[IIOE2-EP37] R/V Hakuho-Maru 2020 cruise

Lead Investigator :

  1. Yukio Masumoto, Dept. of Earth and Planetary Science, The University of Tokyo, Japan

Other Key participants (s):

  1. Hiroaki Saito, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan
  2. Hajime Obata, Atmosphere and Ocean Research Institute, The University of Tokyo, Japan
  3. Iwao Ueki, Japan Agency for Marine-Earth Science and Tecnology, Japan

Period of Project: July 2019 to March 2022

Brief description of the Project:

The current systems of the Eastern Indian Ocean show dynamic seasonal and interannual variations responding to seasonal monsoon and climate variability as well as climate regime shifts. The biogeochemical cycling and ecosystem of the Eastern Indian Ocean also change with physical oceanographic regime. Since the Eastern Indian Ocean is located at the most populated region of the world, the ecosystems there are also influenced by various anthropogenic perturbations such as pollutants, plastic debris, overfishing, etc. The Eastern Indian Ocean is, however, seriously understudied region relative to the Pacific Ocean and the Atlantic Ocean, due mainly to paucity of in situ observations, hence our knowledge on the physical, biological, and biogeochemical processes are limited. Understanding the mechanisms of biogeochemical cycle and ecosystem responses to natural and anthropogenic perturbations, as well as variability in physical conditions, is an emergent issue since increasing human activity is degrading the quality and quantity of marine ecosystem services, on which our society is dependent.

In order to tackle with the emergent issues, it is essential to take an interdisciplinary approach, under which physical oceanographers, biogeochemists, biological oceanographers, and atmospheric chemists work together to unveil physical-chemical-biological interactions in the Eastern Indian Ocean. This research cruise, using R/V Hakuho-Maru, provides one such opportunity and in situ data for better understanding of the above key issues.

Region of study:

The target area of this cruise is the eastern Indian Ocean. There will be two legs in this cruise (Leg-1 and Leg-2). Leg-1 focuses on the upwelling system off the coast of Sumatra and Java, which we could not achieve during the R/V Hakuho-Maru 2018 cruise due to the EEZ permission issue. Leg-2 will observe a section along 88E from the equator down to 30S, which is a follow-on and extension of the R/V Hakuho 2018 cruise, and along 30S from 88E to the Australian coast, focusing on subduction region and meso-scale eddy structures. The following figures indicate the planned cruise tracks and locations of observation stations.

The planned cruise tracks of Leg-1 (left) and Leg-2 (right) of R/V Hakuho-Maru 2020 cruise.