Chemical data assimilation estimates of continental U.S. ozone and nitrogen budgets during the Intercontinental Chemical Transport Experiment–North America

Abstract

Global ozone analyses, based on assimilation of stratospheric profile and ozone column measurements, and NOy predictions from the Real‐time Air Quality Modeling System (RAQMS) are used to estimate the ozone and NOy budget over the continental United States during the July–August 2004 Intercontinental Chemical Transport Experiment–North America (INTEX‐A). Comparison with aircraft, satellite, surface, and ozonesonde measurements collected during INTEX‐A show that RAQMS captures the main features of the global and continental U.S. distribution of tropospheric ozone, carbon monoxide, and NOy with reasonable fidelity. Assimilation of stratospheric profile and column ozone measurements is shown to have a positive impact on the RAQMS upper tropospheric/lower stratosphere ozone analyses, particularly during the period when SAGE III limb scattering measurements were available. Eulerian ozone and NOy budgets during INTEX‐A show that the majority of the continental U.S. export occurs in the upper troposphere/lower stratosphere poleward of the tropopause break, a consequence of convergence of tropospheric and stratospheric air in this region. Continental U.S. photochemically produced ozone was found to be a minor component of the total ozone export, which was dominated by stratospheric ozone during INTEX‐A. The unusually low photochemical ozone export is attributed to anomalously cold surface temperatures during the latter half of the INTEX‐A mission, which resulted in net ozone loss during the first 2 weeks of August. Eulerian NOy budgets are shown to be very consistent with previously published estimates. The NOy export efficiency was estimated to be 24%, with NOx + PAN accounting for 54% of the total NOy export during INTEX‐A.

Transport and mixing patterns over Central California during the carbonaceous aerosol and radiative effects study (CARES)

“…To compare the WRF-Chem forecasts with measurements, background CO mixing ratios need to be included. Time-varying background CO mixing ratios in the Sacramento region were estimated by taking the difference between two regional-scale simulations from the coupled North American Mesoscale (NAM) -Community Multiscale Air Quality (CMAQ) modeling system (Otte et al, 2005): one in which the boundary conditions were obtained from the Real-time Air Quality Modeling System (RAQMS) (Pierce et al, 2007) and one which used fixed boundary conditions. These NAM-CMAQ simulations were run using a parallel version of the Operational NAM-CMAQ that was being tested during the Research at the Nexus of Air Quality and Climate Change experiment conducted in California called CalNex (Cooper et al, 2011; http://www.esrl.noaa.gov/csd/calnex/).…”

An evaluation of real‐time air quality forecasts and their urban emissions over eastern Texas during the summer of 2006 Second Texas Air Quality Study field study

“…BEIS2 biogenic emissions were employed in this study. The RAQMS global model has it own emissions [Pierce et al, 2007], which are mainly based on the EDGAR inventory [Olivier et al, 1996]. An interface component, PREMAQ, which facilitates the transformation of NAM-derived meteorological fields to conform to the CMAQ grid structure, coordinate system, and input data format, has been developed [Otte et al, 2005].…”

“…[70] STEM-2K3 used time-varying lateral and top boundary conditions provided by RAQMS global chemical transport model forecasts [Pierce et al, 2007] with 2-degree horizontal resolution, and updates every 6 h. During this experiment, the STEM-2K3 used the EPA NEI-2001 emission inventory (compiled by Jeffrey M. Vukovich, Baron AMS, Inc.), and is compatible with the inventory developed for the BAMS MAQSIP-RT 15-km horizontal resolution model described above. This includes the CEMS-based point emissions for NO x .…”

A comprehensive evaluation of seasonal simulations of ozone in the northeastern US during summers of 2001–2005

“…Ozonesonde data have recently been used to evaluate models (Mao et al, 2006;Chai et al, 2007;Pierce et al, 2007;Tarasick et al, 2007;Yu et al, 2007). Mena-Carrasco et al (2007) compared simulated O 3 using their regional air quality model STEM with NASA DC-8 and NOAA WP-3 airborne measurements during International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) 2004 and found a strong positive surface level bias and a negative upper tropospheric bias.…”