Statistics of tropospheric radio-refractive-index soundings taken over a 3-year period in the United Kingdom

The paper discusses the statistical distributions of certain refractive-index parameters which are often used in tropospheric radio-propagation problems. The statistics are derived from three years´ results of routine psychrometer soundings made at intervals of 75m, every 6h, to a height of 1200m, by the Meteorological Office at Cardington, Bedfordshire. Parameters discussed are surface refractive index, the lapse in refractive index (lapse rate) measured over the first 75, 150, 500, and 1000m from ground, and the distribution of lapse rates within each height interval of 75m. The distribution of the magnitude and height of occurrence of the largest lapse rates in each sounding, and the associated temperature and humidity changes, are also discussed. The paper also considers seasonal and diurnal variations of these parameters.