At the 2008 NDACC Steering Committee meeting, a decision was made to remove the "Primary" and "Complementary" designations of NDACC measurement sites / stations. These original terminologies were instituted at the inception of the Network for designating a minimum of five stations with long-term measurement commitments, representing the major geographical regions of the globe (i.e., Arctic, Northern Hemisphere (NH) Midlatitudes, Tropics, Southern Hemisphere (SH) Midlatitudes, and Antarctic). At that time, some of these stations were instituted as a combination of several sites, each with various types of instrumentation, such that the sum of all sites comprising a Primary Station included a fairly complete suite of NDACC (then NDSC) instrument types. It was anticipated that numerous Complementary Stations / Sites, at which a smaller number of Network-approved instruments were in operation, or at which the measurement commitment was for a shorter period of time, would augment these Primary Stations.
After nearly two decades of successful Network operations, the need for these designations no longer exists. In fact, their use now leads to some confusion and occasional misunderstanding. For example, some Complementary Sites have built up suites of instruments that are more comprehensive than those at some of the Primary Station sites. And many Complementary Stations / Sites have measurement commitments that are just as long-term as those at Primary Stations.
Further, these designations have occasionally been misinterpreted to imply that the measurements at and data from Complementary Stations are of lesser quality than those at Primary Stations, whereas the requirements to become affiliated with NDACC are identical for the two categories. There is no reduction in the expectations of instrument performance or data quality.
Lastly, some NDACC Principal Investigators felt that a Complementary designation was less advantageous than a Primary designation in justifying a long-term measurement need to their institution or funding agency.
From now on, all sites and stations will be designated simply as NDACC-approved measurement sites / stations. The NDACC Measurements and Analyses Directory is being revised to reflect this change, and measurement locations will be listed under one of the following groupings: NH High Latitudes, NH Midlatitudes, NH Subtropics and Tropics, SH Subtropics and Tropics, SH Midlatitudes, and SH High Latitudes.