Seminar

Abstract

Andreas Herber, Hannes Schulz and Marco Zanatta (AWI) & Greg Kok (DMT)

The Alfred Wegener Institute (AWI) is Germany's polar and marine research institution funded by the Minister of Science and Technology. AWI runs not only several research platforms, such as land stations in the Arctic and Antarctic, ships and aircraft, but also employs its own scientific personnel. We present the work from AWI's sea ice physics section that focuses on the influences of the short-lived climate forcer black carbon (BC) on the Arctic climate system.

We evaluate the mass concentration, the size distribution and mixing state, of refractory black carbon (rBC) particles with a Single Particle Soot Photometer (SP2). Those light-absorbing particles are found as aerosols in the atmosphere or as depositions on surfaces - such as snow and ice. The Arctic climate system is very vulnerable to perturbations of the radiation budget balance by the additional energy absorbed by BC, which is among the main anthropogenic climate positive forcers. Special about the polar climate system are the stable stratification of the cold atmosphere that results in complex layering and the extreme variability of the reflectivity of the surface (albedo) when the snow and ice cover is melting.

Energy absorption due to the BC interaction with solar radiation and clouds and the albedo reduction by BC deposition onto bright snow and ice surfaces are among the major uncertainties in today's climate models. We address those uncertainties in the Arctic with BC measurements by taking an SP2 aboard the AWI's research aircraft POLAR 5 and POLAR 6, which has been done on a regular basis since 2009. Also BC concentrations in snow on sea ice are evaluated with an SP2 combined with a nebulising system. We will present an overview on our airborne campaigns PAMARCMiP and NETCARE that traversed the Western Arctic and the snow sampling campaign BlaCkSnow-AHS at the AWIPEV station in Ny-Ålesund (Svalbard). Those projects aim to refine important model input parameters for the Arctic environment in cooperation with project partners from the climate modelling community.

The low signal to noise ratio of current version of the SP2 leads to a low size detection limit of 80-90 nm. The AWI and the manufacturer of the SP2, Droplet Measurement Technologies, initiated a joint research and development project aimed to improve the detection limit of a “next generation” SP2 (SP2-NG). Effort from AWI and DMT are also focused to design a more user-friendly instrument suited for airborne and long-term measurements.