Atmospheric and oceanic origins of tropical precipitation variability

Jie He, Clara Deser, Brian J. Soden

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The intrinsic atmospheric and ocean-induced tropical precipitation variability is studied using millennial control simulations with various degrees of ocean coupling. A comparison between the coupled simulation and the atmosphere-only simulation with climatological sea surface temperatures (SSTs) shows that a substantial amount of tropical precipitation variability is generated without oceanic influence. This intrinsic atmospheric variability features a red noise spectrum from daily to monthly time scales and a white noise spectrum beyond the monthly time scale. The oceanic impact is inappreciable for submonthly time scales but important at interannual and longer time scales. For time scales longer than a year, it enhances precipitation variability throughout much of the tropical oceans and suppresses it in some subtropical areas, preferentially in the summer hemisphere. The sign of the ocean-induced precipitation variability can be inferred from the local precipitation-SST relationship, which largely reflects the local feedbacks between the two, although nonlocal forcing associated with El Niño-Southern Oscillation also plays a role. The thermodynamic and dynamic nature of the ocean-induced precipitation variability is studied by comparing the fully coupled and slab ocean simulations. For time scales longer than a year, equatorial precipitation variability is almost entirely driven by ocean circulation, except in the Atlantic Ocean. In the rest of the tropics, ocean-induced precipitation variability is dominated by mixed layer thermodynamics. Additional analyses indicate that both dynamic and thermodynamic oceanic processes are important for establishing the leading modes of large-scale tropical precipitation variability. On the other hand, ocean dynamics likely dampens tropical Pacific variability at multidecadal time scales and beyond.

Original languageEnglish (US)
Pages (from-to)3197-3217
Number of pages21
JournalJournal of Climate
Issue number9
StatePublished - May 1 2017


  • Air-sea interaction
  • Atmosphere-ocean interaction
  • Climate models
  • Climate variability
  • ENSO
  • Rainfall

ASJC Scopus subject areas

  • Atmospheric Science


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