Project Details
Projekt
Physical and chemical properties of cloud particle residuals and ice nucleating particles related to high latitude clouds from mixed phase to cirrus level (HALO 2020, CIRRUS-HL)
Subject Area
Atmospheric Science
Term
since 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 442648163
High latitude or arctic cirrus clouds are suspected to have a positive cloud radiative effect (CRE), and thus might contribute to increasing surface temperatures (“Arctic Amplification”). The sign and strength of the CRE of arctic cirrus strongly depends on their cloud microphysical properties, which are ice particle concentration (Nice), effective ice particle radius and ice water content (IWC). These parameters are mainly determined by the ice formation process (heterogeneous vs. homogeneous ice nucleation), and by the cloud formation pathway (in-situ vs. liquid origin). This implies especially for the liquid origin cirrus the participation of ice nucleating particles (INP), which makes their abundance, properties and sources into key factors for the formation, the microphysical and thus radiative properties of high latitude cirrus. However, information about INP at high latitude (Arctic) in general and at higher altitudes in particular is extremely scarce.It is therefore proposed to enhance the knowledge about INP at high altitudes in the Arctic within the HALO mission CIRRUS-HL. This will be done by two different approaches: a) the characterization of ice particle residuals (IPR) in high-latitude cirrus and b) the vertically resolved measurement (mixed-phase to cirrus level) of high temperature INP (> -30°C) outside of cloud in the arctic troposphere. For the characterization of the IPR and INP, the HALO-CVI (Counterflow Virtual Impactor) and the aerosol particle filter sampler (HERA) will be used, respectively. Behind the HALO-CVI, instruments for the physical (number concentration, particle size distribution, black carbon concentration), and chemical (single particle chemical composition by MPI-C) characterization of the CPR and IPR, will applied. The HERA-collected filter samples will be analyzed after the campaign in the TROPOS laboratories concerning physical INP properties (number concentrations and freezing spectra) as well as aerosol particle bulk chemical composition.During in-cloud measurements, the HALO-CVI and HERA should be combined to identify and quantify the INP within the sampled IPR of arctic cirrus but also of cloud particle residuals (CPR, which is the sum of IPR and cloud droplet residuals) in arctic mixed phase clouds which could potentially be the precursor of liquid origin cirrus in high-latitudes.In combination with results from the in-situ measurements of cloud microphysical properties as well as back-trajectory analysis of the encountered air masses, we will a) carry out a unprecedented “closure study” relating in-cloud IPR to outside cloud INP abundance and properties, b) significantly enhance knowledge concerning INP spatiotemporal distribution, properties and sources, and c) get deep insights into the INP effects on the formation and microphysical properties of cirrus clouds.
DFG Programme
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