Climatological characteristics of the tropopause parameters derived from GPS/CHAMP and GPS/SAC-C measurements

摘要

We have analyzed the tropopause parameters using the data retrieved from the GPS occultation experiment on board the CHAMP and SAC-C satellites. In the present study we have considered 3–4 years of data. Tropopause parameters such as temperature, height, pressure, and potential temperature have been separately studied for the tropical and other regions. Comparison of the temperature profiles (obtained near the equator) by the CHAMP and SAC-C satellites with the radiosonde measurements indicates very good agreement at altitudes below the tropopause. Deviations of 1–2 K are seen above the tropopause level. Analysis of the tropopause parameters separately done for the tropics (20°S–20°N) indicates annual variations. The tropopause temperature and pressure variations are strongly correlated, and they both anticorrelate with the tropopause height. Annual oscillation is evident in the variations of tropopause parameters. The sampled data indicate some interannual variations. We have found that there are some differences between the cold point tropopause (CPT) and lapse rate tropopause (LRT) methods of estimates. The global structure of the tropopause indicates clear differences between the tropics and high-latitude regions. Seasonal variation is evident in the parameters; however, they are more prominent in the polar regions. The paper confirms that the CHAMP and SAC-C measurements of the tropopause parameters are complementary as there is very little difference between the two measurements.