Tropospheric Gravity Waves as Observed by the High‐Resolution China Radiosonde Network and Their Potential Sources

Abstract

Abstract Lower atmospheric gravity waves (GWs) can significantly impact waves in the middle and upper atmospheres and are vital for turbulence generation. This paper puts the spotlight on the spatial–temporal variability of tropospheric GW total energy ( E T ) and its potential sources above four regions of interest (ROIs) gathered from high‐resolution radiosonde observations from the China Radiosonde Network during the years 2016–2019. The seasonality of E T above four ROIs shows different characteristics and is dependent on latitudes and underlying terrains, reaching its maximum identified in the winter at middle latitudes. Interestingly, the annual cycles of the maximal E T shift from 35°N in October to 25°N in March of the next year, triggered by the shift in the winter subtropical jet. Based on the random forests regressor, the jet stream between 200 and 125 hPa likely serves as the primary source for the observed GWs above the ROIs with low and middle latitudes, with relative contributions of around 60%. However, the Kelvin–Helmholtz instability between 800 and 125 hPa could be the most recognized source of GWs and contributes around 68.4% to the observed energy. During the rainy season, the E T under scenarios of convective precipitation is around 20% larger than the other. As well, as the near‐surface or low‐level wind interacts with a mountain barrier over the Tibetan Plateau region, 12.4% of the observed E T is attributed to the strength of the low‐level wind.