scholarly journals Ocean bottom pressure variations in the southeastern Pacific following the 1997–98 El Niño event

2003 ◽  
Vol 30 (9) ◽  
Author(s):  
Hiromi Fujimoto
2019 ◽  
Vol 40 (4) ◽  
pp. 513-514
Author(s):  
Takuya Hasegawa ◽  
Akira Nagano ◽  
Hiroyuki Matsumoto ◽  
Keisuke Ariyoshi ◽  
Masahide Wakita

2019 ◽  
Vol 40 (4) ◽  
pp. 505-512
Author(s):  
Takuya Hasegawa ◽  
Akira Nagano ◽  
Hiroyuki Matsumoto ◽  
Keisuke Ariyoshi ◽  
Masahide Wakita

2021 ◽  
Author(s):  
Jianhuang Qin ◽  
Xuhua Cheng ◽  
Chengcheng Yang ◽  
Niansen Ou ◽  
Xiaoqin Xiong

Abstract The study of ocean bottom pressure (OBP) is useful for understanding the barotropic processes variability that contribute to sea level rise. Previous studies have reported the strong OBP anomalies in the Southern Ocean on different time scales. In this study, the characteristic and mechanisms of the energetic interannual OBP variability in the southeastern Pacific are examined using 14 years of GRACE data. It is found that the OBP anomalies are positive (negative) related to the convergence (divergence) of Ekman transport forced by local winds variability. The sea level pressure (SLP) anomalies shows a wavenumber-3 structure in the high latitude of the South Pacific, which benefits a strong and persistent anticyclone over the southeastern Pacific, leading to the positive OBP anomalies there. Such SLP anomalies are similar to the second Pacific-South American (PSA2). Moreover, El Niño–Southern Oscillation (ENSO) plays an important role in the austral spring (August-November) OBP variability and leads the austral autumn (March-June) OBP variability by 1 season. These results highlight the influence of atmospheric variability on OBP anomalies and are validated by a mass conservation (non-Boussinesq) ocean model, which is expected to not only better understanding of OBP mechanisms in a longer time, but also predict OBP variation in the global scale.


2019 ◽  
Vol 10 ◽  
Author(s):  
Bruno O. Gimenez ◽  
Kolby J. Jardine ◽  
Niro Higuchi ◽  
Robinson I. Negrón-Juárez ◽  
Israel de Jesus Sampaio-Filho ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Diego Páez-Rosas ◽  
Jorge Torres ◽  
Eduardo Espinoza ◽  
Adrian Marchetti ◽  
Harvey Seim ◽  
...  

AbstractCurrently, the Galapagos sea lion (GSL, Zalophus wollebaeki) and Galapagos fur seal (GFS, Arctocephalus galapagoensis) are among the most important endemic species for conservation in the Galapagos Archipelago. Both are classified as “Endangered” since their populations have undergone drastic declines over the last several decades. In this study we estimated the abundance of both otariids, and their population trends based using counts conducted between 2014 and 2018 in all their rookeries, and we analyzed the influence of environmental variability on pup production. The GSL population size in 2018 in the archipelago was estimated to be between 17,000 to 24,000 individuals and has increased at an average annual rate of 1% over the last five years after applying correction factors. The highest number of GSL counted in the archipelago was in 2014 followed by a population decline of 23.8% in 2015 that was associated with the El Niño event that occurred during that year. Following this event, the population increased mainly in the northern, central and southeastern rookeries. The GSL pup abundance showed a decreasing trend with the increase in intensity of the El Niño. The GFS population in 2018 was counted in 3,093 individuals and has increased at an annual rate of 3% from 2014 to 2018. A high number of GFS counted in 2014 was followed by a population decrease of 38% in 2015, mainly in the western rookeries. There was interannual population fluctuations and different growth trends among regions of the archipelago. GSL and GFS pup abundance has a strong decreasing tendency with the increase in the subthermocline temperature (ST) and the El Niño 1 + 2 index. Our results provide evidence that both species are highly vulnerable to periodic oceanographic-atmospheric events in the Galapagos Archipelago which impact prey abundance and the flow of energy in the unique Galapagos ecosystem.


2021 ◽  
Vol 13 (7) ◽  
pp. 1242
Author(s):  
Hakan S. Kutoglu ◽  
Kazimierz Becek

The Mediterranean Ridge accretionary complex (MAC) is a product of the convergence of Africa–Europe–Aegean plates. As a result, the region exhibits a continuous mass change (horizontal/vertical movements) that generates earthquakes. Over the last 50 years, approximately 430 earthquakes with M ≥ 5, including 36 M ≥ 6 earthquakes, have been recorded in the region. This study aims to link the ocean bottom deformations manifested through ocean bottom pressure variations with the earthquakes’ time series. To this end, we investigated the time series of the ocean bottom pressure (OBP) anomalies derived from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) satellite missions. The OBP time series comprises a decreasing trend in addition to 1.02, 1.52, 4.27, and 10.66-year periodic components, which can be explained by atmosphere, oceans, and hydrosphere (AOH) processes, the Earth’s pole movement, solar activity, and core–mantle coupling. It can be inferred from the results that the OBP anomalies time series/mass change is linked to a rising trend and periods in the earthquakes’ energy time series. Based on this preliminary work, ocean-bottom pressure variation appears to be a promising lead for further research.


Author(s):  
Hiroaki Tsushima ◽  
Ryota Hino ◽  
Hiromi Fujimoto ◽  
Yuichiro Tanioka ◽  
Fumihiko Imamura

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Luyu Chang ◽  
Jianming Xu ◽  
Xuexi Tie ◽  
Jianbin Wu
Keyword(s):  
El Niño ◽  
El Nino ◽  

2018 ◽  
Vol 31 (24) ◽  
pp. 9869-9879 ◽  
Author(s):  
Jianping Duan ◽  
Lun Li ◽  
Zhuguo Ma ◽  
Jan Esper ◽  
Ulf Büntgen ◽  
...  

Large volcanic eruptions may cause abrupt summer cooling over large parts of the globe. However, no comparable imprint has been found on the Tibetan Plateau (TP). Here, we introduce a 400-yr-long temperature-sensitive network of 17 tree-ring maximum latewood density sites from the TP that demonstrates that the effects of tropical eruptions on the TP are generally greater than those of extratropical eruptions. Moreover, we found that large tropical eruptions accompanied by subsequent El Niño events caused less summer cooling than those that occurred without El Niño association. Superposed epoch analysis (SEA) based on 27 events, including 14 tropical eruptions and 13 extratropical eruptions, shows that the summer cooling driven by extratropical eruptions is insignificant on the TP, while significant summer temperature decreases occur subsequent to tropical eruptions. Further analysis of the TP August–September temperature responses reveals a significant postvolcanic cooling only when no El Niño event occurred. However, there is no such cooling for all other situations, that is, tropical eruptions together with a subsequent El Niño event, as well as extratropical eruptions regardless of the occurrence of an El Niño event. The averaged August–September temperature deviation ( Tdev) following 10 large tropical eruptions without a subsequent El Niño event is up to −0.48° ± 0.19°C (with respect to the preceding 5-yr mean), whereas the temperature deviation following 4 large tropical eruptions with an El Niño association is approximately 0.23° ± 0.16°C. These results indicate a mitigation effect of El Niño events on the TP temperature response to large tropical eruptions. The possible mechanism is that El Niño events can weaken the Indian summer monsoon with a subsequent decrease in rainfall and cooling effect, which may lead to a relatively high temperature on the TP, one of the regions affected by the Indian summer monsoon.


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