scholarly journals A Method for Assessing the State of the Snow and Ice Cover by the Brewster Angle

2021 ◽  
Vol 24 (1) ◽  
pp. 34-47
Author(s):  
V. G. Mashkov ◽  
V. A. Malyshev ◽  
P. A. Fedyunin
Keyword(s):  
Depth Resolution ◽  
Ice Cover ◽  
Brewster Angle ◽  
Ultra Wideband ◽  
Methodological Error ◽  
Fresnel Reflection ◽  
Vertical Polarization ◽  
Helicopter Flight ◽  
Remote Assessment ◽  
Snow And Ice

Introduction. Landing is the most challenging and dangerous part of the helicopter flight. The development of systems facilitating safe landing is a priority task for both Russian and foreign engineering companies. Landing on unprepared sites covered with snow and ice may be determined by the need to deliver cargo and ammunition in combat conditions, during search and rescue operations, evacuations of victims, etc.Aim. Development of a method for remote assessment of the snow and ice cover based on the results of oblique sensing of the underlying surface with a radio signal with vertical polarization.Materials and methods. In the MatLab environment, the authors conducted numerical simulations of Fresnel reflection coefficients of echo signals with vertical polarization in the 40–90 degree sensing range in the operating frequency range when solving the direct and inverse problem of reconstruction of the parameters of snow and ice layers.Results. Intervals of the Brewster angle values were obtained at which the value of the Fresnel reflection coefficient from the boundaries of the snow and ice cover takes minimal. Thus, was found to be – 47...55°, – 55...58° and – 58...61° for dry snow, dry firn and dry ice, respectively. The depth resolution when using an ultra-wideband LFM signal with a frequency from 2 to 8 GHz is about 4 cm. The methodological error in determining the dielectric permittivity of layers by the Brewster angle comprises not more than 3 %.Conclusion. The error in determining the relative permittivity and the depth of k layers under an increase in the RMS values of the noise level from 3.8 to 4.8 with a step of 0.1 for 100 implementations of each with a probability of 0.95 does not exceed 10 %, which confirms the validity of this method. The implementation of which allows you to automate the process of evaluating the possibility of a safe landing, thereby reducing the decision-making time and increasing the level of safety.

Geospatially extracting snow and ice cover distribution in the cold arid zone of India

2019 ◽  
Vol 11 (S1) ◽  
pp. 84-99
Author(s):  
Mahesh Kumar Gaur ◽  
R. K. Goyal ◽  
M. S. Raghuvanshi ◽  
R. K. Bhatt ◽  
M. Pandian ◽  
...  
Keyword(s):  
Arid Zone ◽  
Ice Cover ◽  
Snow And Ice

scholarly journals Modelling Global Ice and Climate Changes Through the Ice Ages

1990 ◽  
Vol 14 ◽  
pp. 23-27 ◽  
Author(s):  
W.F. Budd ◽  
P. Rayner
Keyword(s):  
Sea Ice ◽  
Ice Sheets ◽  
Ice Cover ◽  
Balance Model ◽  
Annual Variations ◽  
Sensitivity Tests ◽  
Mixed Layer Ocean ◽  
Wide Range ◽  
Sensitivity Studies ◽  
Snow And Ice

A global energy balance model has been developed which includes an interactive mixed layer ocean, sea ice, and snow and ice cover on the land. A full annual cycle is included and the model provides a close simulation to the variation of surface temperature through the year over land and over ocean as a function of latitude. The present annual variations of sea ice and snow on the ground are also well simulated. The model has been used for a wide range of sensitivity tests which include variations of the solar constant, surface albedos, and the effects of feed-back, or absence of feed-back, in the reponse of the snow and ice cover. Studies have been made of the model’s response to the long term variations in the Earth’s Orbital characteristics such as changes in the perihelion, the obliquity and the eccentricity as well as various combined changes. Independent sensitivity studies of the response of the model to the presence of the large ice sheets in the northern hemisphere have also been carried out. A series of model runs have been performed to study climatic changes around the globe from 160 000 years Β.P. (Before Present) to the present. An examination is made of the impacts of the orbital changes alone, as well as with the feed-back from the large ice sheets.

The use of Satellite Imagery in Investigating the Dynamics of the Ice and Snow Cover Lake Baikal

2003 ◽  
Vol 34 (1-2) ◽  
pp. 33-50 ◽  
Author(s):  
S.V. Semovski ◽  
N. Yu Mogilev
Keyword(s):  
Snow Cover ◽  
Lake Baikal ◽  
Satellite Imagery ◽  
Ice Cover ◽  
Unfrozen Water ◽  
Processing Strategy ◽  
Noaa Avhrr ◽  
Satellite Information ◽  
Process Studies ◽  
Snow And Ice

The generation and sample applications of a set of multispectral remotely sensed products for investigations of Lake Baikal's ice cover variability are described. During the period from mid-January to the end of April, the lake is completely covered with ice, and by analyzing satellite information it is possible to investigate in detail the distribution and dynamics of the main types of snow and ice cover. Different ice cover classes and unfrozen water distributions are estimated from calibrated and navigated NOAA AVHRR 1.1-km imagery of Lake Baikal for January 1994 through May 1999. The processing strategy and characteristics of the products are reviewed. The utility of this type of multiparameter dataset for modelling applications and process studies is discussed. ERS SAR and Resurs images are used for detailed representation of different ice classes distributions.

The significance of global snow and ice cover for global change studies

GeoJournal ◽  
1992 ◽  
Vol 27 (3) ◽  
pp. 293-297 ◽  
Author(s):  
Roger G. Barry
Keyword(s):  
Global Change ◽  
Ice Cover ◽  
Snow And Ice

scholarly journals DEVELOPMENT AND OPTIMIZATION OF AN ULTRA WIDEBAND MINIATURE MEDICAL ANTENNA FOR RADIOMETRIC MULTI-CHANNEL MULTI-FREQUENCY THERMAL MONITORING

2020 ◽  
pp. 71-81
Author(s):  
Mikhail Sedankin ◽  
Vitaly Leushin ◽  
Alexander Gudkov ◽  
Igor Sidorov ◽  
Sergey Chizhikov ◽  
...  
Keyword(s):  
Radiation Power ◽  
Fdtd Method ◽  
Depth Resolution ◽  
Wide Band ◽  
Biological Tissues ◽  
Dielectric Substrate ◽  
Ultra Wideband ◽  
Antenna Design ◽  
Design Parameters ◽  
Calculated Mass

The article is devoted to the development of a printed ultra-wideband miniature antenna that can be used for microwave radiometry. An antenna design with a ring-shaped radiator has been proposed, which provides reception of microwave radiation from biological tissues in the 1800–4600 MHz range. The results of mathematical modeling of the antenna electromagnetic field in biological tissues using the finite difference time domain (FDTD) method are presented. Optimization of the antenna design has been carried out to ensure acceptable matching parameters and optimal antenna functionality. The developed antenna has a height of 6 mm and a calculated mass of 5 g; it is planned to manufacture a dielectric substrate based on PDMS polymer with the addition of barium titanate. The issues of calculating the antenna parameters (measurement depth, resolution and distribution of radiation power over the volume of biological tissue, sensitivity, etc.) are considered. The research results and design parameters of the developed antenna demonstrated the effectiveness of the new antenna and the possibility of its adaptation to the object of research. Considering the presence of an ultra-wide band and miniature dimensions, the antenna can be a sensor of a multi-frequency multi-channel microwave radiothermograph

scholarly journals Method for Remote State Identification Snow-Ice Cover by the Ratio of Fresnel Reflection Coefficients

2020 ◽  
Vol 23 (5) ◽  
pp. 46-56
Author(s):  
V. G. Mashkov
Keyword(s):  
Landing Site ◽  
Ice Cover ◽  
The State ◽  
Reflection Coefficients ◽  
Fresnel Reflection ◽  
State Identification ◽  
Key Factor ◽  
Helicopter Landing ◽  
Standard Values ◽  
Remote Identification

Introduction. Currently, the development of safe helicopter landing systems as the most complex and dangerous stage of a flight is one of the priority tasks. A significant number of companies in Russia and abroad are engaged in its solution. Landing on unprepared (unequipped) sites with snow-ice cover may be caused by the need to deliver units, cargo and ammunition in combat conditions, search and rescue operations, evacuations of victims, etc. A key factor for a landing decision is information about the height of snow and about the depth of ice cover. In the paper remote identification of the state of snow-ice cover, excluding the need to present any person (crew member or rescue worker) on a landing site is proposed.Aim. To develop a method for the remote identification of the state of snow-ice cover used to determine the possibility of a helicopter - type aircraft safe landing on a reservoir with snow-ice cover.Materials and methods. Numerical simulation of echo signals Fresnel reflection coefficients polarization ratio was realized in MatLab. Vertical and horizontal polarizations in the range from 25 to 45 degrees were simulated.Results. Intervals of polarization relations correspond to the interval density of snow-ice layers for fixed angles. For example, when θ = 34 for dry snow ρds = 100…500 kg/m3 (ε'ds = 1.162…1.984) – Prm = 5.6915...3.3266, dry firn ρdf = 500…700 kg/m3 (ε'df = 1.984…2.51) – Prm = 3.3266...2.8311, dry ice ρdi = 700…913 kg/m3 (ε'di = 2.51…3.179) – Prm = 2.8311...2.4753. A layer reconstruction inverse problem was solved by indirect determining of complex relative permittivity of each successive underlying layer with 10-2 real part resolution. The identity of the obtained characteristics of snow-ice layers with calculated (standard) values was established.Conclusion. Remote identification of components of a snow-ice cover structure allows one to automate the process of evaluating of landing possibility. Thereby it reduces a decision-making time and increases a level of safety. In contrast to the known methods of identification of the surface layer the identification of multilayer medium layers was carried out.

scholarly journals An enhancement to sea ice motion and age products

2019 ◽  
Author(s):  
Mark A. Tschudi ◽  
Walter N. Meier ◽  
J. Scott Stewart
Keyword(s):  
Sea Ice ◽  
Ice Cover ◽  
The Arctic ◽  
Significant Shift ◽  
High Concentration ◽  
Sea Ice Extent ◽  
Previous Version ◽  
Arctic Ice ◽  
The Impact ◽  
Snow And Ice

Abstract. A new version of the sea ice motion and age products distributed at the National Snow and Ice Data Center's NASA Snow and Ice Distributed Active Archive Center has been developed. The new version, 4.0, includes several significant upgrades in processing, corrects known issues with the previous version, and updates the time series through 2018, with regular updates planned for the future. Here, we provide a history of the product development, discuss the improvements to the algorithms that create these products, and compare the Version 4 products to the previous version. While Version 4 algorithm changes were significant, the impact on the products is relatively minor, particularly for more recent years. Trends in motion and age are not substantially different between the versions. Changes in sea ice motion and age derived from the product show a significant shift in the Arctic ice cover, from a pack with a high concentration of older ice, to a sea ice cover dominated by first-year ice, which is more susceptible to summer melt. We also observe an increase in the speed of the ice in recent years, which is anticipated with the annual decrease in sea ice extent.

Variability of light beneath a modified portion of the snow and ice cover of a lake

1984 ◽  
Vol 22 (1) ◽  
pp. 65-71 ◽  
Author(s):  
W. A. Adams ◽  
W. P. Adams ◽  
P. A. Flavelle ◽  
N. T. Roulet
Keyword(s):  
Ice Cover ◽  
Snow And Ice
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