## 2 Materials and Methods
### Meteorological Factors  
Meteorological factors are defined as phenomena occurring in the Earth's atmosphere, which have a direct influence on the conditions prevailing in the southern part of the Baltic Sea [31; 32]. Their strong effect determines both short- and long-term hydrological, biological, and chemical conditions in the area [33]. The key factor that determines conditions prevailing in the southern Baltic Sea is air temperature, measured as the mean kinetic energy of air particles (Figure 2). Air temperature is one of the basic meteorological parameters that influence the occurrence and nature of atmospheric phenomena and physical processes in the atmosphere. Mean air temperature briefly describes thermal conditions in an area and can be used to compare these the conditions across areas and relate them to regional and global air temperatures [34]. Figure 2: Mean daily air temperature by selected ports, 1991–2020 [35; 36]. Air temperature fluctuations strongly affect heat and humidity transportation, which determine the formation of air pressure systems and the atmospheric circulation in the Baltic Sea [37]. Changes in air temperature may cause thunderstorms and sea storms, affecting the safety of navigation and the reliability of LNG operations. Moreover, air temperature has an impact on the intensity of icing, which is especially hazardous in the winter season. Sudden temperature falls may cause freezing of the water surface and icing on ships' hulls, which considerably reduces maneuverability and increases the risk of technical failures. Another important meteorological factor is barometric pressure, which determines air circulation and the development of weather systems [38]. Low barometric pressure is conducive to the formation of cyclones, often coinciding with strong winds and heavy rain, impeding navigation and harbor operations. High barometric pressure, on the other hand, leads to periods of stable weather but may bring fog and/or mist, which restrict visibility and affect the safety of navigation [39]. Barometric pressure plays an important role in the formation of hydrological and meteorological conditions. It is defined as the force of air acting on a measurement unit of the Earth's surface resulting from the mass of an air column situated above a certain point [40]. Fluctuations of the barometric pressure have a major impact on air circulation, the formation of weather systems, and sea state--factors that may affect the safety and efficiency of LNG operations in the southern Baltic. The movement of air masses in the Baltic Sea is characterized by the so-called atmospheric wave [41]. A swell, referred to as the atmospheric wave, forms beyond a concentric cyclone, its height depending on the magnitude of the drop in pressure in the center of the cyclone. This phenomenon strongly affects changes in water levels in the Baltic Sea. The formation of atmospheric waves is related to dynamic changes in the barometric pressure (Table 1) and differences in temperature across atmospheric layers and may lead to sudden changes in water levels, affecting the safety of navigation and harbor operations, including the handling of LNG [42]. Another phenomenon of key importance is the formation of anti-cyclones. An anti-cyclone, or a weather system with high barometric pressure that rises towards its center, has a significant impact on weather conditions in the region. In higher atmospheric layers, an anti-cyclone is a convergence zone, i.e., winds converge towards its center. In lower atmospheric layers, an anti-cyclone is a divergence zone, with winds diverging away from the center and moving towards areas of lower barometric pressure. Anti-cyclones bring