1) Upper ocean salinity budget analysis with model outputs.
By including some modifications in the NCEP Climate Forecast System, version 2, a more realistic MJO simulation and a better simulation of intraseasonal SSS variability are achieved. Based on the simulation outputs, the mechanisms of the MJO-related SSS variability are further explored by conducting a salinity budget analysis over the mixed layer. The analysis indicates a strong spatial variation in physical processes that dominate the local SSS variability. For example, while the role of surface fluxes dominates in the western Indian basin, oceanic advection plays an important role in the eastern Indian and western Pacific oceans (Fig. 1).
2) An OSSE study for multiple time scale variability: The role of TAO/TRITON vs. Argo.
A series of OSSEs are conducted based on an ocean data assimilation system that is under development at the Joint Center for Satellite Data Assimilation (JCSDA) and the Environmental Modeling Center (EMC)/National Centers for Environmental Prediction (NCEP). The experiments explored the efficacy of TAO/TRITON and Argo observations in TPOS about representing the multiple time scale ocean variability. Diagnostics of the experiments suggest that (1) both TAO/TRITON and especially Argo effectively improve the estimation of mean states and low-frequency (Fig. 2) variations; (2) on the intraseasonal time scale (Fig. 3), Argo has more significant improvements than TAO/TRITON (except for regions close to TAO/TRITON sites); (3) on the high-frequency time scale (Fig. 4), both TAO/TRITON and Argo have evident deficits (although for TAO/TRITON, limited improvements were present close to TAO/TRITON sites).
1. Model simulations suggest a strong regional dependency about the role of E-P flux vs. ocean dynamics in the intraseasonal SSS anomalies.
2. OSSE studies suggest the present observational network is inadequate for resolving high frequency variability on a basin wide.
3. TPOS requires higher frequency observations with a basin coverage
Zhu, J., G. Vernieres, T. Sluka, S. Flampouris, A. Kumar, A. Mehra, M. Cronin, D. Zhang, S. Wills, J. Wang, and W. Wang, 2021: Roles of TAO/TRITON and Argo in tropical Pacific observing system: An OSSE study for multiple time scale variability. (under revision).
Zhu, J., A. Kumar, and W. Wang, 2020: Intraseasonal surface salinity variability and the MJO in a climate model. Geophys. Res. Lett., 47, e2020GL088997. DOI: 10.1029/2020GL088997.
All the model data are archived at NOAA supercomputer Gaea and is available upon request.