A LIGHTWEIGHT NO2 INSTRUMENT FOR VERTICAL HEIGHT PROFILES

A new lightweight NO2 instrument that can be flown from a tethered bal loon to give vertical NO2 profiles is described. The detection princip le is the chemiluminescent reaction between NO2 and a solution of lumi nol. The instrument is integrated with a radiosonde to also give tempe rature, humidity, and pressure data. Tests show the instrument is line ar from 2.8 to 75 ppbv but nonlinear below 2.8 ppbv. A calibration cur ve is determined. The sensitivity varies directly with pressure and it has a -3.5% per degree temperature dependence. Data from trial flight s as part of the PACIFIC'93 field study show NO2 data from the surface to 900 m.