Understanding the Indian Ocean Carbon Cycle variability via forward and inverse modeling methods

Seminar by Sreeush M. G. from Indian Institute of Tropical Meteorology

15 October 2019
10:00 - 11:00

The Seminar is being held in Room 1010 (Jasmin) - Intergrated mechanical engineering building. Click here for the campus map.

Indian Ocean exhibits complex biophysical interactions in response to the seasonally reversing monsoons winds. Direct observations and biogeochemistry modeling studies have been employed to parameterize these complex biogeochemical interactions in the past several studies. However, this complex puzzle remains incomplete due to the lack of continuous observations and limitations in our understanding in these ecosystem processes. Considering the significance of parameterizing these ecosystem processes and the need of continuous observations over the Indian Ocean further research on Indian Ocean biogeochemistry is imminent. In this study we have introduced, a new parameterization scheme for seasonally varying community compensation depth (Zc; a depth at which photosynthesis balances the community respiration in the upper ocean productive zones) which is widely used in ocean biogeochemistry models. The seasonally varying Zc is retrieved utilizing the concepts of compensation irradiance which has large spatio-temporal dependency and found that the model seasonality of upper ocean carbon cycle has improved significantly with this new approach for Zc. In an independent effort, available observations of surface ocean pCO2 and upper ocean PO4 were employed in an inverse modeling framework using Bayesian methodologies, and verified the spatio-temporal dependency in Zc and found consistent with our forward model parameterizations. These new approaches to retrieve robust seasonal cycle in the Indian Ocean and its variability in models gave further insights on the variability, trends and the controlling factors of acidification of the Indian Ocean. Further considering the lacuna of scarcity of observations in the Indian Ocean carbon cycle, we have proposed an array of pCO2 observational network for the Indian Ocean Buoy program (the so called RAMA mooring arrays). The study also proposed optimal tracks for Voluntary ship of opportunity observations in the Indian Ocean for underway sampling of pCO2which is a primary focus of Indian Ocean research communities.