Aircraft Measurements of the Microphysical Properties of Stratiform Clouds with Embedded Convection

2021 ◽  
Author(s):  
Tuanjie Hou ◽  
Hengchi Lei ◽  
Youjiang He ◽  
Jiefan Yang ◽  
Zhen Zhao ◽  
...  
Keyword(s):  
Aircraft Measurements ◽  
Microphysical Properties ◽  
Stratiform Clouds

Aircraft measurements of aerosol, cloud droplets and drizzle in stratiform clouds over the northwest Atlantic ocean

2013 ◽  
Author(s):  
Stéphanie Gagné ◽  
Landan MacDonald ◽  
Michael Earle ◽  
W. Richard Leaitch ◽  
Jeffrey R. Pierce
Keyword(s):  
Atlantic Ocean ◽  
Aircraft Measurements ◽  
Cloud Droplets ◽  
Northwest Atlantic ◽  
Aerosol Cloud ◽  
Stratiform Clouds

scholarly journals First Look at the Occurrence of Horizontally Oriented Ice Crystals over Summit, Greenland

2017 ◽  
Author(s):  
Sebastian Cole ◽  
Ryan R. Neely III. ◽  
Robert A. Stillwell
Keyword(s):  
Ground Level ◽  
Cirrus Clouds ◽  
Ice Crystals ◽  
Wind Speeds ◽  
Microphysical Properties ◽  
Stratiform Clouds ◽  
Monthly Changes ◽  
Microphysical Processes ◽  
Monthly Variations

Abstract. The microphysical properties of clouds play a significant role in determining their radiative effect; one of these properties is the orientation of ice crystals. A source of error in current microphysical retrievals and model simulations is the assumption that clouds are composed of only randomly oriented ice crystals (ROIC). This assumption is frequently not true, as evidenced by optical phenomena such as parhelia (commonly referred to as sundogs). Here, observations from the Cloud, Aerosol and Polarization Backscatter Lidar (CAPABL) at Summit, Greenland are utilized along with instruments that are part of the Integrated Characterization of Energy, Clouds, Atmospheric state and Precipitation at Summit (ICECAPS) project in order to determine when, where and under what conditions horizontally oriented ice crystals (HOIC) occur at Summit, Greenland. Between July 2015 and May 2016, HOIC are observed on 86 days of the 335-day study. HOIC occurred within stratiform clouds on 48 days, in precipitation on 32 days and in cirrus clouds on 14 days. Analysis of all of the cases found that, on average, in comparison to ROIC, HOIC occur at higher temperatures, higher wind speeds and lower heights above ground level. Differences were also present in the relative humidities (RHs) at which HOIC and ROIC occurred in stratiform clouds and precipitation but not in cirrus clouds. Analysis over the whole study period revealed monthly variations in the abundance of HOIC with the number of detections peaking in April and October. Monthly changes were also present in the number of days containing HOIC. The results presented here aim to be the first step towards a comprehensive climatology and understanding of the microphysical processes that lead to the formation of HOIC at Summit, Greenland.

scholarly journals Multi-wavelength Raman lidar, sunphotometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

2012 ◽  
Vol 5 (1) ◽  
pp. 589-625
Author(s):  
R. E. Mamouri ◽  
A. Papayannis ◽  
V. Amiridis ◽  
D. Müller ◽  
P. Kokkalis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Properties ◽  
Urban Site ◽  
Aircraft Measurements ◽  
Raman Lidar ◽  
Lidar System ◽  
Aerosol Composition ◽  
Microphysical Properties ◽  
Multi Wavelength

Abstract. A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project which took place between 15–31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers occurred on 20–21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius – reff), single-scattering albedo (ω) and mean complex refractive index (m) at selected heights in the 2–3 km height region. We found that reff was 0.3–0.4 μm, ω at 532 nm ranged from 0.63 to 0.88 and m ranged from 1.45 + 0.015i to 1.56 + 0.05i, in good accordance with in situ aircraft measurements. The final data set of the aerosol microphysical properties along with the water vapor and temperature profiles were incorporated into the ISORROPIA model to infer an in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2–3 km height region gave a variable range of sulfate (0–60%) and organic carbon (OC) content (0–50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; in connection with the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sunphotometer data.

scholarly journals Comparing parameterized versus measured microphysical properties of tropical convective cloud bases during the ACRIDICON–CHUVA campaign

2017 ◽  
Vol 17 (12) ◽  
pp. 7365-7386 ◽  
Author(s):  
Ramon Campos Braga ◽  
Daniel Rosenfeld ◽  
Ralf Weigel ◽  
Tina Jurkat ◽  
Meinrat O. Andreae ◽  
...  
Keyword(s):  
Cloud Condensation Nuclei ◽  
Convective Cloud ◽  
Cloud Base ◽  
Aircraft Measurements ◽  
Cloud Drop ◽  
Convective Clouds ◽  
Microphysical Properties ◽  
Cloud Water Content ◽  
Satellite Retrievals ◽  
Vertical Evolution

Abstract. The objective of this study is to validate parameterizations that were recently developed for satellite retrievals of cloud condensation nuclei supersaturation spectra, NCCN(S), at cloud base alongside more traditional parameterizations connecting NCCN(S) with cloud base updrafts and drop concentrations. This was based on the HALO aircraft measurements during the ACRIDICON–CHUVA campaign over the Amazon region, which took place in September 2014. The properties of convective clouds were measured with a cloud combination probe (CCP), a cloud and aerosol spectrometer (CAS-DPOL), and a CCN counter onboard the HALO aircraft. An intercomparison of the cloud drop size distributions (DSDs) and the cloud water content (CWC) derived from the different instruments generally shows good agreement within the instrumental uncertainties. To this end, the directly measured cloud drop concentrations (Nd) near cloud base were compared with inferred values based on the measured cloud base updraft velocity (Wb) and NCCN(S) spectra. The measurements of Nd at cloud base were also compared with drop concentrations (Na) derived on the basis of an adiabatic assumption and obtained from the vertical evolution of cloud drop effective radius (re) above cloud base. The measurements of NCCN(S) and Wb reproduced the observed Nd within the measurements uncertainties when the old (1959) Twomey's parameterization was used. The agreement between the measured and calculated Nd was only within a factor of 2 with attempts to use cloud base S, as obtained from the measured Wb, Nd, and NCCN(S). This underscores the yet unresolved challenge of aircraft measurements of S in clouds. Importantly, the vertical evolution of re with height reproduced the observation-based nearly adiabatic cloud base drop concentrations, Na. The combination of these results provides aircraft observational support for the various components of the satellite-retrieved methodology that was recently developed to retrieve NCCN(S) under the base of convective clouds. This parameterization can now be applied with the proper qualifications to cloud simulations and satellite retrievals.

scholarly journals Multi-wavelength Raman lidar, sun photometric and aircraft measurements in combination with inversion models for the estimation of the aerosol optical and physico-chemical properties over Athens, Greece

2012 ◽  
Vol 5 (7) ◽  
pp. 1793-1808 ◽  
Author(s):  
R. E. Mamouri ◽  
A. Papayannis ◽  
V. Amiridis ◽  
D. Müller ◽  
P. Kokkalis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Chemical Properties ◽  
Urban Site ◽  
Aircraft Measurements ◽  
Raman Lidar ◽  
Lidar System ◽  
Aerosol Composition ◽  
Microphysical Properties ◽  
Multi Wavelength

Abstract. A novel procedure has been developed to retrieve, simultaneously, the optical, microphysical and chemical properties of tropospheric aerosols with a multi-wavelength Raman lidar system in the troposphere over an urban site (Athens, Greece: 37.9° N, 23.6° E, 200 m a.s.l.) using data obtained during the European Space Agency (ESA) THERMOPOLIS project, which took place between 15–31 July 2009 over the Greater Athens Area (GAA). We selected to apply our procedure for a case study of intense aerosol layers that occurred on 20–21 July 2009. The National Technical University of Athens (NTUA) EOLE 6-wavelength Raman lidar system has been used to provide the vertical profiles of the optical properties of aerosols (extinction and backscatter coefficients, lidar ratio) and the water vapor mixing ratio. An inversion algorithm was used to derive the mean aerosol microphysical properties (mean effective radius (reff), single-scattering albedo ω) and mean complex refractive index (m)) at selected heights in the 2–3 km height region. We found that reff was 0.14–0.4 (±0.14) μm, ω was 0.63–0.88 (±0.08) (at 532 nm) and m ranged from 1.44 (±0.10) + 0.01 (±0.01)i to 1.55 (±0.12) + 0.06 (±0.02)i, in good agreement (only for the reff values) with in situ aircraft measurements. The water vapor and temperature profiles were incorporated into the ISORROPIA II model to propose a possible in situ aerosol composition consistent with the retrieved m and ω values. The retrieved aerosol chemical composition in the 2–3 km height region gave a variable range of sulfate (0–60%) and organic carbon (OC) content (0–50%), although the OC content increased (up to 50%) and the sulfate content dropped (up to 30%) around 3 km height; the retrieved low ω value (0.63), indicates the presence of absorbing biomass burning smoke mixed with urban haze. Finally, the retrieved aerosol microphysical properties were compared with column-integrated sun photometer CIMEL data.

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