Joint Probability of Maxima Method for estuaries (JPMM+)

The JPMM+ code for use in MATLAB is provided in support of the following journal article: Palmer, K., Watson, C. S., Power, H. E., Hanslow, D., Morris, B., & Hunter, J. R., (2026). 'Quantifying the sea level and estuary contributions to changing high water levels in four major Australian estuaries'. Earth's Future (accepted 22 April 2026). The article describes the application of the Joint Probability of Maxima Method for estuaries (JPMM+). The JPMM+ is used for deriving frequency-based exceedance thresholds and for quanitifying the changing heights of water level maxima (high tide peaks) from a set of tide gauge records within a connected estuary system. The JPMM+ builds upon the previous JPMM (Joint Probability of Maxima Method) code functionality. JPMM: separates sea level observations from a tide gauge record into oceanographic components of mean sea level, high tide peaks, and skew surges and subsequently deriving the joint probability distributions of total high water level at coastal locations, including accounting for seasonality in the co-occurence of tides and surges. JPMM+: additionally provides functions for removing fluvial flood events, plotting flood hydrographs, matching entrance high water levels to the respective high water levels propagated into an estuary, and obtaining the propagation and deviation components of estuary high water levels. Included files: mlx_JPMMplus.mlx - Annotated MATLAB Livescript stat.m, statpdf.m, and jpm_exceed.m functions called within JPMM+ for computing statistics data.mat - sample dataset for demonstrating input format requirements tidepeaks_estry - Tide Peaks Toolbox functions adapted for estuaries Related Zenodo records: JPMM (Joint Probability of Maxima) Palmer, K. (2024). Supporting Information: Quantifying the mean sea level, tide, and surge contributions to changing coastal high water levels. Journal of Geophysical Research: Oceans. https://doi.org/10.5281/zenodo.12597330 Tide Peaks Toolbox Palmer, K. (2023). Tide Peaks Toolbox. In Coastal Engineering (Vol. 184, Number September 2023, p. 104354). Zenodo. https://doi.org/10.5281/zenodo.13691729 The sample dataset (data.mat) was collated from the Western Australian (WA) tide data used in the paper, provided by the WA Department of Transport (tide gauges) and Water Information Reporting (river gauges) portals. Grateful thanks to the Government of WA for providing these data open source.