Influence of the AMO and its modulation of the ENSO effects on summer precipitation in Mexican coastal regions

Due to its geographical location and interaction with the two largest oceans, Mexico's climate is strongly influenced by various climatic oscillations. Therefore, association studies between climatic indices and Mexico's climate have scientific and practical importance. Teleconnection patterns have been reported between summer precipitation and various climate oscillations. For the Atlantic Multidecadal Oscillation (AMO), results are not totally coincident, and modulation of El Nino Southern Oscillation (ENSO) effects has not been explored. Correlation analyses between the AMO and Oceanic El Nino Index (ONI)3.4 with summer precipitation (June-September) at individual 203 weather stations in Mexican coastal zones were carried out, and average precipitation was compared according to AMO phases and their combinations with ENSO events. With AMO+, it tends to rain more in the northern Yucatan Peninsula, from Chiapas to Jalisco, and in the southern California Peninsula; with AMO-in Tamaulipas, Sonora and northern California Peninsula. The AMO modulates ENSO effects; ONI correlations pattern strengthens with AMO+. El Nino summers are less dry with AMO-on the Atlantic coast, Sonora and northern California Peninsula; on the Pacific coast, alternating bands are observed. With AMO-, La Nina summers tend to be wetter toward the south with AMO+ and toward the north with AMO-. These changes can be related to variations in the surface and low-level wind regimes previously reported in the literature.