GOCART

GOCART
Name	GOCART
Genre	Atmospheric aerosol and dust model

GOCART

GOCART is a numerical aerosol transport model designed for simulation of mineral dust, sea salt, sulfate, black carbon, and organic carbon in the atmosphere. It was developed to interface with global circulation models and chemical transport models for use in climate research, weather forecasting, air quality assessment, and satellite data interpretation. The model has been applied in studies involving aerosol radiative forcing, dust storms, and long-range transport across continents and oceans.

Overview

GOCART was created to represent emissions, transport, chemical transformation, and removal processes of aerosols within three-dimensional frameworks used in climate and atmospheric sciences. The model has been coupled with general circulation models such as National Center for Atmospheric Research's Community Earth System Model, integrated into forecasting systems developed by National Aeronautics and Space Administration, and used alongside reanalysis products from European Centre for Medium-Range Weather Forecasts and National Centers for Environmental Prediction. It emerged from collaborations among research centers including NASA Goddard Space Flight Center and academic groups in the United States and Europe.

Model Description

GOCART simulates aerosol life cycles using size-binned or bulk representations, parameterized deposition, and simplified gas-to-particle conversion schemes. Its aerosol modules treat sources such as dust uplift parameterizations linked to wind friction velocity, sea-spray generation functions tuned to wave state estimates, and combustion emissions from inventories like those assembled by Global Fire Emissions Database contributors. Physical processes include advection, convection, turbulent mixing, dry deposition based on aerodynamic resistance, and wet removal via in-cloud and below-cloud scavenging. Radiative interactions are calculated using Mie theory inputs and refractive index datasets commonly referenced by investigators at institutions such as Scripps Institution of Oceanography and Max Planck Institute for Meteorology.

Inputs and Outputs

Inputs to GOCART typically comprise meteorological fields (wind, humidity, temperature), emission inventories, aerosol optical properties, and land-surface characteristics. These meteorological fields are produced by models and analyses like Modern-Era Retrospective analysis for Research and Applications, ERA5, and output from models developed by NOAA and Met Office. Emission datasets commonly used include products from Emissions Database for Global Atmospheric Research and regional compilations by European Commission projects. Outputs include three-dimensional aerosol mass concentrations by species, aerosol optical depth, extinction coefficients, dry and wet deposition fluxes, and diagnostic fields used by satellite teams at MODIS and CALIPSO data centers for validation.

Applications and Use Cases

GOCART has been used in investigations of transcontinental dust transport across regions such as the Sahara-to-Americas pathway, suspended particulate impacts over the Amazon Rainforest, and Asian outflow affecting the Pacific Ocean. It supports studies of aerosol radiative forcing in assessments contributing to reports by panels like the Intergovernmental Panel on Climate Change and helps interpret observations from satellite missions including Terra (satellite), Aqua (satellite), and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation. Operational uses include incorporation into forecasting systems at agencies such as NOAA National Weather Service and research projects hosted by universities including Massachusetts Institute of Technology and University of Maryland.

Validation and Performance

Validation of GOCART has involved comparisons with ground-based networks like AERONET, aircraft campaigns organized by groups including ARM Climate Research Facility, and satellite retrievals from instruments such as MODIS and CALIPSO. Performance assessments consider metrics like bias, root-mean-square error, and spatial correlation against observations from observatories run by institutions including Lamont–Doherty Earth Observatory and National Institute of Standards and Technology. Intercomparison studies have placed GOCART alongside other aerosol modules used in international initiatives like the Aerosol Comparisons between Observations and Models efforts and model ensembles coordinated by centers such as World Climate Research Programme.

Implementation and Availability

GOCART is implemented in languages and frameworks compatible with large-scale atmospheric models and has been distributed within modeling systems maintained by groups at NASA Goddard Space Flight Center and partner universities. It is often packaged with modeling infrastructure from projects associated with Earth System Modeling Framework conventions and is compatible with data formats used by NetCDF-based workflows and visualization tools developed at NASA and NOAA. Access to model code and configuration examples is typically provided through institutional repositories and collaborative platforms used by the research community at places such as GitHub and university data centers.

Limitations and Future Development

Limitations of GOCART include simplified chemical treatment for secondary organic aerosol formation, coarse representation of aerosol microphysics compared to detailed bin or sectional models, and sensitivity to uncertainties in emission inventories and meteorological driving fields. Future development directions discussed in community workshops at American Geophysical Union and European Geosciences Union meetings include coupling with advanced microphysical schemes, assimilation of aerosol observations from constellations like Sentinel missions, and refinement of source functions informed by field campaigns coordinated by agencies such as National Science Foundation.

Category:Aerosol models