S-SOM v1.0: a structural self-organizing map algorithm for weather typing

• Published in: Geoscientific Model Development Vol. 14; no. 4; pp. 2097 - 2111
• Main Authors: Doan, Quang-Van, Kusaka, Hiroyuki, Sato, Takuto, Chen, Fei
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 22.04.2021; Copernicus Publications
• Subjects: Algorithms; Climate; Clustering; Comparative analysis; Configuration management; Correlation coefficient; Correlation coefficients; Euclidean geometry; Laboratories; Neighborhoods; Performance evaluation; Pressure data; Pressure distribution; Sea level; Sea level pressure; Self organizing maps; Signal processing; Spatial data; Time series; Topology; Typing; Weather; Weather forecasting; Weather patterns; Japan
• ISSN: 1991-9603; 1991-959X; 1991-962X; 1991-9603; 1991-962X
• DOI: 10.5194/gmd-14-2097-2021

This study proposes a novel structural self-organizing map (S-SOM) algorithm for synoptic weather typing. A novel feature of the S-SOM compared with traditional SOMs is its ability to deal with input data with spatial or temporal structures. In detail, the search scheme for the best matching unit (BMU) in a S-SOM is built based on a structural similarity (S-SIM) index rather than by using the traditional Euclidean distance (ED). S-SIM enables the BMU search to consider the correlation in space between weather states, such as the locations of highs or lows, that is impossible when using ED. The S-SOM performance is evaluated by multiple demo simulations of clustering weather patterns over Japan using the ERA-Interim sea-level pressure data. The results show the S-SOM's superiority compared with a standard SOM with ED (or ED-SOM) in two respects: clustering quality based on silhouette analysis and topological preservation based on topological error. Better performance of S-SOM versus ED is consistent with results from different tests and node-size configurations. S-SOM performs better than a SOM using the Pearson correlation coefficient (or COR-SOM), though the difference is not as clear as it is compared to ED-SOM.