Learning Data-driven Surrogate and Correction Models for Satellite Observations in Numerical Weather Prediction

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Main Authors: Buono, Gian Luca, Hollborn, Stefanie, Potthast, Roland, Schäfer, Jörg, Simon, Martin
Format: Preprint
Published: 2026
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author Buono, Gian Luca
Hollborn, Stefanie
Potthast, Roland
Schäfer, Jörg
Simon, Martin
author_facet Buono, Gian Luca
Hollborn, Stefanie
Potthast, Roland
Schäfer, Jörg
Simon, Martin
contents Satellite observations play a critical role in numerical weather prediction where they are assimilated through an observation operator that maps model states to radiances. In the traditional Ensemble Kalman Filter, these observations are used to update the state by weighting their associated errors against model uncertainties to produce an optimal estimate. This process requires radiative transfer simulations for passive, downward-viewing satellite radiometers operating in the visible, infrared, and microwave spectra. Typically, such simulations rely on numerically integrating physical laws via models like RTTOV. In this paper, we introduce two machine learning surrogate observation operators inspired by modern computer-vision architectures: First, a fully data-driven emulator of radiative transfer, and second, a hybrid incremental correction model that learns only the residual relative to RTTOV, thereby retaining established physics while enabling data-driven refinement in complex conditions such as cloud-affected situations. The residual formulation improves radiance accuracy (lower Root Mean Squared Error (RMSE) than the fully data-driven emulator and RTTOV) and adds only moderate computational costs to the assimilation step. Both models combine 3D convolutions for vertical profile encoding with a 2D U-Net operating on latitude-longitude grids, allowing joint learning of vertical structure, spatial correlations, and inter-channel dependencies. We further provide a theoretical justification for deploying the hybrid surrogate as an observation operator in data assimilation.
format Preprint
id arxiv_https___arxiv_org_abs_2603_22037
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Learning Data-driven Surrogate and Correction Models for Satellite Observations in Numerical Weather Prediction
Buono, Gian Luca
Hollborn, Stefanie
Potthast, Roland
Schäfer, Jörg
Simon, Martin
Atmospheric and Oceanic Physics
Satellite observations play a critical role in numerical weather prediction where they are assimilated through an observation operator that maps model states to radiances. In the traditional Ensemble Kalman Filter, these observations are used to update the state by weighting their associated errors against model uncertainties to produce an optimal estimate. This process requires radiative transfer simulations for passive, downward-viewing satellite radiometers operating in the visible, infrared, and microwave spectra. Typically, such simulations rely on numerically integrating physical laws via models like RTTOV. In this paper, we introduce two machine learning surrogate observation operators inspired by modern computer-vision architectures: First, a fully data-driven emulator of radiative transfer, and second, a hybrid incremental correction model that learns only the residual relative to RTTOV, thereby retaining established physics while enabling data-driven refinement in complex conditions such as cloud-affected situations. The residual formulation improves radiance accuracy (lower Root Mean Squared Error (RMSE) than the fully data-driven emulator and RTTOV) and adds only moderate computational costs to the assimilation step. Both models combine 3D convolutions for vertical profile encoding with a 2D U-Net operating on latitude-longitude grids, allowing joint learning of vertical structure, spatial correlations, and inter-channel dependencies. We further provide a theoretical justification for deploying the hybrid surrogate as an observation operator in data assimilation.
title Learning Data-driven Surrogate and Correction Models for Satellite Observations in Numerical Weather Prediction
topic Atmospheric and Oceanic Physics
url https://arxiv.org/abs/2603.22037