[Seminar on 5 Aug]The link between Pacific Subtropical Cell and Tropical Climate Variability
Dr. YU-HENG TSENG
Climate and Global Dynamics Division, NCAR
10:00 am,5 August,2014
The variability of Pacific Subtropical Cells (STCs) and its causal relation with tropical climate variability is investigated. At interannual time scales, the equatorial SST is significantly correlated with interior STCs in the central Pacific basin (160°E-130°W). The lead-lag correlation analysis of the indices of the STCs, equatorial warm water volume (WWV), wind stress curl and SST anomalies are synthesized to depict the dominant processes in different phases of the existing recharge-discharge mechanisms of El Ni？o that evolves from a recharging stage (interior STCs convergence), to a recharged stage (high WWV), before the warmest SST phase, and followed by a discharging stage (interior STCs divergence) to a discharged stage (low WWV). The corresponding timescales for the completed process (from a recharging stage to a discharged stage) are 8, 10, 2 and 8 months, respectively. By linking the above time scales to the ENSO evolution process, this study provides a detailed subsurface transport mechanism to refine theoretical models and examine the couple ocean-atmosphere general circulation model simulations of ENSO. The processes can be used to predict the El Nino development in 2014.