- Dona Paula, Goa, India.
- +91-0832- 2450327
- iiosc2020[at]nio[dot]org
| Abstract Submission No. | ABS-2022-05-0272 |
| Title of Abstract | Climate change impact on the Arabian sea Oxygen Minimum Zone: Insights from downscaling experiments |
| Authors | Parvathi Vallivattathillam*, Zouhair Lachkar, Marina Lévy, Shafer Smith |
| Organisation | New York University Abu Dhabi |
| Address | New York University Saadiyat Island Abu Dhabi, Abu Dhabi, United Arab Emirates Pincode: 129188 Mobile: 553885119 E-mail: parvathioceanography@gmail.com |
| Country | United Arab Emirates |
| Presentation | Oral |
| Abstract | The land-locked northern boundary and seasonal high productivity in the Arabian sea (AS) leads to the formation and the maintenance of one of the most intense and thickest open ocean oxygen minimum zones (OMZ) there. Earlier studies based on both observation and model sensitivity experiments have reported that this perennial OMZ is highly sensitive to the strength of the monsoonal circulation and surface heating. Model simulations from the fifth phase of Coupled Model Intercomparison project (CMIP5) indicate significant changes in the Indian monsoonal circulation and the atmospheric heat fluxes under climate change. However, the future projection of AS OMZ under climate change remains largely uncertain and ill-understood. This is mainly due to a poor representation of the AS OMZ in the CMIP5 simulations and an important spread in their future oxygen projections for the region. Here we explore how downscaling CMIP5 global simulations with a high-resolution configuration of the Regional Ocean Modeling System (ROMS) model coupled to a nitrogen-based NPZD ecosystem model can help improving the representation of the AS OMZ and reduce the spread in CMIP5 projections. To this end, we performed a climatological ⿿reference simulation, i.e., the control simulation, where ROMS is forced with observed atmospheric and lateral boundary conditions, and a set of corresponding downscaled sensitivity experiment where ROMS is forced with atmospheric and lateral boundary conditions derived from CMIP5 present day and the high emission scenario (RCP8.5) simulations. The control simulation has been extensively validated against the observations for its skill in simulating the physical and biogeochemical variables. We explore the sensitivity of the downscaled oxygen distribution and OMZ to the regional model setup by varying the model resolution from 1/3deg to 1/12deg and expanding the model domain from a small AS-limited domain to one encompassing the full Indian Ocean. The analysis of these simulations reveals a strong sensitivity of the downscaled solutions to the employed horizontal resolution and domain size. Furthermore, we find that both local and remote forcings are important in controlling the predicted evolution of the AS OMZ. |