Monitoring the intensity distribution of earth-air activity around the Mogao Grottoes

There should be an extensive rise and fall of earth-air activity at the land–atmosphere interface. In this study, the relative humidity (RH) of earth-air is monitored at 193 points around the Mogao Grottoes. The results show that the intensity of earth-air activity (IEA) is proportional to RH fluctuations and inversely proportional to atmospheric pressure (AP) fluctuations. Each monitoring point fluctuates synchronously with the changes in the external AP, but the variations in IEA differ significantly from one location to another. IEA decreases from the southeast to northwest and weakens with rising terrain elevation, is lower in areas with dense contour lines and higher in sparse ones, while quicksand weakens IEA. Three types of earth-air fluctuations are identified at the Mogao Grottoes. Such results are important for understanding the spatiotemporal distribution of the earth-air activity at the land–atmosphere interface and preventing the deterioration of cultural wall paintings in caves.