###### Abstract  
To obtain better frequency bands for source bearing estimation, experiments using an ice-mounted geophone were performed at three sites on the Arctic ice cap. By transforming to the frequency domain, errors of the bearing estimation in a number of frequency bands within 1000 Hz and the horizontal peak displacements received by the geophone in the corresponding frequency bands were obtained. After comparing the variation in errors to the peak displacements in the same frequency band, it was found that the errors are related to the peak displacements, and higher peak displacement values mean smaller errors. When the incident angle of the acoustic source and the ice thickness meet certain conditions, some modes of the Lamb waves of the ice plate are excited, the peak displacements in the same frequency band are increased, the errors of bearing estimation are reduced, and the effective frequency band for bearing estimation is broadened. These results provide some new ideas for the bearing estimation of acoustic sources beneath the Arctic ice.  
bearing estimation error; Arctic; cross-ice; underwater acoustic source; ice-mounted geophone; Lamb waves +
Footnote †: journal:  
the average absolute error of bearing estimation to the source was within 10\({}^{\circ}\)[15; 23; 24]. By combining passive seismology approaches with specific array processing methods, [PERSON] et al. [18; 19] demonstrated that the multimodal dispersion curves of sea ice can be calculated without an active source and then used to infer sea ice properties. From the abovementioned studies, we can see that by deploying geophones mounted on ice, much acoustic information about ice and underwater acoustic sources can be obtained. However, it is also found that the studied frequency band of signals received by geophones was mostly under 200 Hz [15; 17; 18; 19; 20; 23; 24].  
[PERSON] and [PERSON] [25] noticed that the reflectivity at a given angle was strongly influenced by the pulse for frequencies above 1 kHz. [PERSON] et al. [26] measured sonic reflectivity below 1 kHz beneath large smooth ice floes in the Arctic Ocean and found that the reflectivity was strongly dependent on frequency as well as grazing angles. [PERSON] and [PERSON] [27] computed the reflection coefficient as a function of the incidence angle and frequency and found that at some incidence angles and frequencies, the reflection coefficient had very low values and was related to the generation of Lamb waves in ice. From these studies, we know that Arctic ice often has different responses to acoustic waves with different frequencies up to 1 kHz. But there have been many studies on signals with frequencies only under 200 Hz using ice-mounted geophones. The effect on source bearing estimation when the signals received by geophones are in the frequency bands that are above 200 Hz is not well known. Which frequency band is better for source bearing estimation is also unknown.  
In this study, we report on cross-ice detection experiments with underwater acoustic sources for bearing and an ice-mounted geophone that were performed during the 11 th Chinese National Arctic Research Expedition. Section 2 introduces the experiments in detail. A 3C geophone was used for bearing estimation. Section 3 briefly describes the methods for source bearing. In Section 4, the bearing estimation results are compared with the peak displacements received by the ice-mounted geophone. The relationship between the errors of bearing estimation and the horizontal peak displacement is studied. The relationship between the Lamb waves and the horizontal peak displacement and bearing estimation error is also studied. Finally, Section 5 summarizes the results.