Editing IPCC:AR6/WGII/Chapter-9 (section)

===== 9.5.5.2.1 Observations =====

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Over equatorial east Africa the short rains (October–November–December) have shown a long-term wetting trend from the 1960s until present ( [[#Manatsa--2013|Manatsa and Behera, 2013]] ; [[#Nicholson--2015|Nicholson, 2015]] ; 2017), which is linked with western Indian Ocean warming and a steady intensification of Indian Ocean Walker Cell ( [[#Liebmann--2014|Liebmann et al., 2014]] ; [[#Nicholson--2015|Nicholson, 2015]] ).

In contrast, the long rainfall season (March–April–May) has experienced a long-term drying trend between 1986 and 2007, with rainfall declines in each of these months and a shortening of the wet season ( [[#Rowell--2015|Rowell et al., 2015]] ; [[#Wainwright--2019|Wainwright et al., 2019]] ). Unlike previous decades, since around 2000, the long rains have exhibited a significant relationship with the El Niño-Southern Oscillation (ENSO) ( [[#Park--2020|Park et al., 2020]] ), as multiple droughts have occurred during recent La Niña events and when the western to central Pacific sea surface temperature gradient was La Niña-like ( [[#Funk--2015|Funk et al., 2015]] ; [[#Funk--2018a|Funk et al., 2018a]] ). Wetter-than-average rainfall years within this long-term drying trend are often associated with a stronger amplitude of the Madden–Julian Oscillation ( [[#Vellinga--2018|Vellinga and Milton, 2018]] ).

In the northern, summer rainfall region (June–September), a decline in rainfall occurred in the 1960s and rainfall has remained relatively low, while interannual variability has increased since the late 1980s ( [[#Nicholson--2017|Nicholson, 2017]] ); the cause of this drying trend is uncertain.

Since 2005, drought frequency has doubled from once every 6 to once every 3 years and has become more severe during the long and summer rainfall seasons than during the short rainfall season ( [[#Ayana--2016|Ayana et al., 2016]] ; [[#Gebremeskel%20Haile--2019|Gebremeskel Haile et al., 2019]] ). Several prolonged droughts have occurred predominantly within the arid and semi-arid parts of the region over the past three decades ( [[#Nicholson--2017|Nicholson, 2017]] ).

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