Focusing on conditions of subsidence when low clouds are present, ground‐based observations in both the North Atlantic and the Southern Ocean reveal strong relationships between cloud boundary (base and top heights) and different measures of lower tropospheric instability. The difference in potential temperature between the surface and 800 hPa (a metric called M) provides a stronger relationship than measures of inversion strength such as the lower tropospheric stability and estimated inversion strength. This is because (1) inversion strength itself does not correlate well with cloud boundaries, and (2) M contains information that appears important for cloud boundaries. These include the surface forcing through the use of sea surface rather than near‐surface air temperature and an upper level close to the real cloud top. These results expand upon previous work on the importance of M as a predictor of cloud morphology. However, important differences are found in low‐cloud conditions for the North Atlantic as compared to the Southern Ocean (for a given value of M): stronger inversions, deeper boundary layers, and much larger sea level pressures. Therefore, the relationship between cloud boundaries and M differs between the two regions. A general circulation model provides similar relationships as observed between M and both cloud top height and temperature but tends to place clouds higher and at colder temperatures than observed for a given M. This might cause issues with the representation of precipitation, cloud cover and radiation in the Southern Ocean.

中文翻译：

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中纬度地区海洋冷空气爆发M参数与低空云高的关系

着眼于低云存在时的沉降条件，在北大西洋和南大洋的地面观测揭示了云边界（基高和最高高度）与对流层较低不稳定性的不同度量之间的强关系。表面和800 hPa之间的电位温差（一种称为M的度量）提供了比反演强度的度量（例如较低的对流层稳定性和估计的反演强度）更强的关系。这是因为（1）反演强度本身与云边界没有很好的关联，并且（2）M包含对云边界似乎很重要的信息。这些包括通过使用海面而不是近地表的空气温度强迫地表，以及接近真实云顶的上层。这些结果扩展了以前关于M作为云形态预测指标重要性的工作。但是，与南洋相比（在给定的M值下），北大西洋的低云条件存在重要差异：反演更强，边界层更深，海平面压力更大。因此，两个区域之间的云边界和M之间的关系不同。普通的环流模型提供了与M以及云顶高度和温度之间观察到的相似关系，但往往比给定的M观测到的云更高和更低的温度。这可能会导致降水，云量和辐射的表示问题。南大洋。与南洋相比（在给定的M值下），北大西洋的低云条件存在重要差异：反演更强，边界层更深，海平面压力更大。因此，两个区域之间的云边界和M之间的关系不同。普通的环流模型提供了与M以及云顶高度和温度之间观察到的相似关系，但往往比给定的M观测到的云更高和更低的温度。这可能会导致降水，云量和辐射的表示问题。南大洋。与南洋相比（在给定的M值下），北大西洋的低云条件存在重要差异：反演更强，边界层更深，海平面压力更大。因此，两个区域之间的云边界和M之间的关系不同。普通的环流模型提供了与M以及云顶高度和温度之间观察到的相似关系，但往往比给定的M观测到的云更高和更低的温度。这可能会导致降水，云量和辐射的表示问题。南大洋。两个区域之间云边界和M之间的关系不同。普通的环流模型提供了与M以及云顶高度和温度之间观察到的相似关系，但往往比给定的M观测到的云更高和更低的温度。这可能会导致降水，云量和辐射的表示问题。南大洋。两个区域之间云边界和M之间的关系不同。普通的环流模型提供了与M以及云顶高度和温度之间观察到的相似关系，但往往比给定的M观测到的云更高和更低的温度。这可能会导致降水，云量和辐射的表示问题。南大洋。