On the relationship between the QBO/ENSO and atmospheric temperature using COSMIC radio occultation data

In this paper, the spatial patterns and vertical structure of atmospheric temperature anomalies, in both the tropics and the extratropical latitudes, associated with the El Niño-Southern Oscillation (ENSO) and quasi-biennial oscillation (QBO) in the upper troposphere and stratosphere are investigated using global positioning system (GPS) radio occultation (RO) measurements from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Formosa Satellite Mission 3 mission from July 2006 to February 2014. We find that negative correlations between the atmospheric temperature in the tropics and ENSO are observed at 17-30 km in the lower stratosphere at a lag of 1-4 months and at a lead of 1 month. Out-of-phase temperature variation is observed in the troposphere over the mid-latitude band and in-phase behaviour is observed in the lower stratosphere. Interestingly, we also find that there is a significant negative correlation at a lag of 1-3 months from 32 km to 40 km in the mid-latitude region of the Northern Hemisphere. The atmospheric temperature variations over mid-latitude regions in both hemispheres are closely related to the QBO. There are also two narrow zones over the subtropical jet zone where the QBO signals are strong in both hemispheres, approximately parallel to the equator. Finally, we develop a new robust index to describe the strength of the ENSO and QBO signal.