## 3 Influence Factor Analysis of the Airport Baggage Flow
### Micro-Factors  
From the micro level, indicators such as dates (including workdays, holidays, winter and summer holidays, etc. ), time intervals, weather, flight types, and the number of routes have different promotion degrees on airport traffic [25; 26; 27]. [PERSON] et al. made a horizontal comparison of different airports from the number of flights, ticket price, transportation mode, airworthiness days, and other aspects [28]. According to his research result, airworthiness days were closely related to weather conditions, and weather conditions and different dates have a significant impact on passenger flow. [PERSON] et al. analyzed the impact of different time intervals (in 30 min), visual distance in the airport areas, flight number, and check-in passenger flow on the security passenger flow of an airport [29]. Through this study, they found that the security passenger flow of different time intervals varied greatly. Meanwhile, the weather conditions were closely related to the number of flights and check-in passenger flow. The flight type (international and domestic flights) and the number of routes have a great impact on the airport baggage flow. For example,passengers on international flights usually have a long journey and travel time, so the baggage demand may be greater than for passengers on domestic flights. Within a regional context, the implementation of visa restrictions has the potential to significantly impede air passenger flow between countries, while disparities in international traffic patterns can be attributed to variations in visa policies across nations [20]. In addition, psychological factors of passengers, airport service, travel purpose, ticket price and discount, and other factors that are difficult to quantify could have a significant impact on the baggage flow. The scientific calculation of the relevant impact weight is one important research direction in the future. According to the literature research, the main influencing factors of departure baggage flow are classified into the following categories, as shown in Table 1. The factors that affect baggage flow can be categorized into two main categories: macro-influences and micro-influences. Macro-influences include the total retail sales of consumer goods, regional industrial structure, regional population, highway transport, railway transport, adjacent airports, etc. Micro-influences include the passenger flow, number of flights/air lines, different types of dates (weekdays or non-workdays, and periods like summer and winter vacations, etc. ), international/domestic flights, visa policies, weather conditions, airport service quality, passengers' psychological factors, purpose of passenger travel, airfare costs and discount strength, etc. Transportation flow forecasts can be categorized based on their time horizon into long term (monthly, quarterly, or annually) and short term (measured in days or time periods of the day) [30; 31; 32]. The selection of feature vectors differs between the two prediction approaches. When forecasting baggage flow over the long term, influencing factors tend to be more macroscopic due to the extended time span. For instance, the size of the baggage flow is closely related to the regional economy, population, and other factors [15; 20]. In making short-term baggage flow forecasts, the relationship between influencing factors and baggage flow is more microscopic, such as weather conditions, passenger flow, weekdays, or holidays [31; 32]. Changes in these factors can lead to significant fluctuations in baggage flow within a short period. Moreover, difficult-to-quantify factors like passengers' psychological states, travel purposes, and airport service levels can contribute to short-term baggage flow fluctuations. Scientifically quantifying these factors represents a key direction in the study of baggage flow demand. Therefore, the airport baggage flow has many affecting factors and is impacted by the joint action of various indicators.