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

Yang, Fan; McGraw, Robert; Luke, Edward P.; Zhang, Damao; Kollias, Pavlos; Vogelmann, Andrew M.

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.

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Yang, Fan / McGraw, Robert / Luke, Edward P. / et al: A new approach to estimate supersaturation fluctuations in stratocumulus cloud using ground-based remote-sensing measurements. 2019. Copernicus Publications.

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