California Laboratory for Atmospheric Remote Sensing
Aerosols
GHGs and air pollutants (e.g., CO and aerosol particles) are co-emitted in the city. Knowledge of the vertical structure of their concentrations is essential for quantifying their effects on air quality and their influence on the Earth's radiation budget. Zeng et al. (2018) inferred the total aerosol loading and aerosol vertical structure in the urban boundary layer using passive hyperspectral measurements. An effective spectral sorting technique was developed to retrieve total aerosol optical depth (AOD) and effective aerosol layer height (ALH) from hyperspectral measurements in the 1.27 μm oxygen absorption band by CLARS-FTS. The method will also be used in this study to map the AOD and derive PM2.5 in LA.
Carbon Monoxide (CO)
Hourly maps of XCO (carbon monoxide column abundance in ppbv) in the LA basin from CLARS-FTS data. Mean wind direction and speed are indicated by the black arrows (Figure from Zeng et al. (2020)).
Carbon monoxide (CO) is a criteria air pollutant affecting human health. Are measured time-resolved CO distributions consistent with emissions inventories from estimates of fossil-fuel combustion combined with chemical-transport modeling? Eight years of remote sensing data from JPL's CLARS-Fourier Transform Spectrometer (FTS) on Mt. Wilson were analyzed to obtain hourly spatial distributions of CO across the LA basin. As shown in the figure, CO is emitted from the main traffic corridors on the west side of the basin and advected to the foothills by the prevailing sea breeze. This pattern is reproduced by the WRF-CHEM chemical-transport model. Emissions vary by day of the week, with significantly lower CO on weekends. CLARS-FTS data on CO provides new insights into the emission and dispersion of CO for policymakers and regulators responsible for managing the exposure of the public to criteria air pollutants. These data also provide a rich source of validation data for existing and future satellite air quality sensors such as GeoCarb and TROPOMI.