Using Geostationary Observations to Improve Ozone Air Quality Forecasts
Abstract
We conduct Observing System Simulation Experiments (OSSEs) to determine the measurement requirements for geostationary observations of ozone over North America to improve the quality of ozone air quality forecasts. The OSSEs take 3-D ozone fields over North America from the MOZART global model as the true atmosphere, and attempt to reproduce them by assimilating pseudo-observations from geostationary orbit into the GEOS-Chem model. The assimilation uses a suboptimal Kalman filter including temporal evolution of the error. The use of two very different models to represent the “true” and “model” state allows for realistic error simulation. An OSSE for July 2001 assuming a thermal IR sensor with the spectral characteristics of the TES instrument shows that assimilation reduces the mean absolute difference in ozone concentrations between the true and model states from 7.4 ± 5.4 ppbv (no assimilation) to 3.7 ± 3.3 ppbv (with assimilation) in the lower free troposphere. However, ozone in surface air is not significantly improved because the instrument is not sufficiently sensitive at low altitude. This result is consistent with sensitivity simulations using the GEOS-Chem model adjoint. An improved measurement capability is required. We will examine the improvements achievable by using a multispectral instrument with observation channels in the UV, visible, and the thermal IR to afford more boundary layer sensitivity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A51M..08Z
- Keywords:
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- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE / Pollution: urban and regional;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE / Instruments and techniques