## 3 Results
### Sound Absorption from Water Temperature from SVP  
The closest KODC measurement sites and the survey months corresponding to the MBES data collection were selected to conduct a comparative analysis between the historical temperature data from KODC and those inferred from the SVP measurements during MBES operations. The results, including temperature and absorption coefficient calculations, are shown in Figure 5.  
At Site A, the distance between the SVP measurement location and the KODC measurement point was approximately 180 m, with near-identical measurement times. The temperature derived from the SVP data was close to the 11-year (2010-2021) mean and within the standard deviation range of the KODC dataset. Temperature fluctuations ranged between 3.61 \({}^{\circ}\)C and 0.70 \({}^{\circ}\)C relative to the KODC mean. Similarly, the absorption coefficients calculated at Site A showed minimal deviation (<3 dB/km) from the KODC average, indicating high reliability in the corrections applied.  
In contrast, Sites B and C exhibited significant spatial and temporal discrepancies. At Site B, the SVP measurement location was approximately 6 km away from the nearest KODC station, and the time difference between measurements was about 1 month. This resulted in notable differences in temperature (up to 8 \({}^{\circ}\)C) and absorption coefficients (up to 15 dB/km).  
Figure 5: (**a**) Comparison of the 11-year mean and standard deviation of temperature at KODC 102-04 point (Site A) with SVP-derived water temperature in April. (**b**) Comparison of the 11-year mean and standard deviation of temperature at KODC 209-04 point (Site B) with SVP-derived water temperature in April. (**c**) Comparison of the 11-year mean and standard deviation of temperature at KODC 208-02 point (Site C) with SVP-derived water temperature in October. (**d**) Comparison of the absorption coefficients at Site A in April between the 11-year average KODC data and SVP data. (**e**) Comparison of the absorption coefficients at Site B in April between the 11-year average KODC data and SVP data. (**f**) Comparison of the absorption coefficients at Site C in October between the 11-year average KODC data and SVP data. The frequency was 300 kHz.  
At Site C, the spatial separation was approximately 10 km, with a measurement time difference of more than 1 month. The temperature and absorption coefficient profiles showed substantial deviations, up to 5 \({}^{\circ}\)C and 15 dB/km, respectively.  
SVP-based temperature and absorption coefficients at Site A were validated against the KODC dataset, thus confirming their reliability. However, for Sites B and C, the spatial and temporal differences led to inconsistencies in temperature and absorption coefficient values. These discrepancies underscore the importance of in situ measurements of SVP during MBES surveys.  
This analysis highlights the importance of accounting for the spatiotemporal variability of temperature and absorption parameters when calibrating MBES backscatter data. Accurate water column measurements--particularly in dynamic environments such as the Korean seas--are essential for minimizing uncertainties in backscatter data and improving the reliability of re-calibrated results.