Global Lightning Flash Counts from ISS LIS Data

[xinamai_pnnl]

Hi I am a new user of the ISS LIS lightning data and also a new member of this forum. I am working with the ISS LIS lightning data and followed this workflow to download and extract the lightning flash locations:
https://www.earthdata.nasa.gov/learn/data-recipes/iss-lis-lightning-flash-___location-quickview-using-python-2-7-gis

According to this workflow, the lightning data should be here:
https://ghrc.nsstc.nasa.gov/pub/lis/iss/data/science/nqc/nc/
but I did not see any data at this path. Instead, I downloaded from here:
https://ghrc.nsstc.nasa.gov/pub/lis/iss/data/science/final/nc/

I downloaded all the data from 2017-2023, and extracted the lightning flash locations using the python script modified from this data recipe:
https://gitlab.com/NASA-GHRC-DAAC/data-recipes/-/blob/master/ISS_LIS_FlashLoc_Quickview.py?ref_type=heads

The annual total global flash counts from my output are as follows:
isslis_flashloc_20170301_20180101: 764303
isslis_flashloc_20180101_20190101: 967754
isslis_flashloc_20190101_20191231: 959854
isslis_flashloc_20200101_20210101: 940514
isslis_flashloc_20210101_20220101: 939891
isslis_flashloc_20220101_20230101: 919965
isslis_flashloc_20230101_20231116: 956203

These numbers are much smaller than the global flash rate of 44 flashes per second (~1.4 billion per year) based on these two papers: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JD032918
https://doi.org/10.1175/BAMS-D-14-00193.1

I am not sure where the issue lies. Did I use the wrong dataset? Any help, suggestions, or thoughts would be much appreciated. Thank you very much!

[gstano]

Hello. Thank you for reaching out.

Checking what you have posted, I believe you have the correct data. The main issue is due to how the lightning are being observed. The LIS instrument was in a low Earth orbit. Therefore, it does not observe the same ___location on the Earth continuously. As a result, the value that you have quoted (1.4 billion flashes per year) is an estimate based on the total flashes observed by the instrument.

The journal article, Global frequency and distribution of lightning as observed from space
by the Optical Transient Detector (https://doi.org/10.1029/2002JD002347), describes the process using the older Optical Transient Detector (OTD) that was the predecessor of the LIS instrument.

I hope that helps clarify things a bit. Please do not hesitate to reach out with additional questions.

[xinamai_pnnl]

Hi, thank you so much for your reply (and sorry for the late response — I thought I’d get an email notification when I received one). Your explanation and the paper you shared were really helpful in helping me understand how to estimate total flashes based on what the instrument observes. If I understand correctly, the estimated total flashes for each grid cell can be calculated as:

estimated total flashes = observed flashes / observation time

I have another question — I’m guessing the answer is probably no, but I thought I’d ask anyway:
Is there any database that continuously records flash events across the contiguous United States?

Thanks again, and I hope you have a great holiday weekend!