Unexpected Local Enhancement of Chromospheric Moreton Waves on the Sun
Abstract
Solar eruptions often drive shock waves. When propagating in the solar corona, strong shock waves would leave imprints on the solar surface in the chromosphere, which are called Moreton waves. Moreton waves generally decay as they move away. However, to our knowledge, for the first time we report that a Moreton wave is significantly enhanced midway during propagation, as revealed by the spectroscopic observations from China's first solar satellite, the Chinese Hα Solar Explorer. Combining magnetic measurements from the Solar Dynamics Observatory, we found that the location of the Moreton wave enhancement corresponds to a magnetic null point at an altitude of ∼70 Mm in the corona. It is demonstrated that the unexpected local enhancement of the Moreton wave is due to mode conversion around the magnetic null point, i.e., fast-mode waves are converted to slow-mode waves which are trapped locally. It is further revealed that, even for ordinary Moreton wave fronts, the Hα Doppler redshift velocity is positively correlated with the height of widespread low-altitude magnetic null points, implying that these low-lying null points, ∼1--7 Mm above the solar surface, facilitate mode conversion with different efficiency, thereby accounting for the spatially inhomogeneous Dopplergram of Moreton wave fronts.
Related
- High-frequency Transverse Waves in Chromospheric Fibrils Revealed by DKIST
- High-Frequency Transverse Waves in Chromospheric Fibrils Revealed by DKIST
- The Role of Non-local Thermal Transport in Flare-Driven Chromospheric Evaporation
- Study of Chromospheric Global-Scale Flows using Local Correlation Tracking Across the past 10 Solar Cycles
- Eight Local Couplings of Gravitational Waves from Unified Field Equations
BibTeX
@misc{ni2026unexpected,
title = {{Unexpected Local Enhancement of Chromospheric Moreton Waves on the Sun}},
author = {Y. W. Ni and J. H. Guo and C. Li and Y. K. Wang and G. Y. Chen and C. Xia and C. Fang and P. F. Chen},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31457},
eprint = {2610.31457},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31457},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Unexpected Local Enhancement of Chromospheric Moreton Waves on the Sun
AU - Y. W. Ni
AU - J. H. Guo
AU - C. Li
AU - Y. K. Wang
AU - G. Y. Chen
AU - C. Xia
AU - C. Fang
AU - P. F. Chen
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31457
UR - https://arxiv.org/abs/2610.31457
AB - Solar eruptions often drive shock waves. When propagating in the solar corona, strong shock waves would leave imprints on the solar surface in the chromosphere, which are called Moreton waves. Moreton waves generally decay as they move away. However, to our knowledge, for the first time we report that a Moreton wave is significantly enhanced midway during propagation, as revealed by the spectroscopic observations from China's first solar satellite, the Chinese Hα Solar Explorer. Combining magnetic measurements from the Solar Dynamics Observatory, we found that the location of the Moreton wave enhancement corresponds to a magnetic null point at an altitude of ∼70 Mm in the corona. It is demonstrated that the unexpected local enhancement of the Moreton wave is due to mode conversion around the magnetic null point, i.e., fast-mode waves are converted to slow-mode waves which are trapped locally. It is further revealed that, even for ordinary Moreton wave fronts, the Hα Doppler redshift velocity is positively correlated with the height of widespread low-altitude magnetic null points, implying that these low-lying null points, ∼1--7 Mm above the solar surface, facilitate mode conversion with different efficiency, thereby accounting for the spatially inhomogeneous Dopplergram of Moreton wave fronts.
ER -