Atmospheric channel for bistatic optical communication: Simulation algorithms

Three algorithms of statistical simulation of the impulse response (IR) for the atmospheric optical communication channel are considered, including algorithms of local estimate and double local estimate and the algorithm suggested by us. On the example of a homogeneous molecular atmosphere it is demonstrated that algorithms of double local estimate and the suggested algorithm are more efficient than the algorithm of local estimate. For small optical path length, the proposed algorithm is more efficient, and for large optical path length, the algorithm of double local estimate is more efficient. Using the proposed algorithm, the communication quality is estimated for a particular case of the atmospheric channel under conditions of intermediate turbidity. The communication quality is characterized by the maximum IR, time of maximum IR, integral IR, and bandwidth of the communication channel. Calculations of these criteria demonstrated that communication is most efficient when the point of intersection of the directions toward the source and the receiver is most close to the source point. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Estimation of the error of the algorithm for reconstructing the reflection coefficient of the Earth surface on the example of images with the low atmospheric turbidity

An algorithm for atmospheric correction of satellite images combining the consideration of the main factors influencing imaging and a number of techniques allowing the computational time to be decreased considerably is analyzed. On the example of a series of images of the South of the Tomsk Region recorded from 7/13/2013 to 7/17/2013 with the low atmospheric turbidity, a comparison of the results of atmospheric correction using the suggested algorithm with the results obtained using the NASA MOD09 algorithm is performed. The correction error is estimated under assumption of a linear change of the reflection coefficient from image to image. Our comparison demonstrates that the results of correction differ within the correction error. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Software package for reconstructing reflective properties of the Earth's surface in the visible and UV ranges

A description of a software package for reconstructing the distribution of the reflection coefficient of the Earth’s surface, as well as procedures developed for a considerable reduction of the computation time, is presented. By an example of a test region in the western coast of Africa, a comparison has been performed for results obtained by the proposed algorithm, the algorithm of homogeneous correction, and the standard MOD09 NASA algorithm. The correlation coefficients of results for this test region are as follows: between the new algorithm and homogeneity correction algorithm, 0.999; between the new algorithm and the MOD09 algorithm, 0.984

Estimation of the influence of cloudiness on the Earth observation from space through a gap in a cloudy field

For atmospheric correction of satellite images, the problem is formulated to estimate the distance from a cloud at which its influence on the satellite image of the Earth surface can be neglected. The Monte Carlo method of conjugate trajectories is used. The gap radius in the field of continuous cloudiness at which the influence of the cloudy medium on the received signal intensity does not exceed 10 % is obtained. It is revealed that for the Lambert law of radiation reflection from the Earth surface, the curve of the dependence of the received signal intensity on the gap radius has a maximum caused by the opposite influence of light scattering by the cloudy medium and radiation reflection by the surface (adjacency effect). To further generalize the examined problem to a stochastic cloud field, the method of direct simulation of photon trajectories in a stochastic medium is compared with G. A. Titov’s method of closed equations in the gap vicinity. A comparison is carried out with the model of the stochastic medium in the form of a cloud field of constant geometric thickness consisting of rectangular clouds whose boundaries are determined by the stationary Poisson flow of points. It is demonstrated that results of calculations can differ at most by 20‒30 %; however, in some cases (for some sets of initial data), the difference for the entire region of cloud cover indices is within 7 %. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Spatiotemporal dynamics of the wind velocity variance from the data of acoustic sounding of the atmospheric boundary layer

In the report spatiotemporal dynamics of the variance of three components of the wind velocity in the atmospheric boundary layer retrieved from measurements with a Doppler mini-sodar is analyzed. During measurements, the variances of the x- and y-components of the wind velocity were in the range 0.001 ≤ Dx, Dy ≤ 10 m2/s2; for the z-component 0.001 ≤ Dz ≤ 1.2 m2/s2. Their increase in the morning hours (at about 11:00, local time) and in the evening hours (from 18:00 till 22:00, local time) was noticed. This was explained by warming and subsequent cooling of the Earth surface accompanied by strengthening of motion of air masses. At night (from 00:00 till 5:00, local time), 0.01 ≤ Dz ≤ 0.56 m2/s2, which is in good agreement with the literature data. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Atmospheric bistatic communication channels with scattering. Part 2. Field Experiments in 2013

Results of field experiments on the influence of atmospheric conditions and some instrumental characteristics on the quality of information transfer in a bistatic optoelectronic communication system (OECS) operating in the visible wavelengths range are considered. The length of the atmospheric channel reached 17 km. Radiation of a copper bromide vapor laser with a wavelength of 510.6 nm was used as a signal source. It is shown that bistatic or over-the-horizon OECSs can operate both under the conditions of a cloudy and cloud-free atmosphere. Average values and standard deviations of communication errors were estimated under different atmospheric-optical conditions when some characteristics of individual instrumentation units varied

Antineutrino-Deuteron Experiment at Krasnoyrsk

This report is represented the results of some experiments, which carried out at the neutrino underground laboratory of Kranoyarsk nuclear plant.Comment: 8 pages, 3 figure