Profiles of MBL Cloud and Drizzle Microphysical Properties Retrieved From Ground‐Based Observations and Validated by Aircraft In Situ Measurements Over the Azores

Abstract

The profiles of marine boundary layer (MBL) cloud and drizzle microphysical properties are important for studying the cloud-to-rain conversion and growth processes in MBL clouds. However, it is challenging to simultaneously retrieve both cloud and drizzle microphysical properties within an MBL cloud layer using ground-based observations. In this study, methods were developed to first decompose drizzle and cloud reflectivity in MBL clouds from Atmospheric Radiation Measurement cloud radar reflectivity measurements and then simultaneously retrieve cloud and drizzle microphysical properties during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) campaign. These retrieved microphysical properties, such as cloud and drizzle particle size (r c and r m,d ), their number concentration (N c and N d ) and liquid water content (LWC c and LWC d ), have been validated by aircraft in situ measurements during ACE-ENA (~158 hr of aircraft data). The mean surface retrieved (in situ measured) r c , N c , and LWC c are 10.9 μm (11.8 μm), 70 cm −3 (60 cm −3 ), and 0.21 g m −3 (0.22 g m −3 ), respectively. For drizzle microphysical properties, the retrieved (in situ measured) r d , N d , and LWC d are 44.9 μm (45.1 μm), 0.07 cm −3 (0.08 cm −3 ), and 0.052 g m −3 (0.066 g m −3 ), respectively. Treating the aircraft in situ measurements as truth, the estimated median retrieval errors are~15% for r c ,~35% for N c ,~30% for LWC c and r d , and~50% for N d and LWC d . The findings from this study will provide insightful information for improving our understanding of warm rain processes, as well as for improving model simulations. More studies are required over other climatic regions. Key Points: • New methods are developed to simultaneously retrieve MBL cloud and drizzle microphysical properties in drizzling clouds • The retrievals are validated with in situ measurements with errors of 15% for r c , 35% for N c , 30% for LWC c and r m,d , and 50% for N d and LWC d . (2020). Profiles of MBL cloud and drizzle microphysical properties retrieved from ground-based observations and validated by aircraft in situ measurements over the Azores.

Joint cloud water path and rainwater path retrievals from airborne ORACLES observations

“…Stratocumulus clouds (Sc hereafter) are the dominant cloud type over Earth's subtropical oceans. Significant advances in our understanding of subtropical Sc have been documented in many previous studies including their typical cloud fractions (Stephens et al, 2012;King et al, 2013;, radiative impacts (Hang et al, 2019), and associated precipitation processes using data from past field experiments (Stevens et al, 2003), long-term ground-based data collection (Mann et al, 2014;Yang et al, 2018), and spaceborne remote sensors (Fox and Illingworth, 1997;L'Ecuyer and Stephens, 2002;Lebsock et al, 2011;Chen et al, 2011;Lebsock et al, 2011;Werner and Deneke, 2020). Despite these advances, until recently observations of cloud and precipitation processes over the Published by Copernicus Publications on behalf of the European Geosciences Union.…”

New Observational Constraints on Warm Rain Processes and Their Climate Implications

“…A brief summary about the ground‐based retrieval (Wu et al., 2020) is presented in the Supporting Information. The retrieved microphysics include cloud‐droplet (drizzle) number concentration N c ( N d (Z) ) liquid water content LWC c (Z) ( LWC d (Z)) and mass weighted mean radius r c (Z) () and r d (Z).…”

“…A brief summary about the ground-based retrieval (Wu et al, 2020) S1c and S1d), opposite to their cloud counterparts, increased from the cloud top downward, peaked in the middle or bottom of the cloud, and decreased further down.…”

“…The retrieved cloud and drizzle microphysical properties during the Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE‐ENA) field campaign (Wu et al., 2020) have 1‐min temporal and 30‐m vertical resolution, which are important for studying warm rain processes. In this study, we used the retrievals to recalibrate the R auto and R accr parameterizations in Khairoutdinov and Kogan (2000) scheme (hereafter called KK) into the new KK scheme (hereafter called NKK).…”

Maritime Cloud and Drizzle Microphysical Properties Retrieved From Ship‐Based Observations During MAGIC

“…In this study, the retrieval methods developed by Wu et al. (2020) were adapted to retrieve MBL cloud and drizzle properties over the Eastern‐North Pacific (ENP) during the Marine ARM (Atmospheric Radiation Measurement) GPCI (Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) Pacific cross‐section intercomparison) Investigation of Clouds (MAGIC) campaign. In the newly developed retrieval methods by Wu et al.…”