Parameterizations for global thundercloud corona discharge distributions

Abstract. Four parameterizations have been developed to simulate global distributions of thundercloud streamer corona discharges (also known as Blue LUminous Events or BLUEs) mainly producing bluish optical emissions associated to the second positive system of N₂ accompanied by no (or hardly detectable) 777.4 nm light emission. BLUEs occur globally between about 7 and 12 times less frequently (Soler et al., 2022) than lightning flashes. The four schemes are based on nonlinear functions of the cloud top height (CTH), the product of the convective available potential energy (CAPE) and total precipitation (TP), the product of CAPE and specific cloud liquid water content (CLWC), and the product of CAPE and specific cloud snow water content (CSWC). Considering that thunderstorms occur on hourly timescales, these parameterizations have been tested using ERA5 hourly data (except for CTH, not available in ERA5) for the meteorological variables considered, finding that the proposed BLUE schemes work fine and are consistent with observations by ASIM. Moreover, the parameterizations have been implemented in a global chemistry-climate model that generates annual and seasonal global distributions for present day and end of 21st century climate scenarios. Present day predictions are in good agreement with recent observations by the Atmosphere Space Interaction Monitor (ASIM).