<p>The H<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$_{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>O plume, injected by the Hunga Tonga–Hunga Ha’apai (HTHH) eruption on 15 January 2022, spread and reached the high-latitude mesopause regions 2 years after the eruption. To investigate the relationships between polar mesospheric clouds (PMCs) and the HTHH eruption-originated H<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$_{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>O anomalies, we have analyzed PMC occurrence rates (ORs), temperature, and water vapor volume mixing ratios (H<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$_{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>O VMRs), based on observational data from Himawari-8/Advanced Himawari Imager (AHI), Himawari-9/AHI, and Aura/Microwave Limb Sounder. To focus the PMC responses to the H<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq1.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="8" /> </InlineMediaObject> <EquationSource Format="TEX">$_{2}$</EquationSource> <EquationSource Format="MATHML"><math> <mmultiscripts> <mrow /> <mn>2</mn> <mrow /> </mmultiscripts> </math></EquationSource> </InlineEquation>O anomalies, we extracted the temperature-independent components in the PMC OR variability, which is defined as <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">${\Updelta }$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Δ</mi> </math></EquationSource> </InlineEquation>PMC. As a result, we found a significant <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="40623_2025_2298_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">${\Updelta }$</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Δ</mi> </math></EquationSource> </InlineEquation>PMC increase (15±5%) in January 2024 in the Southern Hemisphere (SH), which was associated with the HTHH eruption-induced water vapor increase (0.88±0.04 ppmv) at 77.8–87.9 km altitudes in January 2024 in the SH. The finding would be, for the first time, observational evidence of PMC variations induced by volcanic eruptions, which is a striking PMC topic that has long been discussed since the 1883 Krakatoa eruption.</p> Graphic Abstract <p></p>

Responses of polar mesospheric clouds to water vapor anomalies caused by the 2022 Hunga Tonga–Hunga Ha’apai eruption

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2025年10月23日

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Y. Moriyama,
T. T. Tsuda,
Y. Ando,
H. Suzuki,
H. Nakagawa,
T. Nishiyama,
Y.-M. Tanaka,
K. T. Murata,
J. Yue

摘要

The H $_{2}$ $_{2}$ O plume, injected by the Hunga Tonga–Hunga Ha’apai (HTHH) eruption on 15 January 2022, spread and reached the high-latitude mesopause regions 2 years after the eruption. To investigate the relationships between polar mesospheric clouds (PMCs) and the HTHH eruption-originated H $_{2}$ $_{2}$ O anomalies, we have analyzed PMC occurrence rates (ORs), temperature, and water vapor volume mixing ratios (H $_{2}$ $_{2}$ O VMRs), based on observational data from Himawari-8/Advanced Himawari Imager (AHI), Himawari-9/AHI, and Aura/Microwave Limb Sounder. To focus the PMC responses to the H $_{2}$ $_{2}$ O anomalies, we extracted the temperature-independent components in the PMC OR variability, which is defined as ${\Updelta }$ $Δ$ PMC. As a result, we found a significant ${\Updelta }$ $Δ$ PMC increase (15±5%) in January 2024 in the Southern Hemisphere (SH), which was associated with the HTHH eruption-induced water vapor increase (0.88±0.04 ppmv) at 77.8–87.9 km altitudes in January 2024 in the SH. The finding would be, for the first time, observational evidence of PMC variations induced by volcanic eruptions, which is a striking PMC topic that has long been discussed since the 1883 Krakatoa eruption.

Graphic Abstract