Boundary layer characteristics and turbulent exchange mechanisms in highly complex terrain   总被引：2，自引：0，他引：2  

Mathias W. Rotach  Marco Andretta  Pierluigi Calanca  Andreas P. Weigel  Alexandra Weiss 《Acta Geophysica》2008,56(1):194-219

The Mesoscale Alpine Programme’s Riviera project investigated the turbulence structure and related exchange processes in an Alpine valley by combining a detailed experimental campaign with high-resolution numerical modelling. The present contribution reviews published material on the Riviera Valley’s boundary layer structure and discusses new material on the near-surface turbulence structure. The general conclusion of the project is that despite the large spatial variability of turbulence characteristics and the crucial influence of topography at all scales, the physical processes can accurately be understood and modelled. Nevertheless, many of the “text book characteristics” like the interaction between the valley and slope wind systems or the erosion of the nocturnal valley inversion need reconsideration, at least for small non-ideal valleys like the Riviera Valley. The project has identified new areas of research such as post-processing methods for turbulence variables in complex terrain and new approaches for the surface energy balance when advection is non-negligible. The exchange of moisture and heat between the valley atmosphere and the free troposphere is dominated by local “secondary” circulations due to the curvature of the valley axis. Because many curved valleys exist, and operational models still have rather poor resolution, parameterization of these processes may be required.  相似文献   

A comment on: 'A detailed rock magnetic and opaque mineralogy study of the basalts from the Nazca Plate' by H. P. Johnson and J. M. Hall     

E. R. Deutsch  R. R. Pätzold 《Geophysical Journal International》1980,60(3):497-503

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Wave Propagation in Pulsating Stars     

P. Mathias 《Astrophysics and Space Science》1998,260(1-2):131-134

Lissajous diagrams are used to detect phase lags between radial velocity curves associated with different ions. Present in many kind of variable stars, this effect provides an important tool to study the atmosphere dynamics. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Including the Urban Canopy Layer in a Lagrangian Particle Dispersion Model     

Stöckl  Stefan  Rotach  Mathias W.  Kljun  Natascha 《Boundary-Layer Meteorology》2022,183(1):1-33

Boundary-Layer Meteorology - When wind blows over the ocean, short wind-waves (of wavelength smaller than 10 m) are generated, rapidly reaching an equilibrium with the overlying turbulence (at...  相似文献   

Extended structures around yso in Mid-IR broad emission features     

Lynne K. Deutsch  Joseph L. Hora  Harold M. Butner  William F. Hoffmann  Giovanni G. Fazio 《Astrophysics and Space Science》1995,231(1-2):89-92

We present CO(1-0) observations toward the soft gamma-ray repeater SGR 1806-20. We discuss the implications on the distance to the X-ray counterpart: AX 1805.7-2025. We also present an upper limit at = 1.3 mm for the thermal emission from dust and high resolution IRAS maps of the region. SGR 1806-20 is very likely associated with the H II complex W31. The G10.0-0.3 supernova remnant (SNR) could be expanding in the very low density region produced by the wind of the bright O9-B2 star recently detected.National Academy of Sciences / National Research Council Resident Research Associate  相似文献   

Encroachments in floodways of the Mississippi River and Tributaries Project     

Pilar Lopez-Llompart  G. Mathias Kondolf 《Natural Hazards》2016,81(1):513-542

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Comment on: “Corrections to the Mathematical Formulation of a Backwards Lagrangian Particle Dispersion Model” by Gibson and Sailor (2012: Boundary-Layer Meteorology 145, 399–406)     

Stefan Stöckl  Mathias W. Rotach  Natascha Kljun 《Boundary-Layer Meteorology》2018,166(1):153-160

We discuss the results of Gibson and Sailor (Boundary-Layer Meteorol 145:399–406, 2012) who suggest several corrections to the mathematical formulation of the Lagrangian particle dispersion model of Rotach et al. (Q J R Meteorol Soc 122:367–389, 1996). While most of the suggested corrections had already been implemented in the 1990s, one suggested correction raises a valid point, but results in a violation of the well-mixed criterion. Here we improve their idea and test the impact on model results using a well-mixed test and a comparison with wind-tunnel experimental data. The new approach results in similar dispersion patterns as the original approach, while the approach suggested by Gibson and Sailor leads to erroneously reduced concentrations near the ground in convective and especially forced convective conditions.  相似文献   

Geostatistical Simulation with a Trend Using Gaussian Mixture Models     

Jianan Qu  Clayton V. Deutsch 《Natural Resources Research》2018,27(3):347-363

Geostatistics applies statistics to quantitatively describe geological sites and assess the uncertainty due to incomplete sampling. Strong assumptions are required regarding the location independence of statistical parameters to construct numerical models with geostatistical tools. Most geological data exhibit large-scale deterministic trends together with short-scale variations. Such location dependence violates the common geostatistical assumption of stationarity. The trend-like deterministic features should be modeled prior to conventional geostatistical prediction and accounted for in subsequent geostatistical calculations. The challenge of using a trend in geostatistical simulation algorithms for the continuous variable is the subject of this paper. A stepwise conditional transformation with a Gaussian mixture model is considered to provide a stable and artifact-free numerical model. The complex features of the regionalized variable in the presence of a trend are removed in the forward transformation and restored in the back transformation. The Gaussian mixture model provides a seamless bin-free approach to transformation. Data from a copper deposit were used as an example. These data show an apparent trend unsuitable for conventional geostatistical algorithms. The result shows that the proposed algorithm leads to improved geostatistical models.  相似文献   

Toxicity of atrazine to <Emphasis Type="Italic">Scenedesmus quadricauda</Emphasis> under different nitrogen concentrations     

Mathias Ahii Chia  Suleiman Dauda  Talatu Zainab Jibril 《Environmental Earth Sciences》2016,75(11):960

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Landslide deposits as stratigraphical markers for a sequence‐based glacial stratigraphy: a case study of a Younger Dryas system in the Eastern Alps          下载免费PDF全文

Mathias G. Bichler  Martin Reindl  Jürgen M. Reitner  Ruth Drescher‐Schneider  Christian Wirsig  Marcus Christl  Irka Hajdas  Susan Ivy‐Ochs 《Boreas: An International Journal of Quaternary Research》2016,45(3):537-551

Detailed ¹⁰Be and ¹⁴C dating and supporting pollen analysis of Alpine Lateglacial glacial and landslide deposits in the Hohen Tauern Mountains (Austria) constrain a sequence‐based stratigraphy comprising a major landslide (13.0±1.1 ka) overlain by till and termino‐lateral moraines of an advancing (12.6±1.0 ka) and retreating (11.3±0.8 ka) glacier in turn overlain by a minor landslide (10.8±1.1 ka). These results define glacier activity during the Younger Dryas age Egesen stadial bracketed by landslide activities during the Bølling‐Allerød interstadial and the Preboreal. In contrast to recent studies on Holocene glaciation in the Alps, no traces of any Holocene glacier advance bigger than during the Little Ice Age are documented. Furthermore, this study demonstrates the advantages of using an allostratigraphical approach based on unconformity‐bounded sedimentary units as a tool for glacial stratigraphy in formerly glaciated mountain regions, rather than a stratigraphy based on either isolated morphological features or lithostratigraphical characteristics.  相似文献