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Atmospheric Composition Regional Reanalysis

Chemical Weather Forecasting & Ensemble Data Assimilation (WRF-Chem/DART)

WRF-Chem/DART is a regional chemical weather forecast/ensemble data assimilation system (ensemble adjustment Kalman filter) developed by NCAR/ACOM and NCAR/IMAGe.

  • WRF-Chem – the Weather Research and Forecasting (WRF) model with online chemistry.
  • DART – the Data Assimilation Research Testbed (a flexible software environment for exploring different ensemble data assimilation methods, models, and observations).

Integration with inter-agency and intra-Center data assimilation research efforts

  • Wildfire emission estimation and smoke transport forecasting
  • Identifying, evaluating, and improving disproportionate pollutant exposures
Hourly synthetic TEMPO NO2 tropospheric column retrievals temporally average for July 2020 over Denver, CO showing transportation corridors, municipal centers, and diurnal changes due to the morning and evening rush hours.

Tropospheric Chemistry and Emissions Reanalysis for the continental United States (TRACER-1)

First re-analysis to be done at regional scale

  • How has air quality changed during the past 20 years?
  • How have those changes impacted the solar radiation budget?
  • How have anthropogenic and biomass burning emissions changed during the past 20 years?
  • How have the various temporal trends (interannual to diurnal) in air quality changed

To generate TRACER-1, we will use WRF-Chem/DART – the Weather Research and Forecasting model with online chemistry (WRFChem) coupled to the Data Assimilation Research Testbed (DART) ensemble assimilation system with: 

(i) meteorological initial and lateral boundary conditions (ICs/BCs) from NOAA’s North American Forecast Model (NAM); 

(ii) chemical ICs/BCs from NCAR’s Community Atmosphere Model with on line chemistry (CAM-Chem; 2005 – 2018) and Whole Atmosphere Community Climate Model (WACCM; 2019 – 2024) models; 

(iii) assimilation of conventional meteorological observations and a temporally consistent and comprehensive suite of in situ and satellite AC observations that will include AIRNOW surface observations (carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with diameters less than 10 m (PM10), and particulate matter with diameters less than 2.5 m (PM2.5) measurements, and total/partial column and/or profile retrievals of CO, O3, NO2, SO2, aerosol optical depth (AOD), and nitric acid (HNO3) from MOPITT, MODIS, OMI, SCIAMACHY, GOME-2, and TES; 

(iv) ‘top-down’ emissions estimates based on the ‘stat

TRACER-1 will be a unique, long-term, temporally consistent, regional AC reanalysis for the CONUS and its deliverable will be useful for: 

(i) basic AC/AQ research; 

(ii) studying long-term AC/AQ changes and trends; 

(iii) assessing the effectiveness of previous

emissions mitigation efforts; 

(iv) anticipating future AC/AQ changes; 

(v) studying extreme AQ events and/or the impact of extreme WF events on AQ; and

(vi) drawing data driven conclusions about the impacts of long-term, regional AC/AQ change on human health and the environment.