Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach

Structure functions (SFs), which quantify the moments of increments of a stochastic process, are essential complementary statistics to power spectra for analyzing the self-similar behavior of a time series. However, many real-world data sets, such as those from spacecraft monitoring the solar wind,...

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Main Authors: Daniel Wrench, Tulasi N. Parashar
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
Subjects:
Online Access:https://doi.org/10.3847/1538-4357/addc6a
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author Daniel Wrench
Tulasi N. Parashar
author_facet Daniel Wrench
Tulasi N. Parashar
author_sort Daniel Wrench
collection DOAJ
description Structure functions (SFs), which quantify the moments of increments of a stochastic process, are essential complementary statistics to power spectra for analyzing the self-similar behavior of a time series. However, many real-world data sets, such as those from spacecraft monitoring the solar wind, contain gaps, which inevitably corrupt the statistics. The nature of this corruption for SFs remains poorly understood—indeed, often overlooked. In this study, we simulate gaps in a large set of Parker Solar Probe magnetic field intervals to characterize how missing data affect SFs of solar wind turbulence. We find that linear interpolation systematically underestimates the true SF, and we introduce a simple, empirically derived correction factor to address this bias. Learned from data from a single spacecraft, the correction generalizes well to solar wind measured elsewhere in the heliosphere. Compared to conventional gap-handling methods, our approach reduces the mean error for missing data fractions above 20%, and the overall error is reduced by nearly 50% when averaged across all missing fractions tested. We apply the correction to Voyager intervals from the inner heliosheath and local interstellar medium (60%–85% missing) and recover spectral indices consistent with previous studies. The correction factor is released as an open-source Python package, enabling more accurate analysis of scaling in gapped solar wind data sets.
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spelling doaj-art-e6cf3ebe40b24ef9a9de50fb5ea4009f2025-08-20T03:27:07ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198712810.3847/1538-4357/addc6aDebiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven ApproachDaniel Wrench0https://orcid.org/0000-0002-7463-3818Tulasi N. Parashar1https://orcid.org/0000-0003-0602-8381Victoria University of Wellington , Kelburn, Wellington 6012, New ZealandVictoria University of Wellington , Kelburn, Wellington 6012, New ZealandStructure functions (SFs), which quantify the moments of increments of a stochastic process, are essential complementary statistics to power spectra for analyzing the self-similar behavior of a time series. However, many real-world data sets, such as those from spacecraft monitoring the solar wind, contain gaps, which inevitably corrupt the statistics. The nature of this corruption for SFs remains poorly understood—indeed, often overlooked. In this study, we simulate gaps in a large set of Parker Solar Probe magnetic field intervals to characterize how missing data affect SFs of solar wind turbulence. We find that linear interpolation systematically underestimates the true SF, and we introduce a simple, empirically derived correction factor to address this bias. Learned from data from a single spacecraft, the correction generalizes well to solar wind measured elsewhere in the heliosphere. Compared to conventional gap-handling methods, our approach reduces the mean error for missing data fractions above 20%, and the overall error is reduced by nearly 50% when averaged across all missing fractions tested. We apply the correction to Voyager intervals from the inner heliosheath and local interstellar medium (60%–85% missing) and recover spectral indices consistent with previous studies. The correction factor is released as an open-source Python package, enabling more accurate analysis of scaling in gapped solar wind data sets.https://doi.org/10.3847/1538-4357/addc6aInterplanetary turbulenceSolar windTime series analysis
spellingShingle Daniel Wrench
Tulasi N. Parashar
Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
The Astrophysical Journal
Interplanetary turbulence
Solar wind
Time series analysis
title Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
title_full Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
title_fullStr Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
title_full_unstemmed Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
title_short Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-driven Approach
title_sort debiasing structure function estimates from sparse time series of the solar wind a data driven approach
topic Interplanetary turbulence
Solar wind
Time series analysis
url https://doi.org/10.3847/1538-4357/addc6a
work_keys_str_mv AT danielwrench debiasingstructurefunctionestimatesfromsparsetimeseriesofthesolarwindadatadrivenapproach
AT tulasinparashar debiasingstructurefunctionestimatesfromsparsetimeseriesofthesolarwindadatadrivenapproach