Hourly Variability of Density at Radiosonde Heights

Abstract

Estimates of the root mean square change in density at 1, 7, 12, 18, and 25 km are presented for lags of one through 24 hours. The lag variability at all of the heights considered increased with an increase in time. The relative magnitudes of these lag variabilities, expressed as a per cent of the observed mean at each level, show that for a given lag, the variability decreases from 1 to 7 km, increases from 7 to 12 km, and then decreases again from 12 to 25 km. The auto-correlation coefficient was derived from the lag variability and is also presented. The auto-correlation function decayed to zero at a lag of 22.6 hours at 7 km. Correlations greater than zero persisted for more than 24 hours at the other four levels. Observed diurnal variability was less than 1.2 per cent at all levels below 25 km.