Deepa, JS (Deepa, J. S.), Gnanaseelan, C (Gnanaseelan, C.), Parekh, A (Parekh, Anant)

Published in CLIMATE DYNAMICS, FEB 2021

The present study examines the representation of interannual and decadal variability of sea level over the Indo-Pacific region in the Coupled Model Intercomparison Project Phase 5 (CMIP5) historical simulations and future projections. The thermocline ridge region of the Indian Ocean (TRIO) shows strong sea level variability on both the interannual and decadal timescales in the CMIP5 historical simulations. Meanwhile, prominent interannual variability is seen in the tropical western Pacific and central to eastern equatorial Pacific, whereas, the decadal sea level variability is dominant in the North Pacific and western Pacific regions. CMIP5 models project similar spatial patterns of sea level variability over the Indo-Pacific region for the twenty-first century under the mid-range and high future emission scenarios, although with some differences in the amplitude and inter-model disagreement. In the interannual timescale, there is a regional contrast in the projected future variability between the Pacific (with increase in variability with increasing greenhouse gas emissions) and TRIO (with decrease of similar to 6 % variability), which is evident in both RCP4.5 and RCP8.5 future emission scenarios with inter-model consensus. On the other hand, increase in decadal sea level variability (similar to 6 % and similar to 8 % in RCP4.5 and RCP8.5 scenarios respectively) is projected over the North Pacific region (north of 30 degrees N). In the Indian Ocean, increase in decadal sea level variability is projected over the northwestern region including Arabian Sea, though it is not a region of large decadal variability (in the reanalysis and historical simulations). Analysis revealed that the local wind forcing (wind stress curl) plays a dominant role in the sea level variability over the Indo-Pacific region on both interannual and decadal timescales.

Deepa, J.S., Gnanaseelan, C. & Parekh, A. The sea level variability and its projections over the Indo‐Pacific Ocean in CMIP5 models. Clim Dyn (2021). https://doi.org/10.1007/s00382-021-05701-3