## 3 Results and Analyses  
### Comparisons of the Global Distributions of GW Ep Derived from Different RO Datasets  
In order to verify the validity of our procedure for deriving the GW Ep values, and to investigate the consistency of the GW Ep values extracted from different RO missions, the seasonal variations of the global distributions of GW Ep at 20-35 km during the period from February 2013 to January 2016 are derived from different datasets and are compared, as shown in Figure 4. Here, the four seasons are categorized as MAM (March to May), JJA (June to August), SON (September to November), and DJF (December to February). Figure 3: Variations in the monthly values for (**a**) Solar radio flux at 10.7 cm (F10.7) index, (**b**) 30 hPa zonal winds over the equator, used as QBO index, and (**c**) Multivariate ENSO Index (MEI). The statistics in the subgraphs of the first column are calculated from the profiles of all the missions available for the experiment's time period (including COSMIC, METOP-A/B, and GRACE), and the subgraphs of the second and third columns are derived from the profiles of COSMIC and METOP-A/B, respectively. The reason why the datasets from February 2013 to January 2016 are selected in this validation experiment is that the Metop-B data series started in February 2013, and COSMIC still provided a sufficient number of profiles every day over the next three years for the statistics of global GW Ep heat map, as shown in Figure 2. The GW Ep seasonal variations derived independently from the GRACE mission are not listed here due to the limited number of temperature profiles provided by GRACE, which is a disadvantage for constructing the single-day geographic grid data to derive the background temperature when applying the horizontal detrending method. Figure 4 suggests that the magnitudes and the distribution patterns of the GW Ep values derived from the three different datasets, i.e., data of all missions, COSMIC, and METOP-A/B, are of high consistency and the seasonal distribution patterns of the GW values derived from all the three datasets agree well with previous studies [2; 52; 53; 54; 55; 56; 57]. Specifically, the GW Ep values derived from all the three datasets mainly vary between 0.2 to 2 J/kg, and with each of the three datasets, the GW Ep derived is generally higher over the tropical latitude bands than over other regions during all four seasons, and is almost equatorial symmetric in MAM and SON in the tropics. Over the tropics, the distribution of GW Ep is consistent with that of deep convection [17]. In addition, due to the influences of orography and zonal wind, during JJA (the second row)/DJF (the fourth row) in the extratropical regions, the GW Ep values are generally higher over the winter hemisphere than the summer hemisphere [2; 53; 54; 57]. Furthermore, for all three datasets, in JJA (the second row) and SON (the third row) we can see a long leeward region of high Ep values exists, which stretches eastward from 70\({}^{\circ}\) W to around 180\({}^{\circ}\) E, covering the Southern Andes, Drake Passage, and the Antarctic Peninsula. The Ep values over this region reach the maximum in the southern hemisphere (SH) winter and weaken slightly in the SH spring. The eastward propagation of the orographic mountain waves, which is  
Figure 4: Global distribution of 3 years (from February 2013 to January 2016) GW Ep averaged seasonal means (row 1: MAM, row 2: JJA, row 3: SON, and row 4: DJF) over 20–35 km derived from different datasets. generated by the north-south distribution of the Andes, should contribute to the formation of this specific GW Ep distribution pattern [58; 59; 2]. The results shown in Figure 4 verify the validity of the procedure for deriving the GW Ep and the feasibility of combining the data from different RO missions in the present study. Moreover, a mixture of datasets from different RO missions was widely used for studying the GW activities in previous studies [21; 25; 37]. [PERSON] et al.