# Extending UWOC System Applications through Photon Transmission Dynamics Study in Harbor Waters
## 1 Introduction
So, the optical signal's spatial and temporal distribution characteristics show strong randomness [16]. The high cost of underwater measurement adds the complexity of accurately modeling and analyzing the optical signal variation in underwater channels, a topic that has garnered global research interests [17; 18; 19; 20]. Now the most literature about UWOC predominantly concentrates on light transmission properties and communication technology research in several water types, including clear seawater, coastal seawater, Class Harbor II water, pool water, and laboratory sink water [21; 22; 23]. The research on different kinds of harbor waters are limited. There are few studies on the transmission characteristics of light in Harbor-I, Harbor-II, Harbor-III and Harbor-IV water. Studying UWOC in harbor water helps in deep understanding how light behaves in such environments and developing techniques to mitigate these effects. Furthermore, harbors are critical infrastructure with high security needs, and UWOC can facilitate real-time monitoring and control of underwater Autonomous Underwater Vehicles (AUVs), sensors, and instruments for environmental monitoring, underwater inspection, and maintenance tasks, which are essential for the sustainable management of harbor areas. Above all, the current engineering application of UWOC systems is mainly under deep sea and ocean water conditions [24; 25; 26], very little research on laser signal transmission in various harbor waters has limited its wider application. Furthermore, harbor waters are typically more turbid than the open ocean, primarily due to sediment presence, runoff, and human activities. The myriad substances found in harbor water--including salt, organic compounds, dissolved materials, and potential pollutants--have a profound effect on the light's absorption and scattering, thereby affecting the absorption of photons [27]. Specifically, higher concentrations of organic matter and suspended particles in harbor waters tend to increase scattering and absorption. The scattering and absorption effects of light are significantly influenced by the size, composition, and concentration of these particles. Additionally, the dynamics of bubble flow in 2D bubble columns can further affect the transmission characteristics of light signals [28]. This is particularly relevant with methane, which is produced by the anaerobic actions of underwater microorganisms and oxygen, generated through the photosynthesis of aquatic plants in harbor waters. In recent years, the Monte Carlo method has gained popularity for simulating underwater optical signal transmission [29; 30; 31; 32; 33; 34; 35; 36]. [PERSON]'s analysis of underwater channel impulse response and time dispersion across various seawater types, link distances, and received apertures indicates that time dispersion is often negligible, reducing the likelihood of inter-symbol interference [32]. The two-term Henyey-Greenstein Function has been employed for more accurate simulation of power distribution on the receiving surface [29; 33]. [PERSON]'s application of the Monte Carlo method, coupled with the two-term Gamma Function to represent impulse response curves, demonstrates that the two-term Gamma Function model is effective in scenarios with large attenuation lengths [34; 35]. Comparing with other types of water, the scattering phase function commonly used at present are not suitable for Monte Carlo simulation in Harbor water, which may lead to incorrect estimation of channel characteristics. The Fournier-Forand scattering phase function has been recognized in recent studies as a better fit for the characteristics of Petzold Harbor water, particularly when compared to the traditional Henyey-Greenstein, two-term Henyey-Greenstein Function, and Sahu and Shanmugam functions [15]. In this study, we would explore the intricate dynamic characteristics of UWOC systems under four distinct Harbor water conditions, which is vital to develop and extend applications in these water conditions.