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The FATMOSE trial (False Bay Atmospheric Experiment) is a continuation of the cooperative work between TNO and
IMT on atmospheric propagation and point target detection and identification in a maritime environment (South Africa).
The atmospheric transmission, being of major importance for target detection, was measured with the MSRT multiband
optical/IR transmissometer over a path of 15.7 km over sea. Simultaneously a set of instruments was installed on a midpath
lighthouse for collection of local meteorological data, including turbulence, scintillation, sea surface temperature
and visibility. The multiband transmission data allow the retrieval of the size distribution (PSD) of the particles
(aerosols) in the transmission path. The retrieved PSD's can be correlated with the weather data such as windspeed, wind
direction, relative humidity and visibility. This knowledge will lead to better atmospheric propagation models. The
measurement period covered nearly a full year, starting in November 2009 and ending in October 2010. The False Bay
site is ideal for studies on propagation effects over sea because of the large variety of weather conditions, including high
windspeed, expected from the South East with maritime air masses, as well as Northerly winds, expected to bring warm
and dry air from the continent. From an operational point of view the False Bay area is interesting, being representative
for the scenery around the African coast with warships in an active protecting role in the battle against piracy. The yearround
transmission data are an important input for range performance calculations of electro-optical sensors against
maritime targets. The data support the choice of the proper spectral band and contain statistical information about the
detection ranges to be expected. In this paper details on the instrumentation will be explained as well as the methods of
calibration and PSD retrieval. Data are presented for various weather conditions, showing correlations between different
parameters and including statistical behaviour over the year. Examples will be shown of special conditions such as
refractive gain, gravity waves and showers.
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