Causal pathways.pdf (4.69 MB)
Causal pathways linking different flavours of ENSO with the Greater Horn of Africa short rains
journal contribution
posted on 2023-06-09, 22:51 authored by David MacLeod, Richard Graham, Chris O'Reilly, George Otieno, Martin ToddMartin ToddThere is a strong association between canonical El Niño and a wet Greater Horn of Africa (GHA) short rains. However, the link with Modoki El Niño events appears to be significantly weaker. In order to understand this, we present an analysis of observational data and idealised climate model experiments. Idealised atmospheric simulations isolate the direct influence of Pacific heating on the GHA and reveal that neither the longitudinal position nor the observed weaker magnitude of Modoki Pacific heating anomalies can explain the difference in teleconnections. The direct effect of canonical or Modoki Pacific heating patterns on the GHA is similar and neither reproduces the structure of the full GHA teleconnection: they both generate a wet-dry dipole over the GHA instead of large-scale single-signed wet anomalies. Our results indicate that the strong canonical ENSO influence on GHA is indirect, mediated through its strong relationship with the Indian Ocean Dipole (IOD). By contrast, Modoki ENSO is uncorrelated with the IOD, resulting in weak teleconnection to GHA. Understanding these differences aids seasonal forecast interpretation, whilst their representation in models is likely a prerequisite for making accurate projections of changes in extremes over the GHA and beyond.
History
Publication status
- Published
File Version
- Published version
Journal
Atmospheric Science LettersISSN
1530-261XPublisher
WileyExternal DOI
Issue
2Volume
22Page range
1-11Article number
a1015Department affiliated with
- Geography Publications
Full text available
- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2021-01-21First Open Access (FOA) Date
2021-01-21First Compliant Deposit (FCD) Date
2021-01-20Usage metrics
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