Implementation and evaluation of updated photolysis rates in the EMEP MSC-W chemical transport model using Cloud-J v7.3e
Journal article, 2023

The present work describes the implementation of the state of the art Cloud-J v7.3 photolysis rate calculation code in the EMEP MSC-W chemistry-transport model. Cloud-J calculates photolysis rates and accounts for cloud and aerosol optical properties at model run time, replacing the old system based on tabulated values. The performance of Cloud-J is evaluated against aerial photolysis rate observations made over the Pacific Ocean and against surface observations from three measurement sites in Europe. Numerical experiments are performed to investigate the sensitivity of the calculated photolysis rates to the spatial and temporal model resolution, input meteorology model, simulated ozone column, and cloud effect parameterization. These experiments indicate that the calculated photolysis rates are most sensitive to the choice of input meteorology model and cloud effect parameterization while also showing that surface ozone photolysis rates can vary by up to 20 % due to daily variations in total ozone column. Further analysis investigates the impact of Cloud-J on the oxidizing capacity of the troposphere, aerosol–photolysis interactions, and surface air quality predictions. Results find that the annual mean mass-weighted tropospheric hydroxyl concentration is increased by 26 %, while the photolytic impact of aerosols is mostly limited to large tropical biomass-burning regions. Overall, Cloud-J represents a major improvement over the tabulated system, leading to improved model performance for predicting carbon monoxide and daily maximum ozone surface concentrations.

Author

Willem E. van Caspell

Norwegian Meteorological Institute

David Simpson

Chalmers, Space, Earth and Environment, Geoscience and Remote Sensing

Norwegian Meteorological Institute

Jan Eiof Jonson

Norwegian Meteorological Institute

A. Benedictow

Norwegian Meteorological Institute

Yao Ge

Norwegian Meteorological Institute

Alcidi di Sarra

ENEA

Giandomenico Pace

ENEA

Massimo Vieno

UK Centre For Ecology & Hydrology (UKCEH)

Hannah L. Walker

UK Centre For Ecology & Hydrology (UKCEH)

University of Edinburgh

Mathew R. Heal

University of Edinburgh

Geoscientific Model Development

1991-959X (ISSN) 1991-9603 (eISSN)

Vol. 16 24 7433-7459

Driving Forces

Sustainable development

Subject Categories

Physical Chemistry

Meteorology and Atmospheric Sciences

Earth and Related Environmental Sciences

Geosciences, Multidisciplinary

Roots

Basic sciences

DOI

10.5194/gmd-16-7433-2023

Related datasets

Dataset supporting the article: Implementation and evaluation of updated photolysis rates in the EMEP MSC-W chemical transport model using Cloud-J v7.3e, Zenodo [dataset]

URI: https://doi.org/10.5281/zenodo.8282997 DOI: https://doi.org/10.5281/zenodo.8282997

More information

Latest update

1/15/2024