Dr. Marcus Klingebiel, Universität Leipzig
„Temporal Evolution of Cloud Properties in Arctic Cold air Outbreak Cloud Streets” In this study, we examine the temporal evolution of Arctic cold air outbreak cloud streets
and their effects on the atmospheric radiation budget over the Fram Strait. Utilizing
observations from the HALO-(AC)³ aircraft campaign conducted in 2022, we analyze the
structure, microphysical, and macrophysical properties of transitioning cloud streets
and assess their radiative impacts.
Our investigation explores how wind shear and buoyancy forces contribute to the shift
from cloud street formations to isotropic cloud patterns, with a focus on how changes in
wind speed and atmospheric stability, as indicated by the Richardson number, drive this
transition. Results from our case study reveal that reduced wind speeds hinder cloud
street formation, promoting isotropic cloud formations. This shift increases cloud
fraction (from 0.73 to 0.84), cloud top height (from 330 m to 390 m), and liquid water
path, alongside a rise in cloud particle concentrations within the 100 μm to 1000 μm size
range.
Radiative budget observations indicate that organized cloud streets exhibit higher
albedo (0.45) and greater thermal infrared net irradiance (-133 W m⁻²) compared to
isotropic clouds (0.35 and -139 W m⁻², respectively). Our findings highlight the
importance of accurately representing these processes in climate models to enhance
predictions of Arctic amplification and its influence on global climate systems. |
