1. Inverse Estimate of Air Pollutant Emissions with Multi-wavelength Mie-Raman Lidar Observations
- Subjects
Inverse estimate ,Green’s function method ,Tagged tracer ,Chemical Transport Model - Abstract
An inverse modeling system for air pollutant emissions (SO2, NO_X, and NH3) was developed with a Multi-wavelength Mie-Raman Lidar (MMRL), the GEOS-Chem chemical transport model (CTM), and Green’s functions method. MMRL, an improved two-wavelength polarization Mie-scattering Lidar by adding a nitrogen Raman Scatter measurement channel, can provide vertical profiles of seven aerosol optical properties (extinction coefficients (α) at 355 and 532 nm; backscatter coefficient (β) at 355, 532, and 1064 nm; depolarization ratio (δ) at 355 and 532 nm) and are operated at three sites in Japan. To use aerosol vertical profiles from MMRL measurements as observational constraint of the inverse modeling, we developed a Lidar simulator that converts CTM outputs (i.e., aerosol mass concentrations) into the seven aerosol optical properties and allows direct comparison with MMRL measurements. The feasibility and capability of the developed system was demonstrated in an inversion experiment in which we used extinction coefficient at 532 nm from MMRL at Fukuoka in 2015. The inverse experiment shows reduced emissions over China compared with 2010 reflecting recent reductions of Chinese SO2 and NOx emissions. Aerosol optical depth (AOD) derived from a posteriori emission exhibit a decreasing trend over not only China but also the downwind regions (e.g., Japan). This is consistent with AOD provided by the Japanese Aerosol reanalysis.
- Published
- 2018