157 / 2024-09-10 12:47:12
Research of response of ocean salinity and meridional salt transport to climate change based on climate model simulations
Climate model,Ocean salinity,Meridional salt transport,Climate change
Session 23 - Sea level rise: understanding, observing, and modelling
Abstract Accepted
To some extent, the response of global water cycle to climate change can be estimated from the long-term changes in ocean salinity. Based on historical simulations and future climate scenario simulations from the UKESM model, this study investigates the response of ocean salinity and salt transport to climate change. The results indicate that, despite some biases, the UKESM model is able to simulate the large-scale distribution of global ocean salinity. Furthermore, the UKESM model simulation reproduces the trend of increasing salinity in high salinity regions and decreasing salinity in low salinity regions (i.e., the amplification of the existing salinity pattern), which is consistent with the observational data from 1960 to 2022. This study further analyzes the difference between the salinity averaged over high-salinity and low-salinity regions, including the salinity contrast calculated over the sea surface alone (SC0) and the volume from the surface down to 2000 meters (SC2000). The results from the UKESM model simulation show that both SC0 and SC2000 are increasing during the period 1960-2100. The simulated increasing trend of SC0 from 1960 to 2022 (0.12 g kg-1 century-1 and 0.13 g kg-1 century-1 ) is smaller compared to the observational estimate (0.17 g kg-1 century-1 ), while the simulated increasing trend of SC2000 during the period 1960-2022 is close to the observational estimate (0.0028 g kg-1 century-1 ). In terms of the meridional salt transport, both the southward salt transport in the Atlantic basin and the northward salt transport in the Indian-Pacific basin are projected to weaken in the future. Future multi-model ensemble analyses are expected to help us further understand the sources of biases and uncertainties in climate model simulations.