## 1 Introduction
Based on the data from a mesosphere-stratosphere-troposphere (MST) radar station in Gadanki, tropical India, [PERSON] et al. [30] analyzed the energy mechanisms generating the inertial GWs over this station and suggested that the main factors which affect the GWs over Gadanki are convection, jet flow, and wind shear. [PERSON] et al. [31] studied the GW activity in the stratosphere over the globe based on the eight-year SABER/TIMED temperature observations, and they pointed out that deep convection is the main source for the observed tropical GWs and that wind also influences the tropical GW activity. [PERSON] et al. [27] used COSMIC-2 RO data to study the spectra of different equatorial waves in the tropical tropopause and lower stratosphere, including the Kelvin waves, the mixed Rossby gravitational waves, the inertial gravitational waves, the diurnal tide, and the small-scale GWs caused by frequent continental convection and topography, and they pointed out that the GWs in the altitude range of 18-20 km over several tropical regions within the latitudes of 16\({}^{\circ}\)S-0\({}^{\circ}\) are closely related to convection. In previous works that investigated the factors influencing regional GWs, the spatiotemporal distributions of GW parameters and those of each potential factor were usually compared qualitatively. Although some studies presented the correlation coefficients between the GW parameters and the potential influencing factors [24; 30; 32], none of them quantified the relative importance of different factors on the GW activity. To investigate the importance of different factors on the GW activity of a local area, it is better that the main factors that have significant impacts on the GW activity of this area are identified. The Indian region (60\({}^{\circ}\)E-100\({}^{\circ}\)E, 0\({}^{\circ}\)-30\({}^{\circ}\)N) is a specific area characterized by its distinct monsoon phenomenon [33]. From June to September each year, the Indian summer monsoon, which contains large amounts of water vapor, blows from the Indian Oceanto the Indian Peninsula, and the interaction between the monsoon and the mountainous terrain generates convections in the Indian region. Some studies have found that there is a strong correlation between GWs and convections, which are strongly correlated with the Indian monsoon [30; 33; 34]. The variation of GWs in the LS is significantly affected by the accompanying background wind field, which has been recorded in the Indian region [34; 35; 36]. Moreover, the tropical easterly jet (TEJ) prevails over this region during the monsoon period, with its maximum zonal wind speed appearing at a height of around 16 km [37; 38]. It has been noticed that the TEJ leads to the formation of strong zonal wind shears in the troposphere, which generate GWs, and the upward propagation of the waves further enhances the GWs in the LS [30; 39]. Other studies found that when strong tropical cyclones originate from the Bay of Bengal and the Indian Ocean land on the Indian Peninsula, the convections near the cyclone path are strengthened, thus enhancing the activity of GWs [26; 34]. Based on these previous studies, the present work aims to further investigate the relative importance of the main factors that affect the GWs in the LS of the Indian region and to quantify the relative contributions of these factors. Moreover, we also try to analyze the possible physical mechanisms of some influencing factors on the LS GWs in this region. The remainder of this paper is organized as follows. Section 2 introduces the data and methods, including the COSMIC-2 RO data and other data used in this study; the methods for deriving the GW potential energy (Ep) from the RO temperature profiles and for constructing the gridded datasets of the GW Ep in lower stratosphere of 20-30 km (simplified as LS hereafter) and the influencing factors; and the dominance analysis (DA) method for quantifying the contributions of influencing factors to the LS GWs. Section 3 presents the main results.