Double Tropopauses and the Tropical Belt Connected to ENSO

Area of Science:

• Atmospheric Science
• Climatology
• Geophysics

Background:

• Accurate, globally distributed data on the troposphere-stratosphere transition zone is crucial for analyzing double tropopause (DT) events.
• Radio occultation (RO) observations provide the necessary vertical resolution and accuracy for such analyses.

Purpose of the Study:

• To analyze the global and seasonal distribution of double tropopauses (DTs).
• To establish a connection between El Niño-Southern Oscillation (ENSO) phases and the occurrence and distribution of DTs.

Main Methods:

• Utilized radio occultation observations from 2001 to 2018.
• Analyzed global and seasonal characteristics of DTs in relation to ENSO phases.

Main Results:

• Identified hotspot locations for DTs, including near the subtropical jet stream and over high mountain ranges.
• Observed a higher frequency of DTs during the cold La Niña phase and lower rates during warmer El Niño events.
• Found that ENSO phases affect tropopause region structure, with La Niña correlating to lower first lapse rate tropopause altitude near the Niño 3 region.

Conclusions:

• ENSO significantly influences the occurrence and distribution of double tropopauses.
• La Niña conditions favor more DTs, while El Niño conditions lead to fewer, altering tropopause structure and the tropical belt width.