Sea surface temperature (SST) biases in the tropical Atlantic are a long-standing problem among coupled global climate models (CGCMs). They occur in equilibrated state, as well as in initialised seasonal to decadal simulations. The bias is typically characterised by too high SST in upwelling regions and associated errors of wind and precipitation. We examine the SST bias in the state-of-the-art CGCM EC-Earth by means of an upper ocean heat budget analysis. Horizontal advection processes affect the SST bias development only to a small extent, and surface heat fluxes mostly dampen the warm bias. Subgrid-scale upper ocean vertical mixing is too low in EC-Earth when compared to estimates from reanalysis data, potentially giving rise to the warm bias. We perform sensitivity experiments to examine the effect of enhanced vertical mixing on the SST bias in quasi equilibrium present day climate and its impact on projected climate change. Enhanced mixing in historical simulation mode (\({\text {MixUp}}_{pr}\)) reduces the SST bias in the tropical Atlantic compared to the control experiment (\({\text {Control}}_{pr}\)). Associated atmospheric biases of precipitation and surface winds are also reduced in \({\text {MixUp}}_{pr}\). We further perform climate projections under the RCP8.5 emission scenario (\({\text {Control}}_{fu}\) and \({\text {MixUp}}_{fu}\)). Under increasing greenhouse gas forcing, the tropical Atlantic warms by up to \(4.5\,^{\circ }{\text {C}}\) locally, and maritime precipitation increases in boreal winter and spring. We show that the vertical mixing parameterisation influences future climate. In \({\text {MixUp}}_{fu}\), SSTs remain \(0.5\,^{\circ }{\text {C}}\) colder in boreal winter and spring, but increase with the same amplitude in summer and fall. The strength and location of the projected intertropical convergence zone also depends on the ocean vertical mixing efficiency. The rain band moves southward in summer, and its strength increases in winter in \({\text {MixUp}}_{fu}\) as compared to \({\text {Control}}_{fu}\).

热带大西洋地区的海表温度（SST）偏差是全球耦合气候模型（CGCM）中的一个长期存在的问题。它们以平衡状态以及初始的季节到年代际模拟发生。偏差的典型特征是上升流区的SST太高以及相关的风和降水误差。我们通过高层海洋热量收支分析，研究了最新的CGCM EC地球中的SST偏差。水平对流过程仅在很小程度上影响SST偏向的发展，表面热通量大多会抑制暖偏向。与重新分析数据的估计值相比，EC-地球的亚网格规模的上层海洋垂直混合太低，可能导致暖偏。我们进行敏感性实验，以检验垂直混合增强对准平衡当今气候中SST偏差的影响及其对预计的气候变化的影响。在历史模拟模式下增强混合（\（{\ text {MixUp}} _ {pr} \））与对照实验（\（{\ text {Control}} _ {pr} \））相比，减少了热带大西洋地区的SST偏差。\（{\ text {MixUp}} _ {pr} \）中的降水和地面风的大气偏差也减小了。我们还将在RCP8.5排放情景（\（{\ text {Control}} _ {fu} \）和\（{\ text {MixUp}} _ {fu} \））下执行气候预测。随着温室气体强迫的增加，热带大西洋局部变暖高达\（4.5 \，^ {\ circ} {\ text {C}} \\），并且在冬季和春季的北方降水增加。我们证明了垂直混合参数化会影响未来的气候。在\（{\ text {MixUp}} _ {fu} \）中，SST在寒冷的冬季和春季保持\（0.5 \，^ {\ circ} {\ text {C}} \）较冷，但在夏季和秋季以相同的幅度增加。预计的热带辐合带的强度和位置也取决于海洋垂直混合效率。雨带移动在夏天向南，冬天在其强度增加\（{\ {文字的mixup}} _ {}福\）相比，\（{\ {文本控制}} _ {}福\） 。