White-light optical particle spectrometer for in situ measurements of condensational growth of aerosol particles

2005 ◽  
Vol 44 (22) ◽  
pp. 4693 ◽  
Author(s):  
Alexei Kiselev ◽  
Heike Wex ◽  
Frank Stratmann ◽  
Alexandre Nadeev ◽  
Dmitry Karpushenko
Keyword(s):  
White Light ◽  
Aerosol Particles ◽  
In Situ Measurements ◽  
Condensational Growth

Prospective White-light Imaging and In Situ Measurements of Quiescent Large-scale Solar-wind Streams from the Parker Solar Probe and Solar Orbiter

2018 ◽  
Vol 868 (2) ◽  
pp. 137 ◽  
Author(s):  
Ming Xiong ◽  
Jackie A. Davies ◽  
Xueshang Feng ◽  
Bo Li ◽  
Liping Yang ◽  
...  
Keyword(s):  
Solar Wind ◽  
White Light ◽  
Large Scale ◽  
In Situ Measurements ◽  
White Light Imaging

scholarly journals A new approach to estimate supersaturation fluctuations in stratocumulus cloud using ground-based remote sensing measurements

2019 ◽  
Author(s):  
Fan Yang ◽  
Robert McGraw ◽  
Edward P. Luke ◽  
Damao Zhang ◽  
Pavlos Kollias ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Steady State ◽  
Cloud Droplet ◽  
In Situ Measurements ◽  
Quasi Steady State ◽  
Marine Stratocumulus ◽  
Spatial And Temporal Scales ◽  
Stratocumulus Clouds ◽  
Condensational Growth

Abstract. Supersaturation, crucial for cloud droplet activation and condensational growth, varies in clouds at different spatial and temporal scales. In-cloud supersaturation is poorly known and rarely measured directly. On the scale of a few tens of meters, supersaturation in clouds has been estimated from in-situ measurements assuming quasi-steady state supersaturation. Here, we provide a new method to estimate supersaturation using ground-based remote sensing measurements, and results are compared with those estimated from aircraft in-situ measurements in a marine stratocumulus cloud during the ACE-ENA field campaign. Our method agrees reasonably well with in-situ estimations and it has three advantages: (1) it does not rely on the quasi-steady state assumption, which is questionable in clean or turbulent clouds; (2) it can provide a supersaturation profile, rather than just point values from in-situ measurements; and (3) it enables building statistics of supersaturation in stratocumulus clouds for various meteorological conditions from multi-year ground-based measurements. The uncertainties, limitations and possible applications of our method are discussed.

scholarly journals A new approach to estimate supersaturation fluctuations in stratocumulus cloud using ground-based remote-sensing measurements

2019 ◽  
Vol 12 (11) ◽  
pp. 5817-5828 ◽  
Author(s):  
Fan Yang ◽  
Robert McGraw ◽  
Edward P. Luke ◽  
Damao Zhang ◽  
Pavlos Kollias ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Steady State ◽  
Cloud Droplet ◽  
In Situ Measurements ◽  
Quasi Steady State ◽  
Marine Stratocumulus ◽  
Spatial And Temporal Scales ◽  
Stratocumulus Clouds ◽  
Condensational Growth

Abstract. Supersaturation, crucial for cloud droplet activation and condensational growth, varies in clouds at different spatial and temporal scales. In-cloud supersaturation is poorly known and rarely measured directly. On the scale of a few tens of meters, supersaturation in clouds has been estimated from in situ measurements assuming quasi-steady-state supersaturation. Here, we provide a new method to estimate supersaturation using ground-based remote-sensing measurements, and results are compared with those estimated from aircraft in situ measurements in a marine stratocumulus cloud during the Aerosol and Cloud Experiment (ACE-ENA) field campaign. Our method agrees reasonably well with in situ estimations, and it has three advantages: (1) it does not rely on the quasi-steady-state assumption, which is questionable in clean or turbulent clouds, (2) it can provide a supersaturation profile, rather than just point values from in situ measurements, and (3) it enables building statistics of supersaturation in stratocumulus clouds for various meteorological conditions from multi-year ground-based measurements. The uncertainties, limitations, and possible applications of our method are discussed.

The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

2019 ◽  
Author(s):  
Michael Stukel ◽  
Thomas Kelly
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Transport Model ◽  
California Current ◽  
In Situ Measurements ◽  
Power Law Distribution ◽  
Sinking Particles ◽  
Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

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