Hydrology
South Pacific SSTs, not India, built Brazil’s 2014 drought
Open access · cc by · source: Europe PMC
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.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Reanalysis also supplies the hindcast boundary for high-resolution experiments. A 2.2 km convection-permitting model nested in ERA-Interim (1999–2008) then in HadGEM3 produced Europe-wide rain projections; Isca SST experiments for Brazil’s 2014 drought used ERA-Interim circulation as the diagnostic target. Those are model experiments that start from a reanalysis, not additional observations.
Evidence for the claim as stated.
Idealised or nested experiments use small ensembles for a different purpose: tracing a drought to a basin of SST, or asking whether a regional model or its GCM driver sets storm skill. Those spreads are not interchangeable with a 100-member 21st-century probability ratio.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Idealised or nested experiments use small ensembles for a different purpose: tracing a drought to a basin of SST, or asking whether a regional model or its GCM driver sets storm skill. Those spreads are not interchangeable with a 100-member 21st-century probability ratio.
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.
Inspect source passages
South Pacific SSTs, not India, built Brazil’s 2014 drought
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
Precipitation datasets cover 41 years from 1979 to 2019.
The monthly precipitation amounts are given in mm/day and are available over a 41-year period from 1979 to 2019.
11.5% of climatological ensemble members still had strongly increased 500GPH.
with 11.5% of ensemble members featuring strongly increased 500GPH in the study area.
Key findings
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.
Methodology
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).
Limitations
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.
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