The Integrated Characterization of Clouds, Energy, Atmospheric state, and Precipitation at Summit, Aerosol-Cloud Experiment (ICECAPS-ACE)

The Integrated Characterization of Energy, Clouds, Atmospheric state, and Precipitation at Summit, Aerosol-Cloud Experiment (ICECAPS-ACE) project includes operation of a suite of atmospheric instruments that have continuously observed clouds, precipitation, atmospheric structure, and radiation over Summit, Greenland since 2010, with key additions of surface energy budget and aerosol measurements added in 2019. This first-of-its-kind deployment has provided many ground-breaking observations that have contributed to a wealth of scientific research, instrument and technique development, operational support, education, and personnel development.

Scientifically, ICECAPS has provided many new insights into atmospheric processes that impact the atmosphere and surface energy and mass budgets of the Greenland Ice Sheet. Research into atmospheric gases has focused on deriving and evaluating information on vertical profiles of ozone and assessing the drivers of its variability both vertically and over time. Aerosol research has provided the first detailed view of the annual variability of aerosol properties at Summit, and importantly has linked the annual and synoptic variation in aerosol concentrations to circulation patterns, precipitation, the occurrence of fog, and other processes. Extensive cloud research has examined numerous topics including the impact of ice crystal orientation on cloud radiative effects, the overall occurrence and radiative effects of fog over the central ice sheet, and model studies examining the impact and interactions of clouds at multiple levels on the cloud phase, radiative effects, and transitions. ICECAPS cloud and radiation observations have also provided important evaluation for satellite-derived cloud products over bright surfaces, and for climate model representations of cloud radiative effects over the ice sheet. ICECAPS results have been central to a number of additional studies that help to expand the knowledge developed at Summit to the broader Greenland Ice Sheet. Circulation classification techniques have been adapted to understand how clouds, precipitation, radiative effects, and surface temperature vary both at Summit and across the ice sheet as a function of large-scale circulation regime. Similar analyses have examined the spatial distribution of snowfall and its relation to features like large-scale atmospheric ?blocking? events that channel warm, moist air towards Greenland. Collectively, these larger-scale studies are revealing key details about the seasonal and spatial impacts of atmospheric processes on ice sheet mass loss (through melt) and mass gain (through precipitation) that are essential for understanding the fate of the ice sheet. Over the project period from summer 2018 to summer 2022, the ICECAPS team has produced about 20 scientific publications using ICECAPS data, and numerous other publications have resulted via collaborators and other partners.

ICECAPS has also achieved numerous broad impacts on science and society. First, data from the project has contributed to operational weather forecast models on a daily basis and has informed numerous stakeholders, such as airlines, of conditions over Greenland. Observations have been used to evaluate model parameterizations that will help those models to better represent the atmosphere, clouds, and surface interactions over the Greenland Ice Sheet where forecasting is challenging. The data has also been used by multiple space agencies for evaluation of their satellite measurements and by collaborators at numerous institutions that are developing new instrumentation for observing atmospheric phenomena. Beyond science, the project has supported a unique outreach effort that involves hand-held instruments that emulate some of the more sophisticated observations made in the field. These instruments are the basis for working with K-12 communities on related scientific concepts. Many details of the project have also been incorporated in public seminars, mentorship programs, classroom lectures, and more. Lastly, the project has featured prominent roles for numerous students and early career researchers, who have been involved in field work, instrument oversight, data processing, and analysis. Three PhD degrees have been earned by ICECAPS-funded researchers, while ICECAPS team members and data sets have supported multiple other students participating via collaborating institutions.