Lightning Flash Rate in the Lake Maracaibo, Venezuela Related to Sea Surface Temperatures and Tropospheric Air Flow

Abstract

Northern Venezuela's Lower Maracaibo Basin (LMB) has the highest lightning flash rate (LFR) density in the world. The area receives approximately 200 flashes per km^2 annually. Local topography as well as local and global scale climate drivers have been shown to influence the frequency of the lightning storms, known as "Catatumbo Lightning". This research focuses on influences on LFR in the LMB by local and global sea surface temperatures and elements of local tropospheric air from 1996--2015. Sea surface temperature and tropospheric air data from the National Oceanic and Atmospheric Administration are used in Spearman rank correlations to determine relationships to LFR data (Global Hydrology Resource Center) in the basin. Oceanic regions were analyzed, including; the Caribbean Sea, the Pacific Ocean (El Niño Region) and the Atlantic Ocean (Atlantic Meridional Mode region). Four tropospheric elements were analyzed, including temperature, relative humidity, u-wind velocity, and v-wind velocity. All elements were analyzed at all mandatory pressure levels (1000 mb -- 200 mb). The data sets are on a 2.5° x 2.5° gridded scale, with the exception of SST which is 1° x 1°. The data are analyzed on annual and seasonal temporal scales. Many statistically significant correlations were found between LFR and all variables included. Positive relationships were found between SST and LFR in the Caribbean Sea during the warmer seasons and negative relationships were found in the tropical Pacific on an annual scale. Many positive relationships were found between LFR and temperature, over the Caribbean and northern South America, mainly within the planetary boundary layer. There were also a large negative correlation extent between LFR and temperature over South America on the 200 mb level. Positive correlations were found between LFR and relative humidity over the Atlantic Ocean, east of Cuba during the warmer seasons and negative correlations were found during all seasons, mainly to the east of South America into the Atlantic Ocean. Positive relationships between LFR and u-wind were found over the Atlantic, Caribbean, and South America during all seasons at various pressure levels. Between June and November, negative correlations were found in the upper atmosphere to the east of the Lake Maracaibo Basin (LMB) extending into the Atlantic. Positive correlations were found over the LMB between 850 mb and 500 mb between December to May. Many more correlations were found. Influencing factors may include the Western Hemisphere Warm Pool, the El Niño Southern Oscillation, the low-level jets and