The experiment took place during June 1999 at the East Sea in China using the radiosondes developed by us, which measured vertical profiles of atmospheric pressure, temperature, relative humidity and the refractive index structure parameter C2n. The diurnal variation of temperature is less than 3℃ above sea surface up to 800 m, the surface-based nocturnal inversion is weak. The atmosphere temperature on sea surface decreases 1℃ when latitudes increase 1 degree. The measured profile shows the rapid falloff of C2n from the surface to the relatively quiet about 500 m height. The C2n appears constant with altitude from 500 m to 2000 m height. The measured and modeled profiles of potential temperature have been compared.