Can Multi-Mission Altimeter Datasets Accurately Measure Long-Term Trends in Wave Height?

Ian R Young,Agustinus Ribal

doi:10.3390/rs14040974

Ian R Young, Agustinus Ribal

Open Access

https://doi.org/10.3390/rs14040974

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Journal: Remote sensing	Publication Date: Feb 16, 2022
Citations: 17	License type: CC BY 4.0

Affiliation: University of Melbourne, Hasanuddin University

Abstract

A long-duration, multi-mission altimeter dataset is analyzed to determine its accuracy in determining long-term trends in significant wave height. Two calibration methods are investigated: “altimeter–buoy” calibration and “altimeter–altimeter” calibration. The “altimeter–altimeter” approach shows larger positive trends globally, but both approaches are subject to temporal non-homogeneity between altimeter missions. This limits the accuracy of such datasets to approximately ±0.2 cm/year in determining trends in significant wave height. The sampling pattern of the altimeters is also investigated to determine if under-sampling impacts the ability of altimeters to measure trends for higher percentiles. It is concluded that, at the 99th percentile level, sampling issues result in a positive bias in values of trend. At lower percentiles (90th and mean), the sampling issues do not bias the trend estimates significantly.

Highlights

Multi-Mission Altimeter DatasetsOver recent decades, significant research has focused on the temporal variability of global ocean surface wave climate
This paper aims to investigate these issues of calibration method and sampling density for long-duration, multi-mission altimeter data
The analysis shows that the ability of multi-mission altimeter datasets to determine trends in long-term significant wave height is limited by the accuracy and consistency with which each of the altimeter missions can be calibrated

Summary

Introduction

Significant research has focused on the temporal variability of global ocean surface wave climate This includes studies of both long-term trends, potentially as a result of anthropogenic climate change, and the impact of multi-year atmospheric modes on the significant wave height, Hs. Changes in global ocean wave climate are potentially important for a range of reasons, including engineering design and operation of vessels and facilities [1], the impacts on coastal erosion [2] and flooding [3,4], the breakup of polar sea-ice [5], and the dynamics of marine ecosystems [6]. The non-homogeneity manifests as discontinuities over time, which results in unacceptable bias in trend estimation [11,12,13]

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