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The article focuses on the design and use of the new ultraviolet (UV) photometer for in situ measurement of atmospheric ozone (O 3) from research aircraft. It says that a polarization optical-isolator configuration is used to fold the UV-beam within the absorption cells. It also mentions that the photometer has high accuracy, fast sampling rate, and excellent precision.

A chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O) at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS). A low-pressure flow of sample air passes through an ionization volume containing an -particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+) from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument was calibrated every 45 min in flight by introducing a series of H2O mixing ratios between 0.5 and 153 parts per million (ppm, 10-6 mol mol-1) generated by Pt-catalyzed oxidation of H2 standards while overflowing the inlet with dry synthetic air. The CIMS H2O instrument was deployed in an unpressurized payload area aboard the NASA WB- 57F high-altitude research aircraft during the Mid-latitude Airborne Cirrus Properties Experiment (MACPEX) mission in March and April 2011. The instrument performed successfully during seven flights, measuring H2O mixing ratios below 5 ppm in the lower stratosphere at altitudes up to 17.7 km, and as low as 3.5 ppm near the tropopause. Data were acquired at 10 Hz and reported as 1 s averages. In-flight calibrations demonstrated a typical sensitivity of 2000 Hz ppm-1 at 3 ppm with a signal to noise ratio (2σ, 1 s) greater than 32. The total measurement uncertainty was 9 to 11 %, derived from the uncertainty in the in situ calibrations. [ABSTRACT FROM AUTHOR]

The article describes and evaluates a system for converting mixtures of hydrogen in air to water on heated platinum surface and generate low mixing ratio water standards. It states that the technique has proved to be accurate and can be used to produce a wide range of water vapor concentrations on demand easily and reliably. It details how the experiment was conducted which found a water standard that is reportedly expected to be appropriate for in situ-calibration of aircraft hygrometers.

The article presents a study on the effect of nitric acid on frost point hyrgrometer performance. It offers information on chilled mirror hygrometers (CMH) which are used to measure water vapour in the troposphere and lower stratosphere from balloon-borne sondes. It discusses how the study was conducted wherein the potential interference of gas-phase nitric acid with frost point temperature measurements were examined. It also details the results of the study.

The article presents a study that evaluates the performance of the Single Particle Soot Photometer (SP2) and the Integrating Sphere/Integrating Sandwich Spectrophotometer (ISSW) in measuring the concentration of refractory black carbon (BC) in snow. It found that the SP2 can be used to measure the size distribution and mass concentration of BC in the snow. It suggests that estimates of BC mass concentration may be associated with significant underestimates of uncertainty.