The thermohaline intrusion of the warm and saline Atlantic Water (AW) into the Arctic Ocean, referred to as “Arctic Atlantification”, has significant implications and feedback to the dynamics and thermodynamics of the Arctic Ocean. The AW enters the Arctic Ocean through two gateways: Fram Strait and the Barents Sea Opening (BSO). The relative strength of these two AW branches dominates the oceanic heat contribution to the Arctic Ocean. In conjunction with the measurements in key hydrographic sections, numerical ocean modelling provides us with a useful tool to characterize and corroborate the temporal and spatial variability of the AW branches. Simulations are conducted using the regional configuration Arctic and North Hemispheric Atlantic (ANHA) of the ocean/sea-ice model NEMO running at 1/4° and 1/12° resolution. Online passive tracers from the model configuration are used to trace the pathways of the AW inflow in the Arctic Ocean. With the AW becoming more important to the dynamics of the Arctic Ocean, this study aims to examine its variability, transformation, impacts, and ultimately track how it evolves. While the heat in the Fram Strait Branch Water (FSBW) dissipates in a slower process through the mixing with the ambient cold water below sea surface, the vast majority of the heat loss of the Barents Sea Branch Water (BSBW) takes place in Barents Sea due to the sea surface cooling, leading to Cold Atlantic Water (CAW) production during 2013 and 2014. The CAW pulses result in a significant heat content reduction in the eastern Arctic.