Evaluation of NASA GEOSCCM Simulated Trends in Global Surface PM2.5 and Aerosol Optical Properties using Ground-Based and Satellite Observations

Modeling of long-term trends of aerosols and their properties is important for characterizing changes in particulate matter pollution speciation and exposure, as well as for constraining aerosol-climate forcing.

Here we evaluate global and regional long-term trends in surface fine particulate matter (PM_2.5) and aerosol optical properties using simulations performed with the NASA Goddard Earth Observing System Chemistry Climate Model (GEOSCCM), by comparing the model hindcast with observations for the last three decades.

We first compare modeled surface PM_2.5 with ground-based observations from monitoring networks and with global reconstructed PM_2.5 datasets from observations-model data fusion. Total aerosol optical depth (AOD) is compared with long-term satellite measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) and measurements from the ground-based Aerosol Robotic Network (AERONET). Additional aerosol optical properties, such as absorption and scattering coefficients, are evaluated with ground-based observations from the Global Atmosphere Watch (GAW) records.

Comparing the modeled aerosols with a diverse set of observations helps interpret observed and simulated trends, and serves as a benchmark for future GEOSCCM developments.