The Time-Varying Calibration of an Airborne Lyman-α Hygrometer

Abstract

Calibration of an airborne Lyman-α hygrometer against simultaneous measurements of humidity from a dewpoint hygrometer shows that Lyman-α biases drift with time. Analyses of low-level flight data from four days during the 1986 Frontal Air?Sea Interaction Experiment indicate that Lyman-α gains are constant for each Right (? 3 h duration) but different on each day. If not explicitly accounted for, the time-varying bias can introduce a significant error in calculated humidities from the Lyman-α hygrometer.