Abstract. This study investigates how the enhanced loading of microphysically and radiatively active aerosol particles impacts tropical sea breeze convection and whether these aerosol impacts are modulated by the multitudinous environments that support these cloud systems. To achieve these goals, we have performed two large numerical model ensembles, each comprised of 130 idealised simulations that represent different initial conditions typical of tropical sea breeze environments. The two ensembles are identical with the exception of the fact that one ensemble is initialised with relatively low aerosol loading or pristine conditions, while the other is initialised with higher aerosol loading or polluted conditions. Six atmospheric and four surface parameters are simultaneously perturbed for the 130 initial conditions. Analysis of the ten-dimensional parameter simulations was facilitated by the use of a statistical emulator and multivariate sensitivity techniques. Comparisons of the clean and polluted ensembles demonstrate that aerosol direct effects reduce the incoming shortwave radiation reaching the surface, as well as the outgoing longwave radiation, within the polluted ensemble. This results in weaker surface fluxes, a reduced ocean-land thermal gradient, and a weaker sea breeze circulation. Consequently, irrespective of the different initial environmental conditions, increasing aerosol concentration decreases the three ingredients necessary for moist convection: moisture, instability, and lift. As reduced surface fluxes and instability inhibit the convective boundary layer development, updraft velocities of the daytime cumulus convection developing ahead of the sea breeze front are robustly reduced in the polluted environments. Furthermore, the variance-based sensitivity analysis reveals that the soil saturation fraction is the most important environmental factor contributing to the updraft velocity variance of this daytime cumulus mode, but that it becomes a less important contributor with enhanced aerosol loading. It is also demonstrated that enhanced aerosol loading results in a weakening of the convection initiated along the sea breeze front. This suppression is particularly robust when the sea breeze-initiated convection is shallower, and hence restricted to warm rain processes. However, when the sea breeze-initiated convection is deep and includes mixed-phase processes, both the sign and magnitude of the convective updraft responses to increased aerosol loading are modulated by the environment. The less favourable convective environment arising from aerosol direct effects also restricts the development of sea breeze-initiated deep convection. While precipitation is ubiquitously suppressed with enhanced aerosol loading, the magnitude of this suppression remains a function of the initial environment. Altogether, our results highlight the importance of evaluating aerosol impacts on convection systems under the wide range of environments supporting such convective development.

中文翻译：

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环境如何调节气溶胶对热带海风对流系统的影响？

摘要。这项研究调查了微物理和辐射活性气溶胶粒子的增强负载如何影响热带海风对流，以及这些气溶胶影响是否受到支持这些云系统的众多环境的调节。为了实现这些目标，我们执行了两个大型数值模型集合，每个集合包含 130 个理想化模拟，代表热带海风环境中典型的不同初始条件。这两个集合是相同的，除了一个集合在相对较低的气溶胶负载或原始条件下初始化，而另一个集合在较高的气溶胶负载或污染条件下初始化。对于 130 个初始条件，六个大气参数和四个表面参数同时受到扰动。使用统计仿真器和多变量灵敏度技术促进了十维参数模拟的分析。清洁和污染系综的比较表明，气溶胶直接效应减少了在污染系综内到达地表的传入短波辐射以及传出的长波辐射。这导致较弱的表面通量、减小的海陆热梯度和较弱的海风环流。因此，无论初始环境条件如何，增加气溶胶浓度都会降低湿对流所需的三种成分：水分、不稳定性和升力。由于减少的表面通量和不稳定性抑制了对流边界层的发展，在受污染的环境中，在海风锋之前发展的白天积云对流的上升气流速度大大降低。此外，基于方差的敏感性分析表明，土壤饱和度是导致这种白天积云模式上升气流速度变化的最重要的环境因素，但随着气溶胶载荷的增加，它变得不太重要。还表明，增强的气溶胶载荷导致沿海风前沿发起的对流减弱。当海风引发的对流较浅时，这种抑制尤其强大，因此仅限于暖雨过程。然而，当海风引发的对流较深且包含混合相过程时，对增加的气溶胶负载的对流上升气流响应的符号和幅度都受环境调节。气溶胶直接作用产生的不利对流环境也限制了海风引发的深层对流的发展。虽然随着气溶胶载荷的增加，降水普遍受到抑制，但这种抑制的程度仍然是初始环境的函数。总之，我们的结果强调了在支持这种对流发展的广泛环境下评估气溶胶对对流系统影响的重要性。虽然随着气溶胶载荷的增加，降水普遍受到抑制，但这种抑制的程度仍然是初始环境的函数。总之，我们的结果强调了在支持这种对流发展的广泛环境下评估气溶胶对对流系统影响的重要性。虽然随着气溶胶载荷的增加，降水普遍受到抑制，但这种抑制的程度仍然是初始环境的函数。总之，我们的结果强调了在支持这种对流发展的广泛环境下评估气溶胶对对流系统影响的重要性。