Applying Satellite Aerosol Retrievals for Improved Lightning Predictions

Although aerosol enhancement of lighting activity has been recognized, whether and how aerosol observations can be used for improving lightning prediction remain unclear. To test whether detailed knowledge of the background aerosol state can improve predictability of lightning (initiation and characteristics), we first examine whether or not the currently available satellite aerosol products are applicable to provide aerosol properties for lightning predictions, and then study the statistics of aerosol states and lightning features as well as the advantage of awareness of aerosol states for predicting individual lightning cases.

The Multi-angle Imaging Spectroradiometer (MISR), Moderate-resolution Imaging Spectroradiometer (MODIS), and Ozone Monitoring Instrument (OMI) aerosol optical depth (AOD) retrievals are compared over the Houston area. The results show that due to a higher spatial coverage and temporal resolution of available aerosol retrievals, Terra and Aqua MODIS aerosol products have greater potential for improving lightning predictions than those of MISR and OMI alike. To further test if satellite aerosol retrievals can distinguish the differences between the “high” and “low” aerosol loadings, we therefore compare Terra and Aqua MODIS AOD retrievals with the ground-based AERONET AOD retrievals for the 20 cleanest days and 20 most polluted days in 2011 over Houston and in 2008 over northern Alabama, where long-term lightning observations have been archived. The results show that MODIS compares well to AERONET in both clean and polluted cases even for the case of a complicated urban environment (Houston). The comparisons between MODIS and AERONET are best when the AERONET data are averaged over the hour before and the hour after the satellite overpasses, than when averaged over the entire day. This implies that the satellite is able to capture the current state of the atmosphere and that diurnal aerosol variability, at least over Houston and northern Alabama, can be an important consideration in this analysis.

Lightning Mapping Array (LMA) observations and MODIS aerosol retrievals are then used to show the aerosol-lightning statistics over northern Alabama from 2002 to 2013. Moreover, individual lightning cases over Houston and northern Alabama in “high” and “low” aerosol loadings are selected from the Earth Networks Total Lightning Network (ENTLN) and LMA observations to study the usefulness of knowing AOD and particle size for lightning predictions in terms of flash density and initialization.