09:55 〜 10:10
[AAS06-04] Chemical and radiative impacts of the 2022 Hunga Tonga-Hunga Ha'apai eruption: a chemistry-climate model simulation
キーワード：火山噴火、成層圏オゾン、化学気候モデル、フンガトンガ、放射強制力
Large volcanic eruptions inject volcanic ash, sulfur dioxide (SO2), and water vapor into the stratosphere, which can significantly impact both the atmospheric radiative budget and atmospheric chemistry including ozone. The eruption of submarine volcano Hunga Tonga (HT) on January 15, 2022, was an unprecedented large-scale submarine volcanic eruption and its diverse climate effects are still under extensive investigation. This study evaluates the mid- to long-term (~3 years) impacts of the HT eruption on climate and atmospheric chemistry using the global chemistry-climate model CHASER (MIROC5 version). The model incorporates stratospheric and tropospheric ozone chemistry as well as aerosols, including chemical and microphysical processes of sulfate aerosol in the stratosphere.
The temporal revolutions of the injected SO2 and water vapor in the model show strong agreement with the satellite observations. Our simulations indicate that oxidation rates of the injected SO2 are largely enhanced due to the presence of water vapor from the HT eruption which increases OH concentrations in the stratosphere. This led to a relatively short decay time for SO2 (approximately 7 days) as inferred from the observations. The simulated changes in stratospheric aerosol optical depth (sAOD) also align with the satellite observations. There are, however, several discrepancies for the magnitude and timing of the maximal sAOD increases, probably due to the biases in stratospheric circulation simulated by the MIROC5 model. The sulfate aerosols in the stratosphere following the HT eruption, providing larger surface area of aerosols, alter heterogeneous reactions and ozone distributions by ~10%. The HT-related sulfate and water vapor are estimated to respectively cause shortwave radiative cooling (0.1-0.5 W m-2 in global average) and longwave heating (0.05-0.15 W m-2). The impacts of the HT eruption on the stratospheric temperature will be also discussed in the presentation.
The temporal revolutions of the injected SO2 and water vapor in the model show strong agreement with the satellite observations. Our simulations indicate that oxidation rates of the injected SO2 are largely enhanced due to the presence of water vapor from the HT eruption which increases OH concentrations in the stratosphere. This led to a relatively short decay time for SO2 (approximately 7 days) as inferred from the observations. The simulated changes in stratospheric aerosol optical depth (sAOD) also align with the satellite observations. There are, however, several discrepancies for the magnitude and timing of the maximal sAOD increases, probably due to the biases in stratospheric circulation simulated by the MIROC5 model. The sulfate aerosols in the stratosphere following the HT eruption, providing larger surface area of aerosols, alter heterogeneous reactions and ozone distributions by ~10%. The HT-related sulfate and water vapor are estimated to respectively cause shortwave radiative cooling (0.1-0.5 W m-2 in global average) and longwave heating (0.05-0.15 W m-2). The impacts of the HT eruption on the stratospheric temperature will be also discussed in the presentation.