observation and comparison of many spatial distribution maps of ocean front at different moments. However, a particular number of spatial states may only reflect certain spatial or temporal aspects of ocean front. This study designed a collaborative interactive visualization system to simultaneously integrate temporal and spatial analysis of ocean fronts with experts' knowledge, obtaining higher analysis efficiency and more comprehensiveness. The interactive statistical charts facilitate focus + context selection of points of interest in time and space, while the interactive Map-View and Map-Gallery support spatial analysis from overview to details. Moreover, this paper uses an unsupervised learning model named Self-Organizing Mapping network (SOM) to conduct spatio-temporal cluster analysis on different ocean fronts near the China Sea. The clustering results can be customized by user's colors specification, evaluated and interactively adjusted by researchers' knowledge. The spatio-temporal patterns of clustering result can easily mined by collaborative linkage of multi-graphs including unified distance matrix (U-Matrix), component plane, feature parallel coordinates plot, Map-View and other charts. The effectiveness and usability of the proposed system are demonstrated with two case studies.