STABLE ISOTOPIC EVALUATION OF PRECIPITATION FROM UNEXPECTED STORMS, CENTRAL MEXICO

Isotopic analysis is considered to be the one of the most reliable study to evaluate the meteorological events such as sporadic weather conditions. Several studies have shown that isotopic data can be used to determine the trajectory of meteorological phenomena such as cold fronts or winter storms that cross certain areas. In March 2016, a winter storm was formed as a result of a cold-core low system and a jet stream in the northern part of Mexico; 12 of the 32 states in Mexico were affected by snow, sleet, heavy rains and gusts of wind, road closures, power failures, as well as fallen trees and spectacular advertisements. Although just 20% of the winter storms are strong enough to affect the central part of Mexico, the aforesaid winter storm reached the central part producing adverse effects. Successively, the present study was carried out to evaluate the isotopic signatures of the winter precipitation event. Monthly precipitation samples were collected from four sites (Mexico City, Pachuca, Tula and Tulancingo) in the central part of Mexico from March to May 2016. The results showed enrichment of light isotopes, which is associated with the decrease in the contents of ∂¹⁸O and ∂D in precipitation for altitudinal increase. The observed variations are also due to the fact that the upstream precipitation is formed from steam masses which are progressively fragmented isotopically by the loss of heavy isotopes in the preceding rains, where the temperature is less and fractionation of vapor condensation is high. The present work is considered to be the first reported work in Mexico in stable isotopic studies and is the beginning of a monitoring network which will let us explore the prospective research abilities in isotopic signatures in Mexico.

Keywords: Stable isotopes, Winter storm, Central Mexico, Precipitation