A dataset of acoustic profiles from the 9<sup>th</sup> Chinese Arctic Expedition (2018)

<p indent="0mm">Ocean acoustic profile data are key to understanding the physical properties of the ocean, playing a vital role in improving the accuracy of underwater target detection and positioning, optimizing the design of underwater communication networks, and serving as an important indicator for monitoring changes in the marine environment. Direct observation of ocean acoustic profiles eliminates errors caused by model prediction or estimation, providing precise and reliable measurements. The data are of significant value for scientific research, technological development, environmental monitoring, resource exploration, and practical applications. During the 9^th Chinese Arctic Scientific Expedition conducted in the summer of 2018, an acoustic Doppler current profiler was used to directly observe the speed of sound in the ocean for the first time. First-hand measured data of ocean acoustic profiles were obtained from the Chukchi Plateau, the Canada Basin, the Mendeleev Ridge, and other high-latitude regions of the Arctic Ocean. Based on the collection and organization of the acoustic profiler and synchronous CTD observations from the 9^th Chinese Arctic Expedition, and with reference to expedition’s field records, the measured SSP data were processed through standardized quality control procedures, including unification, normalization, and outlier removal, using dedicated data-processing software. Ultimately, a dataset with a vertical resolution of <sc>1 m</sc> is formed, including variables such as date, time, acoustic velocity, and water depth. It is one of the scientific outputs of the 9^th Chinese Arctic Scientific Expedition, and provides a data foundation for multidisciplinary polar research.