Improved wind measurements on research aircraft

Improved techniques for measuring horizontal and vertical wind components a nd state variables on research aircraft are presented. They include a filte ring method for correcting ground speed and position Inertial Navigation Sy stem data with Global Positioning System data,use of moist-air thermodynami c properties in the true;airspeed calculation, postflight calculation of th e aircraft vertical velocity,and calibration of airflow attack and sideslip , angles from the two air-data systems on each aircraft-a radome:gust probe and a pair of fuselage-mounted Rosemount 858Y probes. Winds from the two a ir-data systems are compared for the National Oceanic and Atmospheric Admin istration WP-3D aircraft. As an evaluation, of these techniques, data from the two aircraft during-si de-by-side low-level constant runs are compared for mean and turbulent meas urements of wind; ambient temperature, and absolute humidity. Small empiric al offsets were determined and applied to the two latter scalars as well as to static and dynamic pressures. Median differences between mean horizonta l wind components from nine comparisons were within 0.1 +/- 0.4 m s(-1). Me dian differences in latent heat and sensible heat fluxes and momentum flux components were 3.5 +/- 15 W m(-2), 0 +/- 2.5 W m(-2), and 0 +/- 0.015 Pa; respectively.