Jérôme Riedi

Linking cirrus cloud microphysical properties, their formation history, and their origin – whether liquid or in situ – to global satellite observations will represent a major step toward understanding these clouds, which are climatically important but not yet fully understood. This link is established by integrating Lagrangian microphysical modelling along air parcel trajectories ending at the points of satellite observations. In Part 1 of this study, detailed microphysical Lagrangian cirrus model CLaMS-Ice was coupled with DARDAR-Nice satellite retrievals to establish the DC-Ice (DARDAR → CLaMS-Ice) framework, enabling the derivation of origin-based metrics associated with satellite observations. Here, we evaluate the performance of the DC-Ice for revisited case studies and examine its sensitivity to key model parameters. Simulated ice crystal number concentration (N_i) and ice water content (IWC) are statistically compared with satellite retrievals and in situ observations. DC-Ice shows good agreement with observations for N_i and IWC, except for orographic cirrus, where the IWC from DC-Ice is lower than that from DARDAR-Nice. Sensitivity experiments indicate that variations in the parameterised sedimentation affect the simulated microphysical properties, especially IWC, while temperature fluctuations influence N_i. Nevertheless, it appears from the sensitivity analysis that origin-based metrics proved relatively robust except under most configurations. These findings highlight the viability of incorporating origin-based metrics into satellite observations, paving the way for improved global understanding of cirrus origins and their impact on the climate system. Future development includes the implementation of a three-dimensional sedimentation scheme in CLaMS-Ice and the extension of the framework to tropical regions.

Linking cirrus cloud microphysical properties, their formation history, and their origin – whether liquid or in situ – to global satellite observations will represent a major step toward understanding these clouds, which are climatically important but not yet fully understood. This link is established by integrating Lagrangian microphysical modelling along air parcel trajectories ending at the points of satellite observations. In Part 1 of this study, detailed microphysical Lagrangian cirrus model CLaMS-Ice was coupled with DARDAR-Nice satellite retrievals to establish the DC-Ice (DARDAR → CLaMS-Ice) framework, enabling the derivation of origin-based metrics associated with satellite observations. Here, we evaluate the performance of the DC-Ice for revisited case studies and examine its sensitivity to key model parameters. Simulated ice crystal number concentration (N_i) and ice water content (IWC) are statistically compared with satellite retrievals and in situ observations. DC-Ice shows good agreement with observations for N_i and IWC, except for orographic cirrus, where the IWC from DC-Ice is lower than that from DARDAR-Nice. Sensitivity experiments indicate that variations in the parameterised sedimentation affect the simulated microphysical properties, especially IWC, while temperature fluctuations influence N_i. Nevertheless, it appears from the sensitivity analysis that origin-based metrics proved relatively robust except under most configurations. These findings highlight the viability of incorporating origin-based metrics into satellite observations, paving the way for improved global understanding of cirrus origins and their impact on the climate system. Future development includes the implementation of a three-dimensional sedimentation scheme in CLaMS-Ice and the extension of the framework to tropical regions.

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.

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.

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.

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.

Linking cirrus cloud microphysical properties, their formation history, and their origin – whether liquid or in situ – to global satellite observations will represent a major step toward understanding these clouds, which are climatically important but not yet fully understood. This link is established by integrating Lagrangian microphysical modelling along air parcel trajectories ending at the points of satellite observations. In Part 1 of this study, detailed microphysical Lagrangian cirrus model CLaMS-Ice was coupled with DARDAR-Nice satellite retrievals to establish the DC-Ice (DARDAR → CLaMS-Ice) framework, enabling the derivation of origin-based metrics associated with satellite observations. Here, we evaluate the performance of the DC-Ice for revisited case studies and examine its sensitivity to key model parameters. Simulated ice crystal number concentration (N_i) and ice water content (IWC) are statistically compared with satellite retrievals and in situ observations. DC-Ice shows good agreement with observations for N_i and IWC, except for orographic cirrus, where the IWC from DC-Ice is lower than that from DARDAR-Nice. Sensitivity experiments indicate that variations in the parameterised sedimentation affect the simulated microphysical properties, especially IWC, while temperature fluctuations influence N_i. Nevertheless, it appears from the sensitivity analysis that origin-based metrics proved relatively robust except under most configurations. These findings highlight the viability of incorporating origin-based metrics into satellite observations, paving the way for improved global understanding of cirrus origins and their impact on the climate system. Future development includes the implementation of a three-dimensional sedimentation scheme in CLaMS-Ice and the extension of the framework to tropical regions.

Linking cirrus cloud microphysical properties, their formation history, and their origin – whether liquid or in situ – to global satellite observations will represent a major step toward understanding these clouds, which are climatically important but not yet fully understood. This link is established by integrating Lagrangian microphysical modelling along air parcel trajectories ending at the points of satellite observations. In Part 1 of this study, detailed microphysical Lagrangian cirrus model CLaMS-Ice was coupled with DARDAR-Nice satellite retrievals to establish the DC-Ice (DARDAR → CLaMS-Ice) framework, enabling the derivation of origin-based metrics associated with satellite observations. Here, we evaluate the performance of the DC-Ice for revisited case studies and examine its sensitivity to key model parameters. Simulated ice crystal number concentration (Ni) and ice water content (IWC) are statistically compared with satellite retrievals and in situ observations. DC-Ice shows good agreement with observations for Ni and IWC, except for orographic cirrus, where the IWC from DC-Ice is lower than that from DARDAR-Nice. Sensitivity experiments indicate that variations in the parameterised sedimentation affect the simulated microphysical properties, especially IWC, while temperature fluctuations influence Ni. Nevertheless, it appears from the sensitivity analysis that origin-based metrics proved relatively robust except under most configurations. These findings highlight the viability of incorporating origin-based metrics into satellite observations, paving the way for improved global understanding of cirrus origins and their impact on the climate system. Future development includes the implementation of a three-dimensional sedimentation scheme in CLaMS-Ice and the extension of the framework to tropical regions.