11-yr Cycle Research Articles

Evidence for a 17-year cycle in the IMF directions at 1 AU, in solar coronal hole variations, and in planetary magnetospheric modulations

A dominant 16–17 yr cycle was observed in the net exposure times of the Earth to Toward and Away field directions of the interplanetary magnetic field (IMF). A cycle of the same frequency and phase was observed in the polarity of the long-term hemispheric differences in coronal hole distributions. This was determined from north/south differences in average Fe xiv green line ‘quiet’ regions at high- and mid-latitudes. It is argued that the 17-yr cycle is a fundamental oscillation of coronal hole topology, which is transferred to Earth via variations in the neutral sheet. A comparison of the 17-yr cycle to the 22-yr Hale cycle indicated that they are not identical, but rather, can mix to form a 75-yr cycle plus a 9-yr cycle. Evidence for the 75-yr cycle existed in the Earth's net exposure times to fields from the solar North and South, and in the long-term imbalance of solar quiet regions between the northern and southern hemispheres. The 9-yr cycle was manifested in the mid- to low- latitude Fe xiv modulations and in solar wind velocity variations in the ecliptic. At Earth, evidence for a similar 17-yr cycle was observed in the horizontal magnetic field observations in a multitude of surface magnetic recording stations. In addition, the detection of a 17-yr cycle in the Huancayo neutron monitor cosmic ray series suggests that the effects of this cycle extend to the heliospheric boundaries. It is concluded that sufficient preliminary evidence exists to consider the hypothesis that the Sun contains a magnetic moment with an oscillatory cycle of 17 years.

Is There Evidence for Solar Forcing of Climate in the GISP2 Oxygen Isotope Record?

Changes in solar constant over an 11 yr cycle suggest a certain, but limited, degree of solar forcing of climate. The high-resolution climate (oxygen isotope) record of the Greenland GISP2 (Greenland Ice Sheet Project 2) ice core has been analyzed for solar (and volcanic) influences. The atmospheric14C record is used as a proxy of solar change and compared to the oxygen isotope profile in the GISP2 ice core. An annual oxygen isotope profile is derived from centimeter-scale isotope measurements available for the post-A.D. 818 interval. Associated extreme summer and winter isotope ratios were found to yield similar climate information over the last millennium. The detailed record of volcanic aerosols, converted to optical depth and volcanic explosivity change, was also compared to the isotope record and the oxygen isotope response calibrated to short-term volcanic influences on climate. This calibration shows that century-scale volcanic modulation of the GISP2 oxygen isotope record can be neglected in our analysis of solar forcing. The timing, estimated order of temperature change, and phase lag of several maxima in14C and minima in18O are suggestive of a solar component to the forcing of Greenland climate over the current millennium. The fractional climate response of the cold interval associated with the Maunder sunspot minimum (and14C maximum), as well as the Medieval Warm Period and Little Ice Age temperature trend of the past millennium, are compatible with solar climate forcing, with an order of magnitude of solar constant change of ∼0.3%. Even though solar forcing of climate for the current millennium is a reasonable hypothesis, for the rest of the Holocene the century-scale events are more frequent in the oxygen isotope record than in the14C record and a significant correlation is absent. For this interval, oceanic/atmospheric circulation forcing of climate may dominate. Solar forcing during the surprisingly strong 1470 yr climate cycle of the 11,000–75,000 yr B.P. interval is rather hypothetical.

Structure and rhythmic pattern of glaciofluvial deposits north of Lake Vänern, south‐central Sweden

The glaciofluvial deposits of the Vanern plain, Värmland, form esker systems and trains. Esker trains are defined as series of short eskers, kames and other glaciofluvial deposits. Trains spreading fanlike from the same area are combined into esker systems. Some individual deposits are described. The general pattern differs from the long, coherent eskers typical of eastern Sweden. A rhythmic pattern of depositional units in the esker trains is found to correspond to a 10 to 11 yr cycle, possibly representing the sunspot cycle. Zones of alternating faster and slower retreat of the ice margin are identified. Two lines of slower retreat, the Karlstad and Fryken lines, correspond to the Norwegian Ski line, dated at 10 000 BP (conventional radiocarbon years) and to a slightly younger line. The spacing of the esker trains is controlled by topography in the north, but by basal ice melting, which controlled their flow and spacing on the Ratter terrain in the south.

The interannual variability of temperature in the polar stratosphere during the winter: the influence of the QBO phase and an 11-yr solar cycle

The relation between the temperature of polar stratosphere in winter (from November until March), the phase of the QBO, and the activity of the 11-yr sunspot cycle is investigated. The results obtained by defining the QBO phase separately at 30 and 50 hPa are compared. It is shown that the large distinction in the distribution of major warming cases at various QBO phases exists depending on how the QBO phase is defined (at 30 or 50 hPa). A correlation analysis of the relation of the stratospheric temperature during different QBO phases and the activity of the 11-yr solar cycle has shown that there is significant (99%) correlation only in the westerly phase of QBO, and in February. Comparisons of cases of major winter stratospheric warmings during different phases of QBO with periods of high and low activity of 11-yr sunspot cycle do not result in such a simple conclusion. If warmings not only in January and February are considered, then during westerly and easterly phases of QBO the warmings are observed both in periods of high and low solar activity.

Solar cycle dependence and long-term trends in the wind field of the mesosphere/lower thermosphere

Ground-based observations of the wind field in the mesosphere/lower thermosphere have been used to investigate long-lasting wind variations at mid-latitudes. Besides small solar activity induced variations (11 yr cycle), non-solar induced long-term trends were clearly detected, which could be a hint of anthropogenically caused variations in the wind field near the mesopause region. Comparisons with other observations qualitatively confirm the derived trends, thus indicating common long-term global changes of the dynamical state of the middle atmosphere.

Pulsations and Accretion Geometry in YY Draconis: A Study Based onHubble Space TelescopeObservations

We present 1 A resolution fast ultraviolet spectroscopy of YY Dra, coordinated U, B, V, R, and I photometry, and Hα spectroscopy. The UV continuum is strongly pulsed: we found 16% semiamplitude pulses with period 264.7(1) s; there was no evidence for power at twice this period. The UBV pulses are in phase with the UV continuum pulsation. A color temperature of 105 K was found for the pulse spectrum, with a corresponding area 0.5% of the white dwarf surface. We refine the white dwarf spin period, obtaining Pspin = 529.31 ± 0.02 s. Optical pulses at 273(1) s were also detected; we attribute these to reprocessing in structures fixed in the orbital frame. Variations in the C IV line profile are apparent when the data are folded on Pspin. Faint, broad line wings extending to ±3000 km s-1 appear simultaneously with the continuum pulsation maxima. This implies that accretion was occurring onto both magnetic poles. Consequent constraints on the accretion geometry and white dwarf mass are derived, and a minimum white dwarf mass of 0.62 M☉ is obtained. A color temperature T 30,000 K is derived for the unpulsed emission. We determine a precise orbital period, 0.16537398[17] days, based on an unambiguous 14 yr cycle count. We describe a simple phase-matching technique used in the period search. The UV continuum and UBVR photometry show a single-humped orbital modulation; the I-band light curve shows a double-humped ellipsoidal shape. The deeper I-band minimum occurs at inferior conjunction of the mass donor, which suggests that heating of the L1 point dominates over gravity darkening. I-band light-curve modeling suggests i 50°. Orbital radial velocity variations of semiamplitude 91 ± 10 km s-1 were found in the C IV emission. Combining with the published value Ks = 202 ± 3 km s-1, this yields q = 0.45 ± 0.05. Assuming a Roche lobe-filling main-sequence mass donor and adopting the empirical ZAMS mass-radius relation, we obtain Ms = 0.375 ± 0.014 M☉, Mwd = 0.83 ± 0.10 M☉, and i = 45° ± 4°.

Total ozone and the 11-yr sunspot cycle

The correlations between the total column ozone observed by TOMS and the 11-yr sunspot cycle are lowest in the equatorial region, where ozone is produced, and in the subpolar regions, where the largest amounts are found. In the annual mean the highest, statistically significant, correlations lie between the 5 ° and 30 ° parallels of latitude in either hemisphere—between the area of production and the areas of plenty. This position of the largest correlations suggests that the association between the Sun and the ozone is not a direct, radiative one, but that it is due to solar induced changes in the transport of ozone, that is, to changes in the atmospheric circulation. The highest tropical-subtropical correlations move with the Sun from summer hemisphere to summer hemisphere. The subtropical geopotential heights in the ozone layer are higher in the peaks than in the valleys of the 11-yr sunspot cycle. It is probable that the higher subtropical geopotentials in solar maxima depress the poleward transport of ozone through the subtropics and therefore create an abundance of ozone in the tropics relative to the solar minima. These results are based on a 15-yr series of ozone observations and may thus not necessarily be representative of a longer period.

Temporal changes in the biochemical composition and nutritional value of the particulate organic matter available to surface deposit-feeders:a two year study

Gross sedimentation rates (GSR) were monitored together with the main characteristics of the collected matenal (i.e. organic content, C, N, total proteins, lipids, carbohydrates, available proteins and amino acids) over a 2 yr cycle at a shallow station (18 m) of the bay of Banyuls, France. In addition, sediment pigment concentrations and meiofaunal densit~es were recorded monthly during a 1 yr period. GSR ranged between 0.6 and 317.8 g DW m ' cl'' Spring and summer were characterized by relatively low and constant GSR whereas fall and wlnter were characterized by relat~vely high and hlghly variable GSR. There was a negatlve relationship between GSR and the organic content of material collected within the sediment traps, suggesting the importance of resuspension in controlling GSR. Growth rates of the deposit-feeding bivalve Abra ovata fed sediment trap material collected on 6 sampling dates were also measured. Significant changes in important nutrient components (e.g. available proteins) of sedimenting materials from these different sampling dates correlated with growth differences and confirmed the existence of temporal changes in the quality of the material collected in the sediment traps. The highest growth rate was obtained for the material collected during May 1993, which coincided with maximal meiofauna densities and maximal pigment concentrations at the surface of the sediment. The best descript.ion of growth was obtained when using available proteins and total lipids as the independent variables of simple linear regression models. This supports the use of these parameters as descriptors of food quality. The consequences of our results on the parameterization of changes in food quality within models of continental shelf food webs are discussed. It is suggested that such changes should be simulated through control functions based on available protein contents.

Spectral peculiarities of strong solar bursts

We have investigated spectral features of strong radio burst emission for the 21st cycle of solar activity. The maximum daily radio fluxes in 8 frequency ranges are analyzed. For every year, the classification of these daily spectra is obtained by the cluster analysis method. We have shown that strong bursts are characterized by the stable shape of the mean radio emission spectra. For these bursts the total level of radio emission does not depend on the phase of the solar 11-yr cycle and varies with the quasi-period of 4 yr. The basic features of burst spectra can be explained by the gyrosynchrotron radiation of nonthermal electrons and plasma radiation at the second harmonic of plasma frequency. We supposed that in the generation region of centimetric emission, if the strength of the magnetic field B ≈ 100 G, the number of microbursts can amount to (6–7) × 103. In the generation region of decimetric emission, the energy of Langmuir waves changes as W l ∼ n e 0.4.

Characteristics of Changing Permafrost Temperatures in the Alaskan Arctic, U.S.A.

Temperatures in permafrost were measured annually from 1983 through 1993 in drill holes (nominally 60 m in depth) at three sites in Northern Alaska; West Dock, Deadhorse, and Franklin Bluffs. Active layer and near-surface permafrost temperatures (to 1 m) were measured every 4 h from 1986 through 1993. This paper combines two previously published data sets with numerical simulations to fill the data gap in daily permafrost temperatures from 1m to the depth of penetration of the annual temperature wave (about 20 m). These daily values were used to calculate mean temperature profiles for the annual period, a 10- to 11-yr cycle and for other periods. Calculated profiles were used to revise estimates of the surface amplitude of the 10- to 11-yr cycle at Franklin Bluffs from 0.6 K to about 1 K. The data show that, for the 10- to 11-yr cycle, cooling of the permafrost began prior to 1983 with the warming part of the cycle beginning in the late 1980s. This is consistent with the U.S. Geological Survey data suggesting that their reported cooling may have been part of a natural cycle and not an effect of the disturbance at the ground surface associated with drilling. Themore » means of the measured temperature profiles below the 20 m depth show curvatures toward warmer temperatures. These curvatures may be associated with climatic fluctuations, a cycle or a longer-term warming trend. While these time series of permafrost temperatures are too short to distinguish between these alternatives, it is important to do so because of their possible relationship with the predicted climatic warming. 28 refs., 10 figs., 1 tab.« less

On the 22-year oscillations

Observational data of the solar diameter in Italy during 1876–1937 and in Greenwich during 1851–1937 were analyzed. The Whittaker operator with different smoothing coefficients was used. The average data sets for the analysis of the possible oscillations of the solar diameter during 1876–1937 were obtained. Average values of the solar radius R(t) and absolute values of its time derivative ¦dR(t)/dt¦ were compared with the Wolf number, W(t), and with the integral A(t) = ∫0tW(t)dt + constant. A good correlation r(R′, W) = 〈¦dR(t)/dt¦, W(t)〉 and r(R, A) = 〈R(t), A(t)〉 was found. It was shown that the frequency spectra of R(t) and A(t) are similar. It was found that during odd 11-yr cycles, the solar diameter decreases, whereas during even cycles it increases. A hysteresis-like behavior in the variation of R(t) during the 22-yr solar magnetic cycle was demonstrated.

Regional Radiocarbon Effect Due to Thawing of Frozen Earth

Accelerator mass spectrometry (AMS) measurement of 25 single-year tree rings from AD 1861–1885 at ca. ±3.5‰ precision shows no evidence of an anomalous 11-yr cycle of 14C near the Arctic Circle in the Mackenzie River area. However, the Δ14C measurements are lower on average by 2.7 ± 0.9 (ō)‰ relative to 14C measurements on tree rings from the Pacific Northwest (Stuiver and Braziunas 1993). We attribute this depression of Δ14C to thawing of the ice and snow cover followed by melting of frozen earth that releases trapped 14C-depleted CO2 to the atmosphere during the short growing season from May through August. Correlation of Δ14C with May–August estimated temperatures yields a correlation index of r = 0.60. The reduction in Δ14C is dominated by seven years of anomalous depletion. These years are 1861, 1867–1869, 1879–1880 and 1883. The years 1867–1869 are coincident with a very strong ENSO event.

Productivity cycles of 200–300 years in the Antarctic Peninsula region: Understanding linkages among the sun, atmosphere, oceans, sea ice, and biota

Compared to the rest of the world9s oceans, high-resolution late Holocene paleoclimatic data from the Southern Ocean are still rare. We present a multiproxy record from a sediment core retrieved from a deep basin on the western side of the Antarctic Peninsula that reveals a dramatic perspective on paleoclimatic changes over the past 3700 yr. Analyses completed include measurement of magnetic susceptibility and granulometry, bed thickness, particle size, percent organic carbon, bulk density, and microscopic evaluation of diatom and benthic foraminiferal assemblages and abundances. Downcore variability of these parameters demonstrates the significance of both short-term cycles, which recur approximately every 200 yr, and longer term events (≈2500 yr cycles) that are most likely related to global climatic fluctuations. In the upper 600 cm of the core, lower values of magnetic susceptibility (MS) are correlated with lower bulk density, the presence of thinly laminated units, specific diatom assemblages, and generally higher total organic carbon content. Below 600 cm, magnetic susceptibility is uniformly low, though variability in other parameters continues. The magnetic susceptibility signal is controlled primarily by dilution of ferromagnetic phases with biosiliceous material. This signal may be enhanced further by dissolution of magnetite in the magnetic susceptibility lows (high total organic carbon). The role of variable primary productivity and its relationship to paleoclimate is assessed through the diatom data. In particular, magnetic susceptibility lows are characterized by higher than normal abundances of Chaetoceros resting spores. Corethron criophilum and/or Rhizosolenia spp. also are found, as is a higher ratio of the most common species of Fragilariopsis versus species of Thalassiosira . These assemblages are indicative of periods of high primary productivity driven by the presence of a meltwater stabilized water column. The 200 yr cyclicity noted in other paleoclimatic records around the world suggests a global forcing mechanism, possibly solar variability. In addition to the cyclic changes in productivity, overall elevated productivity is noted below 600 cm, or prior to ca. 2500 yr B.P. This increased productivity may represent the tail end of a Holocene climatic optimum, which is widely recognized in other parts of the world, but as yet is poorly documented in Antarctica.

A bioassay approach to temporal variation in the nutritional value of sediment trap material

Gross sedimentation rates (GSR) are determined weekly over a 1 yr cycle at a shallow station (18 m) of the bay of Banyuls-sur-Mer. GSR range between 0.6 and 107.8 g · m −2 · d −1. Spring and summer are characterized by relatively low and constant GSR whereas fall and winter are characterized by relatively high and highly variable GSR. The shape of the inverse relationship between GSR and organic content suggests the importance of resuspension in controlling GSR. At the studied station resuspension appears to be mainly cued by the wind. Ingestion rates and absorption efficiencies of the deposit-feeding bivalve Abra ovata fed on 14C-labelled sediment trap material collected on eight sampling dates characteristic of the main meteorological regimes are measured. When expressed in terms of organic matter, ingestion rates are similar (3.2 and 4.9 10 −3 mg OM · mg OM −1 · h −1 for materials collected on May 11, 1993 and January 19, 1993, respectively). The relative consistancy of ingestion rates supports the compensatory intake theory. Absorption efficiencies (ranging from 6.4 to 21.0%) are highly affected by sampling dates. During fall and winter, absorption efficiencies are minimal when resuspension is maximal. During spring and summer, absorption efficiencies depend on the quality of materials sedimenting directly from the water column. Temporal differences in the quality of particulate organic matter available to benthic deposit-feeders should be included in the existing models of continental shelf food webs.

On the origin of the long period sawtooth shape of the Late Pleistocene paleoclimate Records: The first derivative of the Earth's orbital eccentricity

The first time derivative of the earth's orbital eccentricity function is sawtooth shaped, and closely mimics the ∼100,000 yr cycles of the oxygen isotope δ18O time series (the proxy for global ice volume change) of the last ∼800,000 yr. Conversely, numerical integration of the data's variance closely reproduces the orbital eccentricity function for the same interval. Such long‐lived, strong correlation does not appear to be coincidental, is consistent with the physics of ice sheets and with the time history of their advance and retreat.

Variability of the solar cycle length during the past five centuries and the apparent association with terrestrial climate

Solar data have been used as parameters in a great number of studies concerning variations of the physical conditions in the Earth's upper atmosphere. The varying solar activity is distinctly represented by the 11-yr cycle in the number of sunspots. The length of this sunspot period is not fixed. Actually, it varies with a period of 80–90 yr. Recently, this variation has been found to be strongly correlated with long-term variations in the global temperature. Information about northernhemisphere temperature based on proxy data is available back to the second half of the sixteenth century. Systematic monitoring of solar data did not take place prior to 1750. Therefore, a critical assessment of existing and proxy solar data prior to 1750 is reported and tables of epochs of sunspot minima as well as sunspot cycle lengths covering the interval 1500–1990 are presented. The tabulated cycle lengths are compared with reconstructed and instrumental temperature series through four centuries. The correlation between solar activity and northern hemisphere land surface temperature is confirmed.

The simulation of complete 11 and 12 year modulation cycles for cosmic rays in the heliosphere using a drift model with global merged interaction regions

Two-dimensional, time-dependent drift models have done exceptionally well in explaining major modulation features, especially during the A less than 0 magnetic polarity cycle of the heliospheric magnetic field when positively charge particles are drifting in along the heliospheric neutral sheet (HNS). These models were found to do well when the heliospheric 'tilt angles' alpha less than approximately 30 deg (le Roux & Potgeiter). However, they seem to do less well when alpha greater than approximately 30 deg during A less than 0 cycles seem to fail when this happens in A greater than 0 cycles. Progress was made in understanding these phases of the modulation cycle when merged interaction regions (MIRs) were incorporated in time-dependent drift models (Potgieter et al.). It was also explicitly shown that in obtaining large step decreases in cosmic rays, the MIRs had to be global, i.e., having a latitudinal extent of more than approximately 60 deg. Other classes of MIRs, such as local MIRs and co-rotating MIRs were found to be of secondary importance for establishing long-term modulation. In a previous paper we studied the effects of two consecutive, identical global MIRs, together with a changing wavy HNS, on long-term modulation (Potegieter & le Roux). This approach gave a very natural and convincing explanation for the observed step decreases in cosmic-ray modulation. Emphasis was placed in the declining and recovery phases of the 11 yr modulation cycle. In this paper, four consecutive, nonidentical global MIRs, in combination with a varying wavy HNS, were included in our time-dependent drift model in order to do simulations closer to what was observed between 1977 and 1987. By doing this we could model, for the first time, complete 11 and 22 yr cycles in the heliospheric modulation of galactic cosmic-rays, including the solar magnetic polarity reversals.

Hydroclimatic relationships with planktonic time series from 1975 to 1992 in the North Sea off Gravelines, France

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 129:269-281 (1995) - doi:10.3354/meps129269 Hydroclimatic relationships with planktonic time series from 1975 to 1992 in the North Sea off Gravelines, France Le Fevre-Lehoerff G, Ibanez F, Poniz P, Fromentin JM Planktonic time series collected since 1975 off Gravelines, France, were analysed in the context of climatic changes. Principal component analysis and the cumulative sums method were applied to 30 data sets which included meteorological and hydrological parameters and planktonic descriptors. Eight groups of biological descriptors were linked to external parameters. The study of winds highlighted the importance of cyclonic and anticyclonic influences. Seven year cycles appeared clearly in air temperature and in species abundance with different trophic levels for species such as Temora longicornis, Oikopleura dioica and Sagitta setosa, whereas an 11 yr cycle appeared for Pseudocalanus minutus. A 3 to 4 yr cycle was detected for atmospheric pressure, precipitation and some species. This cycle may or may not be superimposed on another (for example, on an 11 yr cycle). Time series . Zooplankton . Meteorology . Hydrology . Southern North Sea Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 129. Publication date: December 14, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

Solar magnetic and bolometric cycles recorded in sea sediments

The total carbonate and thermoluminescence (TL) profiles of the GT89-3 Ionian sea sediment core have been measured in the upper 200 cm of the core spanning the last 3100 years in order to test the presence of the Gleissberg (80–90 yr) cycle in the two different time series recorded in the same archive. Two different sampling intervals respectively of 2.5 mm and 2 mm have been chosen for the measurements in order to obtain results independent from sampling effects in the time series. We have revealed the Gleissberg cycle at 83 and 92 yr in both records.

Satellite and rocket studies of relativistic electrons and their influence on the middle atmosphere

Magnetospheric electrons from hundreds of keV to over 10MeV in energy have been systematically measured at geostationary altitude (6.6 R E) for well over a decade. We find evidence of significant diurnal, solar-rotational (27-day), annual, and solar-cycle (11-yr) variations in the fluxes of the relativistic electron component. We have also used low-altitude satellite data and sounding rocket measurements to characterize the location and strength of the relativistic electron precipitation into the atmosphere. We conclude that the magnetospheric electrons, when dumped into the middle atmosphere, represent a very significant ionization source which affects the pattern of conductivity, electric fields, and atmospheric chemistry. These measurements—when combined with global atmospheric modeling—suggest that relativistic electrons provide a robust coupling mechanism to impose long-term solar wind and magnetospheric variability onto the Earth's deep atmospheric regions. A strong 11-yr cycle of relativistic electron effects is found in available atmospheric data sets.