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Impacts of the Pacific Meridional Mode on June–August precipitation in the Amazon River Basin
Author(s) -
Zhang Wei,
Villarini Gabriele,
Vecchi Gabriel A.
Publication year - 2017
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.3053
Subject(s) - climatology , amazon rainforest , anticyclone , precipitation , environmental science , zonal and meridional , forcing (mathematics) , amazon basin , la niña , baroclinity , cyclone (programming language) , atmospheric sciences , geology , oceanography , geography , meteorology , el niño southern oscillation , ecology , field programmable gate array , computer science , computer hardware , biology
This study examines the impacts of the Pacific Meridional Mode (PMM) on Amazon precipitation during June–August using observations and several experiments with the National Oceanic and Atmospheric Administration/Geophysical Fluid Dynamics Laboratory (NOAA/GFDL) Forecast‐oriented Low Ocean Resolution version of CM2.5 (FLOR). We find that the positive (negative) PMM can lead to precipitation surplus (deficit) using both observations and climate simulations with FLOR. The impacts of PMM on Amazon precipitation during June–August are induced by the forcing of sea‐surface temperature (SST) anomalies associated with PMM. Positive PMM can force the baroclinic Gill responses to the heat source in the Pacific with two low‐level cyclones (anticyclones) located west (east) of the heating source. The anomalous low‐level anticyclone and high‐level cyclone located in the Amazon region are associated with low‐level moisture transport from the Atlantic. There is significant positive correlation between the PMM index and moisture flux convergence in most parts of the Amazon basin, with negative correlation in its northwestern part. Such physical mechanisms underlying the linkage between PMM and the Amazon precipitation are supported by both the 500 years control experiment and a suite of perturbation experiments with FLOR.