Outlier Problem in Evaluating Similarity Functions in the Stable Atmospheric Boundary Layer   总被引：1，自引：1，他引：0  

Andrey A. Grachev  Edgar L. Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Boundary-Layer Meteorology》2012,144(2):137-155

The gradient-based similarity approach removes turbulent fluxes as governing parameters and replaces them with vertical gradients of mean wind speed and potential temperature. As a result, the gradient Richardson number, Ri, appears as a stability parameter instead of the Monin–Obukhov stability parameter z/L (L is the Obukhov length). The gradient-based scaling is more appropriate for moderate and very stable conditions when the gradients are large and their errors are relatively small whereas z/L becomes ambiguous in these conditions because turbulent fluxes are small. However, the gradient-based formulation is faced with a problem related to the influence of Ri outliers: outliers with high values of Ri can exist in conditions that are really near-neutral. These outliers are mapped into the very stable range in plots in which Ri is the independent variable and may lead to spurious dependencies for bin-averaged data (spurious bin-averaging). This effect is quite large for functions that are steep for the gradient-based scaling. The present study uses the Surface Heat Budget of the Arctic Ocean (SHEBA) data to examine the problem and proposes two methods, conditional analysis and independent binning, to limit the influence of outliers on bin-averaging. A disadvantage of the conditional analysis is associated with eliminating outliers based on criteria that could be considered as subjective. The independent bin-averaging method does not have this disadvantage, but the scatter of the bin-averaged points is higher than for the conditional analysis, rendering data analysis and interpretation difficult.  相似文献   

Landslide investigations in Russia and the former USSR     

Andrey Kazeev  German Postoev 《Natural Hazards》2017,88(1):81-101

Landslide hazard has always been a focus of research of scientific and industrial organizations in Russia, as well as the former Soviet Union . This research included a broad spectrum of studies of landslide processes based on monitoring data collected at specialized stations nationwide, as well as the data collected and analyzed by various government and academic research institutions. The current study summarizes a vast body of knowledge encompassing an inventory of landslide cases, overview of mechanisms of landslide development and monitoring and slope stability assessments. It presents a new mechanism-based landslide classification and proposes a practical method of increasing slope resistance. Partial findings have been previously presented in numerous publications. We believe these findings have a worldwide significance and can be applied in different regions of our planet.  相似文献   

Development of a Tsunami Inundation Map in Detecting Tsunami Risk in Gulf of Fethiye,Turkey     

Derya Itir Dilmen  Serkan Kemec  Ahmet Cevdet Yalciner  Sebnem Düzgün  Andrey Zaytsev 《Pure and Applied Geophysics》2015,172(3-4):921-929

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Investigation of Tsunami Hydrodynamic Parameters in Inundation Zones with Different Structural Layouts     

Ceren Ozer Sozdinler  Ahmet Cevdet Yalciner  Andrey Zaytsev 《Pure and Applied Geophysics》2015,172(3-4):931-952

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Monitoring viscosity changes from time‐lapse seismic attenuation: case study from a heavy oil reservoir          下载免费PDF全文

Andrey H. Shabelansky  Alison Malcolm  Michael Fehler 《Geophysical Prospecting》2015,63(5):1070-1085

Heating heavy oil reservoirs is a common method for reducing the high viscosity of heavy oil and thus increasing the recovery factor. Monitoring of these viscosity changes in the reservoir is essential for delineating the heated region and controlling production. In this study, we present an approach for estimating viscosity changes in a heavy oil reservoir. The approach consists of three steps: measuring seismic wave attenuation between reflections from above and below the reservoir, constructing time‐lapse Q and Q^?1 factor maps, and interpreting these maps using Kelvin–Voigt and Maxwell viscoelastic models. We use a 4D relative spectrum method to measure changes in attenuation. The method is tested with synthetic seismic data that are noise free and data with additive Gaussian noise to show the robustness and the accuracy of the estimates of the Q‐factor. The results of the application of the method to a field data set exhibit alignment of high attenuation zones along the steam‐injection wells, and indicate that temperature dependent viscosity changes in the heavy oil reservoir can be explained by the Kelvin–Voigt model.  相似文献   

Investigation of Hydrodynamic Parameters and the Effects of Breakwaters During the 2011 Great East Japan Tsunami in Kamaishi Bay     

Ceren Ozer Sozdinler  Ahmet Cevdet Yalciner  Andrey Zaytsev  Anawat Suppasri  Fumihiko Imamura 《Pure and Applied Geophysics》2015,172(12):3473-3491

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Kara-Bogaz-Gol Bay: Physical and Chemical Evolution     

Aleksey N. Kosarev  Andrey G. Kostianoy  Igor S. Zonn 《Aquatic Geochemistry》2009,15(1-2):223-236

Kara-Bogaz-Gol Bay is a large (around 18,000 km²) and shallow (few meters deep) lagoon located east of the Caspian Sea. Its water surface was several meters to several dozens cm lower than in the Caspian Sea, so water flows from the Caspian Sea through a narrow strait into the bay, where it evaporates. Kara-Bogaz-Gol Bay is one of the saltiest bodies of water in the world; its water salinity amounts to 270–300 g/l. Different kinds of salts available in this natural evaporative basin has been used commercially since at least the 1920s. In March 1980, in order to decelerate a continuous fall of the Caspian Sea level, which in 1977 was the lowest over the last 400 years (?29 m), the Kara-Bogaz-Gol Strait was dammed. In response to this human intervention, the bay had already dried up completely by November 1983. In 1992, the dam was destroyed, and Kara-Bogaz-Gol Bay had been filling up with the Caspian Sea water at a rate of about 1.7 m/year up to 1996 as observed by the TOPEX/Poseidon satellite altimetry mission. Since then, Kara-Bogaz-Gol Bay level evolution with characteristic seasonal and interannual oscillations has been similar to that of the Caspian Sea. Physical and chemical evolution of the bay in the twentieth and twenty-first centuries is traced in detail in the paper.  相似文献   

Turbulent measurements in the stable atmospheric boundary layer during SHEBA: ten years after   总被引：4，自引：0，他引：4  

Andrey A. Grachev  Edgar L. Andreas  Christopher W. Fairall  Peter S. Guest  P. Ola G. Persson 《Acta Geophysica》2008,56(1):142-166

This paper surveys results of the comprehensive turbulent measurements in the stable boundary layer (SBL) made over the Arctic pack ice during the Surface Heat Budget of the Arctic Ocean experiment (SHEBA) in the Beaufort Gyre from October 1997 through September 1998. Turbulent fluxes and mean meteorological data were continuously measured and reported hourly at five levels on a 20-m main SHEBA tower. Eleven months of measurements during SHEBA cover a wide range of stability conditions, from the weakly unstable regime to very stable stratification, and allow studying the SBL in detail. A brief overview of the SBL regimes, the flux-profile relationships, the turbulent Prandtl number, and other parameters obtained during SHEBA is given. The traditional Monin—Obukhov approach, z-less scaling, and gradient-based scaling are evaluated and discussed based on the data from SHEBA.  相似文献   

Moderately compact helix antennas with cutoff patterns for millimeter RTK positioning     

Tatarnikov  Dmitry V.  Stepanenko  Anton P.  Astakhov  Andrey V. 《GPS Solutions》2016,20(3):587-594

GPS Solutions - Helical antennas have been developed that feature a cutoff pattern and are suitable for practical positioning at millimeter level. The antennas are in the form of a tube with...  相似文献   

The updated version of SPONSOR land surface scheme: PILPS-influenced improvements     

Andrey B. Shmakin 《Global and Planetary Change》1998,19(1-4)

The parameterization scheme SPONSOR (Semi-distributed ParameterizatiON Scheme of the ORography-induced hydrology) participating in PILPS (Project for Intercomparison of Land-surface Parameterization Schemes) experiments since 1993 is described in more detail than before, taking into account a range of recent modifications. Improvement of the scheme in several aspects (e.g., soil water movement) resulted in significantly improved results for the Cabauw site (used for PILPS (2a) experiments). Then, parameterization of cold seasons/regions processes (water phase transformations within soil and snow cover) was developed for PILPS (2d) experiments carried out with Valdai data. Testing of the scheme against the data of Kolyma water balance station shows that it is able to reproduce the main features of heat and water exchange at the land surface in the permafrost zone quite satisfactorily. It was found that the scheme results are rather sensitive to the soil heat conductivity, especially in the cold seasons. The original method for the calculation of this parameter was developed using a square root function. The surface temperature and dates of crossing the 0°C temperature threshold for Kolyma station were reproduced with satisfactory accuracy. The temporal variation of the deep soil layers' temperatures was modelled satisfactorily too, but the seasonal amplitude of deep soil temperatures was overestimated by the scheme. This disadvantage can possibly be improved by inclusion of vertical inhomogeneity of soil thermal and hydraulic properties in the model.  相似文献