Joint Seminar: Understanding the interaction of solar radiation with atmospheric particles – implications for the radiative transfer and climate modeling

Clouds and aerosol particles contribute to the largest uncertainty in interpreting and

estimating the changes in Earth’s energy budget and, therefore, the understanding of the

interaction between radiation and atmospheric particles is crucial for modelling their climate

forcing. Including optical properties of atmospheric particles to models is a hard task as

modelling the optical properties of aspherical or complex particles is challenging. Field and

laboratory measurements are needed to improve parametrizations.

This talk presents latest experimental results of laboratory and field experiments on the

optical properties of complex aerosol and ice particles. In the first part the depolarization

behavior of dust particles and the optical properties of secondary organic aerosol (SOA) and

coated soot particles are investigated in aerosol chamber experiments. It is shown that the

depolarization properties of dust contain information on the size of the particles, which can

potentially be used to improve lidar retrievals. Another finding is that pure α-pinene SOA

particles possess a measurable absorption. In the second part of the talk the nature and

angular light scattering properties of natural ice particles are discussed. Evidence for

distorted or complex ice crystals has been long available from satellite observation and from

laboratory studies but here I show the first global in-situ measurements of ice crystal

complexity. It was found that natural ice crystals are rarely pristine and that their high degree

of crystal complexity leads to an enhanced backscattering and, consequently, to a decrease

of the cloud asymmetry parameter, making ice clouds more back-reflecting than previously

thought.

Datum

29.03.2017

Uhrzeit

13:30 Uhr

Ort

Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg

ReferentIn

Emma Järvinen, Karlsruhe Insitute of Technology

Chair

Bjorn Stevens

Zur Übersicht