Using the Constellation Observation System of Meteorology, Ionosphere and Climate (COSMIC) radio occultation (RO)
data from December 2008 to November 2009, and the contemporaneous high vertical resolution radiosonde data, the
accuracy of COSMIC RO data in the Qinghai-Tibet Plateau is evaluated. Results show that there is a good consistency
between COSMIC refractivity and those calculated from the radiosondes between 5 and 30km altitude both in day and at
night. Their annual mean fractional refractivity difference is -0.474%, and standard deviation is 1.056%. It illustrates that
the RO data is reliable and may be effectively applied in the Qinghai-Tibet Plateau for the weather and climate research,
or as a reference data to evaluate other observations and the model’ simulations.