Assessment of an updated polar stratospheric cloud parameterisation for the UK Earth System Model (UKESM1.1) within the UK Met Office Unified Model (v13.9) using  CALIOP and MLS observations

Sangha, Isabelle; Abraham, Nathan L.; Orr, Andrew; Lu, Hua; Pitts, Michael C.; Poole, Lamont R.; Weimer, Michael

doi:10.5194/gmd-19-9857-2026

Articles | Volume 19, issue 19

https://doi.org/10.5194/gmd-19-9857-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-19-9857-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 19

Development and technical paper

|

13 Oct 2026

Development and technical paper |

| 13 Oct 2026

Assessment of an updated polar stratospheric cloud parameterisation for the UK Earth System Model (UKESM1.1) within the UK Met Office Unified Model (v13.9) using CALIOP and MLS observations

Isabelle Sangha, Nathan L. Abraham, Andrew Orr, Hua Lu, Michael C. Pitts, Lamont R. Poole, and Michael Weimer

Supplement

https://doi.org/10.5194/gmd-19-9857-2026-supplement

Data sets

CALIPSO Lidar Level 2 Polar Stratospheric Cloud (PSC), V2-00 D. Winker https://doi.org/10.5067/CALIOP/CALIPSO/CAL_LID_L2_PSCMASK-STANDARD-V2-00

MLS/Aura Level 2 Nitric Acid (HNO3) Mixing Ratio V005 G. Manney et al. https://doi.org/10.5067/Aura/MLS/DATA2511

MLS/Aura Level 2 Ozone (O3) Mixing Ratio V005 M. Schwartz et al. https://doi.org/10.5067/Aura/MLS/DATA2516

Model code and software

UKCA branch containing new PSC scheme documented in 'Implementing and evaluating an updated polar stratospheric cloud parameterisation in the UK Earth System Model (UKESM) using CALIOP and MLS observations' I. Sangha https://doi.org/10.5281/zenodo.17949939

Short summary

The UK Earth System Model is updated with an improved polar stratospheric cloud scheme. The performance of the scheme is evaluated against satellite data. While the model fails to form the full range of observed ice, the scheme improves its ability to represent different polar stratospheric cloud types and their variations. This brings the model closer to satellite observations and highlights the need for further development to capture the polar stratospheric clouds with high number densities.