https://repository.kopri.re.kr/handle/201206/14786 2026-04-05T21:56:17Z https://repository.kopri.re.kr/handle/201206/15661 Title: Paleoclimate proxy records suggest reduced tropical Pacific zonal asymmetry under sustained global warming Authors: Chung, Eui-Seok; Kim, Seong-Joong; Rodgers, Keith B.; Jun, Sang-Yoon; Kim, Joo-Hong; Lee, Sun-Seon; Yun, Kyung-Sook Abstract: Pronounced model-observation discrepancies in the changes of tropical Pacific zonal sea surface temperature gradient during the satellite era imply systematic model deficiencies. However, the relatively short high-quality instrumental record hampers robustly determining the response of tropical Pacific sea surface temperature to greenhouse gas increases. By adopting paleoclimate proxy records along with a series of climate model simulations, here we show that the zonal gradient is likely to decrease under sustained strong forcing. Paleoclimate proxy records indicate an overall increase of the zonal gradient over time, which has been accompanied by global-mean cooling associated with decreasing carbon dioxide concentrations. Model simulations are found to broadly reproduce the distinct contrast between warmer high carbon dioxide climates and the opposite climates, albeit with large inter-model discrepancy. The qualitative agreement among paleoclimate proxy records and modeled representations therefore lends some important credence to the sign of model-projected future tropical Pacific mean state change. 2025-02-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/15384 Title: Analysis on the Impact of Antarctic Ozone Hole on Tropical Pacific Warming Pattern Authors: Chung, Eui-Seok 2024-02-28T00:00:00Z https://repository.kopri.re.kr/handle/201206/16191 Title: Multi-decadal climate variability and satellite biases have amplified model-observation discrepancies in tropical troposphere warming estimates Authors: Chung, Eui-Seok; Kim, Seong-Joong; Sohn Byung-Ju; Noh, Young-Chan; John Viju O. Abstract: Most coupled model simulations substantially overestimate tropical tropospheric warming trends over the satellite era, undermining the reliability of model-projected future climate change. Here we show that the model-observation discrepancy over the satellite era has arisen in large part from multi-decadal climate variability and residual biases in the satellite record. Analyses indicate that although the discrepancy is closely linked to multi-decadal variability in the tropical Pacific sea surface temperatures, the overestimation remains over the satellite era in model simulations forced by observed time-varying sea surface temperatures with a La Ni & ntilde;a-like pattern. Regarding moist thermodynamic processes governing tropical tropospheric warming, however, we find a broad model-observation consistency over a post-war period, suggesting that residual biases in the satellite record may contribute to model-observation discrepancy. These results underscore the importance of sustaining an accurate long-term observing system as well as constraining the model representation of tropical Pacific sea surface temperature change and variability. Differences between model-simulated and satellite-based estimates of tropical tropospheric warming can be partially explained by multi-decadal climate variability and biases in the satellite record, suggest comprehensive long-term model-data comparisons. 2024-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16416 Title: Tropical eastern Pacific cooling trend reinforced by human activity Authors: Chung, Eui-Seok; Kim, Seong-Joong; Lee Sang-Ki; Ha Kyung-Ja; Yeh Sang-Wook; Kim Yong Sun; Jun, Sang-Yoon; Kim, Joo-Hong; Kim Dongmin Abstract: It remains unresolved whether the La Ni & ntilde;a-like sea surface temperature (SST) trend pattern during the satellite era, featuring a distinct warming in the northwest/southwest Pacific but cooling in the tropical eastern Pacific, is driven by either external forcing or internal variability. Here, by conducting a comprehensive analysis of observations and a series of climate model simulations for the historical period, we show that a combination of internal variability and human activity may have shaped the observed La Ni & ntilde;a-like SST trend pattern. As in observations, SSTs in each model ensemble member show a distinct multi-decadal swing between El Ni & ntilde;o-like and La Ni & ntilde;a-like trend patterns due to internal variability. The ensemble-mean trends for some models are, however, found to exhibit an enhanced zonal SST gradient along the equatorial Pacific over periods such as 1979-2010, suggesting a role of external forcing. In line with this hypothesis, single-forcing large ensemble model simulations show that human-induced stratospheric ozone depletion and/or aerosol changes have acted to enhance the zonal SST gradient via strengthening of Pacific trade winds, although the effect is model dependent. Our finding suggests that the La Ni & ntilde;a-like SST trend is unlikely to persist under sustained global warming because both the ozone and aerosol impacts will eventually weaken. 2024-01-01T00:00:00Z