[A-OS14] Physical Oceanography (General)

[AOS14-P12] Assessment of the CMIP6 GCM wind fields for Indian Ocean wave climate simulation

*Meenakshi Sreejith^1,2, Remya P G¹, Praveen Kumar B¹, BalaKrishnan Nair¹ (1.Indian National Centre for Ocean Information Services, Hyderabad, India, 2.Kerala University of Fisheries and Ocean Studies, Kochi)

Keywords:CMIP6, Indian Ocean, Ocean surface waves, IOD, ENSO, SAM

A comprehensive understanding of ocean surface waves is vital for a range of activities such as fishing, navigation, tourism, recreation, and design practices. This study presents a 35-year (1980-2014) wind-wave climate simulation of the Indian Ocean (IO) forced with seven CMIP6 Global Climate Models (GCMs). A two-grid global and Indian nested system is implemented using the third-generation wave model WAVEWATCH-III (WWIII). The selected CMIP6 models (BCC-CSM2-HR, EC-Earth3, CMCC-CM2-SR, GFDL-ESM4, CNRM-CM6-1-HR, HadGEM3-GC31-MM, and MPI-ESM1-2-HR) are evaluated based on their performance in comparison with altimeter data and in-situ buoy observations. Various statistical analyses are employed to assess the models' performance, including correlation coefficients, root mean square errors, standard deviations, empirical orthogonal functions, probability density functions, and extreme wave indices. The findings reveal that MPI, BCC, EC, and CNRM demonstrate the highest accuracy in representing wave characteristics in the IO, exhibiting strong correlations with observations and effectively capturing inter-annual variability. Extreme wave analysis using ERA5 as observation showed an increase in rough wave days (daily wave height max >2.5m) of 220 days/years, accurately depicted by MPI, BCC, and EC models. The top three models were then selected to represent climate modes and their effect on IO waves using composite analysis. The results were quantified by using spatial correlation and spatial rmse. EC model performed best in capturing wave fields under the influence of El-Nino Southern Oscillation, Southern Annular Mode and Indian Ocean Dipole. The model showed spatial correlations in the range of 0.7-0.9 for all three climate modes. This study addresses uncertainties surrounding the selection of CMIP6 GCM winds for projection studies in the IO, providing valuable insights for policymaking in effective coastal management strategies.