New approach to measure the stability of the solar radiative regime     

Marius Paulescu  Viorel Badescu 《Theoretical and Applied Climatology》2011,103(3-4):459-470

This paper focuses on different ways of characterizing the solar radiative regime of a day and the stability of this regime. The days may be stratified in classes of cloud shade, observed total cloud cover amount, daily averaged clearness index, and fractal dimension of the solar global irradiance signal. A new Boolean parameter related to solar irradiance fluctuation is defined, namely the sunshine stability number. The time averaged value of the sunshine stability number is used for the characterization of the radiative regime stability during a given time interval. Ranking the days from the view-point of the stability of their radiative regime is performed by using the daily average value of the sunshine stability number and appropriately defined values of disorder and complexity, respectively. Measurements performed in the Romanian town of Timisoara (latitude 45°46?? N, longitude 21°25?? E and 85?m altitude above mean sea level) are used here. They refer to time series of global and diffuse solar irradiance recorded at 15-s time interval between sunrise and sunset during all the days in 2009.  相似文献   

The time-dependent transport of cosmic rays in the heliosphere     

Marius S. Potgieter 《Astrophysics and Space Science》1995,230(1-2):393-403

The modulation of cosmic rays (CRs) in the heliosphere is a dynamic and therefore a highly time-dependent process. Numerical models with only a time-dependent neutral sheet prove to be successful when moderate to low solar activity occurs but fail to describe large and discrete steps in modulated CRs when solar activity is high. To explain this feature of heliospheric modulation, the concept of global merged interaction regions (GMIRs) is required. The combination of gradient, curvature and neutral sheet drifts with these GMIRs has so far been the most successful approach in explaining the 11-year and 22-year cycles in the long-term modulation of CRs.  相似文献   

Modeling the influence of hydroperiod and vegetation on the cross-sectional formation of tidal channels     

Andrea D'Alpaos  Stefano Lanzoni  Simon Marius Mudd  Sergio Fagherazzi 《Estuarine, Coastal and Shelf Science》2006,69(3-4):311

The evolution of the cross section of a salt-marsh channel is explored using a numerical model. Deposition on the marsh platform and erosion and deposition in the channel affect the tidal prism flowing through the cross section, such that the model captures the evolution of the stage–discharge relationship as the channel and marsh platform evolve. The model also captures the growth of salt-marsh vegetation on the marsh platform, and how this vegetation affects flow resistance and the rate of sedimentation. The model is utilized to study the influence of hydroperiod and vegetation encroachment on channel cross section. Numerical results show that a reduction in hydroperiod due to the emergence of the marsh platform causes an infilling of the channel. Vegetation encroachment on the marsh surface produces an increase in flow resistance and accretion due to organic and mineral sedimentation, with important consequences for the shape of the channel cross section. Finally, modeling results indicate that in microtidal marshes with vegetation dominated by Spartina alterniflora, the width-to-depth ratio of the channels decreases when the tidal flats evolve in salt marshes, whereas the cross-sectional area remains proportional to the tidal peak discharge throughout channel evolution.  相似文献   

Effects of hypoxia on gene and protein expression in the blue crab, Callinectes sapidus     

Brouwer M  Larkin P  Brown-Peterson N  King C  Manning S  Denslow N 《Marine environmental research》2004,58(2-5):787-792

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The Tajik Basin: A composite record of sedimentary basin evolution in response to tectonics in the Pamir     

James B. Chapman  Barbara Carrapa  Peter G. DeCelles  James Worthington  Nicoletta Mancin  Miriam Cobianchi  Marius Stoica  Xin Wang  Mustafo Gadoev  Ilhomjon Oimahmadov 《Basin Research》2020,32(3):525-545

Investigation of a >6-km-thick succession of Cretaceous to Cenozoic sedimentary rocks in the Tajik Basin reveals that this depocentre consists of three stacked basin systems that are interpreted to reflect different mechanisms of subsidence associated with tectonics in the Pamir Mountains: a Lower to mid-Cretaceous succession, an Upper Cretaceous–Lower Eocene succession and an Eocene–Neogene succession. The Lower to mid-Cretaceous succession consists of fluvial deposits that were primarily derived from the Triassic Karakul–Mazar subduction–accretion complex in the northern Pamir. This succession is characterized by a convex-up (accelerating) subsidence curve, thickens towards the Pamir and is interpreted as a retroarc foreland basin system associated with northward subduction of Tethyan oceanic lithosphere. The Upper Cretaceous to early Eocene succession consists of fine-grained, marginal marine and sabkha deposits. The succession is characterized by a concave-up subsidence curve. Regionally extensive limestone beds in the succession are consistent with late stage thermal relaxation and relative sea-level rise following lithospheric extension, potentially in response to Tethyan slab rollback/foundering. The Upper Cretaceous–early Eocene succession is capped by a middle Eocene to early Oligocene (ca. 50–30 Ma) disconformity, which is interpreted to record the passage of a flexural forebulge. The disconformity is represented by a depositional hiatus, which is 10–30 Myr younger than estimates for the initiation of India–Asia collision and overlaps in age with the start of prograde metamorphism recorded in the Pamir gneiss domes. Overlying the disconformity, a >4-km-thick upper Eocene–Neogene succession displays a classic, coarsening upward unroofing sequence characterized by accelerating subsidence, which is interpreted as a retro-foreland basin associated with crustal thickening of the Pamir during India–Asia collision. Thus, the Tajik Basin provides an example of a long-lived composite basin in a retrowedge position that displays a sensitivity to plate margin processes. Subsidence, sediment accumulation and basin-forming mechanisms are influenced by subduction dynamics, including periods of slab-shallowing and retreat.  相似文献   

Speciation and role of iron in cloud droplets at the puy de Dôme station     

Marius Parazols  Angela Marinoni  Pierre Amato  Otman Abida  Paolo Laj  Gilles Mailhot 《Journal of Atmospheric Chemistry》2006,54(3):267-281

Iron is the most abundant transition metal in the atmosphere and can play a significant role in cloudwater chemistry where its reactivity is closely related to the partitioning between Fe(II) and Fe(III). The objective of this work is to determine the total iron content and the iron speciation in a free tropospheric site, and to understand which factors influence these parameters. We collected 147 samples of cloudwater during 34 cloud events over a period of four years at the puy de Dôme summit. Besides iron we measured other chemical compounds, solar radiation, physico-chemical and meteorological parameters potentially connected with iron reactivity. The total iron concentrations ranged from 0.1 to 9.1 μM with the major frequency occurring at low levels. The pH and presence of organic complexants seem to be the most significant factors connected with total dissolved iron; while the iron oxidation state seems to be an independent factor. Light intensity, presence of complexants or oxidants (H₂O₂) do not influence the Fe(II)/Fe(Total) ratio, that was quite constant at about 0.75. This could be due to the potential redox that forces the Fe(II)-Fe(III) couple to the reduced form or, more probably to the complexation by Natural Organic Matter, that can stabilize iron in its reduced form and prevent further oxidation. Our field measurements did not show the diurnal cycle observed in surface water and predicted by models of atmospheric chemistry. This result prompts a more careful review of the role of iron and, by analogy, all the transition metals in atmospheric liquid phase, often over-estimated in the literature.  相似文献   

A simplified but accurate spectral solar irradiance model     

M. Paulescu  Z. Schlett 《Theoretical and Applied Climatology》2003,75(3-4):203-212

Summary ¶The paper deals with the computation of solar energy available in a specific location. First, a new formula describing the relation between global solar irradiation and the duration of bright sunshine is established. The analysis of its use shows that global solar clear sky irradiance models are essential tools for daily computation of global irradiation. An integrated spectral atmospheric transmittance model is presented, it can be used to compute beam and diffuse clear sky irradiance for all applications where broadband solar energy input is needed. Since it is desirable to use simplified estimation methods for many applications, a parametric global solar irradiance model, derived from the spectral model, is also presented. This model needs only surface meteorological data as input. The influence of the averaging method used for the input parameters on the model accuracy is evaluated. Comparison of model results with the measurements shows an acceptable level of accuracy with the new model. Finally, an application of daily global solar energy computation is presented.Received May 17, 2002; revised October 14, 2002; accepted February 11, 2003 Published online September 10, 2003  相似文献   

Luminescence dating of Middle Pleistocene proglacial deposits from northern Switzerland: methodological aspects and stratigraphical conclusions          下载免费PDF全文

Sally E. Lowick  Marius W. Buechi  Dorian Gaar  Hans R. Graf  Frank Preusser 《Boreas: An International Journal of Quaternary Research》2015,44(3):459-482

Optically stimulated luminescence (OSL) dating was applied to proglacial deposits from the Klettgau Valley in northern Switzerland, which is understood to record several phases of glaciation prior to the Last Interglacial. The aim was to provide an independent chronology for the different sedimentary units to understand better the complex depositional history of the region. This time range requires care when assessing the reliability of the luminescence protocols applied. Equivalent doses for fine‐ and coarse‐grain quartz remained below 300 Gy, while dose response curves for both fractions continued to display growth above 500 Gy. Dose recovery tests confirmed the ability of the single aliquot regenerative (SAR) protocol to recover laboratory doses of a similar size to burial doses, and isothermal decay measurements confirmed the stability of the quartz signal. Having passed rigorous testing criteria, quartz OSL ages of up to ～200 ka were considered reliable but significantly underestimated expected ages and prompt a reconsideration of earlier interpretations of the stratigraphy for this site. Rather than representing three separate glaciations, quartz luminescence ages instead suggest that these deposits record up to four independent ice advances during Marine Isotope Stage 6. For both single grain and single aliquot feldspar dating, it was not possible to separate the conflicting influences of anomalous fading and partial bleaching. However, uncorrected feldspar central age model ages were found to be in reasonable agreement with quartz age estimates, and suggest that feldspar ages may still offer useful additional information in this region.  相似文献   

The global modulation of Galactic and Jovian electrons in the heliosphere     

Rendani R. Nndanganeni  Marius S. Potgieter 《Astrophysics and Space Science》2018,363(7):156

A full three-dimensional, numerical model is used to study the modulation of Jovian and Galactic electrons from 1 MeV to 50 GeV, and from the Earth into the heliosheath. For this purpose the very local interstellar spectrum and the Jovian electron source spectrum are revisited. It is possible to compute the former with confidence at kinetic energies \(E < 50~\mbox{MeV}\) since Voyager 1 crossed the heliopause in 2012 at \(\sim 122~\mbox{AU}\), measuring Galactic electrons at these energies. Modeling results are compared with Voyager 1 observations in the outer heliosphere, including the heliosheath, as well as observations at or near the Earth from the ISSE3 mission, and in particular the solar minimum spectrum from the PAMELA space mission for 2009, also including data from Ulysses for 1991 and 1992, and observations above 1 MeV from SOHO/EPHIN. Making use of the observations at or near the Earth and the two newly derived input functions for the Jovian and Galactic electrons respectively, the energy range over which the Jovian electrons dominate the Galactic electrons is determined so that the intensity of Galactic electrons at Earth below 100 MeV is calculated. The differential intensity for the Galactic electrons at Earth for \(E = 1~\mbox{MeV}\) is \(\sim 4\) electrons \(\mbox{m}^{-2}\,\mbox{s}^{-1}\,\mbox{sr}^{-1}\,\mbox{MeV}^{-1}\), whereas for Jovian electrons it is \(\sim 350\) electrons \(\mbox{m}^{-2}\,\mbox{s}^{-1}\,\mbox{sr}^{-1}\,\mbox{MeV}^{-1}\). At \(E = 30~\mbox{MeV}\) the two intensities are the same; above this energy the Jovian electron intensity quickly subsides so that the Galactic intensity completely dominates. At 6 MeV, in the equatorial plane the Jovian electrons dominate but beyond \(\sim 15~\mbox{AU}\) the Galactic intensity begins to exceed the Jovian intensity significantly.  相似文献   

Autocorrelation properties of the sunshine number and sunshine stability number     

Viorel Badescu  Marius Paulescu 《Meteorology and Atmospheric Physics》2011,112(3-4):139-154

Two new Boolean parameters are defined: the sunshine number (related to the state of the sky) and the sunshine stability number (which is as a measure of the fluctuation of the radiative regime). Elementary statistical and sequential properties of both parameters are presented in this paper. Actinometric and meteorological data measured at 15?s lag during 2009 in Timisoara (Romania, southeastern Europe) are used. The yearly series of daily averaged sunshine number has negative skewness and kurtosis. The series of daily averaged sunshine stability number has positive skewness and kurtosis. The series of daily averaged values of sunshine number are best described by an ARIMA(0,1,2) model. ARIMA(0,1,0) and ARIMA(0,2,0) models (associated with an appropriately defined white noise) may be used for synthesis of the sunshine number time series. The first model is to be preferred for practical reasons. The series of daily averaged values of sunshine stability number are best described by an ARIMA(2,2,1) model. The ARIMA(0,0,0) model is recommended to be used for generating time series of sunshine stability number. This model may be used for any particular day during the year and the only parameter depending on the day is the white noise standard deviation. A relationship between the white noise standard deviation and the daily averaged sunshine stability number is proposed.  相似文献