Sea ice thickness observation method based on leakage modal acoustic waveguide characteristics

An acoustic waveguide and leaky mode technology, which is applied in the directions of using ultrasonic/sonic/infrasonic waves, using sonic/ultrasonic/infrasonic waves to analyze solids, measuring devices, etc. The problems of low estimated value of thickness spatial distribution and insufficient measurement accuracy of sea ice thickness have achieved the effect of improving the effectiveness and stability of observations, improving the efficiency of model solution, and reducing the difficulty of field operations.

Pending Publication Date: 2021-11-23
HARBIN ENG UNIV
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Problems solved by technology

In recent years, in order to obtain more comprehensive sea ice thickness information, a variety of indirect detection methods have been developed, but they all have certain limitations: the upward-looking sonar detection method is difficult to measure the temporal and spatial continuous thickness change information of the characteristic area and the detection accuracy is limited; The observation range of the aerial observation method is limited by the icebreaking ability of the icebreaker, and the estimated value of the spatial distribution of the sea ice thickness is usually low; The measurement accuracy of ice thickness is insufficient; the advantage of microwave remote sensing detection method and satellite altimetry method is that it can realize the assessment of sea ice thickness on a large horizontal scale, but the accuracy is insufficient when observing thinner ice layers

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  • Sea ice thickness observation method based on leakage modal acoustic waveguide characteristics
  • Sea ice thickness observation method based on leakage modal acoustic waveguide characteristics
  • Sea ice thickness observation method based on leakage modal acoustic waveguide characteristics

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Embodiment approach 1

[0040]Compared with the well-known Lamb wave waveguide characteristics in the infinite free plate, there are two big differences in the derivation and solution process of the waveguide equation in floating ice. On the one hand, due to the asymmetry of the boundary conditions, the floating ice cannot be equivalent to a completely symmetrical structure, so it cannot be simplified to symmetric and antisymmetric modes to solve separately. On the other hand, due to the similar acoustic impedance of ice and water, the elastic wave energy cannot be confined in the ice layer, and the waveguide appears leakage mode. Accompanied by this non-negligible attenuation of energy propagation, the corresponding wavenumber k solution needs to be done in complex space. This method deduces the dispersion equation of the ice waveguide under the ice-water coupling state, and realizes the mode-by-mode solution of the ice-water coupling model based on the complex space peak self-search algorithm, and ...

Embodiment approach 2

[0058] Steps 1-3 are the same as the specific implementation mode 1, but the thickness of the ice layer is set as an uncertain parameter, so as to obtain the QS modal frequency-thickness product-wave velocity dispersion curve of the ice floe waveguide as follows: Figure 6 , the wave velocity of the QS mode under a certain frequency excitation in a given sea ice is obtained through the field ice-acoustic experiment, according to Figure 6 Based on the mapping relationship between the modal wave velocity and the frequency-thickness product, the actual thickness of sea ice in the current ice region can be quickly and accurately estimated.

[0059] In summary, the sea ice thickness observation method proposed in the present invention derives the dispersion equation of the ice-floe waveguide under the ice-water coupling state, and realizes the modal solution of the ice-water coupling model based on the complex space peak self-search algorithm, and obtains the ice-water coupling mod...

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Abstract

The invention provides a sea ice thickness observation method based on leakage modal acoustic waveguide characteristics, and the method comprises the steps: deducing a frequency dispersion equation of a floating ice waveguide in an ice-water coupling state, achieving the one-by-one modal solving of an ice-water coupling model based on a complex space peak value self-search algorithm, obtaining a frequency dispersion curve of a QS modal most sensitive to ice thickness in a full frequency band, avoiding the defect that the global root searching workload of a traditional solving algorithm is large, and determining the sea ice thickness by comparing the QS modal frequency dispersion curve extracted from the actually measured ice sound signals with a theoretical curve, and then realizing sustainable, accurate and easy-to-operate sea ice thickness measurement. According to the invention, basic support can be provided for other polar region sea ice research, and necessary information can be provided for operation tasks such as polar region navigation, polar region resource development and under-ice rescue in time.

Description

technical field [0001] The invention relates to a sea ice thickness observation method based on the ice layer waveguide leakage mode, and belongs to the technical fields of structure detection and polar acoustics. Background technique [0002] As the most important part of the Arctic natural environment, polar sea ice is an important factor affecting global climate change, constantly acting on global heat balance, temperature-salinity dynamic balance, ocean water cycle and atmospheric circulation. However, due to its variable formation mechanism, the internal structure of Arctic sea ice is highly complex: such as melting caves in the ice, melting lakes on the ice surface, and undulations on the ice surface. Although the existing satellite observation methods can accurately monitor the sea ice coverage and its changes, the monitoring accuracy for ice thickness (especially thin ice thickness) is very limited, and other existing ice thickness measurement methods also have their...

Claims

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Application Information

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IPC IPC(8): G01N29/07G01N29/12G01N29/44G01B17/02
CPCG01N29/07G01N29/12G01N29/4472G01B17/02G01N2291/02854G01N2291/011G01N2291/014G01N2291/023Y02A90/10
Inventor 张宇翔马丁一殷敬伟谢志南生雪莉高家辉
Owner HARBIN ENG UNIV
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