Impacts Of Deep Convection On Stratospheric Gravity Waves In The South China During Summer

Deep convection is one of sources of stratospheric gravity waves. Brightness temperature perturbations calculated from AIRS radiance data is used to detect deep convection events and stratospheric gravity wave events in Southern China during summer in order to analysis the connection between deep convection and stratospheric gravity waves. Statistics of the frequencies of gravity waves during 2004-2013 in southern China show that the highest frequency of occurrence of gravity waves occurs in July, which is up to 8%. And the frequency of occurrence of gravity waves at night is larger than its at day. Meanwhile the gravity waves occurred in southern China are mostly excited by deep convection, which is larger than 50%.Additional, Madden-Julian oscillation can influence the weather in southern China, so it may have some impacts on gravity waves. The ratio of frequencies of occurrence of gravity waves in active Madden-Julian oscillation phases and inactive phases are about 3:1, indicating that there are some associations between gravity waves and MJO. The frequencies of gravity waves obviously increase when the MJO actives in the Indian Ocean and decrease when the MJO actives in the Pacific Ocean. The reason is that when MJO actives in the Indian Ocean, the deep convection and wind shear are strong, which is fit for gravity waves development. Meanwhile, the strength of the MJO also have some influence on gravity waves. More gravity waves occurrence in stronger MJO years.Furthermore, as significant deep convection events, typhoon also can excite gravity waves like other deep convection events. Super typhoon ’Soulik’ is selected to study the gravity waves excited by typhoon and analysis the feature and propagation of these gravity waves. Result shows that gravity waves excited by ’Soulik’ always located just behind of typhoon and followed it.30-40km height and 41km height are selected to study the changes of gravity waves between different.heights and their propagation features. The result shows that the gravity waves on 41km height are stronger than that in 30-40km height. Meanwhile wavelet analysis is used to extract feature of these gravity waves. There are two main waves during this typhoon process, including horizon wavelength in 500km and 1300km, while the gravity wave with wavelength 1300km can propagation to Stratosphere.