A Critical examination of the current theories on the ENSO dynamics using an intermediate coupled ocean-atmosphere model

학위논문(박사)--서울大學校 大學院 :大氣科學科,1996.Docto

Ocean Dynamic Processes Responsible for the Interannual Variability of the Tropical Indian Ocean SST Associated with ENSO

The interannual variability of the tropical Indian Ocean SST is investigated by analyzing the ocean assimilation data. It is significant that since 1970, ENSO events frequently followed the Indian Ocean Dipole event. The SST tendency due to the dynamical SST advections over the tropical Indian Ocean sufficiently overwhelms that due to other thermodynamic process during the fall and winter of ENSO. Especially, the strong cooling due to the anomalous vertical advection by the mean upwelling and the warming due to the horizontal advection are attributed to the cold SST during the fall and the warm SST during the winter, respectively. The significant warming between winter and spring over the southwestern Indian Ocean turns out to be due to the vertical advection of the mean subsurface temperature by the anomalous upwelling during the winter and the vertical advection of the anomalous subsurface temperature by the mean upwelling from winter to spring. We speculate that when the Indian Ocean Dipole events concurred with the ENSO, the surface wind is so strong enough as to generate the change in the SST dynamically and overwhelm the SST changes associated with other effects.22Nkc

On the relationship between ENSO and annual cycle in the tropical eastern Pacific

The El Nino-Southern Oscillation (ENSO) is an abnormal change of the annual cycle, and thus, change in ENSO is closely related to change in the annual cycle. So far, it is known that the change in the amplitude of ENSO is negatively correlated to that in the amplitude of the annual cycle. Here we analyzed 500-year simulation of a coupled GCM in order to investigate the relationship between ENSO and annual cycle in the tropical eastern Pacific. The negative correlation between the decadal change in the ENSO amplitude and that in the annual cycle is dominant, yet the positive correlation is also significant for some decadal periods. Here, we propose the possible mechanisms to lead the positive and negative correlations.1

TWO TYPES OF EL NINO EVENTS:

In this study, two types of El Nino events are classified based on spatial patterns of sea-surface temperature (SST) anomaly. One is cold tongue (CT) El Nino, which can be regarded as the conventional El Nino, and the other is Warm Pool (WP) El Nino. The CT El Nino is characterized by relatively large SST anomalies in the NINO3 region (5S-5N, 150-90W), while the WP El Nino is associated with SST anomalies mostly confined to the NINO4 region (5S-5N, 160E-150W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Nino events. Furthermore, difference in the transition mechanism between two types of El Nino is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Nino is not efficient due to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that the zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal current) plays a crucial role in the development of a decaying SST anomaly associated with the WP El Nino, while the thermocline feedback is a key process during the CT El Nino.1

TWO TYPES OF EL NINO EVENTS: CT and WP El Nino

In this study, two types of El Nino events are classified based on spatial patterns of sea-surface temperature (SST) anomaly. One is cold tongue (CT) El Nino, which can be regarded as the conventional El Nino, and the other is Warm Pool (WP) El Nino. The CT El Nino is characterized by relatively large SST anomalies in the NINO3 region (5S-5N, 150-90W), while the WP El Nino is associated with SST anomalies mostly confined to the NINO4 region (5S-5N, 160E-150W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Nino events. Furthermore, difference in the transition mechanism between two types of El Nino is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Nino is not efficient due to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that the zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal current) plays a crucial role in the development of a decaying SST anomaly associated with the WP El Nino, while the thermocline feedback is a key process during the CT El Nino.1

Two types of El Nino events: Cold tongue El Nino and Warm pool El Nino

In this study, two types of El Nino events are classified based on spatial patterns of sea-surface temperature (SST) anomaly. One is cold tongue (CT) El Nino, which can be regarded as the conventional El Nino, and the other is Warm Pool (WP) El Nino. The CT El Nino is characterized byrelatively large SST anomalies in the NINO3 region (5S-5N, 150-90W), while the WP El Nino is associated with SST anomalies mostly confined to the NINO4 region (5S-5N, 160E-150W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Nino events. Furthermore, difference in the transition mechanism between two types of El Nino is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Nino is not efficient due to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that the zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal current) playsa crucial role in the development of a decaying SST anomaly associated with the WP El Nino, while the thermocline feedback is a key process during the CT El Nino.2

한반도 기후변화의 추세와 원인 고찰

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Diverse Arctic Oscillation responses after volcanic eruptions at different latitudes during the last millennium

1

Different surface climate responses after volcanic eruptions at different latitudes: Role of stratospheric polar vortex

2

Non-monotonic Storm Track Change to Carbon Dioxide Removal

1