Having a computer compute refractive con-ditions is definitely faster than doing it by any of the other previously discussed methods. Programs to compute refractivity are available through the Geophysics Fleet Mission Program Library (GFMPL).

In addition to programs that compute refrac-tivity, there are numerous other programs related to refractivity. Different programs are available dependent on the type of computer system used.

The following list contains the names and descriptions of some of the refractivity programs available for the HP-9020, HP-9845 Option 275, and Zenith Z-120 desk top computers:

NAME DESCRIPTION

RIA This program processes radiosonde data, determines thermodynamic indices, and computes refractive index profiles.

ESM This program is capable of determin-ing the probable effectiveness of various U.S. ESM receivers against a predefined set of both U.S. and Soviet emitters. It computes the maximum intercept range of surface-based

ESM receivers for detection of predefine surface-system emitters under user-specified environmental conditions.

ECM The Electronic Counter Measures program is capable of determining the optimum locations and flight paths of attack and tactical jamming aircraft. The program evaluates the effective-ness of a jamming device against an enemy radar under given atmospheric conditions.

SSR This program determines detection ranges for surface search radars against predefine surface targets under user-specified atmospheric conditions.

HEPC This program generates a Historical Electromagnetic Propagation Condi-tions summary or a profile for a user-specified location and time of year (month).

The IREPS program is not listed in the GFMPL library; however, an advanced IREPS program is available with the Tactical En-vironmental

Support System found onboard most of our major carriers and battleships. I strongly recommend that whatever type of computer your command uses, you familiarize yourself with its capabilities and those of the above listed programs.