plus any apparent technical and operational issues or constraints. In addition, this chapter addresses shortfalls potentially affecting current and planned CMW systems, and it briefly describes other technical improvements for augmenting fleet offshore MCM capabilities.
Importance of Environmental Data
A few of the key environmental parameters affecting mine warfare operations include:
Bathymetry. Bathymetry determines options for addressing mine threats and can constrain various MCM techniques. For example, there are limits to the water depth at which explosive ordnance disposal personnel can operate, and bottom depth, slope, and roughness conditions affect the ability of mechanical sweep systems to counter close-tethered mines.
Sound propagation. Complex thermal distributions and sound velocity profiles and losses at the boundaries (bottom, sea surface) significantly affect acoustic propagation and hence the detection ranges achievable with various types of sonars.
Bottom type and composition. Bottom type (e.g., hard rock, firm sand, soft mud) largely determines the levels of bottom reverberation, clutter, and roughness, and bottom sediment type and thickness (along with bottom currents) establish the likelihood of mine burial.
Nonmine minelike bottom object (NOMBO) density. Debris and small bottom features influence the mine densities perceived by various active sonars. If too many minelike bottom objects are present in an area and alternate routes are not feasible, hunting there with sonars or mammals is likely to be very slow and sweeping may be necessary. This parameter is highly sensitive to the characteristics of individual sonars including their spatial resolution and signal processing algorithms.
Tides and currents. Currents and tidal conditions can affect the performance of divers or remote vehicles, or even the ability of warships to do controlled, slow-speed maneuvers to avoid detected objects that may be mines. Tidal currents and turbulence also cause natural fluctuations in pressure that can trigger pressure influence mines and promote mine burial.
Sea state. High sea state and wind conditions can increase ambient noise and surface reverberation and clutter; high sea states can also hamper seakeeping and MCM operations by various units and associated systems.
Water clarity. Optical sensor performance (airborne or undersea) can vary appreciably depending on the optical clarity of the sea (e.g., affecting laser propagation and the use of cameras and/or divers to identify minelike objects as either mines or nonmines).