12A.6 Exploring the Synergistic Use of OMI NO2 Data with CO2 Data Collected from GOSAT and OCO-2: Current Status, Challenges and Implications for Upcoming Carbon Missions

Thursday, 10 January 2019: 2:45 PM
North 124A (Phoenix Convention Center - West and North Buildings)
Tomohiro Oda, USRA/NASA Goddard, Greenbelt, MD; and L. N. Lamsal, N. A. Krotkov, S. Maksyutov, D. Goldberg, Z. Lu, D. Streets, R. Pavlick, T. Kurosu, A. Eldering, T. Lauvaux, and B. Duncan

Carbon dioxide (CO2) emissions from fossil fuel combustion (Fossil fuel CO2 emissions, FFCO2) need to be curbed to achieve the global climate mitigation goal defined under the Paris Agreement. FFCO2 is primarily derived from “bottom-up” emission inventories (EIs), which are thought to be accurately calculated at national level. However, EIs are fundamentally prone to systematic biases due to the calculation method (emission factors x activity data) and they need independent evaluation (e.g., “top-down” estimates from satellite data). Assuring the accuracy of emission estimates is crucial for successful implementation of United Nations Framework Convention on Climate Change (UNFCCC) under the Paris Agreement. Current missions such as Japan’s Greenhouse gas Observing SATellite (GOSAT, 2009-current) and NASA’s Orbiting Carbon Observatory-2 (OCO-2, 2012-current) have routinely collected column CO2 data globally and demonstrated the observing capability of CO2 enhancement signatures from large localized sources such as cities and power plants.

This study explores the synergistic use of NO2 tropospheric columns from the Ozone Monitoring Instrument (OMI) on NASA’s Aura and CO2 data collected from GOSAT and OCO-2 to better quantify FFCO2. Estimating FFCO2 from the CO2 data alone is challenging because CO2 is a long-lived gas and has a high background. NO2 is co-emitted with CO2, so it serves as an excellent tracer of fossil fuel combustion sources of CO2. Furthermore, the ratio of NO2 to CO2 can help us studying the characteristics of the combustion technologies and control devices (e.g. combustion efficiency) that are often poorly represented in EIs.

One of the major challenges in this study is the very limited amount of CO2 data collected over localized sources. While OMI currently has a 2-day revisit time, OCO-2, which is also in the A-train constellation of satellites, collects data with a narrow swath (1.29x2.25km footprint x 8) with a 16 day revisit time. With the lack of a pointing capability, OCO-2 does not routinely collect data for specific sources. GOSAT on the other hand collects data over and near major localized sources globally (3 day revisit) with a target mode observation, but its relatively large footprint (10 km in diameter) limits the data yield due to the clouds (GOSAT and OCO-2 retrievals require a cloud-free condition). Thus, a simple colocation approach does not yet provide robust statistics of soundings over localized source.

To maximize the number of matched NO2/CO2 soundings available for this study, we used a global Eulerian-Lagrangian coupled atmospheric transport model (GELCA) driven by a global high-resolution FFCO2 emissions (ODIAC). Based on the model simulation, we identified CO2 soundings that record CO2 enhancement due to FFCO2 and exclude biogenic contributions. We then calculated the ratios of the collocated NO2 and GOSAT-CO2 data during 2009-2014 over aggregated large continental regions (e.g., North America and East Asia) and examined them by comparing to ratios derived from available gridded EIs. In our presentation, we will also show the results with OCO-2 data and discuss the current challenges and difficulties. We will also discuss targeting strategies for upcoming satellite carbon missions (e.g. OCO-3) to enhance their contribution to global carbon monitoring in combination with OMI data.

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