On Optimum Methods for Obtaining Wind Data from Balloon Sensors

Abstract

A sinusoidal wind field is integrated to give the position of a sensor traveling with a constant vertical velocity. A linear least-squares smoothing technique is employed to calculate the velocity and acceleration of the sensor. The distortion of the computed wind field due to the smoothing technique is determined and a magnification factor is applied to compensate for this distortion. An expression is then derived for the error variance of the magnified computed wind field and this expression is minimized by the proper choice of the length of the smoothing interval. It is shown that for the ROBIN falling sphere the proper choice of both position and velocity smoothing intervals is 0.8 of the vertical wavelength of the wind field. In the case of a ROSE rising sphere the balloon velocity serves as an excellent approximation to the wind velocity. In this case, the optimum position smoothing interval is 0.8 of the vertical wavelength of the wind field.