Utilizing a high vertical and horizontal resolution dataset of SO2 for modelling volcanic eruptions in WACCM

The climate impact of volcanic SO2 is strongly correlated with the injection height into the stratosphere. We have used a dataset created with the dispersion model FLEXPART by combining vertical information from the CALIOP lidar with horizontal SO2 information from AIRS [1]. So far, the dataset represents the eruptions of Sarychev in June 2009 with a vertical resolution of 200 m. The original dataset for SO2 used in WACCM releases all SO2 in one latitude and longitude gridbox, spanning an altitude of 11 to 15 km. Our dataset is distributed over several latitude and longitude gridboxes and spans an altitude of 7.6 to 18.6 km [1].

 We have performed simulations in the Earth system model CESM2 WACCM with our dataset and WACCM’s original volcanic SO2 dataset. Aerosol distributions are compared with observations from the CALIOP lidar to investigate the impact of our dataset’s high vertical and horizontal resolution. We also compare outputs from simulations with the two datasets.

The first simulations with the two datasets show large differences in both horizontal and vertical SO2 distribution in the months following the eruption. This likely affects the duration of the radiative impact from sulfate particles formed from the SO2.

 We are presently investigating differences in aerosol formation and concentrations, time evolution of volcanic sulfate, and climate impact of simulations with the two datasets. Future work involves creation of SO2 datasets for all volcanic eruptions since 2006, with the goal of providing better representation of volcanism in Earth system models.

References

[1] Sandvik, O. S., Friberg, J., Sporre, M. K., and Martinsson, B. G.: Methodology to obtain highly resolved SO2 vertical profiles for representation of volcanic emissions in climate models, Atmos. Meas. Tech., 14, 7153–7165, https://doi.org/10.5194/amt-14-7153-2021, 2021.