7 research outputs found
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Temperature corrections for the VIZ and VAISALA radiosondes
The NWS VIZ radiosonde and the Vaisala RS-80 radiosondes are used worldwide to obtain upper air measurements of atmospheric temperature and moisture. The temperature measured by each sensor is not equal to the atmospheric temperature due to solar and infrared irradiation of the sensor, heat conduction to the sensor from its attachment points, and radiation emitted by the sensor. Presently, only the RS-80 radiosonde applies corrections to the sensor temperature to compensate for these heating sources, and this correction is only considered to be a function of solar angle and pressure. Temperature correction models VIZCOR (VIZ sonde) and VAICOR (Vaisala RS-80 sonde) have been developed that derive the atmospheric temperature from the sensor temperature, taking into account all significant environmental processes that influence the heat transfer to the sensor. These models have been validated by comparing their corrected profiles with atmospheric temperature profiles derived from the NASA multi-thermistor radiosonde. All three radiosondes were flown on the same balloon during the PREFRS radiosonde intercomparison. Excellent agreement has been found between all profiles up to an altitude of 30 km. Since the significant error sources in the VIZCOR, VAICOR and multi-thermistor techniques are largely independent, agreement between all profiles, implies the corrected sensor profiles are providing an unbiased estimate of the true atmospheric temperature
Analysis of Lead in Soils Adjacent to an Interstate Highway in Tampa, Florida
In order to assess the amount and distribution of lead pollution in soils adjacent to a major interstate highway serving the city of Tampa, Florida, a total of 224 samples were collected from 32 transects perpendicular to the roadway. The lead content was measured using atomic absorption spectrophotometry. The highest levels of lead were found at distances of 81, 243, and 729 cm from the road. The results show that there is a weak negative correlation between soil lead and the distance from the roadside, as well as with traffic density. The weakness of the relationship is a result of confounding variables such as turbulence and other microclimatic factors, downslope movement of soils overtime, and human action such as construction and highway landscaping. Nevertheless, over one-third of the samples collected in the study area contain more than 500 μg g−1 lead, levels considered to be hazardous by the United States Centers for Disease Control and the Environmental Protection Agency