【研究紹介】

Developing an agricultural production and land-use change model and examining the land-use scenarios under mitigation policies

呉 文超　　国際農林水産業研究センター／研究員（統合評価モデル）

　On 27^th June, the principal investigator of this project under C03, Dr. Wenchao Wu, made a presentation in the regular seminar of digital biosphere (DB). In the presentation, Dr. Wu first introduced the background and the purpose of the study, which is aimed at developing a high-resolution global land use downscaling model and providing higher land use data to the research community of global environmental change. Then, he explained the research framework developed for this study, which was realized through the coupling of multiple models.

　The specific methods used in the downscaling include multinominal logistic regression and cross-entropy method. For estimating the statistical land use change model, Dr. Wu used the land use and land cover data of the European Space Agency, after aggregating the original 300-meter resolution into the 5-arcminute level. Then, he showed the downscaling results with high-resolution land use maps, using Japan as an example. Finally, he mentioned the obstacles faced in the research and the remaining tasks that need to be done. The project so far mainly has two problems; one is that due to the limitation of the upstream model, grid cells in many coastal areas have not been included in the model, which makes it challenging to derive maps with smooth coastal lines. The second obstacle is that the current coding structure uses loops for calculation and requires a long time to finish the calculation. In the next step, parallel computation needs to be used to improve the speed. In addition, land cover disaggregation should be considered after the spatial disaggregation.

　After Dr. Wu’s presentation, audiences of other research teams asked several clarification questions. They also gave many constructive comments, which are quite helpful in solving the research obstacles and enhancing mutual understanding. Dr. Wu and other scientists also discussed the the potential application of these data in other research projects of DB.

　From 24^th to 27^th July, Dr. Wu joined the observation campaign of DB in Tomakomai experimental forest of the Hokkaido University. During the event, he participated in the field experiment of several other research groups, such as measuring the greenhouse gas flux of forests. He also communicated intensively with other scientists of DB on the way observational data were collected and how these data should be appropriately used in the modeling as critical parameters and input data.

Figure 1. Illustrative example of the downscaling process

Figure 2. Measuring greenhouse gas flux in the Tomakomai experimental forest

Keywords：　Seminar, presentation, downscaling model, land use, field study, communication