MONARCH

Overview

The Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH) is a chemical weather prediction system, formerly known as NMMB/BSC-CTM, that can be used at multiple spatial scales, ranging from regional scales at single-digit kilometre resolutions with explicit convection to coarse-resolution global scales with parameterized convection. MONARCH is continuously developed at the Barcelona Supercomputing Center (BSC) with a focus on mineral dust and other aerosols, atmospheric chemistry (including a gas-phase and aqueous-phase chemistry module), emissions (considering the coupling with the HERMES emission model), data assimilation (based on a Local Ensemble Transform Kalman Filter, LETKF) and workflow management (through the use of Autosubmit). The model's atmospheric dynamics rely on the meteorological Nonhydrostatic Multiscale Model on the B-grid (NMMB) model. Because MONARCH is fully coupled with the meteorological driver, MONARCH has also inherited from NMMB the ability to use different representations for relevant atmospheric processes (e.g. land-surface model or the cloud microphysics representation) and aerosol-radiation-cloud interactions are also available. 

MONARCH maintains daily operations for different regions of the world:

• Global aerosol forecasts are considered in the International Cooperative for Aerosol Prediction (ICAP) ensemble.
• Air quality forecasts are considered in the European Copernicus Atmosphere Monitoring Service (CAMS) ensemble.
• Dust forecasts for Northern Africa, the Middle East and Europe are available through the WMO Barcelona Dust Forecast Center.

Daily dust service at the WMO Barcelona Dust Regional Center

MONARCH represents dust generation and uplift by surface wind and turbulence through different schemes, horizontal and vertical advection, horizontal diffusion and vertical transport by turbulence and convection, dry deposition and gravitational settling, and in-cloud and below cloud-scavenging (i.e. wet deposition). The most recent developments in the MONARCH mineral dust module are described in Klose et al. (2021). 

The daily dust service at the WMO Barcelona Dust Regional Center is based on a regional configuration of the MONARCH model that covers the region of Northern Africa, the Middle East and Europe. The last upgrade of the model includes the following features: 

• Upgrade has been done in June 2023
• MONARCH code: Version 2.1.0
• The model's resolution is set to 0.10º horizontally and 40 layers extending up to approximately 15 km vertically. 
• Meteorological global initial and boundary conditions are from NCEP/GFS at 0.50º x 0.50º
• Specifically for the mineral dust module:
  • The desert dust source function is based on the MODIS dust frequency of occurrence product.
  • The emission scheme is based on Ginoux et al. (2001).
  • The dust size distribution follows a sectorial approach and considers eight transport bins up to 20 micrometres in diameter.
  • Dust initial conditions consider the dust forecast of the previous day.
  • Dynamical mineral dust interacts with short- and long-wave radiation.

The daily execution of MONARCH is done in two HPC clusters hosted by the Barcelona Supercomputing Center (BSC) and the Spanish Meteorological Agency (AEMET) to ensure their availability. This daily execution is managed by Autosubmit, a python-based tool to create, manage and monitor experiments using Computing Clusters, HPC’s and Supercomputers remotely via ssh. It supports experiments running in more than one HPC and for different workflow configurations.

Overview of the MONARCH production log files: