###### Abstract  
Local humidity and temperature monitoring of ground parking aircraft were carried out in this study. Changes in the humidity of different bays and the relationship between local humidity and local temperature were investigated. Moreover, the concept as well as a method of calculating the humidity characteristic coefficient (HCC) were put forward, and two models of aircraft local humidity were established using the humidity and temperature of the thermometer shelter as arguments. Furthermore, bays of an airplane were divided into three groups according to differences in local humidity, and the range of the HCC of each group were determined. The results suggest that the rates of change of local humidity and local temperature are negatively correlated, moreover, the theoretical model shows a linear relationship between humidity and temperature, with a negative slope suggesting changes in humidity are inversely proportional to temperature. The ratio of the local environment slope to the external environment slope has a constant value. Finally, bay sealing and temperature features were found to significantly affect local humidity, and average deviations between the monitored humidity and humidity values predicted using the two temperature models were all less than, or equal to, 7.3% relative humidity. aircraft structure; local environment; humidity environment; humidity model; temperature and humidity  
Humid environments can have chemical and physical effects on aircraft components, especially when condensation occurs due to temperature and humidity changes [1]. For metal structures, the combined effect of humid air and other factors could cause chemical or electrochemical damage to the surface coating of structures [2] leading to electrochemical corrosion of the metal underneath [3, 4, 5, 6]. When exposed to a humid environment, structures made of composite materials can absorb moisture from the air, resulting in a variety of undesirable consequences such as expansion, stratification, and a reduction in strength [7, 8, 9]. For airborne equipment, condensation and free water that occurs in humid environments could cause electrical short circuits [10], blurring of optical lenses, surface mildew, and other problems. Moreover, humid environments give rise to a range of potential problems including changes in the friction coefficient, degradation of lubricants, faulty explosives, and sealing element aging, all of which could lead to mechanical failure of the aircraft [11]. Military aircraft are parked on the ground for more than 95% of the time during service [12], and the figure for civil aircraft is 65%. Most load-bearing structures (such as longerons, spars,ribs bulkheads, and stringers), rubber parts, and airborne equipment are located inside the aircraft and are therefore subject to long-term direct influences from the local environment of the bay. Thus, determining the local environmental characteristics of grounded aircraft is of the utmost importance in assessing the service life of internal components of the aircraft, preventing functional failures, and analyzing the causes of malfunctions [13; 14]. Service environment spectra of components can be generated to assess the corrosion of aircraft parts in the laboratory [15]. At present, the key factors that should be taken into consideration in the preparation of a service environment spectrum are the temperature, humidity, and corrosive media in the atmosphere [16; 17; 18], which are roughly the same as the external environmental factors of the aircraft. If a relationship between the local environment inside the aircraft bay and the external environment can be established, the internal environment of the aircraft can be effectively simulated using existing methods [18; 19], thus, the corrosion of internal parts can be assessed with sufficient accuracy. A lot of effort has been placed on studying the local environment of aircraft. [PERSON] [20] measured and statistically analyzed the temperature and humidity inside the tank of grounded aircraft.