ИСТИНА

https://www.poi.dvo.ru/node/645 METROLOGY OF MARINE MEASUREMENTS: PROBLEM OF COMPLETENESS Yuli D. Chashechkin 1, 1 Ishlinsky Institute for Problems in Mechanics of the Russian Academy of Sciences, Mos-cow, Russia, e-mail: yulidch@gmail.com INTRODUCTION The problem of harmonization of calculations and measurements of processes in the World Ocean is of applied and general scientific interest in the framework for solving prob-lems of weather forecasting and climate variability estimation. Among the most relevant are forecasting of the variability of ocean level and temperature, bio-productivity and general ecology, taking into account the increase in the population of the Earth and the World econ-omy. To the historically traditional data of ocean depth, free surface level and dynamic state, temperature, density profiles, velocity of sea currents, waves measurements, new ones are added each year, obtained with the help of instrument based on ships, boats, coastal sta-tions, aircraft and satellites. Free-floating drifting buoys, both passive and active, are used more and more actively. The data obtained help to develop new models of global circulation, coastal flows currents and small-scale processes including vortices and waves of various types. However, great efforts to improve the instruments and techniques of marine measure-ments, data of laboratory modeling of processes in the ocean still did not lead to the creation of a sufficiently extensive bank of reliable data necessary for improving numerical and ana-lytical models. Among the set of factors that influenced the formation of the current situa-tion, several groups can be identified, related to the ambiguity in the choice of the theoreti-cal basis for the development of a methodology for ocean research, the complexity of per-forming marine research, the difficulty of monitoring of the measurements metrology. Status of oceanic flows theory A number of current problems in marine measurements are caused by the incomplete-ness of theoretical analysis. Although the choice of a system of fundamental equations as a basis for describing processes is not contested, in practice it is difficult to realize due to the underdevelopment of analysis of such complex systems of algebraic-differential equations in partial derivatives. The absence of complete solutions leaves the chance to extrapolate data from the study of particular processes (currents, vortices, waves) to describe complete-ly the oceanic dynamic state or to develop of constitutive models. Along with the fundamental, many other equations systems are used in practice, as truncate ones, to describe separate processes (theories of specific types of waves – surface, internal, inertial or acoustic, and vortices), and constitutive sets including different versions of theory of turbulence [1]. By the Noether theorem, the infinitesimal transformations of the system determine conservation laws. The standards physical quantities for measuring are the distance, which is the invariants of space shift; the time interval (or frequency); mass, temperature, and the functionally related quantities, which are placed in the foundation of metrology. The intro-duction of new systems of equations with intrinsic symmetries means the introduction of new physical quantities, which must be denoted by their own symbols. The constitutive the-oretical models contain parameters that are not determined in the experiment, which makes it difficult to interpret and compare them with other data with their unification into a single database. Measurements of physical quantities However even with the measurements of classical quantities of oceanic waters, there are essential difficulties. The fundamental system is written for the conserved quantities – the mass of the medium as a whole and its individual components, momentum, and energy. In practice, the medium is characterized by the velocity of fluid, which is not directly de-termined by the lack of principles for identifying the "liquid particle". The velocity is not a conserved quantity in the system of fluid mechanics equations, which does not allow us to give an a priori objective evaluation of the error in its determination under the conditions of a particular experiment. The fluid velocity is estimated by indirect methods (measurements of the frequencies of scattered sound or light waves (LDA – tools), positions or velocities of markers (bodies) in the flow (PIV-tools), parameters of heat and mass transfer (thermo-anemometers, electro-diffusion tools), which do not allow to estimate simultaneously with the measurements the data error. One of the reason of errors is uncontrolled interaction of a particular sensor or sounding field with the environment. The conserved value - the momentum -was determined in a number of classical experiments on hydrodynamics (in particular by Hagen, Poiseuille and Reynolds on the flow of liquid), but this determinations were non-local. The total flow in a given capillary or macroscopic tube was measured and further development this tech-nique did not receive. General metrology of marine water velocity measurements is still not developed. Practically important characteristics of the ocean are thermodynamic quantities that are density, temperature, pressure, concentration of solutes, for the measurement of which a large number of sensors have been developed. However, the incompleteness of the equip-ment of real instruments does not allow us here to estimate the magnitude of the parameter and error of its determination simultaneously. To realize the principle of redundancy, which allows to estimate the error by compari-son of data of different methods for measuring the same value (for example, to determine the density, in addition to measurements of temperature, pressure, sea conductivity and den-sitometry, one can use the data of determining the optical refractive index of seawater in dif-ferent parts of the spectrum and speed of sound in different wavelength ranges). Estimates of the effectiveness of the methodology for the excess accuracy of marine measurements can be verified by modeling the measurement systems in the laboratory and, in particular, by performing comparative measurements of the parameters of the same physical phenomenon at the initial stage of the simplest, for example, the parameters of surface or internal wave by the systems of different types. In recent years, methods of remote sounding of marine areas with the help of active and passive recording systems of ground, aviation and space basing have developed greatly. Nevertheless, the connection of registered signal with the fluid flow parameters is indirect and interpretation of the data of such measurements is hampered by interference impact in-troduced by the propagation medium of the probing wave and by the complexity of the pro-cess of its interaction with the medium under study. Most of the data of such measurements are given in relative units, which do not allow determining the real variations of the physical fields of the parameters entering into the fundamental equations. It seems expedient to carry out laboratory testing of such remote sensing instruments simultaneously with the simulation of the physical processes under study. In marine measurement practice, it remains important to assess the influence of the variable fine structure of the medium on the quality of the data obtained, which is compli-cated by the possible perturbing action of the measuring instrument itself or the probing field on the phenomenon under study. Observations of stratified flows with the help of high-ly sensitive high-resolution instruments have shown that the fine structure is an inseparable part of all types of flows in the laboratory as well as in marine environment. All flows start-ing with the slowest creeping ones, for example diffusion induced flows on topography, whose velocities are of the order of а cm/s and to the fastest flows of technogen-ic origin [2] are structured. To solve this problem, it is also useful to carry out a coordinated laboratory simulation of both the phenomena themselves and their observation methods in natural conditions, taking into account the fine structure of the medium. As a basic process, one can consider the technique of measuring the parameters of internal waves, which play an important role in the dynamics of the atmosphere and the ocean. The main characteristics of periodic flows include the frequency of processes, allocat-ed spatial scales (wavelengths), the direction of propagation of the phase of the wave and energy, the amplitude of the waves. One part of the necessary parameters of the wave pro-cesses can be obtained from point measurements (for example, frequency), others - the spa-tial structure for determining the length and direction of wave propagation - requires field measurements. The most sensitive instruments are necessary to measurement parameters of ligaments – fine interfaces bounded the wave beams and vortex structures [3]. To find the amplitude, knowledge of both the magnitude and its gradient is required. The answer to the question of choosing the ratio of the lengths of sensitive sensor elements can also be ob-tained during the agreed laboratory simulation of the physical process and the tool for de-termining its parameter. Conclusion Summing up, it can be seen that only the system of fundamental equations provides the possibility of carrying out coordinated theoretical (analytical and numerical and experi-mental (laboratory and field) studies of the dynamics and structure of currents. To carry out the comparisons it is necessary to realize the requirements of the condi-tion of the completeness of the theoretical description (the solution must satisfy the system of equations and physically justified boundary conditions). The measurement technique, re-cording all fundamental physical quantities entering into the theory of the phenomenon must register large-scale components and resolve the fine-structure components of the studied phenomenon. ACKNOWLEDGMENTS The work was partially supported by Presidium RAS Program I.2.49 "Interaction of physical, chemical and biological processes in the World Ocean" (project А17-117121120015-8 "Mathematical and laboratory modeling of mechanisms of transport and structuring of impurity distribution in the ocean") and FFBR (grant 18-95-00870 " Consistent laboratory and mathematical modeling of periodic flows - vortices and waves - in stratified media") References 1. Chashechkin Yu. D. Differential fluid mechanics – harmonization of analytical, numeri-cal and laboratory models of flows // Mathematical Modeling and Optimization of Complex Structure. 2016. V.40. P. 61-91. DOI: 10.1007/978-3-319-23564-6-5 2. Chashechkin Yu. D., Zagumennyi I. V., Dimitrieva N. F. Unsteady Vortex Dynamics Past a Uniformly Moving Tilted Plate // Topical Problems of Fluid Mechanics - 2018, Pra-gue. February 21 – 23, 2018. Proceedings. 2018. P. 47 – 56. DOI: /10.14311/TPFM.2018.007 3. Chashechkin Yu.D. Waves, vortices and ligaments in fluid flows of different scales // Phys. Astron. Int. J. 2018. V. 2(2). P.105-108. DOI: /10.15406/paij.2018.02.0007