## 2 Data and Methods
### GW Ep Extracted from the COSMIC-2 Temperature Profiles  
When investigating the characteristics of GWs based on satellite observations, GW energy is usually used as a proxy parameter for GW activity [2; 13; 18], which includes the kinetic energy (Ek) and the potential energy (Ep). According to the linear wave theory, the ratio of the kinetic energy to the potential energy (Ek/Ep) is approximate to a constant in the atmosphere. Therefore, the GW activity can be directly characterized by GW Ep [18; 40]. In the present study, for each RO temperature profile, the corresponding GW Ep profile is derived using the horizontal detrending method, and the GWs with vertical wavelengths larger than twice the vertical resolution of RO observations (around 1 km) are extracted by this method.  
The steps for retrieving the GW Ep profiles using the dry temperature profiles are briefly introduced as follows. First, each raw dry temperature profile is interpolated with an interval of 0.1 km, and the horizontal position corresponding to the profile is designated as the mean longitude and latitude within the height range of 20-30 km. Then, for each day, over the whole latitude range of 5\({}^{\circ}\)S-35\({}^{\circ}\)N, all the interpolated temperature profiles are binned into 5\({}^{\circ}\)\(\times\) 5\({}^{\circ}\) longitude \(\times\) latitude grids and the daily mean temperature profile for each grid is derived, which corresponds to the horizontal position of the center point in the grid. Based on the daily mean temperature profiles of all the grids, the daily 3D temperature grid field in the altitude range of 20-30 km is constructed. At each height level between 20 and 30 km, the zonal wavenumbers 0-6 of each 5\({}^{\circ}\) latitude band in the daily 3D temperature grid field are extracted by applying the S-transform, based on which the daily 3D background temperature grid field, with the resolution of 5\({}^{\circ}\)\(\times\) 5\({}^{\circ}\)\(\times\) 0.1 km, is constructed. Through interpolating in the background temperature grid field, the background temperature profile \(\overline{T}\) of each raw dry temperature profile \(T\) is obtained, and the corresponding temperature perturbation profile \(T^{\prime}\) caused by GWs is derived as \(T-\overline{T}\). For each temperature perturbation profile \(T^{\prime}\), the corresponding GW Ep profile is derived using Equation (1).  
\[E_{p}=\frac{1}{2}\frac{g^{2}}{N^{2}}\bigg{(}\frac{T^{\prime}}{\overline{T}} \bigg{)}^{2} \tag{1}\]  
where \(g\) is the gravitational acceleration, and \(N\) is the Brunt-Vaisala frequency calculated based on \(\overline{T}\). For more details on the method for extracting GW Ep from raw temperature profiles, please refer to [PERSON] and [PERSON] [41; 42] and our previous works [43; 44].  
Note that quality checks are carried out on both the original atmPrf files and the derived GW Ep profiles. The atmPrf data files marked as \"bad\" by CDAAC in the global attribute and the GW Ep profiles with non-physical values exceeding the range of 0-50 J/kg within the altitudes between 20 and 30 km are excluded. In the latitudes of 5\({}^{\circ}\)S-35\({}^{\circ}\)N during December 2019 and November 2021, there are 1,907,379 raw COSMIC-2 dry temperature profiles, from which 1,756,160 qualified GW Ep profiles are obtained. In order to obtain spatial information on GW activities at a more detailed scale, the qualified Ep profiles are grided into the boxes with a longitude \(\times\) latitude resolution of 2.5\({}^{\circ}\)\(\times\) 2.5\({}^{\circ}\). For each 2.5\({}^{\circ}\)\(\times\) 2.5\({}^{\circ}\) grid, 33 qualified GW Ep profiles are obtained per month on average, which is sufficient to construct the GW Ep monthly average grid data.