## 1 Introductions  
Multibeam echosounder (MBES) backscatter data require careful consideration of environmental factors, particularly variations in water column properties such as temperature, salinity, and depth [1, 2, 3, 4]. These variations significantly influence the propagation of sound in water, directly affecting bathymetric measurements and backscatter intensity data. Without accounting for these factors, the analysis of seabed characteristics may yield inconsistent results, especially in regions with dynamic oceanographic conditions [5, 6, 7]. MBES systems are widely used in marine research and industrial applications, including for seabed mapping, navigation surveys, marine resource exploration, and environmental monitoring. They provide bathymetric data reflecting the topography and morphology of the seabed, alongside backscatter intensity data indicating the acoustic signal strength from the seabed. Both data types are essential for analyzing the physical characteristics and spatial distribution of seabed substrates in marine environments [8, 9, 10, 11, 12, 13]. Globally, MBES has become a cornerstone technology for detailed seabed characterization and habitat mapping [6, 8]. However, traditional approaches to processing backscatter data often rely on empirical models or averaged water column values, which fail to account for site-specific or temporally varying oceanographic conditions. This has led to discrepancies in the interpretation of backscatter data, particularly in areas characterized by complex environmental variability [5, 7, 14, 15, 16, 17]. The Korean seas present unique challenges for MBES data processing, due to their highly variable seasonal and regional environmental characteristics. Influenced by major currents such as the Kuroshio and Liman currents, these waters exhibit significant changes in temperature and salinity across different regions and seasons [18, 19, 20, 21, 22]. For example, localized shifts in salinity and temperature caused by these currents directly impact the speed of sound and absorption loss in seawater, resulting in variability in backscatter intensity. Despite these challenges, limited research has addressed the integration of site-specific water column parameters into MBES backscatter data processing approaches, particularly considering Korean waters [19, 20, 23, 24]. In Korea, a significant portion of legacy MBES data were collected primarily for simple surveying purposes, rather than scientific research. As a result, these datasets were processed using empirical formulas or without consideration of water column properties at all, failing to reflect temporal and spatial variations in oceanographic conditions [25]. Such practices ignore the physical changes in the water column during data acquisition, leading to potential discrepancies in the backscatter intensity results. These discrepancies are particularly pronounced in regions, such as the Korean seas, with significant seasonal and regional environmental variability. This underscores the need for a systematic approach to re-process legacy MBES data using measured water column parameters [16, 17]. This study aims to address these limitations by utilizing site-specific Sound Velocity Profiler (SVP) and Conductivity-Temperature-Depth (CTD) data to re-evaluate legacy MBES datasets. By correcting MBES datasets that have not adequately considered water column parameters, this study evaluates how underwater absorption affects MBES backscatter data. By re-calculating the absorption loss using water column information and integrating site-specific parameters such as temperature, salinity, and depth, the study seeks to mitigate discrepancies in the backscatter results. This approach enhances the representativeness of legacy MBES datasets in explaining the physical variability of the marine environment, thus improving their applicability for secondary analysis in scientific research and industrial applications.