Sheng Xueli, Dong Chaoping, Guo Longxiang, Yin Jingwei
Acoustic Science and Technology Laboratory, Harbin Engineering University, Harbin, 150001, China.
J Acoust Soc Am. 2021 Oct;150(4):3074. doi: 10.1121/10.0006792.
Sea ice and freshwater ice can be different in terms of physical and acoustic characteristics, such as density, salinity, etc. In this paper, under-ice ambient noise in the Mudan river (Jilin Province, Northeast of China) is analyzed using the data recorded by autonomous hydrophones to test if the river ice environment is an effective analog for studying under-ice noise of multi-year ice sheets in the Arctic. The noise spectrum level below 250 Hz and above 1 kHz decreases linearly with the increase in the logarithmic frequency in a quiet environment. The ice cracks are detected and extracted, and Pearson correlation analysis between meteorological information and cracks is carried out. Frequency correlation matrixes are calculated to obtain the correlation between pairs of frequencies and evaluate the frequency correlation of ice crack noise of two hydrophones under different depths, different distances, and different times. Finally, the paper compares the experimental results with Arctic under-ice noise in the literature. Similarities with Arctic under-ice noise are observed in the experiment, including noise spectrum, cracks' peak frequency, and correlations between temperature and crack intensity. This paper believes that the study of under-ice noise in freshwater rivers can be used to simulate multi-year ice regions in the Arctic in terms of thermal-induced cracks and meteorological correlation. And future research is needed to prove this judgment further.
海冰和淡水冰在物理和声学特性方面可能存在差异，例如密度、盐度等。本文利用自主水听器记录的数据，对中国东北吉林省牡丹江的冰下环境噪声进行了分析，以检验河流冰环境是否是研究北极多年冰盖下冰噪声的有效类比。在安静环境中，250Hz以下和1kHz以上的噪声谱级随对数频率的增加呈线性下降。检测并提取了冰裂缝，并对气象信息与裂缝之间进行了皮尔逊相关分析。计算频率相关矩阵，以获得频率对之间的相关性，并评估不同深度、不同距离和不同时间下两个水听器的冰裂缝噪声的频率相关性。最后，本文将实验结果与文献中的北极冰下噪声进行了比较。实验中观察到与北极冰下噪声的相似之处，包括噪声谱、裂缝的峰值频率以及温度与裂缝强度之间的相关性。本文认为，淡水河冰下噪声的研究在热致裂缝和气象相关性方面可用于模拟北极多年冰区。未来还需要进一步的研究来证实这一判断。
