49 research outputs found
A surface acoustic wave frost-point hygrometer for measurements of stratospheric water vapour
No full textConventional frost-point hygrometers observe frost on their cold point by optical means [1,2,3], thereby requiring several micrometres of ice to form. We have developed a new hygrometer which uses surface acoustic wave (SAW) devices to determine when condensation has occurred. At the oscillation frequencies used (hundreds of MHz), the SAW device is capable of responding to a few monolayers of condensate, increasing sensitivity and reducing response time. The principle of the method has been demonstrated in the laboratory by calibration against a chilled mirror frost-point hygrometer, and the sensor has had a number of technical balloon flights. Here we describe the principle of the technique and present some preliminary results
Solid state ozone sensors for the future: light weight, low power and continuous operation
No full textImproved air-mass factors for ground-based total NO2 measurements: a sensitivity study
No full textWe present an overview of exisiting problems in air-mass factor calculations for NO2 vertical column measurements by UV-visible ground-based spectrometry, Sensitivity studies made using different radiative transfer models allow us to identify and to quantify sources of uncertainties in clculations, and domiment effects are multiple scattering (4%) and profile variations due to diurnal (10%) and seasonal changes (16%
