NEC and The University of Tokyo calculate carbon accumulation rates in Malaysian national park with a 9.4% margin of error

The University of Tokyo's carbon cycle assessment model, VISIT, and NEC's data assimilation technology calculate decarbonization effect in forests with greater efficiency and accuracy than conventional methods Tokyo, March 12, 2026 - The University of Tokyo's Graduate School of Agricultural and Life Sciences, Faculty of Agriculture, and NEC have calculated carbon accumulation rates for Lambir Hills National Park in Malaysia based on observed removals data for greenhouse gases (GHG) utilizing the university's VISIT (Vegetation Integrated SImulator for Trace gases) terrestrial ecosystem model.

NEC's data assimilation technology (patent pending) was used to correct data errors, and observed data was compared with simulated data in order to calculate carbon accumulation rates with a high degree of accuracy, achieving a daily margin of error of 9.4%. NEC is promoting initiatives to quantify GHG removals in forests across Southeast Asia and to develop carbon credits in the forest sector. As part of these efforts, NEC has been conducting joint research with the Graduate School of Agricultural and Life Sciences at The University of Tokyo, which developed the VISIT model, an ecosystem model with strengths estimating carbon stocks and fluxes (*1) in forests in the Asian region.

The VISIT model estimates carbon stocks and fluxes based on forest vegetation, soil, and meteorological data. By combining VISIT with NEC's data assimilation technology, exceptionally high-precision estimation of forest carbon accumulation rates has become possible.

Data assimilation technology is a computational method that improves model accuracy by adjusting model parameters based on differences between model outputs and observed data. NEC's data assimilation technology is designed to enhance the accuracy of carbon flux estimations for the future by linking VISIT with image data obtained from satellite-mounted sensors. A patent application has been filed by NEC for this technology. The VISIT model assesses carbon cycles in terrestrial ecosystems. In addition to enabling estimation of carbon stocks and fluxes using vegetation, soil, and meteorological data, the model can also assess the impacts of land-use changes and climate change. VISIT is particularly well suited for improving accuracy based on observed data and is regarded as highly reliable compared with other similar models.

Furthermore, the VISIT model is applicable to forests across Asia, including Japan. The methodologies recommended by the Verified Carbon Standard (VCS), the world's largest voluntary carbon crediting program, primarily reference models developed for Europe and North America and have not specified models tailored to Asian regions (*2). This joint research utilizing the VISIT model is expected to make important contributions to the advancement of forest carbon credit development in Asia. Data assimilation is a computational method that improves the accuracy of model estimation by correcting model parameters based on differences between model outputs and observed data. The NEC data assimilation technology used in this joint research has the potential, in the future, to enhance the accuracy of carbon flux estimation by linking the VISIT model with satellite-mounted hyperspectral sensors. A patent application has been filed by NEC for this technology.

Currently, the application of data assimilation technology to observational models in the forestry field is not widespread. By applying this technology to the VISIT model, more efficient and highly accurate data collection in forest environments becomes possible, contributing to the advancement of forest conservation initiatives.

Building on the findings obtained through this joint research, NEC will accelerate its initiatives in natural capital accounting and carbon credit development.