Investigations of snowfall processes based on multi-sensor measurements collected during the MOSAiC expedition

Abstract

Snow is a critical part of the Earth’s water cycle. Solid precipitation also crucially affects the radiation balance of the atmosphere while snow on the ground modulates albedo of land surfaces and sea ice. Reliable quantitative information on snowfall fluxes and microphysical parameterizations of solid precipitation processes are important components of development and verification of climate and weather models. Although Artic regions are affected by climate change most profoundly, atmospheric and oceanic observations there have been relatively sparse. The recently completed one year long Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign is intended to partially close a gap in the Arctic observations. A number of sensors measuring snowfall near the ground (e.g., precipitation weighing gauges, optical precipitation sensors, disdrometers) and millimeter-wavelength radars capable to remotely retrieve falling snow rates/fluxes and microphysical properties of snowflakes were deployed onboard of the MOSAiC icebreaker and in the ice camp nearby. The research objectives of this proposal include (i) Analyzing MOSAiC snow measurements from different sensors/gauges and assessing availability and reliability of different precipitation data sets; (ii) Enhancing radar-based snowfall retrievals with mitigating blowing snow effects; (iii) Developing a unified high temporal resolution (~ 30 sec) MOSAiC snowfall rate/flux data product based on radar measurements with accounting for reliable gauge measurements and ground-based measurements of snow depth and its water equivalent; (iv) Statistically investigating relations between precipitation intensity and snowflake habits using scanning radar-based approaches to retrieve snow particle shapes/habits; (v) Analyzing influence of riming, aggregation and secondary ice production processes on snowfall rates/fluxes based on the retrieved habit information and auxiliary measurements; (vi) Investigating possible links between aerosol parameters and snowfall characteristics. The outcome of the proposed studies includes the MOSAiC snowfall rate/flux data product provided for the use of the research community and results of microphysical studies of snowfall processes aimed at improving solid precipitation parameterizations in models.