Evolution of the ocean monsoon regions over the past 250 million years

2021 ◽  
Author(s):  
Jing Han ◽  
Yongyun Hu ◽  
Yonggang Liu
Keyword(s):  
Pacific Ocean ◽  
Mixed Layer ◽  
Ocean Basin ◽  
Subtropical High ◽  
Monsoon Region ◽  
Ocean Mixed Layer ◽  
The Past ◽  
The Pacific ◽  
Monsoon Area ◽  
The Pacific Ocean

<p>A set of deep-time climate simulations each 10Ma years from 250Ma to PI are conducted by using the NCAR-CESM1.2, for understanding the evolution of the ocean monsoon regions driven by tectonic dynamics over the past 250 million years and exploring its variation mechanisms. In recent years, scientists have proposed the concept of a global monsoon system, which includes not only typical monsoon regions (such as the African monsoon region and South Asian monsoon region), but also the atypical Northwest Pacific Ocean monsoon region. Research on the ocean monsoon is very limited, especially in the field of paleoclimate. The results in this paper show that the horizontal gradients of the thickness of the ocean mixed layer may be more important for the formation of the ocean monsoon than land-sea thermal contrast, which is confirmed by the aquaplanet simulations with various gradients of the ocean mixed-layer thickness. Near the Pacific monsoon region in the northern hemisphere, the thickness of the ocean mixed layer has obvious meridional and zonal gradients, which will correspond to the meridional and zonal thermal contrasts. In addition, there are obvious seasonal reversals in the gradients of the ocean mixed-layer thickness in summer and winter, and the corresponding longitudinal and zonal thermal contrast produce seasonal reversals. Over the past 250 million years, the thickness of the ocean mixed layer on the east side of the Pacific Ocean Basin in the Northern Hemisphere has deepened, and the corresponding ocean monsoon area on the east side of the Pacific Ocean has decreased. The changes in the thickness of the ocean mixed layer are closely related to the changes in the surface wind field. Examining the changes in the atmospheric circulations, we find that the Pacific subtropical high strengthens and extends from east to the west bank of the ocean basin, where the atmospheric low-level anticyclonic circulation causes the ocean surface layer to converge and sink and thus causes the ocean mixed layer to deepen. The changes in the Pacific subtropical high are related to changes in the continental monsoon region. Since the 170Ma, the Pangea supercontinent splits up, causing the supercontinent's inland water vapor to increase, the land monsoon area to increase, and the ocean monsoon area to decrease. According to the "monsoon-desert mechanism" of Rodwell and Hoskins, we can understand the relationship between the strengthening of land monsoon condensation heating and the formation of subtropical high over the western ocean.</p>

THE TECTONIC HISTORY OF THE PACIFIC OCEAN BASIN SINCE CHRON 34Y (83 MA)

2017 ◽  
Author(s):  
Nicky M. Wright ◽  
◽  
Maria Seton ◽  
Simon E. Williams ◽  
R. Dietmar Müller
Keyword(s):  
Pacific Ocean ◽  
Ocean Basin ◽  
Tectonic History ◽  
The Pacific ◽  
History Of ◽  
The Pacific Ocean

The pacific Ocean Basin to 1850

2012 ◽  
Author(s):  
Rainer F. Buschmann
Keyword(s):  
World War Ii ◽  
Pacific Ocean ◽  
World History ◽  
Ocean Basin ◽  
World War ◽  
The Pacific ◽  
Military Campaigns ◽  
The Pacific Ocean ◽  
Galleon Trade ◽  
Geographical Feature

The Pacific Ocean is the world's largest and deepest ocean, spanning about one-third of the earth's surface. Despite its size, the Pacific has received only scant global historical attention when compared to the Atlantic and the Indian Oceans. However, the Pacific has played a prominent role intermittently in world history, highlighted by Austronesian expansion, Manila Galleon trade, eighteenth-century European exploration, and the intense island-hopping military campaigns of World War II. At the same time, such historical interest did not translate into a familiar timeline integrating this watery geographical feature into a larger world historical framework. This article argues that there is more discontinuity than continuity to this ocean, and its history is best broken down by three distinct periods of exploration and settlement.

scholarly journals Unknown Tsunami Trigger Hides Along a Creeping Aleutian Fault

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Cody Sullivan
Keyword(s):  
Pacific Ocean ◽  
Subduction Zone ◽  
The Past ◽  
The Pacific ◽  
The Pacific Ocean

A seismically quiet part of the Aleutian Subduction Zone may have caused tsunamis in the past—and may cause future tsunamis that could travel across the Pacific Ocean.

scholarly journals Pacific Sea Levels Rising Very Slowly and Not Accelerating

2019 ◽  
Vol 38 (1) ◽  
pp. 179-184 ◽  
Author(s):  
Albert Parker ◽  
Clifford Ollier
Keyword(s):  
Pacific Ocean ◽  
Sea Level ◽  
Relative Rate ◽  
Tide Gauges ◽  
Sea Levels ◽  
The Past ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Long Term Trend

AbstractOver the past decades, detailed surveys of the Pacific Ocean atoll islands show no sign of drowning because of accelerated sea-level rise. Data reveal that no atoll lost land area, 88.6% of islands were either stable or increased in area, and only 11.4% of islands contracted. The Pacific Atolls are not being inundated because the sea level is rising much less than was thought. The average relative rate of rise and acceleration of the 29 long-term-trend (LTT) tide gauges of Japan, Oceania and West Coast of North America, are both negative, −0.02139 mm yr−1and −0.00007 mm yr−2respectively. Since the start of the 1900s, the sea levels of the Pacific Ocean have been remarkably stable.

scholarly journals Genetic structure of the crown-of-thorns seastar in the Pacific Ocean, with focus on Guam

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1970 ◽  
Author(s):  
Sergio Tusso ◽  
Kerstin Morcinek ◽  
Catherine Vogler ◽  
Peter J. Schupp ◽  
Ciemon F. Caballes ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Pacific Ocean ◽  
Long Distance ◽  
The Past ◽  
The Pacific ◽  
Tropical Coral ◽  
Population Outbreaks ◽  
Geographical Regions ◽  
The Pacific Ocean ◽  
The Western Pacific

Population outbreaks of the corallivorous crown-of-thorns seastar (COTS),Acanthaster ‘planci’ L., are among the most important biological disturbances of tropical coral reefs. Over the past 50 years, several devastating outbreaks have been documented around Guam, an island in the western Pacific Ocean. Previous analyses have shown that in the Pacific Ocean, COTS larval dispersal may be geographically restricted to certain regions. Here, we assess the genetic structure of Pacific COTS populations and compared samples from around Guam with a number of distant localities in the Pacific Ocean, and focused on determining the degree of genetic structure among populations previously considered to be isolated. Using microsatellites, we document substantial genetic structure between 14 localities from different geographical regions in the Pacific Ocean. Populations from the 14 locations sampled were found to be structured in three significantly differentiated groups: (1) all locations immediately around Guam, as well as Kingman Reef and Swains Island; (2) Japan, Philippines, GBR and Vanuatu; and (3) Johnston Atoll, which was significantly different from all other localities. The lack of genetic differentiation between Guam and extremely distant populations from Kingman Reef and Swains Island suggests potential long-distance dispersal of COTS in the Pacific.

Cretaceous Black Shales in the Pacific: The Equatorial Position Hypothesis

2021 ◽  
Author(s):  
Max J. Bouwmeester ◽  
Lydian Boschman ◽  
Nienke Berends ◽  
Jeremy D. Owens ◽  
Ben C. Gill ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Organic Carbon ◽  
Ocean Basin ◽  
Black Shales ◽  
Equatorial Position ◽  
Scientific Drilling ◽  
Geochemical Evidence ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Oceanic Anoxia

<p>Although anoxia is rare in modern oceans, the marine stratigraphic record is punctuated by sedimentary and geochemical evidence for episodes of widespread oceanic anoxia. The last time in Earth history that a large volume of the ocean became anoxic was in the middle Cretaceous: black organic-carbon-rich muds were repeatedly preserved on the deep seafloor during oceanic anoxic events (OAEs).</p><p>Sedimentary and geochemical evidence for oceanic anoxia during OAEs comes mainly from the Atlantic and Tethys Oceans. Data from the Pacific Ocean, which was the largest ocean basin in the middle Cretaceous, is scarce and equivocal. Based on black shales deposited at depths of about 500–1500 m on seamounts, Monteiro et al. (2012) have suggested that at least 50 vol% of the ocean was anoxic at the climax of Cretaceous oceanic anoxia during the late Cenomanian. They also included a single black shale at DSDP Site 585 in the Mariana Basin as evidence for anoxia in the deep Pacific. We will show, however, that this is a mud turbidite reworked from shallower water.</p><p>For this study, we reviewed all available data and publications from scientific drilling that recovered Cretaceous sediments in the Pacific Ocean. The little available Cretaceous record from the Pacific consists mainly of well-oxidized sediments. The exceptions are black shales that occur at depths of about 500–1500 m on seamounts. Takashima et al. (2011) have shown that the Asian and North American continental margins of the Pacific were indeed oxic for most of the late Cenomanian OAE. </p><p>We used a new paleomagnetic reconstruction of the Pacific plate back to 150 Ma to show that all investigated Cretaceous organic-carbon-rich sediments in the Pacific Ocean were deposited while the site was located in the Equatorial Divergence Zone (10°S to 10°N). We therefore argue that organic matter deposition in the Pacific Ocean might not have been directly related to OAEs, but rather be associated with the passage of seamounts beneath the equatorial belt of high productivity.</p><p>Several authors have challenged suggestions that OAEs were characterized by globally pervasive anoxic deep water and pointed to the difficulty in sustaining whole-ocean anoxia, even in warm oceans. We agree and our results show that oceanic anoxia in the Pacific is a local phenomenon superposed on a global trend of expanded oxygen minima in the ocean.</p>

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