新しい手法により海面水温を迅速かつ正確に推定(New Method Estimates Sea Surface Temps Quickly and Accurately)

2026-09-08 ノースカロライナ州立大学(NC State)

ノースカロライナ州立大学(NC State)の研究チームは、限られた観測データから海面水温(SST)を高速・高精度に再構成する新手法「Sparse Discrete Empirical Interpolation Method(S-DEIM)」を開発した。海面水温は気候変動、海洋生態系、天気予報に重要だが、ブイは観測地点が限られ、衛星観測も大気条件の影響を受けるため、高解像度データの推定が必要となる。S-DEIMは、瞬時の観測値と過去データから再帰型ニューラルネットワーク(RNN)で学習した情報を組み合わせる。NOAAの1989~2021年データで学習し、わずか100地点(全格子の0.2%)から高解像度SSTを再構成した結果、従来のDEIM等より約40%高精度で、91%が実測値±1℃以内となった。学習時間もCNNの約1時間半に対し約1分で、学習後の推定は1秒未満。気象予報や長期的な気候予測への応用が期待される。

新しい手法により海面水温を迅速かつ正確に推定(New Method Estimates Sea Surface Temps Quickly and Accurately)
A new method, S-DEIM, improves the estimation of global sea surface temperatures from scarce observational data. Image: Mohammad Farazmand

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疎な現場観測データに基づく地球規模の海面水温の迅速な推定 Rapid Estimation of Global Sea Surface Temperatures From Sparse Streaming In Situ Observations

Cassidy All, Kevin Ho, Maya Magnuski, Christopher Nicolaides, Louisa B. Ebby, Mohammad Farazmand
Journal of Geophysical Research: Machine Learning and Computation  Published: 27 August 2026
DOI:https://doi.org/10.1029/2026JH001279

Abstract

Reconstructing high-resolution sea surface temperatures (SST) from staggered SST measurements is essential for analyzing earth system processes. However, when SST measurements are sparse, the resulting inferred SST fields are rather inaccurate. Here, we show that Sparse Discrete Empirical Interpolation Method (S-DEIM) can be used as a model-free data assimilation method to reconstruct high-resolution SST fields from sparse in situ observations. The S-DEIM estimate consists of two terms, one computed from instantaneous in situ observations using empirical interpolation, and the other learned from the historical time series of observations using recurrent neural networks (RNNs). We train the RNNs using the National Oceanic and Atmospheric Administration’s weekly high-resolution SST data set spanning the years 1989–2021 which constitutes the training data. Subsequently, we examine the performance of S-DEIM on the test data, comprising January 2022 to January 2023. For this test data, S-DEIM infers the high-resolution SST from 100 in situ observations, constituting only 0.2% of the high-resolution spatial grid. We show that the resulting S-DEIM reconstructions are about 40% more accurate than earlier empirical interpolation methods, such as DEIM and Q-DEIM. Furthermore, 91% of S-DEIM estimates fall within mathematical equationC of the true SST. We also demonstrate that S-DEIM is robust with respect to sensor placement: even when the sensors are distributed randomly, S-DEIM reconstruction error deteriorates only by 1%–2%. S-DEIM is also computationally efficient: training the RNN, which is performed only once offline, takes approximately 1 minute. Once trained, the S-DEIM reconstructions are computed in less than a second.

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