Research

Compared to the open ocean, coastal areas and lakes make the light environment more complicated due to the influence of various substances in the atmosphere and water. Therefore, it has been reported that estimation errors occur in the conventional water quality estimation method using satellites used for global observation. We are studying the purpose of elucidating the complex optical properties of coastal areas and lakes and developing new methods for estimating atmosphere and water quality. The research results not only contribute to the elucidation of the effects on the carbon cycle of coastal areas and lakes with high productivity but also as a low-cost, low- labor, eco-friendly constant environmental monitoring method. I believe it can be a technology that supports social infrastructures that are closely related with our life.

Reference：Tokyo Bay Symposium in FY 2018，GCOM-C PI Meeting Documents in FY 2018

Estimation Result of Monthly Average of Chlorophyll-a (phytoplankton pigment) Concentration by GCOM-C/SGLI

In our laboratory, field observations are carried out from ships and land to clarify the reality in the water environment. In Tokyo Bay, one of the main research areas, we are investigating red tide and blue tide by measuring water quality and bottom sediment. In addition, in order to verify the water quality estimation products of the JAXA GCOM-C/SGLI “Sikisai” satellite and clarifying the optical characteristics of each water area, field observations are conducted in various water environments such as Tokyo Bay, Kujukuri and Kashima offshore, Ise - Mikawa Bay, Seto Inland Sea, Ariake Bay, Lake Kasumigaura, Lake Biwa and so on. Furthermore, we are carried out in abroad such as Thailand, Vietnam, Sri Lanka, and Indonesia. It is very important to actually measure the environmental conditions in the fields for the elucidation of the reality and mechanism of the water environments that have not been elucidated so far.

State of water quality investigation in Tokyo Bay (Videos of our field observations are being open on the page of NEWS in the website)

We are developing hydrodynamics and ecosystem simulation models for coastal areas and lakes with extremely complex physical, chemical and biological mechanisms. As an example, in the numerical model of the blue tide generated in Tokyo Bay, we are modeling the biological and chemical processes such as “Proliferation, sedimentation, and decomposition of organic matter, and elution of hydrogen sulfide from the bottom sediment, generation of sulfur by oxidation of hydrogen sulfide, and oxidation of sulfur to sulfate ions” to simulate the generation of the blue tides as sulfur concentration. The development of a numerical simulation model that can accurately represent complex hydrodynamics and ecosystems is important research because it can contribute to understanding the reality of water environments, improving various environmental problems, and predicting the environments.

Reference：Symposium of japan society on water environment in FY 2019

A simulation result of a huge blue tide which has occurred on 24 August, 2015

The use of satellite data is suitable for capturing a wide area, but local remote sensing with drones or fixed digital cameras are effective for small areas. For example, the uploaded video is the time-series change of the blue tide near Chiba Port captured by a fixed camera. It can be seen that the detailed movement of the blue tide distribution, which is difficult to capture by satellite data, shipboard observations, and mooring systems, is captured. In addition, we're researching to develop an automatic monitoring system by drones on tidal flats in Ariake Bay. It is a research to detect the distribution of mussels by deep-learning from images and videos captured by drones and to identify places where mussels are likely to live. These studies are being developed with the aim of automating environmental monitoring using the Internet of Things.

Reference：Development of a Method for Estimating Mussel Mats by an Image Analysis of Deep-Learning (Graduation Thesis of Miyatsuji Takashi )，Development of Estimation Method of Sulfur Concentration using a Fixed Camera (Graduation Thesis of Kikuchi Masakazu))

The blue tide in Chiba Port taken with a fixed camera on August 29, 2016