oceanic conditions. The output generated by the SSP generator module is a sound speed vs. depth profile from the sea surface to the ocean bottom, which is essential in  making  accurate  sensor  range  predictions. APPLICATION The SSP module yields tactically useful information when a basic knowledge of underwater acoustics is applied  to  the  products.  This  information  can  be  used to  make  decisions  regarding  sensor  depth  settings, optimum  frequency  bands  for  search,  and  buoy  pattern. By examining the sound speed profile and other module output, the experienced ASW technician can learn a great deal about available acoustic transmission paths and  sensor  performance. The  optimum  frequency  for  detection  in  the  sonic layer may be determined from the sonic layer cutoff frequency calculated by SSP. The presence, quality, and accessibility of a sound channel to available sensors can be identified from the generated sound speed profile. CZs may exist where the sound speed at the bottom exceeds the sound speed at the source depth, providing there is an experienced analyst with a means to estimate CZ range and width from the shape of the sound speed profile. LIMITATIONS AND ASSUMPTIONS The restrictions as well as the principles taken for granted in using the SSP product areas follows: l SSP allows the operator to review and correct manual  input.  This  prevents  aborting  runs  due  to operator-input  errors. The SSP merging routine combines BT data with a historical  profile  to  form  a  surface-to-bottom temperature/salinity  profile.  The  resulting  merged profile consists of the BT data in the upper portion and the historical profile, modified by the merge, in the lower portion. The lower portion extends from the first depth value below the available BT data to the bottom depth.  Output  from  this  program  is  classified  and should  be  labeled  as  required. The first portion of this chapter was devoted to computer aids generated by the TESS 3 configuration. Now let’s look at the BT collective product. BATHYTHERMOGRAPH COLLECTIVE PRODUCT LEARNING   OBJECTIVES Identify applications, limitations, and assumptions of the bathythermograph collective product. FLENUMMETOCCEN  is  capable  of  providing synoptic  (real-time)  and  historical  bathythermograph (BATHY) observation collectives for a specified area and timeframe. Pre-1985 BATHYs are stored in the Master  Oceanographic  Observation  Data  Set  (MOODS) with   over   4.6   million   observations.   More   recent BATHYs,  which  have  not  yet  been  added  to  the MOODS data base are stored in a separate archive in a format called 4D. The last 12 hours of BATHYs are stored on the operational computers. Output from this program is classified and should be labeled as required. . In deep-water areas, on-scene bathythermograph (BT) data that do not extend below 200 m should be used APPLICATION with caution. l Where no historical profile data are available, operator   entry   of   surface-to-bottom   depth/ temperature/salinity  sound  speed  values  is  required. FUNCTIONAL DESCRIPTION The SSP module provides the operator with a sound speed profile that is representative of local oceanic conditions.  This  module  also  provides  a  link  between environmental  variability  and  sonar  performance.  An on-scene  BT  and  a  historical  depth/temperature/salinity profile are used to compute the sound speed profile and related  data. The  BATHY  collective  product  provides  a convenient means for an activity or unit to retrieve historical data and/or receive synoptic data for a specific area/time period. The product can be used for onboard prediction   systems   or   for   exercise   planning/ reconstruction. LIMITATIONS AND ASSUMPTIONS The synoptic BATHY collective is a simple and easily transmittable product that provides detailed temperature/depth  data. 8-9