This study uses submesoscale‐permitting simulations to explore the formation of temperature inversions at shallow, salinity‐controlled density fronts representative of conditions in the wintertime Bay of Bengal (BoB). Our simulations complement earlier one‐dimensional studies that have largely used mooring records in the BoB to infer mechanisms for causing temperature inversions, by exploring three‐dimensional frontal processes. We use three different initial conditions with the same lateral and vertical gradients in density, with differing lateral contrasts in temperature within the mixed layer. Our simulations evolve unforced for a few inertial periods, are then forced by weak downfront winds for a few more inertial periods to generate an eddy field, after which the winds are turned off. The formation of inversions proceeds via the subduction of low potential vorticity (PV) fluid from the surface during the forced phase. The inversions result from tilting of horizontal temperature gradients into the vertical direction. Tilting is simultaneously the dominant source of negative vertical vorticity in the Lagrangian vorticity budget. Turning off the winds caps the subducted fluid by overlying stratified fluid, creating temperature inversions with O(1–10 km) lateral scales and O(10 m) thickness. The inversions are pycnostads with anticyclonic rotation. The increase in temperature for the strongest inversion in each simulation is comparable to the initial lateral contrast in temperature. The strongest inversions are associated with anticyclonic rotation and low PV. Our results have potential implications for the vertical thermal structure of the upper BoB in coarse‐resolution models that do not resolve subduction at submesoscale fronts.

中文翻译：

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孟加拉湾盐度锋面以下的亚中尺度温度反转的产生

这项研究使用亚尺度尺度的允许模拟方法，研究了代表孟加拉湾（BoB）冬季状况的，盐度受控的浅层盐浓度前沿的温度反转形成。我们的模拟对早期的一维研究进行了补充，这些一维研究通过探索三维前沿过程，大量使用了BoB中的系泊记录来推断引起温度反转的机制。我们使用三种不同的初始条件，它们在密度上具有相同的横向和纵向梯度，并且混合层内的温度具有不同的横向对比度。我们的模拟在一些惯性周期内不受力地演变，然后在弱的前风作用下又在多个惯性周期内受力，以产生涡流场，此后风被关闭。反转的形成是通过在强迫阶段从地表俯冲低势涡（PV）流体而进行的。反转是由于水平温度梯度向垂直方向倾斜而引起的。同时，倾斜是拉格朗日涡度预算中负垂直涡度的主要来源。关掉风，通过覆盖分层流体覆盖俯冲流体，产生侧向尺度为O（1-10 km）和厚度为O（10 m）的温度反演。反转是具有反气旋旋转的比丘达德。在每个模拟中，最强反演的温度升高与温度的初始横向对比度相当。最强的反演与反气旋旋转和低PV相关。