GOSAT-series Satellite Observation

GOSAT-series Satellite Observation

There are high expectations worldwide for the derivation of data from satellite observation data from space. In particular, it will contribute significantly to the accurate understanding of current emissions, which is necessary for each country to set appropriate and ambitious emission reduction targets (Nationally Determined Contributions, NDCs).

Until now, developed countries have calculated and published greenhouse gas emissions and removals based on the United Nations Framework Convention on Climate Change and related decisions of the Conference of the Parties. These calculated values ​​are called "bottom-up" estimates, but there are issues with the emission inventory of these bottom-up estimates. One is the "accuracy of the values," which is due to uncertainties due to the type of greenhouse gas and the inventory technology of each country. The other is the "time lag," which is the fact that it takes years to create a "bottom-up" estimated inventory because official statistics are used.

For example, in Japan, the 2019 edition of the estimates was published in April 2021 (Ministry of the Environment and National Institute for Environmental Studies, 2021). A "top-down estimate" using atmospheric observation data, such as satellite data, can play a complementary role to such bottom-up estimates. In recent years, atmospheric observation data has been distributed at a near-real-time speed, and there are high expectations for its speed.

Promptly constructing a recent emission inventory is important not only as a "base year" for future scenarios, but also for "verifying" the validity of scenarios created in the past, and is extremely important in the global stocktake for quickly verifying the effects of reduction measures and utilizing them in future measures (Janssens-Maenhout et al., 2020).