Forced mechanical lifting through cold pool gust fronts can trigger new convection and, as previous work highlights, is enhanced when cold pools collide. However, as shown by conceptual models, the organization of the convective cloud field emerging from two versus three colliding cold pools differs strongly. In idealized dry large‐eddy simulations we therefore compare collisions between two and three cold pools. The triggering likelihood is quantified in terms of the cumulative vertical mass flux of boundary layer air and the instantaneous updraft strength, generated at the cold pool gust fronts. We find that cold pool expansion can be well described by initial potential energy alone. Cold pool expansion monotonically slows but shows an abrupt transition between an axisymmetric and a broken‐symmetric state mirrored by a sudden drop in expansion speed. We characterize these two dynamic regimes by two distinct power law exponents and explain the transition by the onset of “lobe‐and‐cleft” instabilities at the cold pool head. Two‐cold pool collisions produce the strongest instantaneous updrafts in the lower boundary layer, which we expect to be important in environments with strong convective inhibition. Three‐cold pool collisions generate weaker but deeper updrafts and the strongest cumulative mass flux and are thus predicted to induce the largest midlevel moistening, which has been identified as a precursor for the transition from shallow to deep convection. Combined, our findings may help decipher the role of cold pools in spatially organizing convection and precipitation.

中文翻译：

---

冷池对流的机械强迫：碰撞和能量缩放


通过冷池阵风锋的强制机械提升可以引发新的对流，并且正如之前的工作所强调的那样，当冷池碰撞时，对流会增强。然而，如概念模型所示，两个和三个碰撞冷池产生的对流云场的组织存在很大差异。因此，在理想化的干大涡模拟中，我们比较了两个和三个冷池之间的碰撞。触发可能性根据边界层空气的累积垂直质量通量和冷池阵风锋产生的瞬时上升气流强度来量化。我们发现冷池膨胀可以仅用初始势能很好地描述。冷池膨胀单调减慢，但显示出轴对称和破坏对称状态之间的突然转变，这反映了膨胀速度的突然下降。我们通过两个不同的幂律指数来表征这两种动态状态，并通过冷池头部“裂隙”不稳定性的出现来解释这种转变。两个冷池碰撞在下边界层产生最强的瞬时上升气流，我们预计这在强对流抑制的环境中很重要。三冷池碰撞产生较弱但更深的上升气流和最强的累积质量通量，因此预计会引起最大的中层湿润，这已被确定为从浅对流到深层对流过渡的前兆。总而言之，我们的发现可能有助于破译冷池在空间组织对流和降水中的作用。