연구보고서
- 저자
- 김선태 박사
- 작성일
- 2018.04.24
- 조회
- 376
- 요약
- 목차
In this study, a series of analyses was performed to verify the model performance for predicting major climate variabilities and their spatiotemporal evolution in the Seamless Coupled Prediction System (SCoPS), which is a current APEC Climate Center (APCC) in-house model for seasonal forecast. The capability to predict El Nino-Southern Oscillation (ENSO) and the related oceanic/atmospheric responses; the interbasin relationships among the tropical Pacific Ocean, the Indian Ocean, and
the Atlantic Ocean; and the atmospheric variability and energy structure is of specific interest.
The SCoPS reliably predicted ENSO-induced sea surface temperature (SST) variability, especially during boreal winter; however, the model’s prediction capability decreased during summer, which is a common feature of seasonal prediction models. The prediction skills of the detailed equatorial SST during ENSO events were significantly enhanced with greater amplitudes, even with long-lead forecast times. The SCoPS also skillfully simulated the atmospheric response to ENSO over the Northwestern Pacific and the North Atlantic Ocean. There existed, however, slight spatial shifts and overestimation of the amplitudes of the atmospheric
responses. These biases should be considered for SCoPS-based seasonal prediction, as both these atmospheric systems are important factors in the seasonal climates of East Asia and countries adjacent to the Atlantic Ocean.
The prediction characteristics of the SCoPS in the Indian Ocean atmosphere-ocean coupled modes also were investigated, such as the Indian Ocean basin-wide warming and Indian Ocean dipole modes. In addition to the assessment of prediction skill of each mode, the evolution processes associated with the two modes were analyzed. The major modes over the Indian Ocean were predicted reasonably well by the SCoPS. Because the Indian and Pacific Oceans dynamically interact with one other, detailed examination of this interbasin relationship can advance the APCC’s operational seasonal forecast.
Two atmospheric modes, the North Atlantic Oscillation (NAO) and West Pacific (WP) modes, during winter also were analyzed in depth. The SCoPS better simulated the observed pattern and temporal variation than did the Community Climate System
Model version 3 (CCSM3), which is a previous APCC in-house model. The skill improvement was associated with the realistic representation of winter climatology in the SCoPS, including jet stream structure, lower-tropospheric temperature, and stationary waves. On the other hand, the SCoPS tended to overestimate the relationship between NAO/WP activity and ENSO, and even displayed NAO/WP index prediction skill which is highly reliant on the ENSO phases.
Lastly, the atmospheric energetics of the SCoPS were compared with the observational reanalysis results. The global-scale atmospheric energy structure supported the idea that the SCoPS properly presents the observed atmospheric energy distribution and its cascading structure. It was also confirmed that the SCoPS’s time integration was stable not only numerically, but also physically. On the other hand, the underestimation of baroclinic energy conversion needs to be carefully looked at, especially for the sub-seasonal scale processes that involve baroclinic instability.