Abstract
The impact of the Atlantic Multidecadal Oscillation (AMO) on the variations in the streamflow in the Atrato River Basin (ARB) during the 1965–2016 period was analyzed here by considering the cold (1965–1994) and warm (1995–2015) phases of this oscillation. The mean streamflow increased after 1994 (AMO phase change). This increase is related to the strengthening of the zonal gradients of the sea surface temperature (SST) and sea level pressure (SLP) between the tropical central Pacific and the tropical Atlantic after 1994 (warm AMO phase). These gradients contributed to strengthen the Walker cell related upward movement over northern and northwestern South America, in particular during November-December (ND). Consistently, the frequency (R20 mm) and intensity (SDII) of extreme daily rainfall events increased during the 1995–2015 period. Our results show a connection between the AMO and the increase in the streamflow in the ARB during the last five decades. These results contribute to the studies of resilience and climate adaptation in the region.
Highlights
Colombia is vulnerable to hydrometeorological risks caused by several phenomena of different space-temporal scales [1,2]
In ND, both extreme rainfall indices describe significant increases in most of Colombia, especially in the Caribbean, Pacific, and Andean regions. These results show that the upward change of the mean streamflow in the Atrato River basin (ARB) at Bellavista in ND coincides with the increases in intensity and frequency of extreme rainfall events during the warm AMO (WAMO)
We evaluated how the low-frequency background associated with the Atlantic Multidecadal Oscillation (AMO) modifies the anomaly
Summary
Colombia is vulnerable to hydrometeorological risks (e.g., river overflows, floods, and landslides) caused by several phenomena of different space-temporal scales [1,2]. Kayano et al [38] indicated that the negative multidecadal relation between AMO and the PDO, during the WAMO reinforces the anomalous cooling of the tropical Pacific and favors the settlement of LN events This leads to a configuration of the dipolar pattern with positive rainfall anomalies in northern SA and negative anomalies in central and eastern SA, especially from winter to summer, which is modulated by the anomalous Walker and Hadley cells. Understanding this region’s extreme with of the highest rainfall levels on earth, with an annual mean rainfallhydrometeorological greater than 12,500 events is a priority for the conservation and planning of water resources of a region that shows strong millimeters [7,50,51] Understanding this region’s extreme hydrometeorological events is a contrasts.
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