Abstract
Abstract. This study presents a statistical analysis of the properties of ice hydrometeors in tropical mesoscale convective systems observed during four different aircraft campaigns. Among the instruments on board the aircraft, we focus on the synergy of a 94 GHz cloud radar and two optical array probes (OAP; measuring hydrometeor sizes from 10 µm to about 1 cm). For two campaigns, an accurate simultaneous measurement of the ice water content is available, while for the two others, ice water content is retrieved from the synergy of the radar reflectivity measurements and hydrometeor size and morphological retrievals from OAP probes. The statistics of ice hydrometeor properties are calculated as a function of radar reflectivity factor measurement percentiles and temperature. Hence, mesoscale convective systems (MCS) microphysical properties (ice water content, visible extinction, mass–size relationship coefficients, total concentrations, and second and third moments of hydrometeor size distribution) are sorted in temperature (and thus altitude) zones, and each individual campaign is subsequently analyzed with respect to median microphysical properties of the merged dataset (merging all four campaign datasets). The study demonstrates that ice water content (IWC), visible extinction, total crystal concentration, and the second and third moments of hydrometeor size distributions are similar in all four types of MCS for IWC larger than 0.1 g m−3. Finally, two parameterizations are developed for deep convective systems. The first concerns the calculation of the visible extinction as a function of temperature and ice water content. The second concerns the calculation of hydrometeor size distributions as a function of ice water content and temperature that can be used in numerical weather prediction.
Highlights
Defining clouds and how they interact with the atmosphere is a major challenge in climate sciences and meteorology
In this study we analyze in situ aircraft observations of ice hydrometeor images and simultaneous cloud radar observations collected in tropical Mesoscale convective systems (MCS) in order to characterize the statistical properties of ice microphysics
The overall data analysis of ice hydrometeor properties has been performed as a function of temperature and the range of radar reflectivity factors measured at 94 GHz
Summary
Defining clouds and how they interact with the atmosphere is a major challenge in climate sciences and meteorology. Clouds play an important role in the evolution of the weather and climate on Earth. They affect the dynamics and thermodynamics of the troposphere and impact the radiative transfer of energy in thermal and visible wavelengths by heating or cooling the atmosphere. Clouds represent an important part of the hydrological cycle, due to evaporation and precipitation processes. Dynamic features such as the Madden–Julian oscillation (MJO, perturbation of large-scale circulation leading to an eastward propagation of organized convective activity) can affect the development of deep convective clouds (Madden and Julian, 1994, 1971). Mesoscale convective systems (MCS) are complex clouds and are the result of specific synoptic conditions
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