Vibrational Raman effect is widely used in atmospheric lidar systems, but rotational Raman present several advantages. We have implemented a new setup in the ultraviolet branch of an existing multiwavelength lidar system to collect signal from rotational Raman lines of Oxygen and Nitrogen. We showed that, with an appropriate filter wavelength selection, the systematic error introduced in the particle optical properties due to temperature dependence was less than 4 %. With this new setup, we have been able to retrieve aerosol extinction and backscatter coefficients profiles at 355 nm with 1-h time resolution during daytime and up to 1-min time resolution during nighttime.
<p>Este trabalho apresenta uma experiência de baixo custo de ondas estacionárias em uma corda. Ela usa um aplicativo de <italic>smartphone</italic> para sistema operacional Android, o “PA Tone”, que gera um sinal senoidal ao invés de um caro gerador de ondas comercial. Utilizamos um osciloscópio para analisar a onda senoidal gerada a partir do aplicativo para verificar se houve alguma mudança na forma de onda com o aumento da freqüência. Também usamos um osciloscópio para verificar a confiabilidade dos valores de frequência indicados nas configurações do aplicativo. O gerador de sinais “PA Tone” foi então usado com um oscilador mecânico ligado a uma corda, no clássico experimento de criação de ondas estacionárias, no qual a densidade linear da corda pode ser inferida. Este experimento mostrou que o aplicativo “PA Tone” é uma alternativa viável ao gerador de sinais comercial.</p>
In this study we present results of linear volume depolarization ratio profiles obtained by a depolarization lidar in operation in Natal, Brazil. The DUSTER system has 4 channels, namely: 1064, 532 s/p and 355 nm. This system is calibrated with a half-wave plate using the Δ90° methodology. The data obtained from this system is correlated with AERONET sunphotometer data, and, when available, CALIPSO satellite data. In addition a trajectory model (HYSPLIT) is used to calculate backward trajectories to assess the origin of the dust polluted air parcels. The objective is to create a transport database of Saharan dust.
LALINET is expanding regionally to guarantee spatial coverage over South and Central Americas. One of the network goals is to obtain a set of regional representative aerosol optical properties such as particle backscatter, extinction and lidar ratio. Given the North-South extension and influence of distinct airmass circulation patterns it is paramount to distinguish these optical parameters in order to gain better perfomance in radiation transfer models. A set of lidar ratio data is presented.
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