scholarly journals A method for the division of the conglomerate depositional cycle under Milankovitch cycles

2017 ◽  
Vol 14 (3) ◽  
pp. 611-620
Author(s):  
Panpan Chen ◽  
Nianqiao Fang ◽  
Cunlei Li ◽  
Jianmei Liu
Keyword(s):  
Milankovitch Cycles ◽  
Depositional Cycle

scholarly journals On Time Scales of Intrinsic Oscillations in the Climate System

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 459
Author(s):  
Anastasios A. Tsonis ◽  
Geli Wang ◽  
Wenxu Lu ◽  
Sergey Kravtsov ◽  
Christopher Essex ◽  
...  
Keyword(s):  
Low Frequency ◽  
Milankovitch Cycles ◽  
Data Sets ◽  
External Forcing ◽  
Natural Oscillations ◽  
Climatic Oscillations ◽  
Slow Feature Analysis ◽  
Limited Length ◽  
Past Data ◽  
Cumulative Evidence

Proxy temperature data records featuring local time series, regional averages from areas all around the globe, as well as global averages, are analyzed using the Slow Feature Analysis (SFA) method. As explained in the paper, SFA is much more effective than the traditional Fourier analysis in identifying slow-varying (low-frequency) signals in data sets of a limited length. We find the existence of a striking gap from ~1000 to about ~20,000 years, which separates intrinsic climatic oscillations with periods ranging from ~ 60 years to ~1000 years, from the longer time-scale periodicities (20,000 yr +) involving external forcing associated with Milankovitch cycles. The absence of natural oscillations with periods within the gap is consistent with cumulative evidence based on past data analyses, as well as with earlier theoretical and modeling studies.

Filtering of Milankovitch Cycles by the Thermohaline Circulation

1999 ◽  
Vol 12 (6) ◽  
pp. 1644-1658 ◽  
Author(s):  
David Brickman ◽  
D. G. Wright ◽  
William Hyde
Keyword(s):  
Thermohaline Circulation ◽  
Milankovitch Cycles

scholarly journals Low-latitude climate variability in the Heinrich frequency band of the Late Cretaceous greenhouse world

2014 ◽  
Vol 10 (3) ◽  
pp. 1001-1015 ◽  
Author(s):  
N. J. de Winter ◽  
C. Zeeden ◽  
F. J. Hilgen
Keyword(s):  
Deep Sea ◽  
Linear Response ◽  
Elemental Abundance ◽  
Milankovitch Cycles ◽  
Glacial Cycle ◽  
Low Latitude ◽  
Project Site ◽  
The Tropics ◽  
The Last Glacial ◽  
Drilling Project

Abstract. Deep marine successions of early Campanian age from DSDP (Deep Sea Drilling Project) site 516F drilled at low paleolatitudes in the South Atlantic reveal distinct sub-Milankovitch variability in addition to precession, obliquity and eccentricity-related variations. Elemental abundance ratios point to a similar climatic origin for these variations and exclude a quadripartite structure as an explanation for the inferred semi-precession cyclicity in the magnetic susceptibility (MS) signal as observed in the Mediterranean Neogene for precession-related cycles. However, semi-precession cycles as suggested by previous work are likely an artifact reflecting the first harmonic of the precession signal. The sub-Milankovitch variability, especially in MS, is best approximated by a ~7 kyr cycle as shown by spectral analysis and bandpass filtering. The presence of sub-Milankovitch cycles with a period similar to that of Heinrich events of the last glacial cycle is consistent with linking the latter to low-latitude climate change caused by a non-linear response to precession-induced variations in insolation between the tropics.

Milankovitch cycles and their effects on species in ecological and evolutionary time

Paleobiology ◽  
1990 ◽  
Vol 16 (1) ◽  
pp. 11-21 ◽  
Author(s):  
K. D. Bennett
Keyword(s):  
Time Scales ◽  
Climatic Changes ◽  
Milankovitch Cycles ◽  
Mass Extinctions ◽  
Geological Time ◽  
Evolutionary Time ◽  
Abiotic Environment ◽  
Earth History ◽  
Microevolutionary Change ◽  
Second Tier

The Quaternary ice ages were paced by astronomical cycles with periodicities of 20–100 k.y. (Milankovitch cycles). These cycles have been present throughout earth history. The Quaternary fossil record, marine and terrestrial, near to and remote from centers of glaciation, shows that communities of plants and animals are temporary, lasting only a few thousand years at the most. Response of populations to the climatic changes of Quaternary Milankovitch cycles can be taken as typical of the way populations have behaved throughout earth history. Milankovitch cycles thus force an instability of climate and other aspects of the biotic and abiotic environment on time scales much less than typical species durations (1–30 m.y.). Any microevolutionary change that accumulates on a time scale of thousands of years is likely to be lost as communities are reorganized following climatic changes. A four-tier hierarchy of time scales for evolutionary processes can be constructed as follows: ecological time (thousands of years), Milankovitch cycles (20–100 k.y.), geological time (millions of years), mass extinctions (approximately 26 m.y.). “Ecological time” and “geological time” are defined temporally as the intervals between events of the second and fourth tiers, respectively. Gould's (1985) “paradox of the first tier” can be resolved, at least in part, through the undoing of Darwinian natural selection at the first tier by Milankovitch cycles at the second tier.

Physics and Dynamics of the Atmosphere

2019 ◽  
pp. 71-90
Author(s):  
Han Dolman
Keyword(s):  
Equations Of Motion ◽  
Three Dimensional ◽  
Energy Difference ◽  
Cell System ◽  
Ideal Gas ◽  
Lapse Rate ◽  
Milankovitch Cycles ◽  
Physical Description ◽  
Geostrophic Balance ◽  
Basic Physics

This chapter describes the basic physics and thermodynamics of the atmosphere, starting from the ideal gas law and the hydrostatic equation, from which the lapse rate in the troposphere is derived. The effect of atmospheric moisture on the lapse rate is identified and the Clausius–Clapeyron equation giving the saturated humidity is derived. The effect of moisture on adiabatic vertical transport is shown. Then, the three-dimensional equations of motion are derived in vector form. From these, geostrophic balance and the thermal wind equations are derived. This, with the Coriolis force, gives the physical description of the atmospheric circulation. The driving force behind circulation is identified as the energy difference between the tropics and the extratropics. This is driven by radiation differences, including, at large geological scale, the Milankovitch cycles. Finally, circulation as a three-cell system per hemisphere, and the development of weather systems such as cyclones, are described.

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