Variability of the Marine ITCZ over the Eastern Pacific during the Past 30,000 Years

2004 ◽  
pp. 347-369 ◽  
Author(s):  
Athanasios Koutavas ◽  
Jean Lynch-Stieglitz
Keyword(s):  
Eastern Pacific ◽  
The Past

scholarly journals Centennial-scale variability of the Southern Hemisphere westerly wind belt in the eastern Pacific over the past two millennia

2014 ◽  
Vol 10 (3) ◽  
pp. 1125-1144 ◽  
Author(s):  
B. G. Koffman ◽  
K. J. Kreutz ◽  
D. J. Breton ◽  
E. J. Kane ◽  
D. A. Winski ◽  
...  
Keyword(s):  
Particle Size ◽  
Wind Speed ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Zonal Wind ◽  
Ice Core ◽  
Eastern Pacific ◽  
The Past ◽  
West Antarctic ◽  
Lower Elevation

Abstract. We present the first high-resolution (sub-annual) dust particle data set from West Antarctica, developed from the West Antarctic Ice Sheet (WAIS) Divide deep ice core (79.468° S, 112.086° W), and use it to reconstruct changes in atmospheric circulation over the past 2400 years. We find a background dust flux of ~4 mg m−2 year−1 and a mode particle size of 5–8 μm diameter. Through comparing the WAIS Divide record with other Antarctic ice core particle records, we observe that coastal and lower-elevation sites have higher dust fluxes and coarser particle size distributions (PSDs) than sites on the East Antarctic plateau, suggesting input from local dust sources at these lower-elevation sites. In order to explore the use of the WAIS Divide dust PSD as a proxy for past atmospheric circulation, we make quantitative comparisons between both mid-latitude zonal wind speed and West Antarctic meridional wind speed and the dust size record, finding significant positive interannual relationships. We find that the dust PSD is related to mid-latitude zonal wind speed via cyclonic activity in the Amundsen Sea region. Using our PSD record, and through comparison with spatially distributed climate reconstructions from the Southern Hemisphere (SH) middle and high latitudes, we infer that the SH westerlies occupied a more southerly position from circa 1050 to 1400 CE (Common Era), coinciding with the Medieval Climate Anomaly (MCA). Subsequently, at ca. 1430 CE, the wind belt shifted equatorward, where it remained until the mid-to-late twentieth century. We find covariability between reconstructions of El Niño–Southern Oscillation (ENSO) and the mid-latitude westerly winds in the eastern Pacific, suggesting that centennial-scale circulation changes in this region are strongly influenced by the tropical Pacific. Further, we observe increased coarse particle deposition over the past 50 years, consistent with observations that the SH westerlies have been shifting southward and intensifying in recent decades.

scholarly journals Flora and Vegetation of Clipperton (La Passion) Atoll, North-Eastern Pacific Ocean: Three Centuries of Changes and Recent Plant Dynamics

2019 ◽  
pp. 1-31
Author(s):  
Xenia Jost ◽  
Christian H. Jost ◽  
Jean-Yves Meyer
Keyword(s):  
Pacific Ocean ◽  
Anthropogenic Activities ◽  
Abiotic Factors ◽  
Vascular Plant ◽  
Plant Cover ◽  
First Record ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
The Past ◽  
North Eastern

The terrestrial flora and vegetation of Clipperton (La Passion) atoll, a very remote and small (170 ha of land) French island located in the North-Eastern Pacific Ocean, at ca. 1,000 km west of the Mexican coast, have dramatically changed during the past three centuries. This paper, based on historical testimonies, previously published floristic studies, and an extensive plant inventory conducted during the “International Scientific Expedition PASSION 2015”, show that the atoll has experienced particularly active and rapid vegetation dynamics with alternating plant cover expansion and regression phases. Our results provide the first comprehensive assessment of vegetation cover and vascular plant species distribution based on georeferenced data and mapped with GIS software, as well as the first record of two newly established non-native weeds. The current composition and abundance of native and alien vascular plant communities (15 species including only 4 native taxa) appear to depend not only on abiotic factors (e.g. substrate and climatic events) but also on biotic interactions with animal communities (e.g. native seabirds and crabs). Anthropogenic activities and disturbances (e.g. coconut palm, pig, rat and weed introductions) that have occurred in the past 100 years have also played an important role in explaining the past and current floristic changes.

scholarly journals Humpback whales extend their stay in a breeding ground in the Tropical Eastern Pacific

2019 ◽  
Vol 77 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Isabel Cristina Avila ◽  
Carsten F Dormann ◽  
Carolina García ◽  
Luis Fernando Payán ◽  
María Ximena Zorrilla
Keyword(s):  
National Park ◽  
Arrival Time ◽  
Anthropogenic Activities ◽  
Breeding Site ◽  
Eastern Pacific ◽  
Humpback Whales ◽  
Tropical Eastern Pacific ◽  
The Past ◽  
Management Plans ◽  
Breeding Grounds

Abstract During the austral winter, G-stock humpback whales, Megaptera novaeangliae, migrate to the Tropical Eastern Pacific to breed. To analyse if the whale migration times have changed over time, we analysed 31 years (1988–2018) of arrival and departure times to Gorgona National Park, Colombia, an important breeding site. During this period, whales have significantly changed their arrival time, coming now earlier, but their departure time has not changed significantly. Hence, humpback whales now stay 1 month longer than 31 years ago. Humpbacks arrived in Gorgona at the earliest during the beginning of May and stayed at the most until late December. The change observed in the arrival time to breeding grounds could be related to ice sheet mass changes in autumn in Antarctica and increase in population size over the past decades but we were unable to determine which factor is more important in explaining the observed trend. Management decisions in Colombia need to account for a longer stay, specifically restricting anthropogenic activities from 1May to 31December. We urge other researchers to review their data, in case this shift is evident in other regions and management plans need to be updated.

A multidecadal-scale tropically-driven global teleconnection over the past millennium and its recent strengthening

2020 ◽  
pp. 1-51
Author(s):  
Xiaofang Feng ◽  
Qinghua Ding ◽  
Liguang Wu ◽  
Charles Jones ◽  
Ian Baxter ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Eastern Pacific ◽  
The Arctic ◽  
Boreal Winter ◽  
Past Century ◽  
Tropical Eastern Pacific ◽  
Atmospheric Teleconnection ◽  
Temperature Changes ◽  
The Past ◽  
Circulation Mode

AbstractIn the past 40 years, the global annual mean surface temperature has experienced a non-uniform warming, differing from the spatially uniform warming simulated by the forced responses of large multi-model ensembles to anthropogenic forcing. Rather, it exhibits significant asymmetry between the Arctic and Antarctic, intermittent and spatially varying warming trends along the Northern Hemisphere (NH) mid-latitudes and a slight cooling in the tropical eastern Pacific. In particular, this “wavy” pattern of temperature changes over the NH mid-latitudes features strong cooling over Eurasia in boreal winter. Here, we show that these non-uniform features of surface temperature changes are likely tied together by tropical eastern Pacific sea surface temperatures (SSTs), via a global atmospheric teleconnection. Using six reanalyses, we find that this teleconnection can be consistently obtained as a leading circulation mode in the past century. This tropically-driven teleconnection is associated with a Pacific SST pattern resembling the Interdecadal Pacific Oscillation (IPO), and hereafter referred to as the IPO-related Bipolar Teleconnection (IPO-BT). Further, two paleo-reanalysis reconstruction datasets show that the IPO-BT is a robust recurrent mode over the past 400 and 2000 years. The IPO-BT mode may thus serve as an important internal mode that regulates high-latitude climate variability on multidecadal time scales, favoring a warming (cooling) episode in the Arctic accompanied by cooling (warming) over Eurasia and the Southern Ocean (SO). Thus, the spatial non-uniformity of recent surface temperature trends may be partially explained by the enhanced appearance of the IPO-BT mode by a transition of the IPO toward a cooling phase in the eastern Pacific in the past decades.

scholarly journals The Operational GFDL Coupled Hurricane–Ocean Prediction System and a Summary of Its Performance

2007 ◽  
Vol 135 (12) ◽  
pp. 3965-3989 ◽  
Author(s):  
Morris A. Bender ◽  
Isaac Ginis ◽  
Robert Tuleya ◽  
Biju Thomas ◽  
Timothy Marchok
Keyword(s):  
Positive Impact ◽  
Weather Prediction ◽  
Model Performance ◽  
Cloud Microphysics ◽  
Horizontal Resolution ◽  
Ocean Model ◽  
Eastern Pacific ◽  
Geophysical Fluid Dynamics Laboratory ◽  
The Past ◽  
Gfdl Model

Abstract The past decade has been marked by significant advancements in numerical weather prediction of hurricanes, which have greatly contributed to the steady decline in forecast track error. Since its operational implementation by the U.S. National Weather Service (NWS) in 1995, the best-track model performer has been NOAA’s regional hurricane model developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The purpose of this paper is to summarize the major upgrades to the GFDL hurricane forecast system since 1998. These include coupling the atmospheric component with the Princeton Ocean Model, which became operational in 2001, major physics upgrades implemented in 2003 and 2006, and increases in both the vertical resolution in 2003 and the horizontal resolution in 2002 and 2005. The paper will also report on the GFDL model performance for both track and intensity, focusing particularly on the 2003 through 2006 hurricane seasons. During this period, the GFDL track errors were the lowest of all the dynamical model guidance available to the NWS Tropical Prediction Center in both the Atlantic and eastern Pacific basins. It will also be shown that the GFDL model has exhibited a steady reduction in its intensity errors during the past 5 yr, and can now provide skillful intensity forecasts. Tests of 153 forecasts from the 2004 and 2005 Atlantic hurricane seasons and 75 forecasts from the 2005 eastern Pacific season have demonstrated a positive impact on both track and intensity prediction in the 2006 GFDL model upgrade, through introduction of a cloud microphysics package and an improved air–sea momentum flux parameterization. In addition, the large positive intensity bias in sheared environments observed in previous versions of the model is significantly reduced. This led to the significant improvement in the model’s reliability and skill for forecasting intensity that occurred in 2006.

scholarly journals Shift in Pacific Sea Level Trends Will Affect the West Coast

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Terri Cook
Keyword(s):  
Pacific Ocean ◽  
Sea Level ◽  
West Coast ◽  
Eastern Pacific ◽  
Eastern Pacific Ocean ◽  
The West ◽  
Sea Levels ◽  
The Past

The first study on the shift toward higher sea levels in the eastern Pacific Ocean over the past 5 years indicates it will continue, leading to much higher seas on the western coasts of the Americas.

Occurrence and biogeographic significance of Heliaster (Echinodermata: Asteroidea) from the Pliocene of southwest Florida

1988 ◽  
Vol 62 (01) ◽  
pp. 126-132 ◽  
Author(s):  
Douglas S. Jones ◽  
Roger W. Portell
Keyword(s):  
Central American ◽  
Eastern Pacific ◽  
Whole Body ◽  
Marine Fauna ◽  
Western Atlantic ◽  
Southwest Florida ◽  
Extant Species ◽  
Geologic Record ◽  
Central American Isthmus

Whole body asteroid fossils are rare in the geologic record and previously unreported from the Cenozoic of Florida. However, specimens of the extant species,Heliaster microbrachiusXantus, were recently discovered in upper Pliocene deposits. This marks the first reported fossil occurrence of the monogeneric Heliasteridae, a group today confined to the eastern Pacific. This discovery provides further non-molluscan evidence of the close similarities between the Neogene marine fauna of Florida and the modern fauna of the eastern Pacific. The extinction of the heliasters in the western Atlantic is consistent with the pattern of many other marine groups in the region which suffered impoverishment following uplift of the Central American isthmus.

Observations of the continuum near the galactic centre

1967 ◽  
Vol 31 ◽  
pp. 405
Author(s):  
F. J. Kerr
Keyword(s):  
Galactic Centre ◽  
The Past ◽  
Centre Region ◽  
The Continuum

A continuum survey of the galactic-centre region has been carried out at Parkes at 20 cm wavelength over the areal11= 355° to 5°,b11= -3° to +3° (Kerr and Sinclair 1966, 1967). This is a larger region than has been covered in such surveys in the past. The observations were done as declination scans.

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