Principal components and spatial patterns of rain over Northern Italy, in relation to wind and geopotential fields

Summary A statistical study of precipitation over the Po Valley and the Alps during four winters, based on the application of a principal component (p.c.) method, exhibited a good correlation between the first three rotated eigenvectors of the cross-product matrix (between time series of data recorded at 70 stations) and three typical atmospheric circulation schemes over Northern Italy. The study is here continued, by relating these results to meteorological fields evaluated over a region wider than the area previously considered. Our attention mainly concentrated on the fields of time trend of geopotential height at 850 hPa over Europe, between latitude 34.5 and 51 degrees North and longitudes 0 and 21 degrees East. This was suggested by some peculiar relationships shown by the statistical distributions of geopotential height and wind direction and speed with respect to the first three p.c.’s. These relationships made us think of the possibility to use those trends as predictors of precipitation fields. Our analysis puts into evidence that three spatial patterns of geopotential, height time trend can be safely associated to the first three p.c.’s and, as a consequence, to the three precipitation modes corresponding to the spatial distributions of the eigenvectors, previously identified by us. They can therefore be considered meaningful precursors of precipitation field patterns over Northern Italy and Alpine regions.

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Riassunto Uno studio statistico della precipitazione sulla pianura padana e sulle Alpi durante quattro inverni, basato sull’applicazione del metodo delle componenti principali (c.p.), ha mostrato una buona correlazione fra i primi tre autovettori rotati della matrice dei prodotti incrociati (fra le serie temporali dei dati registrati in 70 stazioni) e tre tipici schemi di circolazione atmosferica sull’Italia del Nord. Lo studio viene qui prosequito, mettendo in relazione tali risultati con campi meteorologici valutati su una zona piú ampia di quella precedentemente considerata. La nostra attenzione si è prevalentemente concentrata sui campi di tendenza temporale dell’altezza di geopotenziale a 850 hPa sull’Europa, a latitudini comprese tra 34.5 e 51 gradi Nord e longitudini fra 0 e 21 gradi Est. Ciò è stato suggerito da alcune relazioni peculiari mostrate dalle distribuzioni statistiche di altezza di geopotenziale e di direzione ed intensità del vento rispetto alle prime tre c.p., che ci hanno fatto pensare alla possibilità di usare tali tendenze come predittori del campo di precipitazione. La nostra analisi ha messo in evidenza il fatto che tre distribuzioni spaziali di tendenza temporale del campo di altezza di geopotenziale possono essere con sicurezza associate alle prime tre c.p. e., quindi, ai tre modi di precipitazione corrispondenti alle distribuzioni spaziali degli autovettori precedentemente da noi identificati. Essi possono pertanto essere considerati significativi precursori del campo di precipitazione sull’Italia del Nord e sulle regioni alpine.

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Резюме Статистическое исследование выпадения осадков над долиной реки По и Альпами в течение четырех зим, основанное на применении метода главных компонент, обнаруживает хорошую корреляцию между первыми тремя вращающимися собственными векторами матрицы векторного произведения (между временными последовательностями данных, зарегистрированных на 70 станциях) и тремя схемами типичной атмосферной циркуляции над Северной Италией. В этой работе продолжены исследования. Полученные результаты связывайотся с метеорологическими полями, вычисленными над областью, которая шире ранее рассмотренной области. Главное внимание мы обращаем на поля временного хода для геопотенциальной высоты при 850гПа над Европой, между 34.5^щ и 51^щ северной широты и между 0^щ и 21^щ восточной долготы. Это следует из специальных соотношений, полученных с помощью статистических распределений геопотенциальной высоты и направления и скорости ветра относительно первых трех главных компонент. Эти соотношения позволяют нам использовать исследованные тенденции, как предсказатели полей вьшадения осадков. Нам анализ подтверждает, что три пространственным распределения временного хода для геопотенциальной высоты могут быть связаны с первыми тремя главными компонентами и, как следствие, с тремя моделями выцадения осадков, которые соответствуют пространственным распределениям собственных векторов, ранее идентифицированных в работе [Ш]. Следовательно, они могут рассматриватяся как предвестники для распределений полей осадков над Северной Италией и над Альпами.

     

The CaCO3 profiles of deep and shallow Mediterranean sea cores as indicators of past solar-terrestrial relationships

Summary 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.     

Trend of Ozone in the free troposphere above Europe

Summary Ozone observations were made one century ago by the Sch?nbein technique at meteorological observatories in the alpine region. Within the intrinsic limitations of the technique, historical readings have been converted to present-time concentrations (p.p.b.v.). The evaluated ozone level in the free troposphere (17 p.p.b.v.) was twice as large as at the surface; comparable values were obtained by chemical and spectroscopic technique in the first half of our century. Furthermore, the reconstructed ozone trend in the free troposphere shows a sharp increase after the ’50s, as already observed at the surface at midlatitudes of the northern hemisphere.     

Statistical study of the trajectories of the air masses flow in the Alpine area

Summary As a part of our activity in the transboundary transport, this study examines a five years’ trajectory climatology interesting Northern Italy. Our analysis is twofold: firstly we examine the statistics of air masses arriving at an Alpine location (Brenner Pass) separating between rainy only trajectories and all trajectories, and, secondly, we study the climatology of trajectories, going out from the Po Valley. Trajectories are computed by means of a simple three-dimensional trajectory method using the wind data obtained by the analysis of the ECMWF. The distribution of the arrival (or departure) directions of the trajectories is presented and commented. The differences in the travel times for the different directions are presented as well. The vertical distribution of the trajectories is finally computed. The main results are discussed.     

Surface ozone at mid latitudes in the past century

Summary Surface ozone observations were made from the second half of the past century up to the first decades of the present century at many observatories in the world using the Sch?nbein technique. Although there are some uncertainties about that technique and on possible interferences, accurate readings can be converted to present-time concentrations (p.p.b.v.). The analysis of data series gathered at some sites at mid-latitudes of the Northern and Southern hemispheres leads to the conclusion that a century ago the mean ozone level was about 10 p.p.b.v., the seasonal course changing in relation with local climatology. From that time anthropogenic emissions have increased the ozone level, more at Northern than at Southern latitudes.     

Regularities and similarities in plasma broadened spectral line widths (Stark widths)

Regularities and similarities in plasma broadened line widths have been studied by a comprehensive analysis of existing experimental data. Regularities are expected on the basis of general atomic structure considerations, and should be evident for spectral series, for corresponding transitions in homologous atoms and in isoelectronic sequences. Furthermore, similarities of line widths are expected for multiplets, supermultiplets and, to a lesser degree, for transition arrays. A comprehensive examination of literature data has been undertaken, which shows generally a close adherence of the measured data to the expected regularities. A few notable exceptions are also given.     

Phonon and magnon widths in metamagnets

Microscopic expressions for the couplings of the phonons corresponding to the rigid motions of the waters of hydration with both transverse and longitudinal spin fluctuations are given for the linear chain metamagnetic systems FeCl₂·2H₂O, CoCl₂·2H₂O, and CoBr₂·2H₂O. The processes which can give large, temperatures dependent widths of spin waves and of some phonons for temperatures approaching the Neél temperature are discussed.     

Multistability,intermittency and remerging Feigenbaum trees in an externally pumped ring cavity laser system

We study a Fabry-Pérot cavity containing a saturable absorber and driven by an external laser. It is shown that the output field as a function of the input field and bistability parameter exhibits multistability, intermittency and remerging Feigenbaum trees.     

Fine structure, partial widths and spreading widths of isobaric analogue resonances

Formulas for the microscopic calculation of partial widths and spreading widths, derived from several theories of the isobaric analogue resonances, are compared and critically examined. It is shown that the statistical assumptions used in the derivation of these formulas are not in contradiction with the fine-structure data, in contrast to recent speculations. The accuracy with which partial and spreading widths can be calculated is discussed. The theoretical values of the partial widths, and thus the determination of the spectroscopic factors, involve poorly known phenomenological parameters (essentially the shape of the symmetry potential). Thence, only relative values of the spectroscopic factors can at present be accurately determined. The calculation of the spreading width depends critically upon our knowledge of isospin violation in the nucleus. Recent calculations of the spreading widths are re-examined in the light of these results.     

Correlation widths in quantum-chaotic scattering

An important parameter to characterize the scattering matrix S   for quantum-chaotic scattering is the width Γcorr${\Gamma }_{\mathrm{corr}}$ of the S  -matrix autocorrelation function. We show that the “Weisskopf estimate” d/(2π)c_∑Tc$d/(2\pi ){\sum }_c{T}_c$ (where d   is the mean resonance spacing, Tc$T_c$ with 0?Tc?1$0?T_c?1$ the “transmission coefficient” in channel c   and where the sum runs over all channels) provides a good approximation to Γcorr${\Gamma }_{\mathrm{corr}}$ even when the number of channels is small. That same conclusion applies also to the cross-section correlation function.     

Pulse widths and time dilatation

The temporal widths of a light pulse as measured in different inertial frames are shown to have a relation more complicated than that of a simple time dilatation. The result is compared with the dilatation in the twin paradoxGedanken experiment. The light pulse measurement requires two observers in two different frames. The measurements of the observers are compared. For the twin experiment a comparison is made between two clocks which have undergone different histories between the two points at which their world lines intersect.     

d band widths in CdMg and CuZn alloys

The binary alloys Cd₃Mg, Mg₃Cd and ZnCu 20% at. have been studied using X-ray photoelectron spectroscopy (XPS). The Cd 4d bandwidths are reduceThe Cu 3d band in ZnCu 20% is found to have a width of 1.1 ± 0.1 eV and binding energy of 3.5 ± 0.1 eV. The results are discussed.     

Fission widths and multi-dimensional barrier penetration

A multi-dimensional fission barrier is constructed which is simple enough to permit a complete partial-wave solution of the coupled-channel scattering problem. By employing it to study the multi-channel barrier resonances it produces, we discover that their widths are not directly related to any simple property of the elements of the transmission matrix, but rather to the eigenvalues of this matrix. Whenever one of these eigenvalues occurs near zero, it produces a resonance with an unexpectedly large width. In this sense, multi-dimensional barriers can cause an unforeseen “enhancement” of resonance widths.     

Charmonium decay widths in magnetized matter

The European Physical Journal A - In this paper, we investigated the spectroscopy of heavy tetraquarks through a relativistic diquark-antidiquark model. To this aim, the two-bosonic Klein-Gordon...     

Mechanisms and widths of two-proton decay

A method for calculating the widths of two-proton decay of nuclei with regard to its deep subbarrier character is proposed. The structure and coupling of the channels of facilitated two-proton decay of spherical nuclei are considered for the diproton and uncorrelated mechanisms of two-proton decay.