Investigation of Arctic Atmospheric Inertial Gravity Waves Using GPS Radiosonde Observations

Based on GPS radiosonde observations collected during the Chinese National Arctic Research Expedition (CHINARE) shipborne campaigns from July to September in 2018, 2020, and 2021, this study investigates the characteristics of inertial gravity waves (IGWs) in the summer lower stratosphere (15–25 km) over the Arctic, including their wavelengths, intrinsic frequencies, amplitudes, energy, and propagation properties. The results show that the vertical wavelengths derived from temperature perturbations are generally larger than those obtained from wind perturbations, with mean values of approximately 3.8 km and 2.3 km, respectively. The horizontal wavelengths are mostly confined within 600 km, with a mean value of about 400 km. The ratio of horizontal to vertical wavelength reaches 60–100, indicating that IGWs in the lower stratosphere propagate predominantly in the horizontal direction. The perturbation amplitudes in the Arctic are smaller than those typically observed at mid-latitudes: temperature perturbations are generally below 1 K (mean ≈ 0.55 K), and wind perturbations are below 2 m/s (mean ≈ 0.85 m/s). The periods of Arctic IGWs range from 5 to 12 hours. The total wave energy is primarily concentrated below 5 J/kg and increases with height, suggesting stable upward propagation of wave energy. Moreover, the horizontal propagation of IGWs exhibits a pronounced eastward preference, with only a small fraction propagating westward, which is consistent with the filtering effect of the background wind in the lower stratosphere.