Evolution of the Climate Forcing During the Two Years After the Hunga TongaHunga Ha'apai Eruption

AbstractWe calculate the climate forcing for the 2ys after the 15 January 2022, Hunga TongaHunga Ha'apai (Hunga) eruption. We use satellite observations of stratospheric aerosols, trace gases and temperatures to compute the tropopause radiative flux changes relative to climatology. Overall, the net downward radiative flux decreased compared to climatology. The Hunga stratospheric water vapor anomaly initially increases the downward infrared radiative flux, but this forcing diminishes as the anomaly disperses. The Hunga aerosols cause a solar flux reduction that dominates the net flux change over most of the 2yrs period. Hunga induced temperature changes produce a decrease in downward longwave flux. Hunga induced ozone reduction increases the shortwave downward flux creating small subtropical increase in total flux from mid2022 to 2023. By the end of 2023, most of the Hunga induced radiative forcing changes have disappeared. There is some disagreement in the satellite measured stratospheric aerosol optical depth (SAOD) observations which we view as a measure of the uncertainty; however, the SAOD uncertainty does not alter our conclusion that, overall, aerosols dominate the radiative flux changes.

Evolution of the Climate Forcing During the Two Years After the Hunga TongaHunga Ha'apai Eruption Academic Article