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Air-sea interaction processes play a dominant role with respect to detection ranges of shipborne radar and infrared sensor
systems. Especially in the littoral most often temperature and humidity gradients affect propagation paths and are the
reason for abnormal phenomena such as ducting or mirage. Besides refractivity, spray and aerosols ejected from the sea
surface can further degrade the quality of shipborne surveillance systems. Thus environmental effects might seriously
hamper ship self defense.
During the Ligurian Air-Sea Interaction Experiment (LASIE '07 - 16.06.-26.06.2007) the Federal Armed Forces
Underwater Acoustics and Marine Geophysics Research Institute (FWG) carried out simultaneous in-situ measurements
of meteorological and oceanographic parameters to study air-sea interaction processes with respect to littoral boundary
layer variability.
The characterization of the environment included both, in-situ measurements of atmospheric and sea surface parameters.
Investigations were carried out on board RV PLANET, RV URANIA and at the ODAS-Italy1 buoy of the Italian
National Council of Research (CNR). On board RV PLANET the sea surface and meteorological conditions were
analyzed by two multi-sensor buoys, ship sensors and radiosondes. Emphasis was given to the vertical structure of the
Marine Boundary Layer (MBL) and its variability. It was analyzed by a one lense lidar ceilometer CL31, a tethersonde
system TT12 and radiosondes RS92 (Vaisala). The latter were launched every three hours. The TT12 consisted of three
radiosondes, which could be adapted to separate altitudes of special interest. The experiment was characterized by
changing meteorological conditions resulting in offshore and onshore blowing winds. In the first case the air temperature
TAir was higher than the sea surface temperature TWater leading to a very stable surface layer. This situation was
associated with a strong temperature inversion and a very clear atmosphere with a visibility of about 70 km. The second
case (TAir<TWater) was dominated by convection processes and a pronounced aerosol production. Good correlation was
found for the Mixing Layer Height (MLH) by the lidar ceilometer and the radio soundings.
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