Clouds are an important, yet poorly understood, component of the Arctic’s radiative budget. Clouds affect both the downwelling shortwave radiation by reflecting solar radiation back to space and upwelling longwave radiation by absorbing and re-emitting part of the radiation to the surface. Climate models have difficulties to simulate the cloud radiative effect in the Arctic due to misrepresented cloud microphysics, which stem from a lack of in situ observations of atmospheric properties relevant to cloud formation and cloud microphysics. Aerosols, acting as cloud condensation nuclei (CCN) and ice nucleating particles (INP), play a determining role in modulating the formation, lifetime, and radiative effects of Arctic clouds.
In this project, the student will make use of a unique dataset of CCN measurements collected over an entire year onboard a research vessel in the central Arctic Ocean (MOSAiC expedition). The student will derive the first ever annual cycle of CCN properties in the central Arctic. Such properties include the number concentration of CCN, activation ratio (ratio of particles capable of activating in cloud droplets at a given supersaturation versus total aerosol number concentration), critical diameter (diameter at which aerosols can activate into cloud droplets), and aerosol hygroscopicity (tendency of aerosols to absorb water). The students will then explore the processes leading to the observed seasonal cycle. This seasonal cycle will also be compared to measurements made at land-based monitoring Arctic sites.
Overall, the student should have a great interest for atmospheric processes and data analysis. If you are interested in this project or want to learn more about it, please contact Julia Schmale ([email protected]) or Benjamin Heutte ([email protected]).