Analysis of South Atlantic Anomaly Influence on Low‐Earth Orbit Lightning Observations

Abstract The low‐Earth orbit Optical Transient Detector (OTD) and Lightning Imaging Sensor (LIS) instruments, spanning 1995–2023, have spatiotemporal patterns within their metadata that are consistent with the South Atlantic Anomaly (SAA). While the SAA had a known influence on these instruments, this study details new variability and impacts. A large volume of radiation‐triggered events can cause the First‐In First‐Out (FIFO) buffer overflow to occur, which temporarily “blinded” LIS and OTD. Patterns of FIFO and the instrument status flags displayed an evolving intensity and areal extent of SAA interference, affecting climatological view‐time records. The interference had a strong relationship to the sunspot number with Pearson correlation values of −0.50 and −0.48 ( p < 0.0001 for both) for the view‐time anomaly and FIFO occurrence, respectively, over the entire record. For the LIS instruments, the size of the affected region was zero in their early respective records then peaked at millions of square kilometers during solar minimum. LIS on the Tropical Rainfall Measuring Mission (TRMM, TLIS) observed a seasonal cycle with the worst interference during the JJA season and least during DJF. All three instruments found a westward drift of the SAA, at 0.54° y −1 , 0.22° y −1 , and 0.70° y −1 for TLIS, OTD, and International Space Station LIS (ILIS), respectively. However, while both LIS instruments noted a northward drift, OTD had a southward drift. The influence of external factors including the thermosphere, properties of the radiation, orbital characteristics, and hardware degradation remain to be examined to describe the implications for the SAA itself.