| 05 May 2026
Origin and evolution of satellite-observed cirrus clouds using Lagrangian microphysical modeling – Part 1: Method and case studies
Abstract. Cirrus clouds pose a challenge due to their complex microphysics and processes involved in their formation and growth. Satellite observations capture the instantaneous state of cirrus, offering limited insight into their formation history. Here, we introduce DC-Ice (DARDAR → CLaMS-Ice), a novel framework that defines origin-based metrics to characterize cirrus origin and evolution from satellite observations with Lagrangian microphysical modeling. Air parcel back trajectories are computed using Chemical Lagrangian Model of the Stratosphere (CLaMS), starting from DARDAR-Nice satellite observation point. Along these trajectories, the CLaMS-Ice microphysical box model simulates cirrus formation and evolution. Key origin-based metrics are derived to be associated with satellite observations, including ice formation pathways (homogeneous vs heterogeneous), ice crystal origin (liquid-phase or in situ), and their age (time since ice formation). DC-Ice is applied to three case studies representative of typical meteorological conditions in midlatitudes. The analysis shows that cirrus properties evolve continuously, with small-scale temperature fluctuations regulating supersaturation and ice nucleation, thereby influencing subsequent microphysical processes. Reconstructed vertical cloud profiles reveal that liquid-origin cirrus is more prevalent at lower altitudes, while in situ-origin cirrus dominates at higher altitudes, with nucleation pathways varying with cloud age and environmental conditions. A comprehensive evaluation and sensitivity analysis will be presented in Part 2 to quantify uncertainties. These studies form the basis for linking microphysical properties and the history of cirrus clouds to global satellite observations using the DC-Ice approach. The future aim is to gain broad geographical and seasonal information on cirrus clouds, improving their representation in global models.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Atmospheric Chemistry and Physics.
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Review of Origin and evolution of satellite-observed cirrus clouds using Lagrangian microphysical modeling - Part 1: Method and case studies” by Saiprakash et al. 2026.
The article introduced the DC-Ice framework, which combines satellite observations with Lagrangian parcel modeling including ice microphysics. It allows a more natural approach to characterizing cirrus origin and evolution than analyzing only Eulerian snapshots, which lack the history of ice formation, growth, and exposure to environmental conditions. The Chemical Lagrangian Model of the Stratosphere with ice microphysics is used for back-trajectory calculations from the satellite observation point. Three distinct case studies from mid-latitudes (frontal slow updraft cirrus, fast updraft cirrus, and orographic cirrus) are presented to demonstrate the capabilities of this approach. Ice nucleation mechanism, ice crystal origin, and cloud age were analyzed in detail. The results also highlight the importance of small-scale fluctuations in temperature on ice formation and cirrus evolution.
The proposed Lagrangian approach is interesting and logical for cirrus evolution, considering the critical role of history in ice crystal evolution. The manuscript has the potential to be a nice contribution to ACP. However, some improvement in presentation style is needed. It was challenging to follow the discussion of several multi-panel figures. Some of the information and related discussion are not very critical for the main points. I request that the authors simplify some of the result discussion (make it more concise) and move some of the supporting panels/plots to the supplement to avoid distraction. Moreover, caution should be exercised when considering closed/adiabatic Lagrangian parcels for analysis. Cloud parcels experience significant mixing with each other and with the local environment. These small spatiotemporal scale mixing/variabilities are highly important for individual crystal formation, growth, and overall cloud evolution, especially considering the long trajectory timescale under consideration. The current approach neglects these aspects, which could lead to spurious results/conclusions. The authors should clearly discuss why it may or may not be a problem for the cirrus evolution. Also, I didn’t see any discussion of ice crystal shapes/habits or how that’s factored into the process rates (like deposition, radiation, sedimentation, etc.). They also play a critical role in controlling cirrus lifetime and should be clearly addressed.
Here are a few other specific comments: