A Global Analysis Of Gravity Wave Potential Energy In The Stratosphere Derived From GPS Radio Occultation Data With COSMIC

Gravity waves (GWs) is one of the fundamental waves in the atmosphere, which play a crucial role in the dynamics and transport processes in the upper atmosphere and the lower atmosphere. Gravity waves can be generated by convection, topography and wind shear in the low atmosphere and propagate upward into the upper atmosphere. As GWs propagate upward, they can be reflected, refracted or broken at the critical layer and dumping the energy and momentum into the background, those processes changes the structure of the temperature and the mean wind.In this investigation, we use the dry temperature data of COSMIC from2007-2012and the ECMWF wind data in the same period to study the gravity wave potential energy(Ep) in the stratosphere, and discuss the characteristics of potential energy over time, altitude and latitude with the background wind.We analyzed altitude-time section of different latitude.In the tropic, Ep observed show that particularly gravity waves with vertical wavelengths between3and10km interact with the QBO. We find reasonably good agreement between their variations with time and height. The max value of Ep appears during east wind shear and below zero wind line, the magnitudes decreased when the wind change into west wind. The downward speed of potential energy QBO is about1km per month equal to QBO of zonal wind. We also find semiannual oscillation (SAO) above35km in the tropic stratosphere.In the middle and high latitude, we find seasonal variations which showed stronger activity during winter and min value in summer.We showed the global distribution of Ep at20-30km and30-35km. Below30km, large Ep detected at low latitudes from25(?) to25(?) centered around the equator, and they are particularly enhanced over the regions where active convection is expected, which means those gravity waves are generated by cumulus convection. The large value of Ep is also found at high latitude in the winter hemisphere, which may generated by polar jet.When we examining the latitude distribution of gravity waves Ep, our primary interest is the spring of southern hemisphere high latitude around the polar night jet. Large Ep above the jet core are distributed upward and poleward along the zonal wind contour lines. When we use relative perturbation of temperature as gravity activity, we also found poleward distribution of large Ep caused by the subtropical jet below15km. By examining the distribution of gravity wave Ep and zonal wind we found that wind shear is a source of gravity waves, background wind also has a very important effect on the propagation of gravity waves. When gravity waves breaking, it may changes the state of the background wind field.