The diffusive regime of double-diffusive convection   总被引：2，自引：0，他引：2  

D. E. Kelley  H. J. S. Fernando  A. E. Gargett  J. Tanny  E. zsoy 《Progress in Oceanography》2003,56(3-4):461

The diffusive regime of double-diffusive convection is discussed, with a particular focus on unresolved issues that are holding up the development of large-scale parameterizations. Some of these issues, such as interfacial transports and layer-interface interactions, may be studied in isolation. Laboratory work should help with these. However, we must also face more difficult matters that relate to oceanic phenomena that are not represented easily in the laboratory. These lie beneath some fundamental questions about how double-diffusive structures are formed in the ocean, and how they evolve in the competitive ocean environment.  相似文献   

Assessment of Planetary Boundary-Layer Schemes in the Weather Research and Forecasting Mesoscale Model Using MATERHORN Field Data   总被引：1，自引：0，他引：1  

Reneta Dimitrova  Zachariah Silver  Tamas Zsedrovits  Christopher M. Hocut  Laura S. Leo  Silvana Di Sabatino  Harindra J. S. Fernando 《Boundary-Layer Meteorology》2016,159(3):589-609

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Coexistence of fault‐propagation and fault‐bend folding in curve‐shaped foreland fold‐and‐thrust belts: examples from the Northern Apennines (Italy)     

Fernando Calamita  Paolo Pace  Sara Satolli 《地学学报》2012,24(5):396-406

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Mine Burial in the Shoaling Zone: Scaling of Laboratory Results to Oceanic Situations     

Testik  F.Y. Voropayev  S.I. Fernando  H.J.S. Balasubramanian  S. 《Oceanic Engineering, IEEE Journal of》2007,32(1):204-213

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Chandra smells a RRAT     

Bryan M. Gaensler  Maura McLaughlin  Stephen Reynolds  Kazik Borkowski  Nanda Rea  Andrea Possenti  Gianluca Israel  Marta Burgay  Fernando Camilo  Shami Chatterjee  Michael Kramer  Andrew Lyne  Ingrid Stairs 《Astrophysics and Space Science》2007,308(1-4):95-99

“Rotating RAdio Transients” (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population. B.M.G. acknowledges the support of NASA through LTSA grant NAG5-13023 and of an Alfred P. Sloan Fellowship.  相似文献   

High-fidelity broadband prediction of regional seismic response: a hybrid coupling of physics-based synthetic simulation and empirical Green functions     

Castro-Cruz  David  Gatti  Filippo  Lopez-Caballero  Fernando 《Natural Hazards》2021,108(2):1997-2031

Natural Hazards - The prediction of the seismic response of critical structures is highly sensitive to many aspects, among which the earthquake source and the geological setting are prominent. The...  相似文献   

A spring and wooded habitat at FLK Zinj and their relevance to origins of human behavior     

Gail M. Ashley  Doris Barboni  Manuel Dominguez-Rodrigo  Henry T. Bunn  Audax Z.P. Mabulla  Fernando Diez-Martin  Rebeca Barba  Enrique Baquedano 《Quaternary Research》2010,74(3):304-314

The 1959 discovery of the hominin fossil Zinjanthropus boisei brought the world's attention to the rich records at Olduvai Gorge, Tanzania. Subsequent excavations of archaeological level 22 (FLK Zinj) Bed I uncovered remains of Homo habilis and a high-density collection of fossils and Oldowan stone tools. The occurrence of this unusual collection of bones and tools at this specific location has been controversial for decades. We present paleoecological data that provide new insights into the origin of FLK Zinj. Our recent excavations 200 m north of the site uncovered a 0.5-m-thick tufa mound draped by Tuff IC, in the same stratigraphic horizon as level 22. Stable isotope analyses indicate that the carbonates were deposited by a freshwater spring. Phytolith analysis of the waxy clay under Tuff IC revealed abundant woody dicotyledon and palm phytoliths, indicating that the site was wooded to densely wooded. The time equivalency and close physical proximity of the two environments indicate the two are related. This study has provided the first documented evidence of springs in Bed I and these data have important implications for the interpretation of hominin behavior in meat acquisition and the ongoing debate on scavenging versus hunting.  相似文献   

Intercomparison and analyses of the climatology of the West African Monsoon in the West African Monsoon Modeling and Evaluation project (WAMME) first model intercomparison experiment   总被引：3，自引：3，他引：0  

Yongkang Xue  Fernando De Sales  W. K.-M. Lau  Aaron Boone  Jinming Feng  Paul Dirmeyer  Zhichang Guo  Kyu-Myong Kim  Akio Kitoh  Vadlamani Kumar  Isabelle Poccard-Leclercq  Natalie Mahowald  Wilfran Moufouma-Okia  Phillip Pegion  David P. Rowell  Jae Schemm  Siegfried D. Schubert  Andrea Sealy  Wassila M. Thiaw  Augustin Vintzileos  Steven F. Williams  Man-Li C. Wu 《Climate Dynamics》2010,35(1):3-27

This paper briefly presents the West African Monsoon (WAM) Modeling and Evaluation Project (WAMME) and evaluates WAMME general circulation models’ (GCM) performances in simulating variability of WAM precipitation, surface temperature, and major circulation features at seasonal and intraseasonal scales in the first WAMME experiment. The analyses indicate that models with specified sea surface temperature generally have reasonable simulations of the pattern of spatial distribution of WAM seasonal mean precipitation and surface temperature as well as the averaged zonal wind in latitude-height cross-section and low level circulation. But there are large differences among models in simulating spatial correlation, intensity, and variance of precipitation compared with observations. Furthermore, the majority of models fail to produce proper intensities of the African Easterly Jet (AEJ) and the tropical easterly jet. AMMA Land Surface Model Intercomparison Project (ALMIP) data are used to analyze the association between simulated surface processes and the WAM and to investigate the WAM mechanism. It has been identified that the spatial distributions of surface sensible heat flux, surface temperature, and moisture convergence are closely associated with the simulated spatial distribution of precipitation; while surface latent heat flux is closely associated with the AEJ and contributes to divergence in AEJ simulation. Common empirical orthogonal functions (CEOF) analysis is applied to characterize the WAM precipitation evolution and has identified a major WAM precipitation mode and two temperature modes (Sahara mode and Sahel mode). Results indicate that the WAMME models produce reasonable temporal evolutions of major CEOF modes but have deficiencies/uncertainties in producing variances explained by major modes. Furthermore, the CEOF analysis shows that WAM precipitation evolution is closely related to the enhanced Sahara mode and the weakened Sahel mode, supporting the evidence revealed in the analysis using ALMIP data. An analysis of variability of CEOF modes suggests that the Sahara mode leads the WAM evolution, and divergence in simulating this mode contributes to discrepancies in the precipitation simulation.  相似文献   

Rb/Sr ages of rocks from the Chilean metamorphic basement     

Fernando Munizaga  Luis Aguirre  Francisco Herve 《Earth and Planetary Science Letters》1973,18(1):87-92

Eleven whole rock Rb/Sr age determinations from the Chilean metamorphic basement — formerly considered as Precambrian — define two limiting reference isochrons of 342 and 273 my. Analized rocks are phyllites and schists of sedimentary origin with mineralogical assemblages mainly corresponding to the greenschist facies.Two metamorphic series characterize the Chilean metamorphic basement: an eastern low P/T series, and a western high P/T series. Four of the analyzed samples belong to the former and seven to the latter.The obtained age is interpreted as the age of a main metamorphic episode of the basement. This episode would have taken place in the Upper Paleozoic.  相似文献   

Interaction of a negatively buoyant line plume with a density interface     

C.Y. Ching  H.J.S. Fernando  Y. Noh 《Dynamics of Atmospheres and Oceans》1993,19(1-4)

Laboratory experiments were carried out to investigate the interaction between turbulent line buoyant plumes and sharp density interfaces, with the aim of using the results to interpret oceanic observations pertinent to crack openings in the polar ice-cap (leads). These openings take the form of long narrow channels, and are often modeled as line bouyant plumes. The plumes descend as in a homogenoous fluid, impinge on the density interface, and then spread horizontally as gravity currents. Depending on the Richardson number , where Δb is the buoyancy jump across the interface, l_D is the half-width of the plume before the impingement and q₀is the buoyancy flux per unit length of the source, different flow patterns were identified. When Ri < 0.5, the plumes penetrate deep into the bottom layer, deflect horizontally and then spread while showing little vertical rise. When 0.6 < Ri < 5, the penetration is significant, but the fluid bounces back after entraining heavy fluid from the lower layer and then spreads horizontally above the interface as a gravity current. Appreciable mixing between this current and the lower layer was detected when Ri <1. When Ri > 10, the penetration was small and a sharp-nosed gravity current emerged some time after the impact. Measurements were made on the penetration depth, the velocities of the gravity current and the subsurface flow towards the plume, the entrainment rate and other wave parameters. Possible implications of the results for oceanic cases are also discussed.  相似文献