Maritime cloud and drizzle microphysical properties retrieved from ship-based observations during MAGIC

Jordann Brendecke1, Xiquan Dong1
1Department of Hydrology and Atmospheric Sciences, University of Arizona

The Marine ARM GPCI Investigation of Clouds (MAGIC) field campaign provided a wealth of information looking at the stratocumulus to cumulus transition (SCT) over the Eastern-North Pacific (ENP), however, the lack of cloud in-situ measurements still left many cloud microphysical properties unknown. Using the observations of Marine W-band ARM cloud radar (MWACR), ceilometer, and 3-channel microwave radiometer onboard the ship, we retrieve the single-layer, low-level cloud-droplet effective radius and drizzle median radius (rc and rm,d), number concentration (Nc and Nd), and liquid water content (LWCc and LWCd) using the methods in Wu et al. (2020). Based on the results during MAGIC, we found that both cloud-base and –top heights increase approximately 0.75 km from LA until ~-140° before leveling off. Low cloud fractions ranged from ~65% near -130° to ~25% near Hawaii. Bin-averaged LWPs and CCNs stayed nearly constant at 100 g m-2 and 150 cm-3. Retrieved rc decrease approximately 2μm from -126° to -156° while rm,d increased more than 20μm from -124° to Hawaii. Mean retrieved values of rc, rm,d, Nc, Nd, LWCc, LWCd are 12.1 μm, 55.8 μm, 97.9 cm-3, 0.09 cm-3, 0.40 g m-3, 0.05 g m-3, respectfully. Compared to the mean values over the Azores in Wu et al. (2020), the mean cloud and drizzle microphysical properties during MAGIC are mostly greater. This information allows for a better understanding of the SCT over the ENP and can be used to better improve model simulations.

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