Bias correction of reanalysis-based wind stress using scatterometer derived equivalent neutral wind has been a common practice in producing the forcing datasets used in recent global ocean model intercomparisons (OMIPs). Here we systematically evaluate the effect of this wind correction procedure on the simulation of the Pacific North Equatorial Countercurrent (NECC) with multiple sets of model experiments. The weak NECC evident in earlier OMIPs employing the Coordinated Ocean-ice Reference Experiments (COREs) forcing dataset persists with the new JRA55-do (Japanese 55-year Reanalysis) forcing dataset. Two factors appear to significantly affect the Pacific NECC in forced ocean simulations: i) the bias correction procedure using QuikSCAT derived winds and ii) whether or not the ocean current is considered in the bulk formula. In the forced ocean simulations, the QuikSCAT correction weakens the averaged NECC transports by about 60%. Taking the ocean currents into account in the bulk formula may weaken the averaged NECC transports by about 26%–30%. Under the current OMIP protocol the above two procedures are used together to force the ocean model resulting in a double-counting of ocean surface current feedback on wind stress because the QuikSCAT estimates the equivalent 10-m neutral winds relative to surface current. We further systematically verify and investigate the impacts of this double-counting of the ocean surface currents on the modeled Pacific NECC using offline linear Sverdrup transport analysis, in which the observational data of vector wind and surface current are used to calculate the surface wind stress. It shows that including the ocean current in the bulk formula may reduce the zonal Sverdrup transport (ZST) by about 6.6 Sv (33%) and the further double-counting of the ocean current leads to an additional reduction of 6.4 Sv (48%). Next, using “perfect model” experiments with output from a coupled ocean–atmosphere model we further identify that the double-counting of current feedback in the bulk formula results in approximately 21% weakened volume transport. The built-in nonlinear processes in the model, such as the advection and friction terms, may partly damp the reduction due to the double-counting of the ocean current. However, the double-counting bias can only explain 26%–30% of the Pacific NECC simulation bias and the other part of the bias, around 30%, caused by the correction with QuikSCAT has not been explained. We speculate that this part may be explained by the retrieval biases in QuikSCAT wind data and the use of annual mean climatological wind adjustment factors.

使用散射计导出的等效中性风对基于再分析的风应力进行偏差校正已成为最近全球海洋模型比对 (OMIP) 中使用的强迫数据集的常见做法。在这里，我们通过多组模型实验系统地评估了这种风校正程序对太平洋北赤道逆流 (NECC) 模拟的影响。在采用协调海冰参考实验 (CORE) 强迫数据集的早期 OMIP 中明显的弱 NECC 在新的 JRA55-do（日本 55 年再分析）强迫数据集上仍然存在。在强迫海洋模拟中，有两个因素似乎对太平洋 NECC 有显着影响：i) 使用 QuikSCAT 导出的风的偏差校正程序和 ii) 是否在整体公式中考虑了洋流。在强制海洋模拟中，QuikSCAT 校正将平均 NECC 传输减弱了约 60%。在散装公式中考虑洋流可能会使平均 NECC 输运减弱约 26%–30%。在当前的 OMIP 协议下，上述两个程序一起使用来强制海洋模型导致对风应力的海面洋流反馈的双重计算，因为 QuikSCAT 估计相对于表面洋流的等效 10 米中性风。我们使用离线线性 Sverdrup 输运分析进一步系统地验证和研究了这种海洋表面流的重复计算对模拟的太平洋 NECC 的影响，其中使用矢量风和表面流的观测数据来计算表面风应力。结果表明，在散装公式中包括洋流可能会使纬向 Sverdrup 输运 (ZST) 减少约 6.6 Sv (33%)，并且进一步重复计算洋流导致额外减少 6.4 Sv (48%) . 接下来，使用“完美模型”实验以及来自耦合海洋-大气模型的输出，我们进一步确定了体积公式中电流反馈的重复计算导致大约 21% 的体积传输减弱。模型中内置的非线性过程，例如平流和摩擦项，可能会部分抑制由于洋流的重复计算而导致的减少。然而，重复计算偏差只能解释太平洋 NECC 模拟偏差的 26%–30%，而由 QuikSCAT 校正引起的其他部分偏差（约 30%）尚未得到解释。