# Spatio-Temporal Distribution of Deep Convection Observed along the Trans-Mexican Volcanic Belt
## 5 Conclusions
To our knowledge, the midsummer drought is observed and documented for the first time using satellite-observed deep convective cloud frequencies as an identification marker in the region. Whereas the first peak in the DDC frequency and precipitation can be associated with the moisture advection from the oceans [66; 68], the second peak observed in September might be affected by the increase in tropical cyclone activity [60], as mentioned before. Another relevant outcome is the solid relationship between the terrain configuration and the observed DCC frequency with the higher correlation coefficient of 0.77 computed along a cross-section with the highest elevations. The complex terrain of the TMVB seems to be essential for the generation of deep convective clouds by forced convection and significantly controls the satellite-observed DCC and extreme precipitation frequencies. Similar results have been reported before in central Mexico using model simulations [69]. Moreover, observations from one radar site covering Mexico city show a similar behavior [27]. Due to their geographical position, the mountains of the TMVB, located in central Mexico, have a direct influence on wet air masses from both the Pacific Ocean and the Gulf of Mexico [66; 70] and dry air masses related to the cold fronts propagated from the north [31; 61]. This is also reinforced by the analysis from the sub-region perspective, which provides a first insight into the relative impact of different local and large-scale conditions and accompanying physical processes that lead to the observed spatio-temporal variability of deep convective clouds and associated severe weather. The high cloudiness over all of the Gulf of Mexico allows the identification of the possibly important role of sea breeze [52] and the position of the mountains (perpendicular to moisture advection) for the eastern portion of the Neotropical sub-region. Cold fronts and Fohn effects [34; 55] influence the Nearctic sub-region; i.e., drylands in the north portion of the domain. The analysis of the behavior of convective events allowed the identification of similarities across the Transition sub-region. This relation is associated with the influence of moisture advection processes from the Pacific Ocean and the Gulf of Mexico [66]. The greatest observed DCC frequency in this sub-region seems to be a result of complex interactions between terrain, moisture fluxes and relatively cold air masses from the north. Finally, the analysis of the inter-annual variability of observed deep convective clouds shows years with clearly positive and negative anomalies, though both the variability within the domain for one year and the domain-averaged variability within one year can be as large as between years. A future study regarding this topic will benefit from a temporal extension of the observational datasets. Even though the development of deep convection here seems to have a strong regional component (i.e., terrain configuration), the moisture availability for their initiation is related to changes in wind patterns. Changes in the weather patterns can be associated with the El Nino Southern Oscillation, the Pacific Decadal Oscillation or the Madden-Julian Oscillation [64; 71; 72; 73]. In this sense, a larger dataset is required to investigate the relative impact of these climatic oscillations on DCC frequency, and future work should be focused on this topic as well. Considering that the independent types of observational datasets used in this study show a clear relationship, this represent an encouragement to continue and extend these kinds of satellite-based studies on deep convective clouds and associated severe weather, especially in situations with an absence of large-scale radar coverage, as is the case for Mexico. In that sense, this study contributes considerably to a first characterization of the environment in which extreme weather phenomena occur.