DOI: 10.1016/j.gloplacha.2014.12.001
论文题名: Rapid longitudinal migrations of the filament front off Namibia (SE Atlantic) during the past 70kyr
作者: Romero O.E. ; Crosta X. ; Kim J.-H. ; Pichevin L. ; Crespin J.
刊名: Global and Planetary Change
ISSN: 0921-8181
出版年: 2015
卷: 125 起始页码: 1
结束页码: 12
语种: 英语
英文关键词: Benguela
; Diatoms
; Millennial and submillennial time scale
; Productivity
; Sea-surface temperature
; SW Atlantic
; Upwelling filaments
Scopus关键词: boundary current
; diatom
; geochemical method
; longitudinal gradient
; micropaleontology
; primary production
; proxy climate record
; sea level change
; sea surface temperature
; sediment core
; temperature profile
; upwelling
; water depth
; Atlantic Ocean
; Atlantic Ocean (Southeast)
; Namibia
; Bacillariophyta
英文摘要: Although productivity variations in coastal upwelling areas are mostly attributed to changes in wind strength, productivity dynamics in the Benguela Upwelling System (BUS) is less straightforward due to its complex atmospheric and hydrographic settings. In view of these settings, past productivity variations in the BUS can be better investigated with downcore sediments representing different productivity regimes. In this study, two sediment cores retrieved at ca. 25°-26°S in the BUS and representing different productivity regimes were studied. By using micropaleontological, geochemical and temperature proxies measured on core MD96-2098, recovered at 2910. m water depth in the bathypelagic zone at 26°S off Namibia, variations of filament front location, productivity and temperature in the central BUS over the past 70. kyr were reconstructed. The comparison with newly-generated alkenone-based sea-surface temperature (SST) and previously obtained data at site GeoB3606-1 (~. 25°S; ca. 50. km shoreward from MD96-2098) allowed the recognition of four main phases: (1) upwelling front above the mid slope (70. kyr-44. kyr), (2) seaward displacement of the upwelling front beyond the mid slope (44. kyr-31. kyr), (3) main upwelling front over the hemipelagial (31. kyr-19. kyr), and (4) shoreward contraction of the upwelling filament, and decreased upwelling strength over most of the uppermost bathypelagic (19. kyr-6. kyr). The latitudinal migration of the Southern Hemisphere westerlies and the consequent contractions and expansions of the subpolar gyre played a significant role in millennial and submillennial variability of SST off Namibia. The strength of the southeasterly trade winds, rapid sea-level variations and the equatorward leakage of Antarctic silicate might have acted as amplifiers. Although late Quaternary variations of productivity and upwelling intensity in eastern boundary current systems are thought to be primarily linked to the variability in wind stress, this multi-parameter reconstruction shows that interplaying mechanisms defined the temporal variation pattern of the filament front migrations and the diatom production off Namibia during the past 70. kyr. © 2014 Elsevier B.V. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84919884144&doi=10.1016%2fj.gloplacha.2014.12.001&partnerID=40&md5=de36fc922e1223059e18c438fac51545
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资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/11563
Appears in Collections: 全球变化的国际研究计划 气候变化与战略
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作者单位: MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Str., Bremen, Germany
Recommended Citation:
Romero O.E.,Crosta X.,Kim J.-H.,et al. Rapid longitudinal migrations of the filament front off Namibia (SE Atlantic) during the past 70kyr[J]. Global and Planetary Change,2015-01-01,125.