The Gulf Stream (GS) is central to the global redistribution of heat due to the transport of large volumes of warm water from the tropics to high latitudes and the extreme ocean heat loss to the atmosphere. This study assesses the extent to which winter surface heat fluxes and wind stress curl can drive interannual variations of the full‐depth GS transport. Intensification of the GS has been observed (e.g., April 1977) immediately after a winter of frequent cold air outbreaks that led to a deepening of the mixed layer and subsequent steepening of meridional temperature gradients to the south of the GS. This forcing process is further investigated here using the ORCA12 hindcast (1978–2010) from the global, eddy‐resolving, ocean‐only Nucleus for European Modeling of the Ocean model in order to understand GS forcing mechanisms. Lagrangian analysis is also undertaken to examine the impact on the southern recirculation gyre. Results show that surface heat fluxes and wind stress curl can act in concert to effect year‐to‐year changes of up to 38% of the spring GS transport at 70°W. However, anomalous heat losses (∼200 Wm^‐2) over the western Subtropical Gyre are found to be the dominant cause of peaks in GS transport via two mechanisms: (1) a strengthening of cross‐stream density gradients on the northern flank of the GS from an intense cooling (up to 4°C) in the Slope Water and (2) a westward intensification of the southern recirculation, which can also limit the formation of deeper mixed layers to the south of the GS near 70°W.

中文翻译：

---

海热通量在推动湾流运输的年际变化中的主要作用

湾流（GS）是热带热量在全球范围内重新分配的核心，这是因为将大量的热水从热带地区输送到高纬度地区，以及海洋热量极度散失到大气中。这项研究评估了冬季表面热通量和风应力卷曲在多大程度上可以驱动全深度GS传输的年际变化。在冬季频繁发生的冷空气暴发之后，立即观测到了GS的强化，例如，这导致了混合层的加深，继而使GS南部的子午温度梯度变陡。为了进一步了解GS强迫机制，这里使用来自全球，解决涡流的仅海洋核的ORCA12后继卫星（1978-2010）对这一强迫过程进行了进一步研究。还进行了拉格朗日分析，以检查其对南部再循环环流的影响。结果表明，在70°W时，地表热通量和风应力卷曲可以协同作用，从而影响高达GS的春季GS运输量的38％的逐年变化。但是，异常热量损失（约200 Wm^‐2）被发现是通过两种机制导致GS运移高峰的主要原因：（1）由于强烈的冷却作用（高达4个），GS北部侧面的横流密度梯度得到加强°C）和（2）南部回流的向西加剧，这也可以限制GS南部70°W附近较深混合层的形成。