## 1 Introduction
Existing research has largely focused on the navigation process of ships; for instance, [PERSON] and colleagues conducted air pollution monitoring studies on vessels sailing across vast sea areas using a verified and effective methodology [12]. Additionally, studies have been conducted on emissions during the berthing and departure of ships at ports, such as the work by [PERSON] et al. on monitoring emissions during the docking and undocking periods of ships at a specific port [13]. Due to the diverse characteristics of ports worldwide based on their usage and performance, it is not feasible to uniformly describe the proportion of emissions from different port areas. Building on the existing research, it is concluded that the main sources of land-based emissions at cargo ports originate from port operation vehicles and heavy vehicles entering the port area [14], while at passenger ports, the primary source of land-based emissions comes from electricity consumption. Currently, land-based transportation vehicles in ports are primarily subject to emission reduction measures, that involve the use of renewable energy to satisfy electricity needs and the optimization of port layouts. Research on carbon dioxide emission monitoring is categorized into non-real-time and real-time monitoring. Non-real-time monitoring of carbon dioxide emissions includes determination by activity-based inventory models, or by energy consumption types and quantities combined with traffic data for post-calculation [15]. Real-time monitoring focuses on the performance enhancement of fixed equipment [16; 17]. This study selects drones equipped with pollution gas sensors as the monitoring entity. As a device capable of real-time monitoring of carbon dioxide emissions within ports, drones offer flexibility and efficiency, low operational costs, adaptability to hazardous environments, and real-time data collection. Currently, extensive research on the application of drones in fire rescue has been conducted, such as fire monitoring and reconnaissance, aerial release of firefighting agents, and search and rescue operations [18; 19]. In recent years, research on the use of drones for atmospheric monitoring and real-time carbon dioxide emission monitoring has gradually commenced. For instance, [PERSON] et al., in their 2017 paper, involved the use of drones equipped with cameras and environmental air quality monitoring payloads to conduct atmospheric monitoring over targeted areas and their airspace [20]. [PERSON] et al., in 2020, conducted research on drone monitoring of ship exhaust, refining the application of mobile monitoring platforms for ship exhaust [21]. In the realm of port shipping, in 2022, [PERSON] et al. utilized ship-borne drones to monitor air pollution from vessels sailing across vast water areas [12]. However, there remain numerous issues to be addressed in research on drone monitoring of carbon dioxide emissions, such as the study of drone flight duration and endurance capabilities, air traffic control, and drone monitoring path planning. Compared to other mobile monitoring platforms, such as ground vehicles and ships, drones offer distinct advantages for port carbon dioxide emission monitoring. Firstly, drones can bypass ground obstacles and cover large areas quickly, which is particularly important in the complex environment of ports. Ground vehicles are restricted by predefined roads and pathways, while drones can navigate freely over terrain and obstacles. This allows them to reach emission sources more efficiently and conduct real-time monitoring without the constraints of fixed paths. Secondly, drones can operate in hazardous environments, such as near fuel storage zones or high-emission industrial areas, where human-operated vehicles may face safety risks. Thirdly, drones provide real-time emissions data, which is crucial for accurate and timely monitoring. Even within a two-dimensional (2D) simulation, this study demonstrates that drones can find more efficient monitoring paths than ground vehicles.