We report on a Polar Mesospheric Cloud (PMC) front structure observed on July 2, 2007 over Greenland. This structure appears to be localized solitary wave, with a sharp boundary that separates a cloud and cloud-free region. Near-coincident temperature measurements indicate a 20 K temperature difference between these two regions that likely contributed to the sharp PMC front boundary. Gravity wave (GW) temperature amplitude and buoyancy frequency show that large amplitude GWs and the formation of a stable atmospheric layer between two unstable regions supported the formation of a pronounced mesospheric temperature inversion that destroyed PMCs. Given the absence of an inversion layer close to the location of PMC front, it is not clear if a similar thermal duct but with colder temperatures supported the formation of a single wave resulting in the formation of the observed PMC front. The buoyancy frequency structure with stable and unstable regions also indicates mesospheric wave propagation, and is present in both the cloud and cloud-free regions. We identify a tropospheric low-pressure area and a frontal system as potential sources of these mesospheric GWs. Ray-tracing simulations indicate that GWs from these sources propagated to the mesosphere and may have contributed to the observed PMC variability.

我们报告了2007年7月2日在格陵兰岛上观测到的极地中层云（PMC）的前部结构。这种结构似乎是局部孤立波，具有将云和无云区域分开的尖锐边界。近乎一致的温度测量结果表明，这两个区域之间存在20 K的温差，这很可能导致了尖锐的PMC前边界。重力波（GW）的温度振幅和浮力频率表明，大振幅的GWs和两个不稳定区域之间稳定的大气层的形成支持了明显的中层温度反演的形成，该反演破坏了PMC。鉴于在PMC前沿位置附近没有反演层，尚不清楚是否有类似的热导管但温度较低，是否支持单波的形成，从而导致观察到的PMC前沿的形成。具有稳定和不稳定区域的浮力频率结构还指示中球波传播，并且同时存在于云区域和无云区域。我们确定了对流层低压区和额叶系统是这些中层GWs的潜在来源。射线追踪模拟表明，来自这些来源的GW传播到中层，可能有助于观测到的PMC变异性。我们确定了对流层低压区和额叶系统是这些中层GWs的潜在来源。射线追踪模拟表明，来自这些来源的GW传播到中层，可能有助于观测到的PMC变异性。我们确定了对流层低压区和额叶系统是这些中层GWs的潜在来源。射线追踪模拟表明，来自这些来源的GW传播到中层，可能有助于观测到的PMC变异性。