Low Visibility Formation and Forecasting on the Northern Coast of Brazil   总被引：1，自引：0，他引：1  

Natalia Fedorova  Vladimir Levit  Aliton Oliveira da Silva  Deydila Michele Bonfim dos Santos 《Pure and Applied Geophysics》2013,170(4):689-709

Visibility analysis and forecast at the Maceio International Airport in the Brazilian Northeast (NEB) was the principal goal of this investigation. Surface meteorological data of the Maceio International Airport were used for low visibility frequency study. Low visibility in NEB was provoked more frequently by light fog (LF) formation (1,098 or 92 h month^?1 on average). Haze and fog were very rare (81 h and one event per year, respectively on average). Light fog with a visibility less than 2 km usually was detected together with rain or drizzle. Low visibility was observed more frequently at night and during the rainy season. Applications of the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for light fog forecast were tested. Thermodynamic processes were studied by vertical profile, elaborated by: (1) National Centers for Environmental Prediction (NCEP) reanalysis data for Maceio (because of some radiosonde absence) and (2) forecast vertical temperature and humidity profiles were produced, using Air Parcels Trajectories of the HYSPLIT model at the pattern levels. The synoptic situations before and during low visibility phenomena were analyzed using different products of NCEP reanalysis, the high resolution (10 km) ETA model and infrared satellite images. Wave disturbance in the trade winds field, localized on the northwest periphery of the South Atlantic subtropical High, usually accompanied the phenomena. A humidity advection, weak ascendant movement and thermal inversion absence at the low levels were created by these waves. The middle level’s descendent movement provoked the humidity accumulation at levels below. Satisfactory results of the HYSPLIT model applications for light fog forecast were obtained with 12 h antecedence. In particular, stable level forecast by the ETA model was forecast satisfactorily with 12 h antecedence; vertical movements were predicted better with up to 48 h antecedence. The PSU/NCAR mesoscale model (MM5) and PAFOG models were tested for analysis and forecast of an intensive fog event. Intensive fog provoked a fatal accident of a small airplane near the Maceio Airport in 2007. These fog formation processes were studied by NCEP reanalysis data, the high resolution regional model MM5, and satellite and radar data. Fog formation was simulated by PAFOG model and satisfactory results were obtained with 10 h antecedence.  相似文献   

Evaluation of a multi-model approach to estimate leaf wetness duration: an essential input for disease alert systems     

Gama  Andre B.  Perondi  Daniel  Dewdney  Megan M.  Fraisse  Clyde W.  Small  Ian M.  Peres  Natalia A. 《Theoretical and Applied Climatology》2022,149(1-2):83-99

Theoretical and Applied Climatology - Disease alert systems (DAS) of the AgroClimate platform are intended to facilitate grower decision-making when planning fungicide applications. These DAS...  相似文献   

Tsunami hazard and exposure on the global scale     

Finn Løvholt  Sylfest Glimsdal  Carl B. Harbitz  Natalia Zamora  Farrokh Nadim  Pascal Peduzzi  Hy Dao  Helge Smebye 《Earth》2012,110(1-4):58-73

In the aftermath of the 2004 Indian Ocean tsunami, a large increase in the activity of tsunami hazard and risk mapping is observed. Most of these are site-specific studies with detailed modelling of the run-up locally. However, fewer studies exist on the regional and global scale. Therefore, tsunamis have been omitted in previous global studies comparing different natural hazards. Here, we present a first global tsunami hazard and population exposure study. A key topic is the development of a simple and robust method for obtaining reasonable estimates of the maximum water level during tsunami inundation. This method is mainly based on plane wave linear hydrostatic transect simulations, and validation against results from a standard run-up model is given. The global hazard study is scenario based, focusing on tsunamis caused by megathrust earthquakes only, as the largest events will often contribute more to the risk than the smaller events. Tsunamis caused by non-seismic sources are omitted. Hazard maps are implemented by conducting a number of tsunami scenario simulations supplemented with findings from literature. The maps are further used to quantify the number of people exposed to tsunamis using the Landscan population data set. Because of the large geographical extents, quantifying the tsunami hazard assessment is focusing on overall trends.  相似文献   

Evaluation of atmospheric boundary layer characteristics simulated by the regional model     

M. M. Smirnova  K. G. Rubinshtein  V. P. Yushkov 《Russian Meteorology and Hydrology》2011,36(12):777-785

Carried out is the comparison of the temporal courses of temperature and wind speed at different levels as well as of the wind and temperature profiles in the atmospheric boundary layer obtained from the WRF regional model forecasts and using the upper-air in situ and remote measurements in Moscow region. The errors in temperature and wind speed forecasts at different levels are computed as well as the statistical estimates of the forecast of temperature inversions, atmospheric stratification types, and monthly mean wind speed profiles on the basis of model forecasts and acoustic sounding.  相似文献   

Glaciation and ~ 770 Ma Ediacara (?) Fossils from the Lesser Karatau Microcontinent,Kazakhstan     

Joseph G. Meert  Anatoly S. Gibsher  Natalia M. Levashova  Warren C. Grice  George D. Kamenov  Alexander B. Ryabinin   《Gondwana Research》2011,19(4):867-880

The Cambrian explosion, c. 530–515 Ma heralded the arrival of a diverse assembly of multicellular life including the first hard-shelled organisms. Fossils found in Cambrian strata represent the ancestors of most modern animal phyla. In contrast to the apparent explosiveness seen in the Cambrian fossil record, studies of molecular biology hint that the diversification observed in Cambrian strata was rooted in ancestry extending back into the Ediacaran (635–542 Ma). Fossil evidence for this mostly cryptic phase of evolution is derived from the soft-bodied fossils of the Ediacaran biota found throughout the world and bilaterian embryos found in the Doushantuo lagerstätte in South China. The first appearance of Ediacara fauna is thought to have followed the last of the ~ 750–635 Ma Neoproterozoic glacial episodes by 20–30 million years. In this paper, we present evidence for the oldest discovery of the ‘Ediacara’ discoidal fossils Nimbia occlusa and Aspidella terranovica (?) that predate the early Cryogenian glaciations by more than fifty million years. There is considerable disagreement over the significance of discoidal Ediacaran fossils, but our findings may support earlier suggestions that metazoan life has roots extending deeper into the Proterozoic Eon. We also confirm the presence of a Late Cryogenian (e.g. “Marinoan”) glaciation on the Lesser Karatau microcontinent including dropstones and striated clasts within the glacial strata.  相似文献   

Ries crater and suevite revisited—Observations and modeling Part I: Observations     

Dieter Stöffler  Natalia A. Artemieva  Kai Wünnemann  W. Uwe Reimold  Juliane Jacob  Birgit K. Hansen  Iona A. T. Summerson 《Meteoritics & planetary science》2013,48(4):515-589

We report results of an interdisciplinary project devoted to the 26 km‐diameter Ries crater and to the genesis of suevite. Recent laboratory analyses of “crater suevite” occurring within the central crater basin and of “outer suevite” on top of the continuous ejecta blanket, as well as data accumulated during the past 50 years, are interpreted within the boundary conditions imposed by a comprehensive new effort to model the crater formation and its ejecta deposits by computer code calculations (Artemieva et al. 2013). The properties of suevite are considered on all scales from megascopic to submicroscopic in the context of its geological setting. In a new approach, we reconstruct the minimum/maximum volumes of all allochthonous impact formations (108/116 km³), of suevite (14/22 km³), and the total volume of impact melt (4.9/8.0 km³) produced by the Ries impact event prior to erosion. These volumes are reasonably compatible with corresponding values obtained by numerical modeling. Taking all data on modal composition, texture, chemistry, and shock metamorphism of suevite, and the results of modeling into account, we arrive at a new empirical model implying five main consecutive phases of crater formation and ejecta emplacement. Numerical modeling indicates that only a very small fraction of suevite can be derived from the “primary ejecta plume,” which is possibly represented by the fine‐grained basal layer of outer suevite. The main mass of suevite was deposited from a “secondary plume” induced by an explosive reaction (“fuel‐coolant interaction”) of impact melt with water and volatile‐rich sedimentary rocks within a clast‐laden temporary melt pool. Both melt pool and plume appear to be heterogeneous in space and time. Outer suevite appears to be derived from an early formed, melt‐rich and clast‐poor plume region rich in strongly shocked components (melt ? clasts) and originating from an upper, more marginal zone of the melt pool. Crater suevite is obviously deposited from later formed, clast‐rich and melt‐poor plumes dominated by unshocked and weakly shocked clasts and derived from a deeper, central zone of the melt pool. Genetically, we distinguish between “primary suevite” which includes dike suevite, the lower sublayer of crater suevite, and possibly a basal layer of outer suevite, and “secondary suevite” represented by the massive upper sublayer of crater suevite and the main mass of outer suevite.  相似文献   

Geochemistry of paleozoic terrigenous sediments from the Oldoi terrane, eastern Central Asian orogenic belt, as an indicator of geodynamic conditions during deposition     

Yu. N. Smirnova  A. A. Sorokin  L. I. Popeko  Yu. V. Smirnov 《Geochemistry International》2013,51(4):306-325

The analysis of the major and trace element geochemistry of Paleozoic terrigenous sediments from the Oldoi terrane, eastern Central Asian orogenic belt, supports a predominantly felsic source consisting of granites and recycled sediments. The geological data suggest that detrital material could be derived from Early Paleozoic granitoids, which were identified within tectonic blocks in the Silurian and Devonian terrigenous successions. The analysis of conventional discrimination diagrams indicates that the initial stage was marked by deposition along a passive continental margin, which continued in island-arc or active continental margin environments. This interpretation is consistent with geological evidence, such as the presence of volcanic interlayers and lenses in the Middle-Late Devonian successions and granitoids with ages of 386 +/- 10 and 371+/- 5.5 Ma. The timing of changes in geodynamic settings constrained by tectonic reconstructions corresponds to the age of the inception of the Norovlya continental-margin magmatic arc.  相似文献   

Investigating dynamic coupling in geospace through the combined use of modeling,simulations and data analysis     

Ioannis A. Daglis  Georgios Balasis  Natalia Ganushkina  Fiori-Anastasia Metallinou  Minna Palmroth  Risto Pirjola  Ioanna Tsagouri 《Acta Geophysica》2009,57(1):141-157

Comprehensive understanding of the dynamics of the coupled solar wind-magnetosphere-ionosphere system is of utmost interest, both from the perspective of solar system astrophysics and geophysics research and from the perspective of space applications. The physical processes involved in the dynamical evolution of this complex coupled system are pertinent not only for the Sun-Earth connection, but also for major phenomena in other astrophysical systems. Furthermore, the conditions in geospace collectively termed space weather affect the ever increasing technological assets of mankind in space and therefore need to be understood, quantified and efficiently forecasted. The present collaborative paper communicates recent advances in geospace dynamic coupling research through modeling, simulations and data analysis and discusses future directions.  相似文献   

Interstellar scintillation of the radio source associated with the gamma-ray burst of May 8, 1997     

T. V. Smirnova  V. I. Shishov 《Astronomy Reports》2000,44(7):421-425

The variability of the radio source associated with the gamma-ray burst of May 8, 1997, detected using the VLA, is analyzed. This variability can be explained as weak scintillations at 4.86 and 8.46 GHz and the refractive component of saturated scintillations at 1.43 GHz. Possible distances for the source are discussed. The scintillation parameters are in best agreement with the observations if the source is at a cosmological distance and has an angular size ～2 microarcseconds (µas) at 4.86 GHz and an expansion speed of the order of 25 µas/year.  相似文献   

Two contrasting petrotectonic domains in the Kokchetav megamélange (north Kazakhstan): Difference in exhumation mechanisms of ultrahigh‐pressure crustal rocks,or a result of subsequent deformation?     

K. Theunissen  N. L. Dobretsov  A. Korsakov  A. Travin  V. S. Shatsky  L. Smirnova and  A. Boven 《Island Arc》2000,9(3):284-303

Abstract In northern Kazakhstan the WNW striking Kokchetav megamélange includes different crustal sequences with high‐pressure/ultrahigh‐pressure (HP/UHP) remnants of their 540–520 Ma subduction metamorphism. Two domains separated by the north‐east trending Chaglinka fault are distinguished. The western domain exhibits NE–SW structures within a single Kumdy–Kol megaunit of diamond‐bearing UHP metasediments and high‐temperature (HT) eclogites. The eastern domain consists of the composite Kulet megaunit with the Kulet UHP unit (coesite‐bearing metasediments, whiteschists and eclogites), the Enbek–Berlyk medium‐pressure (MP) unit (kyanite‐bearing, high‐alumina rocks with interleaved coronitic metagabbro), and ortho‐ and paragneisses with eclogites and amphibolites included. All eclogites in the eastern domain are of the relatively low temperature (LT) type. Sillimanite is common and appears after kyanite in the sheared MP unit. A regional and moderately ESE plunging linear fabric coincides with the fold‐axis of the foliation poles from the eastern domain. Whether this also reflects a regional top to the WNW transport, as inferred from the dextral strike‐slip on steeply to SSW dipping foliation, needs further study. Top to the WNW shear is shown by weakly inclined low pressure (LP) cordierite rocks that flank the eastern domain in the south. Some new ³⁹Ar/⁴⁰Ar mica cooling ages (519, 521 Ma) from the Kulet UHP micaschists reflect the same early stage evolutionary event as was previously shown for the Kumdy–Kol UHP rocks (515, 517 Ma) in the west. Similar ³⁹Ar/⁴⁰Ar ages (500, 517 Ma) are recorded by micas and amphibole that outline a top to NNW shear fabric in the non‐subducted Proterozoic basement, north of the megamélange. A 447 Ma overprint of the MP sequences is considered to reflect the strike‐slip deformation with sillimanite and the reworking of an early kyanite‐bearing tectonite. Biotites from the LP cordierite rocks yielded approximately 400 Ma ³⁹Ar/⁴⁰Ar ages. In case they reflect the WNW shear deformation, the latter is considered to be associated with a regional granite magmatism (420–460 Ma) extending south of the eastern domain. In their present different structural domains the Kulet and Kumdy–Kol UHP units display a similar early stage event. Subsequent LP deformation, which is likely to be associated with regional granite magmatism (420–460 Ma), is assumed to have obliterated any common or uniform early exhumation structure for the whole megamélange. The north‐east structured Kumdy–Kol domain is assumed to have preserved the most information about the early stage exhumation. This domain is at an angle to the regional WNW strike of the megamélange.  相似文献