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Robert Wood, Kuan-Ting O, Christopher S. Bretherton, Johannes Mohrmann, Bruce. A. Albrecht, Paquita Zuidema, Virendra Ghate, Chris Schwartz, Ed Eloranta, Susanne Glienke, Raymond A. Shaw, Jacob Fugal, and Patrick Minnis

is consistent with the frequent penetration of veil clouds by the lidar. If veil clouds did not have such low N d but instead had values close to the accumulation-mode aerosol in the surface mixed layer (~75 cm −3 ; see Part II ), then from Eq. (1) , τ ~ 5, in which case, lidar would not penetrate the cloud. Indeed, for a threshold optical depth of 3, below which lidar will penetrate ( Winker and Poole 1995 ), N d must be below approximately 20 cm −3 . Thus, the low optical thickness of

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Kuan-Ting O, Robert Wood, and Christopher S. Bretherton

coalescence-scavenging rate is derived from the stochastic collection equation as a function of and . With the parameterization, the relative importance of updraft, aerosol concentration, cloud thickness, and adiabaticity in coalescence-scavenging process are accessed. Section 5 offers a conclusion. 2. Parcel model a. Basic model formulations A Lagrangian adiabatic parcel model with explicit two-dimensional bin microphysics spanning aerosol and water droplet sizes is formulated to simulate the

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Bruce Albrecht, Virendra Ghate, Johannes Mohrmann, Robert Wood, Paquita Zuidema, Christopher Bretherton, Christian Schwartz, Edwin Eloranta, Susanne Glienke, Shaunna Donaher, Mampi Sarkar, Jeremy McGibbon, Alison D. Nugent, Raymond A. Shaw, Jacob Fugal, Patrick Minnis, Robindra Paliknoda, Louis Lussier, Jorgen Jensen, J. Vivekanandan, Scott Ellis, Peisang Tsai, Robert Rilling, Julie Haggerty, Teresa Campos, Meghan Stell, Michael Reeves, Stuart Beaton, John Allison, Gregory Stossmeister, Samuel Hall, and Sebastian Schmidt

using the technique proposed by O’Connor et al. (2005) . For optically thin clouds that were detected by both the HCR and the HSRL, the cloud drop size distributions were also retrieved [see Wood et al. (2018) for an example from a CSET flight]. When the aircraft was flying above the MBL in surveying mode (at a flight level of ∼6 km), the HCR and HSRL were operated pointing downward to observe MBL cloud and aerosol fields from the flight level to the surface. For clouds that are 5 km below the

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Johannes Mohrmann, Christopher S. Bretherton, Isabel L. McCoy, Jeremy McGibbon, Robert Wood, Virendra Ghate, Bruce Albrecht, Mampi Sarkar, Paquita Zuidema, and Rabindra Palikonda

° × 2° box (centered on aircraft location or trajectory) that have successful retrievals of cloud type that are not clear sky. We additionally only focus on warm low liquid cloud fraction by selecting for cloud tops under 4 km with liquid tops. A random overlap assumption is made for pixels masked by deep/high clouds. Cloud droplet number concentration is calculated from GOES retrievals following Painemal and Zuidema (2011) using cloud optical thickness and cloud effective radius. Both CF and N d

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Christopher S. Bretherton, Isabel L. McCoy, Johannes Mohrmann, Robert Wood, Virendra Ghate, Andrew Gettelman, Charles G. Bardeen, Bruce A. Albrecht, and Paquita Zuidema

and optical thickness retrievals over the Southeast Pacific with VOCALS-REx in-situ measurements . J. Geophys. Res. , 116 , D24206 , https://doi.org/10.1029/2011JD016155 . Painemal , D. , P. Minnis , and M. Nordeen , 2015 : Aerosol variability, synoptic-scale processes, and their link to the cloud microphysics over the northeast Pacific during MAGIC . J. Geophys. Res. Atmos. , 120 , 5122 – 5139 , https://doi.org/10.1002/2015JD023175 . 10.1002/2015JD023175 Rogers , R. R. , and M

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M. Christian Schwartz, Virendra P. Ghate, Bruce. A. Albrecht, Paquita Zuidema, Maria P. Cadeddu, Jothiram Vivekanandan, Scott M. Ellis, Pei Tsai, Edwin W. Eloranta, Johannes Mohrmann, Robert Wood, and Christopher S. Bretherton

in aerosol concentrations ( Wang et al. 1993 ; Sandu et al. 2010 ; Yamaguchi et al. 2017 ; Abel et al. 2017 ). The Cloud System Evolution in the Trades (CSET) field campaign was conducted during July and August 2015 ( Albrecht et al. 2019 ) with the goal of improving the process-level understanding of the transition from stratocumulus to cumulus cloud regime in the North Pacific. During CSET, the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Gulfstream V

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Mampi Sarkar, Paquita Zuidema, Bruce Albrecht, Virendra Ghate, Jorgen Jensen, Johannes Mohrmann, and Robert Wood

thickness, lifting the cloud base ( Fig. 7 ) and facilitating an earlier decoupling of the cloud layer from its surface moisture source. Together these three transitions provide a diversity in initial aerosol and inversion height conditions that lend them well to further exploration through dedicated modeling studies. The bulk of rain both near the surface and in-cloud is provided by the larger drops ( Fig. 11 ) in both stratocumulus and cumulus regions. More than 90% of the rain rates come from

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