Ganeshan Manisha, Yang Yuekui, Palm Stephen P
Morgan State University Baltimore MD USA.
NASA Godddard Space Flight Center Greenbelt MD USA.
J Geophys Res Atmos. 2022 Nov 16;127(21):e2022JD036801. doi: 10.1029/2022JD036801. Epub 2022 Nov 10.
Clouds and blowing snow (BLSN) occur frequently over Antarctica, where it is critical to understand their feedbacks to surface and atmospheric boundary layer processes. Dome C, an elevated East Antarctic station, dominated by lengthy periods of surface longwave (LW) radiative cooling, is selected to reveal cloud and BLSN impacts within a largely stable environment. The sky condition is classified as clear, cloudy, or BLSN, using 3 years of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations satellite data. Co-located and contemporaneous in situ observations are used to investigate the relationship of sky condition with surface and atmospheric boundary layer thermal structure, focusing on seasonal variability. Results show that increased downwelling LW radiation from clouds abate surface radiative cooling losses, contributing to warming during all seasons. An increase of 3°C in the mean surface air temperature is observed during spring, whereas, a more dramatic rise (around 10°C), due to accompanying large-scale subsidence, is observed during fall and winter in association with clouds. For all seasons, the wind speed and wind speed shear are strongest during BLSN events, and the surface-based inversion is weakened by cooling which peaks in a shallow above-surface turbulent layer. The stronger background stability during fall and winter seasons, restricts turbulence and BLSN depths generally to the lowest tens of meters. The Earth's cryosphere is among the most rapidly evolving yet least well-observed regions, and knowledge of clouds and BLSN interactions with the typical stable atmospheric boundary layer can help further understand energy and moisture exchanges.
吹雪（BLSN）和云层在南极洲频繁出现，了解它们对地表和大气边界层过程的反馈至关重要。位于东南极高地的 Dome C 站，长期受地表长波（LW）辐射冷却影响，在这个基本稳定的环境中被选来揭示云层和吹雪的影响。利用3年的云 - 气溶胶激光雷达和红外探测器卫星观测数据，将天空状况分为晴朗、多云或吹雪。同时同地的现场观测用于研究天空状况与地表和大气边界层热结构的关系，重点关注季节变化。结果表明，云层增加的向下长波辐射减少了地表辐射冷却损失，有助于四季变暖。春季平均地表气温升高3°C，而秋季和冬季，由于伴随大规模下沉，与云层相关的气温升高更为显著（约10°C）。在所有季节中，吹雪事件期间风速和风速切变最强，地表逆温因冷却而减弱，冷却在浅层近地表湍流层达到峰值。秋冬季节较强的背景稳定性通常将湍流和吹雪深度限制在最低的几十米。地球冰冻圈是变化最迅速但观测最少的区域之一，了解云层和吹雪与典型稳定大气边界层的相互作用有助于进一步理解能量和水分交换。
