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Synchronization of the Recent Decline of East African Long Rains and Northwestern Asian Warming

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Authors

Lead Presenter

Samson Hagos - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division

Co-Author

Chuan-Chieh Chang - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Po-Lun Ma - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Sandro Lubis - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Karthik Balaguru - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Pengfei Shi - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Oluwayemi A. Garuba - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
L. Ruby Leung - Pacific Northwest National Laboratory (PNNL) - Atmospheric, Climate, and Earth Sciences Division
Abstract

The East African March-April-May (MAM, “long rains”) precipitation decline in recent decades remains a puzzle marked by various proposed large-scale drivers. Here, the interannual variability of the long rains and their recent drying trend are examined using global model simulations and observations. Comparison of a control simulation and re-initialized simulations in which land-surface feedback is suppressed shows that much of the long rains deficit experienced between 1980 and 2014 is synchronized with the warming of the northwestern Asian landmass. In agreement with the modeling results, multiple observational datasets reveal a strong negative correlation between MAM mean East African rainfall amount and the surface temperature over northwestern Asia. Idealized simulations further indicate that warming in northwestern Asia weakens the regional Hadley Cell and diverts the monsoonal transport of moisture away from Eastern Africa toward Europe and southern Africa, highlighting the role of remote land surface warming on the observed precipitation decline.

Related Meeting/Event
EESM PI Meeting 2024
Category
Water Cycle and Hydroclimate
Modes of Variability and Teleconnections, Trends
Extremes Events
Funding Program Area(s)
RGMA
Additional Resources:
NERSC (National Energy Research Scientific Computing Center)
Project(s)
Water Cycle and Climate Extremes Modeling
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