15 research outputs found
Equatorial insolation: from precession harmonics to eccentricity frequencies
Since the paper by Hays et al. (1976), spectral analyses of climate proxy records provide substantial evidence that a fraction of the climatic variance is driven by insolation changes in the frequency ranges of obliquity and precession variations. However, it is the variance components centered near 100 kyr which dominate most Upper Pleistocene climatic records, although the amount of insolation perturbation at the eccentricity driven periods close to 100-kyr (mainly the 95 kyr- and 123 kyr-periods) is much too small to cause directly a climate change of ice-age amplitude. Many attempts to find an explanation to this 100-kyr cycle in climatic records have been made over the last decades. Here we show that the double maximum which characterizes the daily irradiation received in tropical latitudes over the course of the year is at the origin in equatorial insolation of not only strong 95 kyr and 123 kyr periods related to eccentricity, but also of a 11-kyr and a 5.5-kyr periods related to precession
Sea-surface temperatures at the sub-Antarctic islands Marion and Gough during the past 50 years
Sea-surface temperatures (SSTs) have been measured at Marion and Gough islands for nearly 50 years. These are some of the longest records of their kind in the sub-Antarctic. We present the trend, the seasonal cycle, and the time-frequency characteristics of the SST for both islands, which rose by 1.4°C at Marion Island and by 0.5°C at Gough Island over the 50-year period. Intermittent temperature oscillations, with periods of between 1 and 5 years, were observed throughout the record. A 5-year periodicity, compatible with an Antarctic CircumpolarWave signature, dominated after 1990 in both records. We also observed a strong low-frequency component with a period varying from 9.3 to 11.4 years at Marion Island, and a much weaker component with a period varying from 9.9 to 11.8 years at Gough Island
Decadal time scale variability recorded in the Quelccaya summit ice core δ 18 O isotopic ratio series and its relation with the sea surface temperature
Equatorial insolation: from precession harmonics to eccentricity frequencies
International audienceSince the paper by Hays et al. (1976), spectral analyses of climate proxy records provide substantial evidence that a fraction of the climatic variance is driven by insolation changes in the frequency ranges of obliquity and precession variations. However, it is the variance components centered near 100 kyr which dominate most Upper Pleistocene climatic records, although the amount of insolation perturbation at the eccentricity driven 100-kyr period is much too small to cause directly a climate change of ice-age amplitude. Many attempts to find an explanation to this 100-kyr cycle in climatic records have been made over the last decades. Here we show that the double maximum which characterizes the daily irradiation received in tropical latitudes over the course of the year is at the origin in equatorial insolation of not only a strong 100-kyr, but also of a 11-kyr and a 5.5-kyr periods related respectively to eccentricity and to precession
Evidence for the Antarctic circumpolar wave in the sub-Antarctic during the past 50 years
Investigation of the Interannual Variability of the Tropical Atlantic Ocean from Satellite Data
Pseudostalked barnacles Xenobalanus globicipitis attached to killer whales Orcinus orca in South African waters
Several records describe pseudostalked barnacles Xenobalanus globicipitis attached to killer whales Orcinus
orca, yet little is known of this association in Southern African waters. Here we describe Xenobalanus
prevalence on killer whales in South African waters and assemble previous records. Killer whales were
photographed opportunistically between July and September 2013. Sex and age class were determined, and if
Xenobalanus were present, attachment site and colony size noted. A prevalence of 50% was recorded, with
barnacles most commonly observed on the dorsal fin and tail flukes. The high prevalence of Xenobalanus on
killer whales in South African waters and lack thereof on killer whales at Marion Island implies that these are
separate populations, and thus we suggest Xenobalanus prevalence is an additional means to distinguish
between these populations.National Research Foundation (NRF) Thuthuka programme, the South African Department of Science and Technology through the NRF, the Mohamed bin Zayed Species Conservation Fund (project number: 10251290) and the International Whaling Commission’s Southern Ocean Research Partnership.http://link.springer.com/journal/125262016-12-31hb201