Geometrical and Microphysical Properties of Clouds Formed in the Presence of Dust above the Eastern Mediterranean

In this work, collocated lidar–radar observations are used to retrieve the vertical profiles of cloud properties above the Eastern Mediterranean. Measurements were performed in the framework of the PRE-TECT experiment during April 2017 at the Greek atmospheric observatory of Finokalia, Crete. Cloud geometrical and microphysical properties at different altitudes were derived using the Cloudnet target classification algorithm. We found that the variable atmospheric conditions that prevailed above the region during April 2017 resulted in complex cloud structures. Mid-level clouds were observed in 38% of the cases, high or convective clouds in 58% of the cases, and low-level clouds in 2% of the cases. From the observations of cloudy profiles, pure ice phase occurred in 94% of the cases, mixed-phase clouds were observed in 27% of the cases, and liquid clouds were observed in 8.7% of the cases, while Drizzle or rain occurred in 12% of the cases. The significant presence of Mixed-Phase Clouds was observed in all the clouds formed at the top of a dust layer, with three times higher abundance than the mean conditions (26% abundance at −15 °C). The low-level clouds were formed in the presence of sea salt and continental particles with ice abundance below 30%. The derived statistics on clouds’ high-resolution vertical distributions and thermodynamic phase can be combined with Cloudnet cloud products and lidar-retrieved aerosol properties to study aerosol-cloud interactions in this understudied region and evaluate microphysics parameterizations in numerical weather prediction and global climate models.

[1]  G. Biskos,et al.  New particle formation in the southern Aegean Sea during the Etesians: importance for CCN production and cloud droplet number , 2016 .

[2]  T. Petäjä,et al.  Atmospheric new particle formation as a source of CCN in the eastern Mediterranean marine boundary layer , 2015 .

[3]  Doina Nicolae,et al.  An automatic observation-based aerosol typing method for EARLINET , 2018, Atmospheric Chemistry and Physics.

[4]  A. Stohl,et al.  The Finokalia Aerosol Measurement Experiment – 2008 (FAME-08): an overview , 2010 .

[5]  A. Nenes,et al.  Size-resolved CCN distributions and activation kinetics of aged continental and marine aerosol , 2011 .

[6]  J. Lelieveld,et al.  A multi-model, multi-scenario, and multi-domain analysis of regional climate projections for the Mediterranean , 2019, Regional Environmental Change.

[7]  P. Seifert,et al.  The day-to-day co-variability between mineral dust and cloud glaciation: a proxy for heterogeneous freezing , 2019, Atmospheric Chemistry and Physics.

[8]  Vincenzo Cuomo,et al.  CIAO: the CNR-IMAA advanced observatory for atmospheric research , 2010 .

[9]  Albert Ansmann,et al.  Retrieval of ice-nucleating particle concentrations from lidar observations and comparison with UAV in situ measurements , 2019, Atmospheric Chemistry and Physics.

[10]  R. Engelmann,et al.  HETEAC: The Aerosol Classification Model for EarthCARE , 2016 .

[11]  G. Biskos,et al.  Biomass-burning impact on CCN number, hygroscopicity and cloud formation during summertime in the eastern Mediterranean , 2016, Atmospheric Chemistry and Physics.

[12]  Albert Ansmann,et al.  The automated multiwavelength Raman polarization and water-vapor lidar PollyXT: The neXT generation , 2016 .

[13]  U. Lohmann,et al.  Global indirect aerosol effects: a review , 2004 .

[14]  S. Reimann,et al.  Abundance and sources of atmospheric halocarbons in the Eastern Mediterranean , 2017 .

[15]  Gianandrea Mannarini,et al.  Numerical analysis of a Mediterranean ‘hurricane’ over south-eastern Italy: Sensitivity experiments to sea surface temperature , 2011 .

[16]  Doina Nicolae,et al.  A neural network aerosol-typing algorithm based on lidar data , 2018, Atmospheric Chemistry and Physics.

[17]  Hemispheric contrasts in ice formation in stratiform mixed-phase clouds: disentangling the role of aerosol and dynamics with ground-based remote sensing , 2021, Atmospheric Chemistry and Physics.

[18]  L. Mona,et al.  Investigation of Volcanic Emissions in the Mediterranean: “The Etna–Antikythera Connection” , 2020, Atmosphere.

[19]  J. Delanoë,et al.  Antarctic clouds, supercooled liquid water and mixed phase, investigated with DARDAR: geographical and seasonal variations , 2018, Atmospheric Chemistry and Physics.

[20]  B. Weinzierl,et al.  Aerosol classification by airborne high spectral resolution lidar observations , 2012 .

[21]  A. Ansmann,et al.  Remote sensing and modelling analysis of the extreme dust storm hitting the Middle East and eastern Mediterranean in September 2015 , 2016 .

[22]  Ville Vakkari,et al.  A generalised background correction algorithm for a Halo Doppler lidar and its application to data from Finland , 2015 .

[23]  Albert Ansmann,et al.  Ice nucleating particles over the Eastern Mediterranean measured by unmanned aircraft systems , 2016 .

[24]  C. Bretherton,et al.  Improving our fundamental understanding of the role of aerosol−cloud interactions in the climate system , 2016, Proceedings of the National Academy of Sciences.

[25]  T. Storelvmo,et al.  Observational constraints on mixed-phase clouds imply higher climate sensitivity , 2015, Science.

[26]  A. Nenes,et al.  Parameterizing the competition between homogeneous and heterogeneous freezing in ice cloud formation – polydisperse ice nuclei , 2009 .

[27]  P. Kollias,et al.  Ice particle production in mid-level stratiform mixed-phase clouds observed with collocated A-Train measurements , 2017 .

[28]  A. Nenes,et al.  Atmospheric Chemistry and Physics Cloud Condensation Nuclei Measurements in the Marine Boundary Layer of the Eastern Mediterranean: Ccn Closure and Droplet Growth Kinetics , 2022 .

[29]  P. Lionello,et al.  Links of the significant wave height distribution in the Mediterranean sea with the Northern Hemisphere teleconnection patterns , 2008 .

[30]  Ulla Wandinger,et al.  Target categorization of aerosol and clouds by continuous multiwavelength-polarization lidar measurements , 2017 .

[31]  L. Remer,et al.  Review: Cloud invigoration by aerosols—Coupling between microphysics and dynamics , 2014 .

[32]  M. D. Petters,et al.  Predicting global atmospheric ice nuclei distributions and their impacts on climate , 2010, Proceedings of the National Academy of Sciences.

[33]  P. Lionello,et al.  The relation between climate change in the Mediterranean region and global warming , 2018, Regional Environmental Change.

[34]  Sandra L. LeGrand,et al.  The AFWA dust emission scheme for the GOCART aerosol model in WRF-Chem v3.8.1 , 2019, Geoscientific Model Development.

[35]  J. Jacobeit Variations of trough positions and precipitation patterns in the mediterranean area , 1987 .