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Seeking reasons for the differences in size spectra of electrified storms over land and ocean
Author(s) -
Bang Sarah D.,
Zipser Edward J.
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025150
Subject(s) - precipitation , climatology , storm , mesoscale meteorology , lightning (connector) , convection , forcing (mathematics) , environmental science , tropical cyclone , thunderstorm , scale (ratio) , mesoscale convective system , meteorology , convective storm detection , atmospheric sciences , geology , geography , physics , power (physics) , cartography , quantum mechanics
This study expands upon the results of Bang and Zipser (2015), which demonstrated that oceanic precipitation features with lightning tended to be over 10 times larger and more stratiform than those over continents and suggested the hypothesis that some form of external forcing is acting in ways that lead to both larger features and stronger updrafts over tropical oceans. In this work, we evaluate this hypothesis by using reanalysis data to compare large‐scale vertical motion and thermodynamic data for radar precipitation features in archetypal land and ocean regimes in the Congo and Central Pacific. We then expand our study to the entire Tropical Rainfall Measuring Mission (TRMM) domain (35°S to 35°N) over all seasons. Over the ocean, there is a tendency for stronger large‐scale upward motion, linear organization of the convective region, and larger precipitation areas in systems with lightning. By comparison, over land, features with lightning tend to be smaller, in environments of higher instability, with little difference in large‐scale vertical motion. Expanding our analysis to 21 different regions, we highlight those in which seasonal synoptic patterns and water temperature gradients lead to distributions that are exceptions to the findings that ocean storms with lightning tend to be larger and more mature than land storms with lightning. These findings support the hypothesis that most land storms have updrafts sufficiently strong to develop lightning in their early growth stages, while ocean storms require large‐scale ascent and growth into mesoscale convective systems before convective scale updrafts become strong enough to provide the necessary conditions for lightning.