This file contains general guidelines for research vessels operating around GTMBA deep-sea moorings (both surface and subsurface). We recommend that chief scientists contact the GTMBA project prior to cruise departure for more specific information regarding a particular area of operations, including the positions of surface and subsurface moorings.

Some general information and guidelines for operating around these moorings are as follows:

1. A safe operating distance is at least 2 nautical miles downwind and/or downcurrent from a mooring.
2. CTD casts up to 1000 m depth can be made at this distance. CTD casts to greater than 1000 m depth should be made at distances proportionately greater than 2 nautical miles.
3. No expendibles (e.g. XBTs) within 2 nautical miles of a mooring.
4. No refuse or other jetsam thrown overboard within 5 nautical miles of the moorings.
5. Positions of Global Tropical Moored Buoy Array surface buoys can change over the course of a few days to a week (depending on the current regime) by up to 2 nautical miles. This is the diameter of a "watch circle" within which the buoy moves due to the stretch of the nylon mooring line.
6. The GTMBA Project Office is interested in obtaining ship measurements within a few miles of a mooring for quality control purposes. No special efforts need to be taken for collection of the shipboard data, except to follow the general guidelines above. The following measurements would be appreciated:
   • CTD casts to at least 500 m depth.
   • Shipboard ADCP data for comparison with moored ADCPs.
   • Shipboard weather observations (wind speed and direction, wet and dry bulb temperatures, cloud amount, precipitation, sea state, etc.).

For further information please contact:

atlasrt@noaa.gov
GTMBA Project Office