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Quantifying the possible existence of undocumented Atlantic warm‐core cyclones in NOAA/CIRES 20th Century Reanalysis data

Prior to 1966, the lack of satellite imagery led to an unknown number of tropical cyclones (TCs) in the Atlantic Basin remaining undetected by traditional surface observational networks. Previous research has shown that this historical undersampling has led to difficulties in interpreting long‐term trends in TC activity. In this study, advances in global reanalysis methods are used to further guide existing TC Best‐Track revision efforts, specifically for the pre‐satellite era. First, a series of atmospheric proxies of TC passage in the NOAA/CIRES 20th Century Reanalysis dataset are constructed for the satellite‐era. Next, similar magnitude signatures (not corresponding to known Best‐Track TCs) are identified in the pre‐satellite era and subjected to further synoptic verification. Surface observations are used to categorize candidate events into three confidence bins. A small but significant number of the candidate events are cases that warrant further examination by ongoing reanalysis efforts. As this method shows promise for use in other TC basins around the world, preliminary results suggest that this technique may potentially lead to a more complete climatological record of global TC incidence and an improved understanding of long‐term trends in activity.