South Pacific SSTs, not India, built Brazil’s 2014 drought
Isca experiments show 2013/14 South Pacific and South Atlantic SST anomalies favored the blocking high that dried SE Brazil; Indian Ocean SSTs did not.
Source
Revisiting remote drivers of the 2014 drought in South-Eastern Brazil
Study at a glance
- Design
- Computational / modelling — Isca AGCM experiments with regional 2013/14 SST anomalies vs observed SE Brazil drought
- N
- Idealized SST-forcing experiments; observational context spans 41 years (1979–2019)
- Population
- Southeastern Brazil precipitation and South Atlantic blocking in Jan–Feb 2014
- Outcome
- South Pacific/South Atlantic SST anomalies favoring the drought-blocking high
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Authors diagnosed January–February 2014 precipitation, 500 hPa height, and SST from CMAP, ERA-Interim, and OISST, then ran Isca climatology versus regional 2013/14 SST anomaly experiments (global, tropical Pacific, extra-tropical South Pacific, South Atlantic, Indian Ocean).
What they found
JF 2014 was the driest in 41 years under a persistent South Atlantic blocking high. Global and extra-tropical South Pacific SSTs shifted 500 hPa heights toward that block; tropical Pacific-only forcing did not; Indian Ocean forcing produced no significant South Atlantic height response. Internal variability remains large even with fixed SSTs.
The limits
What it doesn't show
Isca is an idealized AGCM (T42) with prescribed SSTs, so it cannot fully couple ocean–atmosphere feedbacks or resolve SACZ mesoscale convection. Ensemble-mean responses mix many members, and agriculture impacts are context, not a result.
Key terms
- SACZ
- South Atlantic Convergence Zone, the main austral-summer rain band for SE Brazil.
- 500GPH
- 500 hPa geopotential height; a persistent high here blocked rain in 2014.
- Isca
- Idealized atmospheric GCM used for SST-sensitivity experiments.
- Blocking anticyclone
- Stationary high that steered storms away from SE Brazil for 5–6 weeks.
- Rossby wave train
- Eastward-propagating atmospheric waves that can link Pacific SSTs to South Atlantic heights.
Flashcards
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Quiz yourself
The 2014 drought’s key synoptic feature was:
Common questions
What synoptic feature caused the drought?
A 5–6 week South Atlantic blocking high that suppressed the SACZ.
Did tropical Pacific SSTs alone do it?
No; tropical-Pacific-only forcing did not yield significant South Atlantic height anomalies.
What about the Indian Ocean/MJO idea?
Prescribed Indian Ocean SST anomalies produced no significant South Atlantic 500GPH response.
Was 2014 unusually dry?
The study-area precipitation rate was the lowest in 41 years.
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