Visualization of small density fluctuations of the atmosphere with spatial frequency filters

Rosa, Bogdan; Sagan, Arkadiusz; Haman, Krzysztof E.; Szoplik, Tomasz

doi:10.1117/12.509599

Cited by 3 publications

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“…Compared with the older version 2,3 the main improvement is a new shape of the wind shield. The new shield protects the sensing element (∅ = 2,5 µm thermo-resistive tungsten wire) more efficiently against the impact of cloud droplets that affect the temperature measurement 4,5 . The wire resistance increases with temperature.…”

Section: Introductionmentioning

confidence: 99%

Simulation and analysis of dynamic heating in the ultrafast aircraft thermometer measurements

et al. 2005

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The ultrafast aircraft thermometer is an airborne device designed for measuring temperature in clouds with centimeter spatial resolution. Its sensor consists of 5mm long and 2.5µm thick thermo-resistive wire protected against impact of cloud droplets by a shield in the form of a suitably shaped rod, placed upstream. However the disturbances of airflow around this rod result in noise in the temperature record. Suction applied through slits located on both sides of the rod reduces the noise generated by vortices shed from the rod and lowers the probability of droplet-wire collisions. Our recent theoretical analysis and numerical simulations led to optimization of this device and additionally clarified the role of the sampling method in processing of the analogue output of the thermometer. In this paper we try to deepen our understanding of the nature of the noise as well as to improve calculations of the corrections connected with the dynamic heating. For this purpose we have done extensive three-dimensional numerical simulations of the airflow around the protective rod and the sensing wire, which permitted precise computation of dynamic heating and showed how applying the suction removes the thermal boundary layer from the rod and damps the sources of the noise.

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Section: Introductionmentioning

confidence: 99%

Simulation and analysis of dynamic heating in the ultrafast aircraft thermometer measurements

et al. 2005

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Optimization of the atmospheric temperature field measurements

et al. 2004

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Three filters for visualization of phase objects with large variations of phase gradients

2009

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We propose three amplitude filters for visualization of phase objects. They interact with the spectra of pure-phase objects in the frequency plane and are based on tangent and error functions as well as antisymmetric combination of square roots. The error function is a normalized form of the Gaussian function. The antisymmetric square-root filter is composed of two square-root filters to widen its spatial frequency spectral range. Their advantage over other known amplitude frequency-domain filters, such as linear or square-root graded ones, is that they allow high-contrast visualization of objects with large variations of phase gradients.

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Visualization of small density fluctuations of the atmosphere with spatial frequency filters

Cited by 3 publications

References 0 publications

Simulation and analysis of dynamic heating in the ultrafast aircraft thermometer measurements

Simulation and analysis of dynamic heating in the ultrafast aircraft thermometer measurements

Optimization of the atmospheric temperature field measurements

Three filters for visualization of phase objects with large variations of phase gradients

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