Radiosonde observations of temperature, relative humidity and wind properties are compared at two neighbouring stations – Tallinn-Harku in Estonia and Jokioinen in Finland – with the aim to optimize radiosonde network and measurement times. The comparison is carried out for the period of 1993–2009 when both stations used similar equipment. Midnight and noon soundings are compared separately. It is concluded that the profiles of the temperature and wind speed at these two stations are similar, but those of the relative humidity differ significantly, showing coefficient of correlation over 0.7 only near the tropopause. Wind roses are similar in summer, but somewhat different in winter, especially in the stratosphere during the daytime.
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