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Six years of surface remote sensing of stratiform warm clouds in marine and continental air over Mace Head, Ireland
Author(s) -
Preißler Jana,
Martucci Giovanni,
Saponaro Giulia,
Ovadnevaite Jurgita,
Vaishya Aditya,
Kolmonen Pekka,
Ceburnis Darius,
Sogacheva Larisa,
Leeuw Gerrit,
O'Dowd Colin
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025360
Subject(s) - environmental science , liquid water path , moderate resolution imaging spectroradiometer , atmospheric sciences , albedo (alchemy) , cloud albedo , air mass (solar energy) , spectroradiometer , aerosol , hysplit , effective radius , remote sensing , meteorology , cloud computing , cloud cover , satellite , boundary layer , physics , geology , reflectivity , art , galaxy , computer science , optics , operating system , quantum mechanics , thermodynamics , art history , astronomy , performance art
Abstract A total of 118 stratiform water clouds were observed by ground‐based remote sensing instruments at the Mace Head Atmospheric Research Station on the west coast of Ireland from 2009 to 2015. Microphysical and optical characteristics of these clouds were studied as well as the impact of aerosols on these properties. Microphysical and optical cloud properties were derived using the algorithm SYRSOC (SYnergistic Remote Sensing Of Clouds). Ground‐based in situ measurements of aerosol concentrations and the transport path of air masses at cloud level were investigated as well. The cloud properties were studied in dependence of the prevailing air mass at cloud level and season. We found higher cloud droplet number concentrations (CDNC) and smaller effective radii ( r eff ) with greater pollution. Median CDNC ranged from 60 cm −3 in marine air masses to 160 cm −3 in continental air. Median r eff ranged from 8 μm in polluted conditions to 10 μm in marine air. Effective droplet size distributions were broader in marine than in continental cases. Cloud optical thickness (COT) and albedo were lower in cleaner air masses and higher in more polluted conditions, with medians ranging from 2.1 to 4.9 and 0.22 to 0.39, respectively. However, calculation of COT and albedo was strongly affected by liquid water path (LWP) and departure from adiabatic conditions. A comparison of SYRSOC results with MODIS (Moderate‐Resolution Imaging Spectroradiometer) observations showed large differences for LWP and COT but good agreement for r eff with a linear fit with slope near 1 and offset of −1 μm.