Abstract:

The Arctic is one of the most sensitive regions to climate change. Since cloud phase can influence radiative balance, weather processes, and interact with aerosols, and is also one of the critical parameters currently lacking in climate models, studying cloud phase can provide new perspectives for assessing Arctic climate change. Based on the CALIPSO-GOCCP cloud phase dataset from 2006 to 2020, combined with CALIPSO VFM aerosol products, ERA5 reanalysis data, and NSIDC sea ice data, this study analyzed the 3D structure of Arctic cloud phase. Also, the relationships between cloud phase and aerosol distribution, meteorological factors, and sea ice concentration (SIC) are mentioned in this study. The research finds that Arctic cloud cover and liquid-containing cloud fraction (F_LCF) are significantly higher over ocean regions than over land, with such spatial differences primarily driven by underlying surface topography, thermal conditions, and aerosol transport. Additionally, F_LCF is most prominent in summer, followed by autumn, and lower in winter and spring, a pattern mainly due to seasonal differences in temperature, aerosol concentration, and atmospheric dynamics. The vertical distribution of F_LCF decreases rapidly with increasing altitude and latitude. Moreover, we find that spatial differences in F_LCF distribution are primarily driven by topography, thermal conditions, and transport of aerosols. Over land, F_LCF is positively correlated with surface temperature, with correlation coefficients around 0.8, but negatively correlated with the frequency of occurrences (F_FoOs) of ice-nucleating aerosols, lower tropospheric static stability (LTSS), and the component of wind at 100 hPa, with correlation coefficients around –0.5. Over oceans, F_LCF is also positively correlated with surface temperature and negatively correlated with the U component of wind at 100 hPa U. However, F_LCF over oceans is positively correlated with the F_FoOs of ice-nucleating aerosols, with correlation coefficients around 0.6. However, F_LCF in the Pacific Arctic is negatively correlated with LTSS, with a correlation coefficient of –0.61, while over the Atlantic Arctic, F_LCF shows a positive correlation with LTSS, with a correlation coefficient of 0.7. The relationship between F_LCF and SIC is predominantly negative, particularly in summer, with a correlation coefficient of about –0.3. However, positive correlations between F_LCF and SIC are found in some sea-ice edge regions, with correlation coefficients around 0.3.

Key words: Arctic, cloud phase, 3D structure, land-ocean differences, meteorological conditions, sea ice