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We demonstrate the presence of solar flare as well as neutron capture effects in the isotopic composition of rare gases in the Fermo regolith breccia acquired on its parent body based on the measurements of tracks, rare gases and radionuclides. The track density along a 3.2 cm long core decreases by a factor of about 6 and by more than a factor of 13 within the meteorite, indicating small (2-9 cm) and asymmetrical ablation. Rare gases show a large trapped component; the isotopic ratios, particularly 20 Ne/ 22 Ne ≅ 11 and 20 Ne/ 36 Ar = 10 are indicative of a solar component. The galactic cosmic-ray exposure age is determined to be 8.8 Ma. Activities of a dozen radionuclides ranging in half-life from 16 day 48 V to 0.73 Ma 26 Al are consistent with their expected production rates. Track, rare gas and radionuclide data show that the meteoroid was a small body (≤ 120 kg) and had a simple, one-stage exposure history to cosmic rays in the interplanetary space. However, 82 Kr and 128 Xe show an excess due to neutron irradiation on the parent body of the meteorite. The presence of solar gases and the neutron capture effects indicate several stages of irradiation on the parent asteroid. The chemical composition of Fermo confirms that it belongs to the H group of ordinary chondrites with lithic clasts having varying compositions. δ 15 N is found to be 8.3 ± 1.2%0, close to the typical values observed in H chondrites.

The vertical thermal profile of the lower atmosphere can be remotely measured by the Radio Acoustic Sounding System (RASS). A RASS operating at the acoustic wavelength λa ∼ 1 m was designed and developed twenty years ago. It is suitable for monitoring the temperature profile of the lower troposphere and has been utilised for studies of the atmospheric boundary layer in different conditions and for the application of control strategies to air pollution emissions. The acoustic antenna is composed by 9 folded horns covering an area of 7x7 m2; the two radar antennas are composed by arrays of dipoles with square reflector of 2.8x2.8 m2 for each antenna. Therefore the metric RASS can be utilised only in a settled station. Recently we have designed and developed a decimetric RASS (λa = 0.34 m) with smaller antennas, which can be used as a mobile system. It can be housed and carried by a trailer. As it is known, increasing the sounding frequency gives a decreasing of the sounding range. Comparisons of results obtained by both the metric and the decimetric RASS in different atmospheric conditions are presented and discussed.

We have previously shown that the very low activity of the cosmogenic 44Ti in meteorites records the galactic cosmic ray (GCR) flux over a century time-scale (Bonino et al., 1995). The heliospheric magnetic field (HMF) variations are the principal source of the GCR modulation in the heliosphere. We present here new measurements which extend our investigation over the last two centuries. The 44Ti activity at the time of fall has been obtained on the basis of the recently revised value of its half-life of 59.2 years. We basically confirm our earlier findings (Bonino et al., 1997). The 44Ti profile, with the time of fall of the meteorites, shows variations in phase in agreement with those expected. The magnitude of oscillations is ∼ 4 times higher than expected (∼ 6%) on the basis of the GCR flux over the past centuries deduced from sunspot number since 1700 and by the neutron monitor and balloon measurements in the last decades. The higher 44Ti production rate during prolonged solar quiet periods (Gleissberg minima) may imply that during these minima the HMF was weaker than during the recent minima of the 11-year solar cycle.

In this paper we present the δ18O profile of Globigerinoides ruber measured in the GT90/3 shallow water Ionian sea core, dated with high precision. The δ18O profile covers the period 1200–1900 AD, with a resolution of 3.87 years. This long record of 700 years of δ18O allows us to identify the imprint of the solar cycle in a climatic record. In fact, the spectral analysis of the time series performed with different methods shows a dominant periodicity of about 11 years with an amplitude of ≈0.07‰. The signal is in opposition to the sunspot number cycle. This component is identified at a high significance level by Monte Carlo Singular Spectrum Analysis (MC-SSA).

We report on a measurement of the ${}^{44}\mathrm{Ti}$ half-life aimed at lowering existing systematic uncertainties in this value, which is important to astrophysics. The half-life was measured by following the decay of ${}^{44}\mathrm{Ti}$ relative to ${}^{60}\mathrm{Co}$ for about 5 yr and the measurements were performed independently in three laboratories---Argonne, Jerusalem, and Torino. We suggest to combine our result, $59.0\ifmmode\pm\else\textpm\fi{}0.6$ yr, with the one from the accompanying Letter by G\"orres et al., $60.3\ifmmode\pm\else\textpm\fi{}1.3$ yr, to obtain a current ``best value'' for the half-life of ${}^{44}\mathrm{Ti}$ of $59.2\ifmmode\pm\else\textpm\fi{}0.6$ yr ( $1\ensuremath{\sigma}$ error).

Production of cosmogenic radioisotopes in meteorites depends on the galactic cosmic ray flux, which is controlled by the heliospheric magnetic field (HMF), which, in turn, depends on the solar activity. The radioisotopes can, therefore, serve as proxy records of the behaviour of the heliosphere in the past, in particular over prolonged solar quiet periods, such as during Gleissberg or Maunder minima, when the production rate of radioisotopes is expected to change significantly. For this purpose we have measured the 44 Ti (T 1/2 =66.6 yr) in ten stony meteorites, which fell between 1840–1992. The results indicate that the production of 44 Ti was significantly higher when the solar activity was persistently low, indicating that the HMF was weak during such periods, enabling higher flux of cosmic rays to enter the inner heliosphere.

A fundamental contribution to the understanding of several physical processes influencing the galactic-cosmic-ray (GCR) variations can be given by proxy data of the past GCR flux obtained in terrestrial archives and meteorites which extend the range of the studies. The most prominent spatial and temporal GCR variations are of solar origin. The solar modulation affects the intensity of GCR, particularly below 1 GeV and, therefore, the isotopes production rates in the Earth's atmosphere, in planetary surfaces and in meteorites where the GCRs induce nuclear interactions. Measurements and analyses of cosmogenic radioisotopes in terrestrial archives like tree rings, ice cores and sediments are presented. Effects due to variations in the geomagnetic field, climatic changes and exchange within different terrestrial reservoirs which affect the isotopes deposition rates are also discussed. The study of cosmogenic radioisotopes in meteorites, which are exposed to GCR in the interplanetary space, has the advantage that the production of radioisotopes is not affected by terrestrial processes.

A long-lasting and deep-fog episode, occurred in the western region of the Po Valley (Italy) during February 1992, has been studied by means of remote-sensing systems, coupled to more conventional meteorological instruments operating at ground level. The temperature profiles were monitored by a metric RASS and the three components of the wind profiles were measured by a Doppler Sodar. The typical altitude coverage of the metric RASS is 80–1000 m; therefore, it is suitable to measure fog-capping thermal inversions and temperature profiles above the fog layer, so that it makes it possible to follow with continuity the growth, the evolution and the end of the fog episode accompanied by subsidence conditions.

Different fluxes and spectra of galactic cosmic rays (GCR) and solar cosmic rays result in a wide variety of radioactive and stable-nuclides production rates. The records of cosmic-ray interactions, have been studied in terrestrial archives, in meteorites, cosmic dust and lunar samples. We present here some results obtained in our laboratory on the study of cosmogenic radionuclides produced in meteorites which fell in the last century. The laboratory is situated in the underground station of Monte dei Cappuccini, Torino, at a depth of 70 m water equivalent to reduce the cosmic-ray background level. To measure γ-activity in meteorites we have set up a highly efficient and selective Ge−NaI(Tl) γ-ray spectrometer surrounded by a passive shield. The solar modulation affects the intensity of GCR and therefore the isotopes production rates in meteorites. The 11 y solar cycle is well reproduced by the variations of22Na (T 1/2=2.6 y) in meteorites which fell during the past three solar cycles. The44Ti (T 1/2=66.6 y) activity measured in eight chondrites which fell in the last 110 y is qualitatively consistent with the century-scale solar-activity variation, called the Gleissberg cycle. The increase is roughly four times higher, than expected (about 5%) for a GCR flux calculated by a model in which the solar-activity modulation is determined solely by the sunspot number indexR. This result suggests a much weakened modulation of GCR during the prolonged Gleissberg minimum during which highly ordered magnetic fields set up in the heliosphere.

A renewed interest in the dynamic and thermal structure of the atmospheric boundary layer (ABL) has recently revived, due to the contribution that this layer can provide to the improvement of skill of weather prediction and climate simulation in the most advanced general circulation models. The attention is particularly focused on non-stationary and non-homogeneous turbulent structures of this transition layer, for which many parametrization schemes, based on local-and non-local-closure assumptions, have been proposed. However, also stationary, non-homogeneous, continous-turbulence conditions can give rise to some complication in the ABL parametrization when air stability becomes stronger and stronger. In this situation, the governing scales of the classical non-local Monin-Obukhov similarity theory are no more representative, and new local scales must be derived from local forcings of the flux. This paper summarizes a few relevant points of the local-similarity theory and shows the results of a local-scaling analysis obtained by observation data of wind and temperature profiles in the ABL in the northern Po Valley

We have measured the thermoluminescence (TL) profile of the Mediterranean Sea core CT85.5 at the same depths where the cosmogenic-isotope10Be production peak at 35 ky BP was found. Strong TL peaks are evident at 37.5 ky and 35.6 ky BP. The Fourier analysis of the TL time series running from 32.5 ky to 42.6 ky at 100 y sampling interval shows 2500 y and 500 y periodicities. We suggest that the Sun was «active» at the time of the10Be enhancement.

An accurate dating of recent Ionian Sea sediment cores has been performed by the210Pb radiometric method and by a detailed tephroanalysis. The markers of the historical volcanic eruptions which occurred in the Campanian area (Vesuvius, Phlegrean Fields, Ischia) during the last two millenia have been identified along the cores. Among the others, the famous Plinian Vesuvius eruption of 79 AD, which buried the Roman town of Pompei, has been recognized. Direct210Pb dating is limited to the last two centuries. The tephroanalysis demonstrates that the sedimentation rate estimated by the210Pb method is correct and it is constant, at least for the last 2 ky. The presence of the137Cs peak due to the intense activity of nuclear-weapon testing in the atmosphere in 1963–64 AD assures that the top of the core is present and not disturbed. The high precision of the core dating allows to transform the depth scale into a time scale with an accuracy of ∼1%. The analysis of several cores taken in the same area demonstrates that the results presented here are of general validity, at least in this region. The carbonatic mud deposited in the last millennia in the Gallipoli Terrace can be successfully utilized for investigating the environmental conditions in the recent past.

The measurement of44Ti produced by spallation reaction of cosmic rays in meteorites fell in the last hundred years can be used for investigations on century-scale variations of solar activity. The low specific activity and the interferences of natural background and of meteorite gamma emitters are the main difficulties to be surmounted in this measurement. A selective γ-spectrometer consisting of a HP Ge and a NaI(T1) detectors in coincidence and anticoincidence has been set up in the underground (70 m w.e.) Laboratory of Monte dei Cappuccini, which allows to obtain a reliable measurement of44Ti(44Sc).

We study the total carbonate profiles of three coastal cores extracted from the continental shelf in the Ionian Sea and of two deep-sea cores extracted from the Tyrrhenian abissal plane. An overall similarity between the two deep-sea profiles and among the three coastal profiles is observed, indicating the complete reproductibility of this type of experimental measurements. In the case of the coastal cores, a constant sedimentation rates=(0.0646±0.0007) cm/y has been determined by radiometric methods and by tephroanalysis. For the deep-sea cores, the spectra of the upper and lower halves of the carbonate depth profiles display the same periodic components, suggesting that the sedimentation rate is nearly the same along the entire deep cores as well. The use of a careful tephroanalysis, the recognition of the Ignimbrite layers of Campanian origin at the expected depths and the similarity between the upper part (5000y) of the carbonate profile of the deep-sea core with that of the coastal cores provide the indication that, on the average, 1 cm of sediment is deposited in about 100 y. We show that the trend of the carbonate record in the deep-sea core is well approximated by a signal obtained by linearly superposing the obliquity and the precession parameters of the Earth rotation axis. Since these astronomical factors contribute to the temporal variations of the Earth insolation, and since the CaCO3 content of the sediment is presumably affected by climatic factors, this result supports the evidence of astronomical control on the Earth's climate, as already pointed out by several authors who analysed the power spectra of δ18O, δD and CO2 temporal series from sediment and ice cores. After removal of the «astronomical» trend, the carbonate record displays a dominant periodicity at approximately 12000 y. The 12000 y wave, taken with the opposite sign, corresponds to the trend of the radiocarbon record in tree-rings. This result becomes particularly relevant in view of the existence of common periodicities of about 200 y waves (Suess wiggles) which have already been detected in the carbonate profiles of the coastal cores and in tree-ring radiocarbon data.

A large-volume HPGe gamma-ray spectrometer in a NaI(Tl) well has been set up underground at 70 m.w.e. depth for whole body counting of cosmogenic radionuclides in meteorites. The detectors are housed in a 20 cm thick lead shield with a lining of cadmium and OFHC copper. The scintillator is simultaneously operated in anticoincidence as well as in coincidence in selected energy channels to achieve low background levels (in the range of counts per day) and high specificity. In this way a large number of radionuclides such as26Al,44Ti,60Co,22Na,54Mn, and shorter-lived nuclides produced in extraterrestrial materials like meteorites and lunar rocks can be analysed. Results on Bouvante and Bereba achondrites and Dhajala and Torino chondrites are presented.

The authors confirm and extend the results previously reported on the carbonate profile of the GT14 Ionian Sea core (Cini Castagnoli et al., 1990). A second, much longer core (2.81 meters) named GT89/3, has been taken about 1 km apart from the previous one. The carbonate profiles of the two cores are impressively similar; the details of the CaCO{sub 3} variations in the two sediments match on the scale of the sampling interval {Delta}d = 2.5 mm used for both cores. The authors show that {Delta}d corresponds to the mud deposited in a time interval {Delta}t = 3.87 {plus minus} 0.04 years, a value which is constant throughout the entire length of the cores. This precision is achieved by the tephroanalysis of the two cores. In this approach the markers of well-known historical eruptions in the Vesuvius area are recognized (Pompei, AD 79, Pollena, AD 472, Ischia, AD 1301), providing a precise dating which accurately tunes that obtained by the radiometric method. The correlation between the carbonate profile of the GT14 core and the tree-ring radiocarbon record has been discussed in (Cini Castagnoli et al., 1990); here the authors extend these results and show that the same correlation holds atmore » least up to 1690 BC. Due to the longer length of the GT89/3 time series, they also show that three periodic components at about 206 yr, 228 yr and 179 yr may now be resolved in the carbonate series, in close agreement with the results already found for the radiocarbon record.« less

The calcium carbonate (CaCO{sub 3}) profile of a recent sediment core, drilled in the Ionian Sea in 1979, is studied. The CaCO{sub 3} content of the sediment has been measured at regularly spaced intervals of {Delta}d=0.25 cm corresponding to {Delta}t=3.87 yr from AD 170 to the present. The CaCO{sub 3} profile of the core closely resembles the radiocarbon time series as deduced from tree ring data. The two records have a correlation coefficient of about 0.8 and show strikingly similar long-term variations. This result presumably follows from the fact that both systems take part in the carbon cycle. The spectral analysis of the CaCO{sub 3} time series reveals the presence of the well known periodicity with period ca: 200 years, characteristic of the {Delta}{sup 14}C record. Since the CaCO{sub 3} content of sea sediments is governed by biological, physical and chemical processes in surface sea waters, which in turn are strongly influenced by climatic conditions, and since the {approx}200 yr {Delta}{sup 14}C wave is known to be governed by solar modulation of galactic cosmic rays, the tuning of these two records on the same frequencies suggests a strong Sun-climate relationship.

The heliospheric magnetic field (HMF) is controlled by solar activity, as established by measurements over the last few decades, but its characteristics when the sun was quiet for prolonged periods, such as during Gleissberg or Maunder minima, are not known. Titanium-44, produced in meteorites, provides a monitor of the galactic cosmic ray (GCR) flux and allows estimation of the modulation effect of the sun for the period 1883 to 1992. The titanium-44 activity is consistent with the expected value, but the increase, due to the last Gleissberg minimum, is four times greater than expected for a GCR modulation based solely on sunspot numbers. This result implies that the HMF was weaker than at present and as a result the GCR flux (for energy greater than 1 gigaelectron volt) was higher between 2.2 to 3.6 protons per square centimeter per second per 4π steradians at 1 to 3 astronomical units in solar cycles 12 to 15.

We show the δ 13 C profile of Globigerinoides ruber measured in the GT90/3 shallow-water Ionian sea core. This core is dated with high accuracy (better than 1%) using radiometric and tephroanalysis methods, for the last 2000 years. The core, extracted from the Gallipoli platform, was sampled at contiguous steps of thickness 2.5 mm, corresponding to 3.87 years. The δ 13 C profile covers the period 1147–1975 AD. During the first seven centuries it appears fairly flat, while it shows a steep increase between 1760 and 1950 of ∼0.3‰. The analysis of the time series performed using different methods shows a dominant decadal periodicity throughout the record. The 11-year component is identified at high significance level by Monte Carlo singular spectrum analysis (MC-SSA); the SSA-reconstructed-11-year component is in phase with the sunspot solar cycle. The average amplitude of this component is A 11y =0.04‰. It is commonly accepted that δ 13 C variations in symbiontic foraminifera mainly record the effects of symbiont density and of photosynthetic activity, varying with ambient light level. The δ 13 C peak-to-trough 11-year variation (0.08‰) can be related to solar irradiance variation of 0.1% on decadal time scale, like that measured in space in the last 20 years. By supposing that the observed δ 13 C modern increase of ∼0.3‰ is also produced by a solar irradiance variability on a longer time scale, through the same mechanisms, we estimate a secular increase of the total solar irradiance between 1760 and 1950 of (0.3/0.08)∗0.1% ≅ 0.37%. This value is at the higher limit of the long term variability estimates (0.25%–0.35%) that are currently proposed. Finally, in the light of the available experimental evidences, we discuss possible ways in which direct solar forcing can be modified by atmospheric processes in order to give the observed δ 13 C signal.

Portales Valley is an unusual meteorite with H6 chondritic matrix, interspersed by heterogeneous distribution of metallic veins. Four fragments with different abundances of veins, as determined by their bulk densities (3.49–4.86 gcm −3 ) were analysed for measurement of the cosmogenic radionuclides 57 Co, 54 Mn, 22 Na, 60 Co, 44 Ti and 26 Al using a gamma ray spectrometer. Chondritic and metallic proportions were estimated for each fragment. One sample was essentially free of metal veins. The shielding depth of each fragment (14 to 81 gcm −2 ) was estimated using cosmic ray heavy nuclei tracks which varied by more than two orders of magnitude in the four fragments, ranging between 4 to 1.7×10 6 cm −2 . The activity ratio 22 Na/ 26 Al was found to be similar (1.53±0.03) in the four fragments, independent of shielding depth and consistent with the expected activity at the time of fall during the beginning phase of the solar cycle 23.

We present measurements and data analysis of the oarbon stable isotopes (delta^13C) in the planktonic Globigerinoides ruber extracted from the GT9O/3 shallow water lonian sea core, dated with high precision. It is commonly accepted that delta^13C variations in symbiontic foraminifera mainly record the effects of productivity and of photosynthetic activity, varying with the ambient light level. Therefore from this time series we can deduce information on the sea surface illumination at the time of the planktonic foraminifera growth. The profile (359 points) covers the period 590-1979 AD, with a resolution of 3.87 years and it is an extension of the time series (215 points) previously published in this journal. The spectral analysis of the longer time series confirms the presence of the 11 y signal, with amplitude —0.08 per mille (peak-to-trough), found in the shorter time series in phase with the sunspot solar cycle; furthermore it shows the presence of two centennial cycles of 100 and 200 years, with amplitude 0.08 per mille and 0.02 per mille respectively. These components are identified at high significance level by Monte Carlo singular spectrum analysis (MC-SSA). A comparison between the delta^13C profile and the historical aurorae series (600-1500 AD) shows that the long-term delta^13C variations are at least partially generated by the solar activity modulation and in phase with the solar output, as represented by the solar wind interaction with the magnetosphere.

The RASS can measure thermal vertical profiles of the lower atmosphere with an accuracy generally within a few tenths K. Several systems have been designed and built with different purposes. The RASS of the first generation, produced up to mid-1980's are suitable to measure temperature profile in the PBL. The RASS of second generation, obtained by the addition of an acoustic source to wind profiler radars can measure the temperature profile throughout the troposphere starting the measurement at altitude of few hundred meters and in some cases of few kilometers.

In this letter, we report the profiles (∼160 samples) of 10Be, 9Be, Zn in a Mediterranean sediment core spanning the last 60 kyr. We show the existence of a 10Be peak, whose absolute age is estimated to be 34±3 kyr BP, based on its stratigraphic position between two tephra layers originating from two volcanic eruptions (Campanian Ignimbrite and Citara), dated by K-Ar, 40Ar-39Ar and 14C methods. This peak is similar to the increase in the 10Be concentration observed in Vostok and Dome C ice cores at the same age. The increase with approximately similar amplitude in both ice and sediment cores at different latitudes and hemispheres cannot be explained by changes in the archives. The present result supports the view of a well defined global enhancement of the 10Be flux, related to an increase of the 10Be production rate and not to a redistribution of the 10Be fallout between different latitudes.

In this paper, we compare the carbonate record obtained by us (Cini-Castagnoliet al., Nuovo Cimento C,15 (1992) 547) in the CT85-5 Tyrrhenian deep-sea core with that obtained by Kegwin and Jones (J. Geophys. Res. C,99 (1994) 12397) in the western North Atlantic GPC-9 Bahama core, during the period of climate stage 3 (20–62 ky BP). Both time series are radiocarbon tested. An overall similarity between the two carbonate profiles is observed. The Tyrrhenian and the Bahama records show a maximum correlation coefficientr2=0.6 for a time shift of 900 y, the latter preceding the former. By using the method of superposition of epochs, we show that the two series display a similar variability on the time scale between 2000 and 5000 y. Periods and phases of the oscillations agree within experimental errors. We have recently found in CT85-5 the10Be peak discovered in Vostok ice core at about 35 ky BP; so this marker could be searched in GPC-9 in order to synchronize in absolute way the past ocean conditions.

The thermoluminescence (TL) and carbonate profiles are measured in shallow water Ionian Sea cores, dated precisely by radiometric and tephroanalysis methods. Their time series, covering the last 4000 years, are obtained at time intervals of 3.096 and 3.87 years. We show that the 10.8 yr cyclicity is always present in each of time series analysed. A study of the amplitudes and phases of the wave is performed by the method of superposition of epochs. The phase shift of the TL and of the CaCO3 waves is ∼π. The persistency of the wave is assured in the last 3000 years by the cyclogram analysis. The power involved in this component of the signals is however small. Since the time series which we have extracted from the Ionian Sea cores bear some relation to the climatic factors forcing the deposition of the coastal carbonatic mud, these results may be interpreted as a proof that the Schwabe cycle of the Sun, associated with the irradiance variability, is directly involved in the climatic changes of the terrestrial archives.

Abbiamo analizzato i profili della concentrazione del carbonato di calcio (CaCO3) in quattro cores di sedimenti recenti del Mar Ionio, che coprono un intervallo di ∼5000 anni, ed il profilo della termoluminescenza (TL) in uno di questi cores che copre un intervallo di ∼2000 anni. La velocita di sedimentazione e stata determinata con grande precisione utilizzando metodi radiometrici e di tefroanalisi e si e dimostrata costante ed identica per i quattro cores. I profili di CaCO3 e di TL sono stati cosi trasformati in serie temporali. La precisione delle scale temporali ha permesso l'analisi accurata di significative ciclicita presenti nelle serie temporali ottenute e di individuare la loro possibile origine solare. Le serie di CaCO3 sono perfettamente riproducibili e rivelano, in particolare, le periodicita di circa 90 anni (ciclo di Gleissberg) e di circa 200 anni presenti anche nel14C degli anelli degli alberi. Questa periodicita e accompagnata da due bande laterali che suggeriscono che l'onda di 200 anni e modulata da una componente con periodo di ∼2000 anni, come si trova anche nel radiocarbonio. L'analisi della serie temporale di TL rivela ben definite periodicita a 137.7 a, 59 a, 28.5 a, 22 a, 12.06 a, 10.8 a, che hanno notevoli corrispondenze con le periodicita trovate nelle macchie solari e nelle aurore. Inoltre, il battimento delle due onde con periodo decennale produce un treno d'onda con periodo di 11.4 a ed una modulazione d'ampiezza di 206 a gia citata, ed i nodi del treno d'onda coincidono con i minimi delle macchie solari. I risultati ottenuti indicano un possibile meccanismo comune, di origine solare e/o climatica che controlla indici differenti in reservoirs terrestri.

The thermoluminescence (TL) profile of the GT14 Ionian Sea core has been recently analyzed in connection with other records of solar activity. Phenomenological similarities among the TL profile, the radiocarbon record in tree-rings and the variations of the mean anuual sunspot number Rz suggest a solar control of the TL signal. In this paper we consider new readings of the TL profile of the GT14 core which were obtained at different glow temperatures. While the main spectral peaks discussed in previous papers are observed in all readings, a few new significant periodic components may now be separated from the noise background. Among these, a strong 22 yr (Hale) cycle is evident, together with a periodicity of 28.5 yr which has already been detected in the spectrum of the sunspot number series. We finally test the temporal persistency of the main TL periodic components by using a cyclogram method and we explore the effects of background noise by considering the TL profile of bleached samples.

We briefly discuss how the thermoluminescence (TL) profile of a young marine sediment provides phenomenological information on the changes in the environmental conditions in the past 18 centuries. The main periodicities present in the TL profile are studied and the similarities between the TL variations and the fluctuations in the contemporary tree-ring A 14 C signal are considered. An interesting result is the presence, in the TL data, of a well-defined 11-year cycle which is stable and ‘in phase’ for the entire period analysed. We also discuss how four dominant periodicities present in the TL data may be rewritten as the sum of an 11.4-year and of an 82.6- year cycle (reminiscent respectively of the Schwabe and of the Gleissberg cycles of solar activity), which are both amplitude modulated by a 206-year wave. This last periodicity has already been shown to play a dominant role in the A 14 C record. These results suggest that the TL profiles of recent marine sediments may be successfully used as a new line of evidence for solar variability in the past centuries.

In order to investigate the extent to which 10Be concentrations in polar ice record solar activity on the level of individual Schwabe solar cycles, we have measured 10Be concentrations over the interval from 1180 to 1800 A.D. in an ice core from Greenland, using the accelerator mass spectrometer of the ETH Zurich. The data were analysed using the cyclogram method of time series analysis which showed that 10Be concentrations varied with a period which ranged between 9 and 11.4 y. Schwabe-type 10Be variations were visible even during the Maunder Minimum (1645–1715 A.D.), an interval of almost no visible sunspots. During this period 10Be concentrations varied with a periodicity which slowly increased from 9 to 11 y. 10Be concentrations were higher during the Maunder Minimum than during minima in the 11 y Schwabe cycle. This suggests the presence of residual solar modulation even during Schwabe solar cycle minima.

A Radio-Acoustic Sounding System (RASS) with acoustic wavelength λa ~ 1 m was designed and successfully tested. The system proved to be capable of measuring the vertical temperature profile in the Planetary Boundary Layer (PBL) with an accuracy and vertical resolution comparable to that of traditional apparatus (radiothermosondes borne by tethered or disposable balloons, thermosondes borne by aircraft and so on), yet combined with the advantages typical of remote sensing techniques. Up to the summer of 1983 the system needed attendance by an operator who had to identify the acoustic sounding frequency affording the fundamental condition of Bragg resonance between acoustic and radio wavelengths. Features and performance of the new completely automatic RASS arrangement are presented. These include the possibility of obtaining average thermal vertical profiles at preset time intervals. Maximum range of measurements obtained in about 1000 1 2 -h averages was: in 90% of cases ⩾ 600m; in 50% of cases ⩾ 1100m. Such results indicate the usefulness of automatic RASS as a tool for meteorological purposes and for the application of air pollution control strategies.

The thermoluminescence profile of an Ionian Sea recent sedimentary core, constructed with 467 equispaced data points and spanning 18 centuries from 170 to 1974 A.D. is studied. Several time series analysis methods reveal two evident periodicities on the centennial time scale, at 137 years and 118 years, both with their second harmonics. Together with these slow cyclic variations two sharp periodicities appear on the decennial time scale, at 12.1 years and 10.8 years. In the present study the amplitude and phase of these waves have been determined and it is shown that their summation accounts for more than 50% of the standard deviation of the whole time series and that they correctly reproduce the basic characteristics of the data.

A meteorite shower fell at Torino, Italy on May 18, 1988. Petrographic studies indicate that the stone is an H6 chondrite having features of moderate to severe shock. Chemical analyses of the meteorite are reported. Cosmic ray produced He-3, Ne-21 and Xe-126 yield an exposure age of about 48 Ma. The cosmic ray track densities in three fragments range between 1.8 to 5 x 10 to the 5th/sq cm suggesting about 99 percent mass ablation in the atmosphere,. Twelve radioisotopes with half lives ranging between 5.6 days to 7.3 x 10 to the 5th years have been measured with high precision. Marginal signals were observed for several short-lived nuclides and upper limits were obtained for the activity levels of eight radionuclides, some of which have not been hitherto detected in fresh falls. The data are generally consistent with the nuclide production by galactic cosmic rays when modulation due to the solar cycle is taken into consideration. 23 refs.

An anisotropic Meyer and Deitz potential has been used to describe the interaction between rare gas atoms and carbon atoms in graphite. Potential energies of adsorption have been calculated by extending to this interaction law the method developed by Steele for the Lennard-Jones case. Energy band structures for rare gases adsorbed on the basal plane of graphite have been calculated. A discussion of the effects of the introduced anisotropy shows that the general conclusions already drawn when using Lennard-Jones Isotropie potentials are not altered in any substantial manner, even if potential barriers to surface migration are about 50% higher in this case.

A radio acoustic sounding system (RASS), operating at an acoustic frequency ƒ ∼ 360 Hz, proved to be capable of measuring the vertical temperature profile in the planetary boundary layer (PBL) with an accuracy and vertical resolution comparable to those of traditional apparatus (radiothermosondes borne by tethered or disposable balloons, thermosondes borne by aircraft and so on, yet combined with the advantages typical of remote sensing techniques. Since summer 1983 the system has been running in a completely automatic way by means of a microprocessor and can provide the average thermal profile at preset time intervals (typically 0.5 h). (Previously, the acoustic sounding frequency affording the fundamental condition of Bragg resonance between acoustic and radio wavelengths had to be identified by an operator). The maximum range of measurement has been ∼ 1000 m in 50% of cases. Temperature measurements are reliable from an altitude of a few tens of meters. Results for different thermodynamic stability conditions, together with good performances achieved in adverse atmospheric conditions such as strong wind, snow, rain, etc., are presented here. Such results indicate the usefulness of the automatic RASS as a tool for meteorological purposes and for the application of air pollution control strategies. Maximum sounding range attained for different areas of the acoustic antenna is also analysed in order to evaluate the performance of an automatic mobile RASS.

This paper presents a climatological diffusion model for computing seasonal sulphur dioxide concentrations. The area under investigation is located in the Po Valley (Northern Italy), and is characterized by prevailing conditions of weak winds, with the presence of mountain and valley breeze. A large number of sulphur dioxide sources are located in this area: they are both urban emissions (due to home heating) and industrial emissions. A physical parametrization of the planetary boundary layer was achieved by using the results of experimental campaigns in the site. A detailed source inventory was compiled in order to supply correct input to the model. The paper presents the results obtained by simulations over a period of 2 years. The agreement between measured and computed concentrations confirms the soundness of the physical parametrizations of the model and makes it suitable to use it for planning future urban and industrial emissions in the area.

Thermoluminescence from the different layers of a recent core drilled in the Tyrrhenian Sea has been measured. The sedimentation rate of 0.115 cm y−1 previously determined by the210Pb−226Ra method allows the profile of TL to be obtained in the last 1500 years. We notice that sharp peaks in the TL intensity appear during the years in which records of hystorical supernovae explosions are given. A working model of the process based on the irradiation of dust in the upper atmosphere by γ-rays produced in the SN burst allows a satisfactory energy estimate of the observations to be done. Moreover, the profile shows the modulation of the irradiations of the Earth environment produced by the Sun in the past.

The vertical temperature profile of the lower troposphere can be measured with a radio-acoustic sounding system (RASS). A comparison of the thermal profiles measured with the RASS and with traditional methods showsa) RASS ability to produce vertical thermal profiles at an altitude range of 170 to 1000 m with temperature accuracy and height discrimination comparable with conventional soundings,b) advantages of remote sensing as offered by new sounder,c) applicability of RASS both in assessing evolution of thermodynamic conditions in PBL and in sensing conditions conducive to high concentrations of air pollutants at the ground level.

The results of the spectral analysis of the time variations of the thermoluminescence (TL) intensity measured at 4 y intervals in a recent Ionian Sea sediment core from 1500 A.D. to 1974 A.D. are presented. The presence of an 11 y wave is clearly demonstrated not only by the power spectral density analysis but also by two other methods:a) the superposition of the 11 y epochs andb) the stretching index of the 11 y cyclogram. Moreover, the fan map of the stretching index of the cyclograms at different perioditities shows that the oscillations in the band (11±0.5) y are regularly frequency-modulated on a time scale around 90 y. The two kind of periodicities could be related to the Schwabe and the Gleissberg cycles of solar activity which appear in phase with the TL cycles. We confirm, therefore, our previous suggestion that the TL profiles from sea sediments could be a useful tool for monitoring the solar-terrestrial effects in the past.

Comparison of turbulent-diffusion parametersσ v andσ z, evaluated through different experimental tests carried out in the Po Valley in the range (102÷104) m downwind the source, under neutral and unstable conditions, is presented and discussed. Two kinds of methods of tracer dispersion were adopted. The first one dealth with no-lift balloon diffusion in the range (102÷103) m, while the second one was relative to SF6 dispersion in the range (103÷104) m. In the present paper the two sets of data are joined and a single series of best-fit curves covering the whole measured range (102÷104) m is derived. The results show different behaviours forσ y andσ z; in fact, it is possible to extrapolateσ y trends from one set of data (SF6) to the other one (no-lift balloons) without changing the analytical expression and the values of their coefficients. Forσ z, instead, some new considerations are needed. In fact, for the unstable categories here considered (B/C andC) it is necessary to change the analytical form of theσ z trend. This is due to the effect of convection resulting in an increase of dσ z/dx. Finally, the exponent of the sampling time τ, in theσ y vs. τ relationship, was found equal to 0.2, in the range (16÷128) min.

The profiles of the concentration of210Pb precipitated from the atmosphere are measured in Tyrrhenian Sea cores, all collected in about the same region. From the disequilibrium226Ra−210Pb the sedimentation rate has been found and its uniformity has been tested. The measured activities of210Pb unsupportedin situ in the different layers show an exponential behaviour as a function of depth, thus demonstrating that the sedimentation rate is constant. Moreover the fall-out has been estimated in two different cores, and the agreement is excellent (respectively 62 and 58 atoms/cm2 min). A case of mixing in the top layers during collection mishandling is also presented: the fluctuations in the activity measurements are evident and prevent the sedimentation rate to be univocally determined.

The sounding range of a RASS (Radio Acoustic Sounding System) for remote measurement of the atmospheric thermal profile is determined both by the structural peculiarities of the system (wavelength, size of antennas, acoustic and radar power, etc.) and by the properties of the atmosphere (turbulence, wind, temperature and humidity). In this report we experimentally investigate the effect of antenna size and the number of cycles in the acoustic pulse on the range of a metric RASS (acoustic wavelength ∼1 m). We find good agreement between theory and experiment.