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Topic: Orbital forcing

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atomic orbitals

f orbital

orbital resonance

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Orbital elements

orbital velocity vector

orbital position vector

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Avg Orbital Speed

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	Orbital forcing - Wikipedia, the free encyclopedia
		Orbital forcing, or Milankovitch theory, describes the effect on climate of slow changes in the tilt of the Earth 's axis and shape of the orbit.
		These orbital changes change the total amount of sunlight reaching the Earth by up to 25% at mid-latitudes (from 400 to 500 watts per cubic meter at latitudes of 60 degrees).
		Comparisons of plate tectonic continent reconstructions and paleoclimatic studies show that the Milankovitch cycles have the greatest effect during geologic eras when landmasses have been concentrated in polar regions, as is the case today.
	en.wikipedia.org /wiki/Orbital_forcing (477 words)

	Milankovitch cycles - Wikipedia, the free encyclopedia
		It has been suggested that this article or section be merged with Orbital forcing.
		Since orbital variations are predictable, if one has a model that relates orbital variations to climate, it is possible to run such a model forward to "predict" future climate.
		Two caveats are necessary: firstly, that anthropogenic effects ( global warming) are likely to exert a larger influence, at least over the short term; and secondly that since the mechanism by which orbital forcing affects climate is not well understood, there is no very good model relating climate to orbital forcing.
	en.wikipedia.org /wiki/Milankovitch_cycles (1648 words)

	Orbital forcing of calcilutite-marl cycles in southeast Spain
		Orbital forcing of calcilutite-marl cycles in southeast Spain and an estimate for the duration of the Berriasian stage.
		According to Berger (1978a), the main terms in the series of orbital quasi-periodicities during the last 5 Ma are 23.7, 22.4 and 19.0 ka for precession, 41.0, 39.7, 53.6, 40.5 and 28.9 ka for obliquity, 99.6, 94.5 and 123.3 ka for the short cycle of eccentricity, and 412.9 ka for the long cycle of eccentricity.
		On the other hand, the assumption of orbital forcing may be rejected, if the rest of the peaks do not match the orbital periodicities.
	www.lumina.demon.nl /thesis/Ch4b/index.html (5012 words)

	Milankovitch Forcing of Early Cenozoic Climates (Site not responding. Last check: 2007-11-05)
		To investigate the impact of orbital forcing upon the hydrologic system in a warm climate world, we have carried out a series of climate model experiments in which we vary orbital forcing and the resulting solar insolation distribution across a precessional half-cycle.
		The magnitude of modeled response to changes in orbital forcing is sufficiently large that some record of orbital forcing and hydrological response may be detectable in high-resolution geologic records preserved in these regions.
		In the absence of cryosphere-driven processes, hydrologic responses to orbital forcing were likely the primary influences on climate and sedimentation during the early Cenozoic.
	www.es.ucsc.edu /~lcsloan/Lisa/lcsmilank2.html (247 words)

	Orbital cyclicities above and below the Cretaceous / Paleogene boundary
		In all spectra the orbital periods expected at -65 Ma (Berger et al., 1989a/b) are marked together with a band comprising ±10% of their value.
		The orbital periods at -65 Ma (Berger et al., 1989a/b) are marked together with a band that comprises ±10% of their value.
		The influence of orbital forcing on the thickness and frequency of occurrence of turbidites in the Maastrichtian of Zumaya, is much weaker and random processes probably play an important role.
	www.lumina.demon.nl /thesis/Ch3b/index.html (8159 words)

	Variation of insolation due to orbital parameters of the Earth (Milankovitch forcing)
		The orbital and spin motions of the earth can be summarized by several numbers called orbital parameters.
		The direction to which the spin axis is tilted with respect to the axis of orbital motion (the line normal to the orbital plane) changes by an effect called precession.
		The obliquity, or the tilt angle, is the angle between the spin axis and the axis of orbital motion.
	web.sfc.keio.ac.jp /~masudako/edu/text/quatbook/variat/node5.html (659 words)

	NOAA Paleoclimatology Program - Orbital Variations and Milankovitch Theory (Site not responding. Last check: 2007-11-05)
		Orbital changes occur over thousands of years, and the climate system may also take thousands of years to respond to orbital forcing.
		Recent Calculations of Earth Orbital Parameters and Insolation by A. Berger are archived at the WDC Paleo.
		If the earth's axis were "straight up and down" relative to the orbital plane, as in the right-hand image, there would be no seasons, since every point on the earth would receive the same amount of sun each day of the year.
	www.ngdc.noaa.gov /paleo/milankovitch.html (863 words)

	Ice age biography .ms (Site not responding. Last check: 2007-11-05)
		Many now believe that anthropogenic forcing from increased " greenhouse gases " would outweigh any Milankovitch (orbital) forcing; and more recent consideration of the orbital forcing suggests that even in the absence of human perturbation the present interglacial would last at least 50,000 years.
		The present ice ages are the most studied and best understood, particularly the last 400,000 years, since this is the period covered by ice cores that record atmospheric composition and proxies for temperature and ice volume.
		While Milankovic forcing predicts that cyclic changes in the Earth's orbital parameters can be expressed in the glaciation record, additional explanations are necessary to explain which cycles are observed to be most important in the timing of glacial periods.
	great-ice-age.biography.ms (1398 words)

	10.1007/s00382-004-0469-y (Site not responding. Last check: 2007-11-05)
		The orbital induced signal of decreased boreal summer insolation in northern mid and high latitudes (Fig. 1 a) is represented by a surface temperature drop of 1.4 K between 30°N and 50°N during the last 7,000 years (Fig. 2 a–c).
		Since the precessional forcing is dominant in the tropics (Fig. 1), we speculate that the tropical Pacific provides for a rectification effect to the varying seasonal distribution of the solar radiation.
		With this forcing we are able to relate the effect of the astronomical forcing to the temperature change influenced by anthropogenic emissions of greenhouse gases.
	www.mpimet.mpg.de /~lorenz.stephan/cdy-accbc/fulltext.html (9556 words)

	Citebase - Orbital forcing of palynofacies in the Jurassic of France and the United Kingdom
		Orbital forcing of palynofacies in the Jurassic of France and the United Kingdom
		The cycles are attributed to precession, obliquity, and eccentricity forcing.
		Terrestrially derived organic particles record the effects of orbital cyclicity on land, which may be controlled by orbital cycles different from those controlling marine sediment deposition.
	citebase.eprints.org /cgi-bin/citations?id=oai:eprints.soton.ac.uk:1367 (288 words)

	Lisa Cirbus Sloan: Publications 2004 (Site not responding. Last check: 2007-11-05)
		Mid-Holocene orbital forcing of regional-scale climate: A case study of western North America using a high-resolution RCM, Diffenbaugh, N.S., and Sloan, L.C., Jour.
		Orbital suppression of wind driven upwelling in the California Current at 6 ka, Diffenbaugh, N.S., Sloan, L.C., and Snyder, M.A., Paleoceanography, 18 (2), 1051, 10.1029/2003PA000865, 2003.
		Orbital Forcing and Eocene Continental Temperatures, Sloan, L. Cirbus and Morrill, C., Palaeogeography, Palaeoclimatology, Palaeoecology, v.
	www.es.ucsc.edu /~lcsloan/lcs_pubs_04.htm (1612 words)

	Milankovitch and Tuning
		This difference is primarily due to the sun's displacement from the geometric center of the earth's orbit to one of the two foci of the orbital ellipse.
		The equatorial plane precesses with a period of 25.8 Kyr and the orbital plane precesses with a period of 70 Kyr.
		Orbital, precessional, and insolation quantities for the earth from -20 myrs to +10mrs.
	www.mit.edu /~phuybers/General/good2.html (7434 words)

	Articles - Climate change (Site not responding. Last check: 2007-11-05)
		External factors, called climate forcings, are divided into natural factors, such as variations in solar radiation, and anthropogenic factors (those attributed to human activities).
		The 100,000 year ice age cycles are controlled by orbital forcing - variations in the seasonal and geographical distribution of insolation ; and in the total insolation.
		The forcing for these cycles is believed to be orbital variation but the imposed forcing appears to be too small to account for the effects; thus it is generally believed that variations in CO act to amplify the signal.
	www.kamero.net /articles/Climate_change?mySession=22ce937caa46c38a037458fca32a0290 (1389 words)

	Vegetation and soil feedbacks on the response of the African monsoon to orbital forcing in the early to middle Holocene (Site not responding. Last check: 2007-11-05)
		Vegetation and soil feedbacks on the response of the African monsoon to orbital forcing in the early to middle Holocene.
		We find that replacing today's orbital forcing with that of the mid-Holocene increases summer precipitation by 12% between 15 and 22º N. Replacing desert with grassland, and desert soil with more loamy soil, further enhances the summer precipitation (by 6 and 10% receptively), giving a total precipitation increase of 28%.
		When the simulated climate changes are applied to a biome model, vegetation becomes established north of the current Sahara/Sahel boundary, thereby shrinking the area of the Sahara by 11% owing to orbital forcing alone, and by 20% owing to the combined influence of orbital forcing and the prescribed vegetation and soil changes.
	www.sage.wisc.edu /pubs/abstracts/kutzbachNature1996.html (250 words)

	Nat' Academies Press, Effects of Past Global Change on Life (1995) (Site not responding. Last check: 2007-11-05)
		FORCING OF LATE CENOZOIC CLIMATIC CHANGES In the first section of this chapter, we summarized two major regimes of late Cenozoic climatic change in and around the North Atlantic area: (1) the long-term cooling (and regional drying) that preceded Northern Hemisphere glaciation, and (2) the ice age cycles of the past 2.5 to 3 m.y.
		Tectonic Forcing of Climate (pre-2.5 Ma) The most likely causes of climatic trends persisting for millions of years are tectonic changes in the configuration of the solid Earth that underpins the climate system, particularly changes in geography related to plate-tectonic processes.
		Although orbital variations have no doubt influenced climate through all of geologic time, once ice sheets appeared in the Northern Hemisphere, they provided a particularly effective means of amplifying insolation forcing from within the climate system.
	books.nap.edu /books/0309051274/html/118.html (11541 words)

	Global ocean response to orbital forcing in the Holocene
		Global upper ocean evolution in the Holocene is studied in two coupled ocean-atmosphere models under orbital forcing conditions at 3, 6, 8, and 11 ka.
		The annual mean sea surface temperature (SST) changes in the early to mid-Holocene are found to be forced mainly by the annual mean insolation forcing with an overall symmetric response of colder equator (<0.5°C)/warmer high latitudes (<0.4°C in the Southern Ocean and >1°C in the Arctic).
		In contrast, the temperature response in the thermocline is dominated by an antisymmetric pattern with a cooling (warming) in the Northern (Southern) Hemisphere midlatitudes.
	www.agu.org /pubs/crossref/2003/2002PA000819.shtml (269 words)

	Milankovitch Forcing of Early Cenozoic Climates (Site not responding. Last check: 2007-11-05)
		In this paper we test the idea that orbital forcing and resulting distributions of solar radiation played a role in determining continental interior temperatures during the Eocene.
		Temperature responses to the specified orbital forcing are most evident at middle and high latitudes.
		We suggest that orbital variation and resulting insolation responses must be included in paleoclimate modeling studies that aim to explain proxy data and paleoclimate conditions for specific times in Earth history.
	www.es.ucsc.edu /~lcsloan/Lisa/lcsmilank1.html (307 words)

	ABSTRACT: Glacial termination-sensitivity to orbital and CO2 forcing in a coupled climate system model. (Site not responding. Last check: 2007-11-05)
		To address the ice-sheet response under the effects of both perpetual orbital and CO2 forcing, sensitivity experiments are conducted with two different orbital configurations (11 kaBP and 21 kaBP) and two different atmospheric CO2 concentrations (200 ppmv and 280 ppmv).
		This study reveals that, although both orbital and CO2 forcing have an impact on ice-sheet maintenance and deglacial processes, and although neither acting alone is sufficient to lead to complete deglaciation, orbital forcing seems to be more important.
		Since the summer temperature, rather than winter temperature, is found to be dominant for the ice-sheet mass balance, orbital forcing has a larger effect than CO2 forcing in deglaciation.
	cgrg.geog.uvic.ca /abstracts/YoshimoriGlacialTo.html (350 words)

	Paleoclimate change- Orbital forcing
		Second, he claimed that these seasonal variations were caused by two orbital phenomena known as precession and eccentricity.
		Precession changes the date at which the earth reaches its perihelion (point on the orbital path closest to the Sun) serving to amplify or dampen seasonal climatic variability.
		By the 1920s, Milankovitch's theory of orbital forcing was practically complete, though some of his calculations would take another two decades to finish.
	www.geo.umn.edu /courses/1001/summer2004/notes/13_paleoclimate_change.htm (1460 words)

	Nat' Academies Press, Abrupt Climate Change: Inevitable Surprises (2002) (Site not responding. Last check: 2007-11-05)
		Furthermore, the more rapid the forcing, the more likely it is that the resulting change will be abrupt on the time scale of human economies or global ecosystems.
		When the freshwater forcing is reduced to pre-LPTM values, deepwater is again formed in the Southern Hemisphere, with a hysteresis characterized by case (b) in Figure 3.1.
		Radiative forcing is increased from years 1000 to 1140, equivalent to a doubling of CO2, and then held constant.
	books.nap.edu /books/0309074347/html/107.html (4233 words)

	ABSTRACT: Orbital forcing of Arctic climate: mechanisms of climate response and implications for continental glaciation. (Site not responding. Last check: 2007-11-05)
		ABSTRACT: Orbital forcing of Arctic climate: mechanisms of climate response and implications for continental glaciation.
		Progress in understanding how terrestrial ice volume is linked to Earths orbital configuration has been impeded by the cost of simulating climate system processes relevant to glaciation over orbital time scales (103—105 years).
		The majority of the mid- to high latitude response to orbital forcing is organized by the properties of sea ice, through its influence on radiative feedbacks that nearly double the size of the orbital forcing as well as its influence on the seasonal evolution of the latitudinal temperature gradient.
	cgrg.geog.uvic.ca /abstracts/JacksonOrbitalProgress.html (318 words)

	published in SCIENCE
		According to Croll, and to Milankovitch after him (3, 4), the main orbital parameters that affect insolation and its distribution are the Earth's orbital eccentricity, obliquity (tilt of the Earth's poles towards the sun), and precession (lag between equinox and perihelion).
		In 1994, Muller (31) postulated that the sudden onset of the 100 k.y.
		O imply that the global ice volume is forced predominately by orbital inclination and obliquity, other aspects of climate seem to be driven by eccentricity or precession.
	muller.lbl.gov /papers/sciencespectra.htm (3559 words)

	Orbital or Thermal Causes of Glaciation in New Zealand - Geological Sciences - University of Canterbury
		Because this is largely precessionally forced (see data in Berger, 1992) the model predicts the largest positive westerly anomaly at c.47 ka.
		If the westerly forcing hypothesis is correct, glacial advances will be in synchrony with precessional maxima, of short duration and characterized by rapid glacier growth and decay under relatively mild conditions.
		If the westerly forcing hypothesis is correct, similar controls on glaciation would be expected in Northern Hemisphere regions subject to dominant westerly flow.
	www.geol.canterbury.ac.nz /research/glaciation_nz.html (2036 words)

	[No title]
		Olsen, H. Astronomical forcing of meandering river behaviour: Milankovitch cycles in Devonian of East Greenland.
		Weedon, G.P. The recognition and stratigraphic implications of orbital forcing of climate and sedimentary cycles.
		Kelly, S.B. and Sadler, S.P. Equilibrium and response to climatic and tectonic forcing: a study of alluvial sequences in the Devonian Munster Basin, Ireland.
	www.stratadata.co.uk /clbib.html (1248 words)

	Orbital forcing of the African summer monsoon (Site not responding. Last check: 2007-11-05)
		In this paper, we examine the orbital signal in Earth's climate with a coupled model of intermediate complexity (ECBilt).
		The orbital influence on climate is studied by isolating the obliquity and precession signal in several time-slice experiments.
		The response of the African monsoon to orbital-induced insolation forcing can be divided into a response to insolation forcing at high northern latitudes and a response to insolation forcing at low latitudes, whereby the former dominates.
	www.knmi.nl /~weber/abstracts/abstrerik.html (234 words)

	Orbital climate forcing of δ¹³C excursions in the late Paleocene–early Eocene (chrons ...
		We demonstrate that these transient decreases are the expected result of nonlinear insolation forcing of the carbon cycle in the context of a long carbon residence time.
		The transients occur at maxima in Earth's orbital eccentricity, which result in high-amplitude variations in insolation due to forcing by climatic precession.
		The construction of accurate orbital chronologies for geologic sections older than ∼35 Ma relies on identifying a high-fidelity recorder of variations in Earth's orbital eccentricity.
	www.agu.org /pubs/crossref/2003/2003PA000909.shtml (406 words)

	A long marine history of carbon cycle modulation by orbital-climatic changes -- Herbert 94 (16): 8362 -- Proceedings ...
		orbital forcing in warmer climates of the middle and earlier Tertiary.
		and 41 kyr) orbital insolation and tectonic perturbations to climate
		Gale, A. (1995) in Orbital Forcing Timescales and Cyclostratigraphy, Geol.
	www.pnas.org /cgi/content/full/94/16/8362 (5746 words)

	IODP
		Evidence for modulation of climate by orbital forcing and atmospheric greenhouse gas concentrations is substantial, yet our understanding of the climatic response to such forcing remains controversial due to ambiguities in existing proxy-based reconstructions.
		Such data are critical for assessing temperature and ice sheet stability to variable insolation and greenhouse gas forcing.
		As such, this research is extremely relevant to the NERC mission in terms of understanding environmental change with relevance to the quality of life in the future.
	www.nerc.ac.uk /funding/earthsci/iodpgrants.shtml (1103 words)

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