A high-resolution simulation of CO2 at 1×1 km horizontal resolution using the Weather Research and Forecasting Greenhouse gas (WRF-GHG) model was conducted, focusing on the Kanto region in Japan. The WRF-GHG simulations were performed using different anthropogenic emission inventories: EAGrid (Japan, 1 km), EDGAR (0.1o), and EDGAR-downscaled (0.01o). Our analysis showed that the simulations using EAGrid better captured the diurnal variability in observed CO2 compared to EDGAR and EDGAR-downscaled emissions at two continuous monitoring sites. The 1×1 km simulation performed better in simulating CO2 variability observed in surface sites (hourly) and aircraft observations, compared to the 27×27 km simulations. We compared the vertical profile distribution of CO2 and found that all the simulations performed similarly. During February (May), the anthropogenic (land biosphere) fluxes were the primary contributor to the vertical distribution of CO2 up to an altitude of 3200 m (4500 m), beyond which long-range transport influenced by lateral boundary conditions from Eurasia played a greater role. The sensitivity analysis of boundary conditions showed a systematic bias (~ 4 ppm) persisting above 3200 m altitude when fixed (a constant value) boundary conditions are applied, as compared to the simulation with boundary conditions from a global model. We also compared the WRF-GHG simulated column-averaged XCO2 from Orbiting Carbon Observatory-2 (OCO-2) satellite and found a statistically significant spatial correlation (r=0.47) in February. However, we found a weaker spatial correlation (0.17) in May, which could be caused due to under-representation of intense land biosphere activity in WRF-GHG.

The Thermal And Near infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT) launched in Jan. 2009 has demonstrated accurate and precise CO2 and CH4 distribution measurements from space. The globally acquired data have contributed to reduce the uncertainties in global and regional flux inverse estimates. In response to the urgent need for monitoring carbon emissions from intense localized sources, such as cities and power plants, we have been developing a next generation instrument that should be able to detect and map plumes from the intense sources with a 1km spatial resolution. We design our system to implement both targeted observations for intense local sources with high spatial resolution and wide-swath observations for covering the earth’s entire surface with 2-axes pointing system and two telescopes. We have developed airborne imaging spectrometer suites with three imaging spectrometers: 0.47 µm for nitrogen dioxide (NO2), 0.76 µm for oxygen (O2) and solar-induced chlorophyll fluorescence (SIF) and 1.6 µm for carbon dioxide (CO2) and methane (CH4). The airplane observations successfully recorded CO2 and NO2 enhancements over a power plant in Greater Nagoya Area. In our presentation, we will present our first emission estimates based on the simultaneous CO2 and NO2 observation.

In almost Japanese megacities, various CO2 and CH4 emission source like industrial activity (power plant, landfills, gas factory, water processing plants), and agricultural activity (rice cultivation, pig farm) are concentrated within a few tens kilometers region. In order to estimate CO2 and CH4 emission rate for above various different sources, we newly developed airborne Imaging-spectrometer suites which consist of NIR spectrometer for O2-A band measurement and SWIR spectrometer for CO2/CH4 measurement. We also developed quick algorithm based on nonlinear fitting of synthetic spectrum to observation spectrum by optimization of column density of CO2 / CH4 and instrumental characteristic parameter simultaneously. The algorithm takes less than 20 second per 1 retrieval by using laptop computer, and we will challenge further acceleration by more than tens of times in order to realize real-time observation. For the first flight, we selected the eastern part of the Nagoya urban area, in which there are large CO2 emission sources, including a coal power plant and the transportation sector, and possible CH4 sources from agriculture, energy manufacturing, and waste that are geographically mixed. The results of observing the Hekinan power plant (coal-fired power generation) over Aichi Prefecture on Feb. 16, 2018 are shown in Figure 1. At the Hekinan Power Station, enhancement of CO2 column-averaged mole fractions are observed, and it can be seen that the high concentration area extends toward the downwind side. The accuracy of column density calculated by the quick algorithm will be validated with ground observation data. We estimated emission rate of CO2 of Hekinan Power plant.