Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing

Ryan M. Dewey; Caitriona Mary Jackman; Mathias Rojo; Lina Z. Hadid; Beatriz Sánchez-Cano; Charles F. Bowers; Jim M. Raines; Susan T. Lepri; Stefano Livi; Jesse T. Coburn; Sae Aizawa; Yeimy J. Rivera; Weijie Sun; Jiutong Zhao; James A. Slavin; Daniel Heyner; Daragh M. Hollman; Alexander D. Shane

doi:10.1029/2026GL123323

Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing

Ryan M. Dewey
, Caitriona Mary Jackman
, Mathias Rojo
, Lina Z. Hadid
, Beatriz Sánchez-Cano
, Charles F. Bowers
, Jim M. Raines
, Susan T. Lepri
, Stefano Livi
, Jesse T. Coburn
, Sae Aizawa
, Yeimy J. Rivera
, Weijie Sun
, Jiutong Zhao
, James A. Slavin
, Daniel Heyner
, Daragh M. Hollman
, Alexander D. Shane

University of Michigan
Dublin Institute for Advanced Studies
Centre National d'études Spatiales
Sorbonne Université
University of Leicester
Southwest Research Institute
Center for Astrophysics | Harvard & Smithsonian
University of California, Space Sciences Laboratory
Technical University Braunschweig
University of Colorado

Research output: Contribution to journal › Article › peer-review

Abstract

Mercury experiences the most intense and variable solar wind (SW) conditions in the solar system due to its close, eccentric orbit about the Sun. In addition to variation driven by coronal source and solar cycle, the SW arriving at Mercury varies periodically as the planet's heliocentric distance changes by over 50% per orbit. We use 30 years of SW measurements near Earth and scale them to Mercury's orbital distance to determine the importance of this “seasonal” change in the SW. We find the seasonal change to be substantial, systematic, and significant, and that it dominates over other sources of variability (e.g., fast vs. slow SW) and even exceeds the relative change at Earth from ICMEs compared to the ambient SW. As a result, Mercury's magnetosphere is expected to exhibit substantial seasonal effects.

Original language	English
Article number	e2026GL123323
Journal	Geophysical Research Letters
Volume	53
Issue number	12
DOIs	https://doi.org/10.1029/2026GL123323
Publication status	Published - 28 Jun 2026

Keywords

Mercury
orbital eccentricity
seasonal
solar wind

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10.1029/2026GL123323

Cite this

Dewey, R. M., Jackman, C. M., Rojo, M., Hadid, L. Z., Sánchez-Cano, B., Bowers, C. F., Raines, J. M., Lepri, S. T., Livi, S., Coburn, J. T., Aizawa, S., Rivera, Y. J., Sun, W., Zhao, J., Slavin, J. A., Heyner, D., Hollman, D. M., & Shane, A. D. (2026). Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing. Geophysical Research Letters, 53(12), Article e2026GL123323. https://doi.org/10.1029/2026GL123323

@article{7713891cde4e4923ae3e9f1772214904,

title = "Mercury's Eccentric Orbit as a Driver of Significant {\textquotedblleft}Seasonal{\textquotedblright} Change in Upstream Solar Wind Forcing",

abstract = "Mercury experiences the most intense and variable solar wind (SW) conditions in the solar system due to its close, eccentric orbit about the Sun. In addition to variation driven by coronal source and solar cycle, the SW arriving at Mercury varies periodically as the planet's heliocentric distance changes by over 50\% per orbit. We use 30 years of SW measurements near Earth and scale them to Mercury's orbital distance to determine the importance of this {\textquotedblleft}seasonal{\textquotedblright} change in the SW. We find the seasonal change to be substantial, systematic, and significant, and that it dominates over other sources of variability (e.g., fast vs. slow SW) and even exceeds the relative change at Earth from ICMEs compared to the ambient SW. As a result, Mercury's magnetosphere is expected to exhibit substantial seasonal effects.",

keywords = "Mercury, orbital eccentricity, seasonal, solar wind",

author = "Dewey, \{Ryan M.\} and Jackman, \{Caitriona Mary\} and Mathias Rojo and Hadid, \{Lina Z.\} and Beatriz S{\'a}nchez-Cano and Bowers, \{Charles F.\} and Raines, \{Jim M.\} and Lepri, \{Susan T.\} and Stefano Livi and Coburn, \{Jesse T.\} and Sae Aizawa and Rivera, \{Yeimy J.\} and Weijie Sun and Jiutong Zhao and Slavin, \{James A.\} and Daniel Heyner and Hollman, \{Daragh M.\} and Shane, \{Alexander D.\}",

note = "Publisher Copyright: {\textcopyright} 2026. The Author(s).",

year = "2026",

month = jun,

day = "28",

doi = "10.1029/2026GL123323",

language = "English",

volume = "53",

journal = "Geophysical Research Letters",

issn = "0094-8276",

publisher = "John Wiley and Sons Inc",

number = "12",

}

Dewey, RM, Jackman, CM, Rojo, M, Hadid, LZ, Sánchez-Cano, B, Bowers, CF, Raines, JM, Lepri, ST, Livi, S, Coburn, JT, Aizawa, S, Rivera, YJ, Sun, W, Zhao, J, Slavin, JA, Heyner, D, Hollman, DM & Shane, AD 2026, 'Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing', Geophysical Research Letters, vol. 53, no. 12, e2026GL123323. https://doi.org/10.1029/2026GL123323

TY - JOUR

T1 - Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing

AU - Dewey, Ryan M.

AU - Jackman, Caitriona Mary

AU - Rojo, Mathias

AU - Hadid, Lina Z.

AU - Sánchez-Cano, Beatriz

AU - Bowers, Charles F.

AU - Raines, Jim M.

AU - Lepri, Susan T.

AU - Livi, Stefano

AU - Coburn, Jesse T.

AU - Aizawa, Sae

AU - Rivera, Yeimy J.

AU - Sun, Weijie

AU - Zhao, Jiutong

AU - Slavin, James A.

AU - Heyner, Daniel

AU - Hollman, Daragh M.

AU - Shane, Alexander D.

PY - 2026/6/28

Y1 - 2026/6/28

N2 - Mercury experiences the most intense and variable solar wind (SW) conditions in the solar system due to its close, eccentric orbit about the Sun. In addition to variation driven by coronal source and solar cycle, the SW arriving at Mercury varies periodically as the planet's heliocentric distance changes by over 50% per orbit. We use 30 years of SW measurements near Earth and scale them to Mercury's orbital distance to determine the importance of this “seasonal” change in the SW. We find the seasonal change to be substantial, systematic, and significant, and that it dominates over other sources of variability (e.g., fast vs. slow SW) and even exceeds the relative change at Earth from ICMEs compared to the ambient SW. As a result, Mercury's magnetosphere is expected to exhibit substantial seasonal effects.

AB - Mercury experiences the most intense and variable solar wind (SW) conditions in the solar system due to its close, eccentric orbit about the Sun. In addition to variation driven by coronal source and solar cycle, the SW arriving at Mercury varies periodically as the planet's heliocentric distance changes by over 50% per orbit. We use 30 years of SW measurements near Earth and scale them to Mercury's orbital distance to determine the importance of this “seasonal” change in the SW. We find the seasonal change to be substantial, systematic, and significant, and that it dominates over other sources of variability (e.g., fast vs. slow SW) and even exceeds the relative change at Earth from ICMEs compared to the ambient SW. As a result, Mercury's magnetosphere is expected to exhibit substantial seasonal effects.

KW - Mercury

KW - orbital eccentricity

KW - seasonal

KW - solar wind

UR - https://www.scopus.com/pages/publications/105042366616

U2 - 10.1029/2026GL123323

DO - 10.1029/2026GL123323

M3 - Article

AN - SCOPUS:105042366616

SN - 0094-8276

VL - 53

JO - Geophysical Research Letters

JF - Geophysical Research Letters

IS - 12

M1 - e2026GL123323

ER -

Mercury's Eccentric Orbit as a Driver of Significant “Seasonal” Change in Upstream Solar Wind Forcing

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Keywords

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