Flask measurements from two GC-ECD systems are provided here in two overlapping
categories. "Otto" was a flask system in operation from 1995 to as late as 2021
depending on the trace gas being measured. Measurements specific to Otto are
provided in the subdirectory of the same name. 

Otto was replaced in 2021 by a third-generation flask GC-ECD system called FE3.
FE3 measurements are provided in combination with the older Otto measurements
in the directory called "fECD" (i.e. flask ECD). Measurements from both systems
are packed into datafiles differentiated by ground site. 

The older Otto-only files will remain available for now. However, at some point
in the next year or two, we will remove the Otto subdirectory and continue
moving forward only with the new fECD files.