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IARD article at the 3rd International IR
Target, Background Modeling&Simulation
Workshop, ONERA, Toulouse, |
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Investigation of natural environment impact on the
target’s surface and its signature. Yossi Bushlin,
Alex Lessin, |
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abstract Dew
and dust layers on target's surfaces can significantly affect the thermal
state and IR signature of targets placed in desert environments, which are
characterized by extremely varying environment loads (solar, ambient air
temperature, etc.). An attempt was made to implement RadThermIR software for
the prediction of temperature and signature of the benchmark object CUBI
covered by dew or dust layers. The
effect of radiation overcooling at clear-sky nights leads to the temperature
fall on target surfaces looking at sky direction. Sometimes this fall is deep
enough to cause dew precipitation. A dew layer may arise on the target
surface if its temperature falls below a dew point value. Water precipitation
causes the cessation of the surface temperature fall and its stabilization
(water condensation releases significant latent heat and this prevents the
following temperature decrease). RadThermIR
scripts were implemented for the definition of environment conditions for the
target, which lead to the dew precipitation, and for the calculation of the
precipitation water amount. Such behavior of dew water leads to a time-shifted
phase in the target thermal state and, accordingly, in its IR signature. Dust
layers on the target's surface affect optical properties of the surface and
may serve as additional thermal insulation when they are thick enough. Both
these effects may change the target's temperature and signature
distributions. Parametric calculations by RadThermIR were performed for
various dust thickness and optical properties. This data was used in the
contrast target/background analysis. The
obtained dust/dew layer results will be used in the planning of the next CUBI
experiment in natural desert environments. |