scholarly journals Radial S wave velocity structure of the D" region under a spot of the east central Pacific Ocean

2012 ◽  
Vol 51 (3) ◽  
Author(s):  
Luis F. Terán-Mendieta. ◽  
Raúl. W. Valenzuela
Keyword(s):  
Pacific Ocean ◽  
Wave Velocity ◽  
Velocity Structure ◽  
S Wave ◽  
Central Pacific ◽  
East Central ◽  
Central Pacific Ocean ◽  
D Region

Se determino la estructura radial de velocidades para la onda S en la base del manto en un área del Océano Pacifico centro-oriental centrada en los 19°N, 132°0. Se aplico la técnica de la constante de disipación en el dominio de la frecuencia a las ondas S y Sdiff de un sismo producido en las islas Tonga y registrado en el noreste de los Estados Unidos. Se trabajo con 29 modelos diferentes, entre los cuales se incluían modelos con una discontinuidad de la velocidad y también el Modelo Preliminar de Referencia de la Tierra (PREM). De acuerdo con el ajuste a la constante de disipación en el dominio de la frecuencia y a las formas de onda en el dominio del tiempo, se considero que PREM es el mejor modelo. Esto implica que en esta ubicación D" tiene un espesor de 150 km y un gradiente de velocidad ligeramente negativo conforme aumenta la profundidad. No se encontró una discontinuidad de la velocidad en la parte superior de D". La estructura de velocidades observada es consistente con el comportamiento de D"como una capa térmica limítrofe y también con la posibilidad de que el material del manto se enriquezca en hierro como consecuencia de reacciones químicas con el núcleo. Ademas este modelo sugiere que en esta región existen temperaturas ligeramente elevadas en la base del manto. Por otra parte, no se esperaría encontrar una discontinuidad en esta zona puesto que ahí no se ha producido subducción en los últimos 180 millones de años.

scholarly journals Primary Production in the Water Column as Major Structuring Element of the Biogeographical Distribution and Function of Archaea in Deep-Sea Sediments of the Central Pacific Ocean

Archaea ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Franziska Wemheuer ◽  
Avril Jean Elisabeth von Hoyningen-Huene ◽  
Marion Pohlner ◽  
Julius Degenhardt ◽  
Bert Engelen ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Primary Production ◽  
Deep Sea ◽  
Archaeal Community ◽  
Central Pacific ◽  
Central Pacific Ocean ◽  
Deep Sea Sediments ◽  
And Function ◽  
Functional Profiles ◽  
Archaeal Communities

Information on environmental conditions shaping archaeal communities thriving at the seafloor of the central Pacific Ocean is limited. The present study was conducted to investigate the diversity, composition, and function of both entire and potentially active archaeal communities within Pacific deep-sea sediments. For this purpose, sediment samples were taken along the 180° meridian of the central Pacific Ocean. Community composition and diversity were assessed by Illumina tag sequencing targeting archaeal 16S rRNA genes and transcripts. Archaeal communities were dominated by CandidatusNitrosopumilus(Thaumarchaeota) and other members of theNitrosopumilaceae(Thaumarchaeota), but higher relative abundances of the Marine Group II (Euryarchaeota) were observed in the active compared to the entire archaeal community. The composition of the entire and the active archaeal communities was strongly linked to primary production (chlorophyll content), explaining more than 40% of the variance. Furthermore, we found a strong correlation of the entire archaeal community composition to latitude and silicic acid content, while the active community was significantly correlated with primary production and ferric oxide content. We predicted functional profiles from 16S rRNA data to assess archaeal community functions. Latitude was significantly correlated with functional profiles of the entire community, whereas those of the active community were significantly correlated with nitrate and chlorophyll content. The results of the present study provide first insights into benthic archaeal communities in the Pacific Ocean and environmental conditions shaping their diversity, distribution, and function. Additionally, they might serve as a template for further studies investigating archaea colonizing deep-sea sediments.

The Birds of Fanning Island, Central Pacific Ocean

The Condor ◽  
1925 ◽  
Vol 27 (5) ◽  
pp. 185-196 ◽  
Author(s):  
Harold Kirby,
Keyword(s):  
Pacific Ocean ◽  
Central Pacific ◽  
Central Pacific Ocean

scholarly journals The Relationship between Equatorial Mixed Rossby–Gravity and Eastward Inertio-Gravity Waves. Part II

2016 ◽  
Vol 73 (5) ◽  
pp. 2147-2163 ◽  
Author(s):  
Juliana Dias ◽  
George N. Kiladis
Keyword(s):  
Pacific Ocean ◽  
Gravity Waves ◽  
Companion Paper ◽  
Empirical Orthogonal Functions ◽  
Central Pacific ◽  
The West ◽  
Orthogonal Functions ◽  
Central Pacific Ocean ◽  
The Relationship ◽  
Zonal Propagation

Abstract Space–time spectral analysis of tropical cloudiness data shows strong evidence that convectively coupled n = 0 mixed Rossby–gravity waves (MRGs) and eastward inertio-gravity waves (EIGs) occur primarily within the western/central Pacific Ocean. Spectral filtering also shows that MRG and EIG cloudiness patterns are antisymmetric with respect to the equator, and they propagate coherently toward the west and east, respectively, with periods between 3 and 5 days, in agreement with Matsuno’s linear shallow-water theory. In contrast to the spectral approach, in a companion paper it has been shown that empirical orthogonal functions (EOFs) of 2–6-day-filtered cloudiness data within the tropical Pacific Ocean also suggest an antisymmetric pattern, but with the leading EOFs implying a zonally standing but poleward-propagating oscillation, along with the associated tropospheric flow moving to the west. In the present paper, these two views are reconciled by applying an independent approach based on a tracking method to assess tropical convection organization. It is shown that, on average, two-thirds of MRG and EIG events develop independently of one another, and one-third of the events overlap in space and time. This analysis also verifies that MRG and EIG cloudiness fields tend to propagate meridionally away from the equator. It is demonstrated that the lack of zonal propagation implied from the EOF analysis is likely due to the interference between eastward- and westward-propagating disturbances. In addition, it is shown that the westward-propagating circulation associated with the leading EOF is consistent with the expected theoretical behavior of an interference between MRGs and EIGs.

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