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

Abstract

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 importance of Aitken mode aerosol particles for cloud sustenance in the summertime high Arctic – a simulation study supported by observational data

“…The exception is the AC0_AK20 case in RAMS where there is no stable cloud at 6 h. The ss values in this simulation are high since the statistics are based on a relatively low number of supersaturated grid boxes, which, in this case, reach high ss values due to a low condensational sink. The median numbers agree well with typical ss values reported for clean marine stratocumulus clouds at mid-latitudes (Hudson and Noble, 2014;Yang et al, 2019). However, the 99th percentiles show high supersaturations with values above 1 % for most of the simulations.…”

The importance of Aitken mode aerosol particles for cloud sustenance in the summertime high Arctic: A simulation study supported by observational data

“…The 490 exception is the case AC0_AK20 in RAMS where there is no stable cloud at 6 h. The ss values in this simulation are high since the statistics are based on a relatively low number of supersaturated grid boxes, which in this case reach high ss values due to a low condensational sink. The median numbers agree well with typical ss values reported for clean marine stratocumulus clouds at mid-latitudes (Hudson and Noble, 2014;Yang et al, 2019). However, the 99th percentiles show high supersaturations with values above 1 % for most of the simulations.…”

Spaceborne Cloud and Precipitation Radars: Status, Challenges, and Ways Forward

“…For similar reasons, spaceborne sensors would struggle to assess if low-level clouds precipitate and if the precipitation they produce evaporates before reaching the surface. According to a study by Yang et al (2019) precipitation evaporation is not uncommon and as much as 69% of drizzle from single-layer marine stratocumulus never reaches the surface.…”

“…According to a study by Yang et al. (2019) precipitation evaporation is not uncommon and as much as 69% of drizzle from single‐layer marine stratocumulus never reaches the surface.…”