Characterization of Arctic mixed phase clouds at regional and small scales

Abstract : Previous observations suggest that Mixed Phase Clouds (MPC) occur frequently in the Arctic and often persist for many days due to a combination of local processes (microphysical and radiative for instance) and larger scale meteorological conditions. These low-level liquid containing clouds exert a large influence on the surface radiative fluxes and feedbacks on Arctic climate. However, understanding the spatial phase distribution within MPC remains a challenge. In this study, the MPC macrophysical and microphysical properties are investigated at a regional scale using CloudSat and CALIPSO observations (2007-2010) and at smaller scale with airborne in situ measurements performed in the Svalbard region. Results show that MPCs have a mean frequency of occurrence ranging from 30% (end of winter) to 55% (in autumn) in the Arctic. In the Svalbard region, the frequencies of occurrence are significantly higher with values ranging from 45% to 60%. MPCs are especially located at low altitudes, below 3000m, where their occurrence reaches 90%, particularly in winter, spring and autumn. Moreover, results highlight that MPCs are statistically more frequent over open sea than sea ice or land. These observations also allow us to assess how already performed small scale airborne measurements are representative of the variety of clouds encountered in the Arctic. In situ measurements (44 vertical profiles obtained during ASTAR, POLARCAT, SORPIC) are statistically analyzed to derive representative profiles of MPC microphysical and optical properties (optical depth, liquid/water fraction, ice crystals habit). These analyses should contribute to a better understanding of processes occurring in arctic MPC.
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Submitted on : Saturday, January 28, 2017 - 3:09:56 PM
Last modification on : Tuesday, May 14, 2019 - 11:00:36 AM

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  • HAL Id : insu-01448602, version 1

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Olivier Jourdan, Guillaume Mioche, Julien Delanoë, Christophe Gourbeyre, Régis Dupuy, et al.. Characterization of Arctic mixed phase clouds at regional and small scales. 17th International Conference on Clouds and Precipitation 2016, Jul 2016, manchester, United Kingdom. ⟨insu-01448602⟩

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