How are El Nino and La Nina events improved in an eddy-resolving ocean general circulation model?
Date：2015-05-18
The simulation of the equatorial Pacific temperature and currents associated with ENSO in LICOM_H has rarely been explored in previous studies. Two numerical experiments, one using LICOM_H and one using LICOM_L, were conducted to help understand how the finer resolution of LICOM_H helps to improve the simulation of ENSO. Main findings can be summarized as follows:
(1) The finer resolution improves the simulation of the mean state of, for example, the vertical temperature gradient in the upper ocean. Also, the vertical velocity near the surface is comparable with the Ekman current estimated from the observed wind stress.
(2) The vertical advections of temperature in the temperature equation are improved due to the contributions of both temperature gradient and velocity.
(3) Through heat budget analysis, the differences in vertical advections are much greater than those of zonal and meridional advection between LICOM_H and LICOM_L. This is manifested in the key roles played by the thermocline feedback and Ekman feedback in causing the amplitude of ENSO.
(4) Although the external wind stress forcing is exactly the same in the LICOM_H and LICOM_L experiments, the regression of temperature on wind stress is better reproduced in LICOM_H compared to that in LICOM_L, due to the above-mentioned more reasonable ENSO feedbacks.
Heat budget analysis averaged over the Ni？o3 region (5°N–5°S, 150–90°W) in the upper ocean (0–100 m) for the warm phase (red) and cold phase (blue) in (a) High Resolution Model and (b) Low Resolution Model. Units: °C/month.
Citation: Hua, L.-J., and Y.-Q. Yu, 2015: How are El Ni？o and La Ni？a events improved in an eddy-resolving ocean general circulation model? Atmos. Oceanic Sci. Lett., 8, 000–000, doi:10.3878/AOSL20150015.
Link: http://159.226.119.58/aosl/EN/abstract/abstract560.shtm
