Climatological monthly mean lightning flash densities (LDENS) and convective cloud-top heights (CTH)
determined following Murray et al., JGR, 2012, doi:10.1029/2012JD017934 from MERRA-2 meteorology (1980-2019).

These fields are provided for user convenience when simulating more recent periods than current
lightning availability. However, users should always first check with Lee Murray via e-mail to
lee.murray@rochester.edu or at http://ees.rochestere.edu/atmos/data for the most recent available 
lightning products.

Use of climatological lightning flashes is more appropriate than the use of none. However, lightning is no
longer co-located with active convective transport of HOx-rich surface air, and the photochemical impact
is therefore underestimated. Therefore, time-varying lightning should always be preferred for science
applications.

- Lee T. Murray, U. Rochester