Impact of quasi-biennial oscillation on the inter-annual variability of the tropopause height and temperature in the tropics: A study using COSMIC/FORMOSAT-3 observations

The effect of quasi-biennial oscillation (QBO) on the temperature of cold point tropopause (T-CPT) and its height (H-CPT) is being investigated using radio occultation measurements by COSMIC/FORMOSAT-3. Observations comprising of 935,863 numbers of occultations have been used to study the zonal mean seasonal variability in T-CPT and H-CPT from January 2007 to December 2011. Results are shown over 30 degrees N-30 degrees S geographic latitudes. In general, T-CPT is found to be the coldest in February and the warmest in August H-CPT attains maximum height during December-February and minimum during July-August Interestingly, H-CPT shows maxima at off-equator region (around 20 degrees N or 20 degrees S) during all the seasons in both hemispheres. H-CPT at off-equatorial region, in reference to the equatorial region, is slightly higher (similar to 1.0 km) during winter as compared to monsoon season (similar to 0.5 km) in Northern Hemisphere (NH). Inter-annual variation in T-CPT and H-CPT found to be clearly influenced by the QBO. Westerly (easterly) phase generates warm (cold) T-CPT, which consequently results a decrease (increase) in H-CPT. It is concluded that QBO induces the changes in T-CPT by as much as 2 degrees C and in H-CPT by 0.5 km. (C) 2014 Elsevier B.V. All rights reserved.