Prototyping chemical composition and air quality prediction systems
For the past years, ACOM has been running near-real time prediction systems to support the community including stakeholders and also to test the performance of ACOM’s suite of community chemical transport models in near-real time. The collection of products is displayed on ACOM’s Forecast webpage (https://www2.acom.ucar.edu/acresp/forecasts-and-near-real-time-nrt-products) and output is also made accessible for download.
The collection of products includes global chemical predictions with the Whole Atmosphere Community Climate Model (WACCM), regional predictions over the U.S. with the Weather Research and Forecasting model with Chemistry (WRF-Chem) (in collaboration with RAL), near-real time carbon monoxide retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument and near-real-time fire emissions from the Fire Inventory from NCAR (FINN).
WACCM predictions began in 2018 and replaced the global predictions that had been run for many years with the now discontinued MOZART-4 model. The 10-day global predictions are in high demand for use as boundary conditions for regional modeling. As such they are also used in the regional WRF-Chem prediction system, which provides 2-day forecasts of relevant chemical and meteorological parameters at 12 km spatial resolution over the U.S. Recently a 4 km domain has been added over Colorado.
The regional predictions are continuously evaluated with surface observations of ozone and PM2.5 and work is underway to comprehensively evaluate the forecasts and revise the setup and address shortcomings in the performance such as a high summertime ozone bias in the Eastern and South-Eastern U.S., degraded performance over the Western U.S. during wintertime and an underestimate in surface PM2.5 during wildfire episodes. In addition, targeted forecast products have been added in the past years and include products and evaluation in collaboration with the NASA Tropospheric Ozone Lidar Network (TOLNet) and online evaluation of WRF-Chem with NO2 column retrievals from TropOmi.
