TY - JOUR
T1 - Size-dependent ice nucleation by airborne particles during dust events in the eastern Mediterranean
AU - Reicher, Naama
AU - Budke, Carsten
AU - Eickhoff, Lukas
AU - Raveh-Rubin, Shira
AU - Kaplan-Ashiri, Ifat
AU - Koop, Thomas
AU - Rudich, Yinon
N1 - This study was funded by the Israel Science Foundation (grant no. 236/16). The authors are grateful for funding from the German Research Foundation (DFG) through the research unit FOR 1525 (INUIT) under KO 2944/2-2 for Carsten Budke and Thomas Koop, as well as a Mercator Fellowship for Yinon Rudich; the authors acknowledge support from the Helen Kimmel Center for Planetary Sciences and the de Botton Center for Marine Sciences. Analyses and visualizations of MERRA data in this study were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC (http://giovanni.sci.gsfc.nasa.gov/Giovanni, last access: August 2018). PM10 data are available from the Israel Ministry of Environmental Protection website (http://www.svivaaqm.net/Default.rtl.aspx, last access: August 2018). Other data used in this study can be retrieved from https://osf.io/gpuqt (last access: August 2018). Author contributions. NR and YR designed the experiments, carried out the field measurements, conducted freezing experiments in WISDOM and wrote the paper. CB, LE and TK designed and performed freezing experiments in BINARY. SRR performed back trajectory analyses. NR and IKA performed the chemical analyses of filters. All authors contributed to the discussion, analysis of data and the writing of the paper. Financial support. This research has been supported by the Israel Science Foundation (grant no. 236/16), the German Research Foundation (DFG) through the research unit FOR 1525 (INUIT grant no. KO 2944/2-2), the Helen Kimmel Center for Planetary Sciences and the de Botton Center for Marine Sciences.
PY - 2019/9/3
Y1 - 2019/9/3
N2 - The prediction of cloud ice formation in climate models remains a challenge, partly due to the complexity of ice-related processes. Mineral dust is a prominent aerosol in the troposphere and is an important contributor to ice nucleation in mixed-phase clouds, as dust can initiate ice heterogeneously at relatively low supercooling conditions. We characterized the ice nucleation properties of size-segregated mineral dust sampled during dust events in the eastern Mediterranean. The sampling site allowed us to compare the properties of airborne dust from several sources with diverse mineralogy that passed over different atmospheric paths. We focused on particles with six size classes determined by the Micro-Orifice Uniform Deposit Impactor (MOUDI) cutoff sizes: 5.6, 3.2, 1.8, 1.0, 0.6 and 0.3 μm. Ice nucleation experiments were conducted in the Weizmann Supercooled Droplets Observation on a Microarray (WISDOM) setup, whereby the particles are immersed in nanoliter droplets using a microfluidics technique. We observed that the activity of airborne particles depended on their size class; supermicron and submicron particles had different activities, possibly due to different composition. The concentrations of ice-nucleating particles and the density of active sites (ns) increased with the particle size and particle concentration. The supermicron particles in different dust events showed similar activity, which may indicate that freezing was dominated by common mineralogical components. Combining recent data of airborne mineral dust, we show that current predictions, which are based on surface-sampled natural dust or standard mineral dust, overestimate the activity of airborne dust, especially for the submicron class. Therefore, we suggest including information on particle size in order to increase the accuracy of ice formation modeling and thus weather and climate predictions.
AB - The prediction of cloud ice formation in climate models remains a challenge, partly due to the complexity of ice-related processes. Mineral dust is a prominent aerosol in the troposphere and is an important contributor to ice nucleation in mixed-phase clouds, as dust can initiate ice heterogeneously at relatively low supercooling conditions. We characterized the ice nucleation properties of size-segregated mineral dust sampled during dust events in the eastern Mediterranean. The sampling site allowed us to compare the properties of airborne dust from several sources with diverse mineralogy that passed over different atmospheric paths. We focused on particles with six size classes determined by the Micro-Orifice Uniform Deposit Impactor (MOUDI) cutoff sizes: 5.6, 3.2, 1.8, 1.0, 0.6 and 0.3 μm. Ice nucleation experiments were conducted in the Weizmann Supercooled Droplets Observation on a Microarray (WISDOM) setup, whereby the particles are immersed in nanoliter droplets using a microfluidics technique. We observed that the activity of airborne particles depended on their size class; supermicron and submicron particles had different activities, possibly due to different composition. The concentrations of ice-nucleating particles and the density of active sites (ns) increased with the particle size and particle concentration. The supermicron particles in different dust events showed similar activity, which may indicate that freezing was dominated by common mineralogical components. Combining recent data of airborne mineral dust, we show that current predictions, which are based on surface-sampled natural dust or standard mineral dust, overestimate the activity of airborne dust, especially for the submicron class. Therefore, we suggest including information on particle size in order to increase the accuracy of ice formation modeling and thus weather and climate predictions.
UR - http://www.scopus.com/inward/record.url?scp=85072027692&partnerID=8YFLogxK
U2 - 10.5194/acp-19-11143-2019
DO - 10.5194/acp-19-11143-2019
M3 - مقالة
SN - 1680-7316
VL - 19
SP - 11143
EP - 11158
JO - Atmospheric Chemistry and Physics
JF - Atmospheric Chemistry and Physics
IS - 17
ER -