Seminar: Natalia Roldan-Henao | UMD
In-Person PHYS 401
Location
Physics : 401
Date & Time
February 12, 2025, 11:00 am – 12:00 pm
Description
TITLE: "Climatology of Cloud-Land-PBLH Coupling Across Different ARM Sites”
ABSTRACT: Planetary boundary layer (PBL) processes regulate land-atmosphere interactions, influencing cloud formation and evolution, convection initiation, and air quality. Over land, surface fluxes drive convective cloud development, creating a coupled cloud-surface system. However, the coupling state of continental clouds remains underexplored due to complex land-atmosphere interactions. However, the coupling states between these clouds and the surface remain uncertain, particularly over continental regions where complex thermodynamic processes complicate their characterization. This study leverages data from the Atmospheric Radiation Measurement (ARM) program to investigate cloud-surface coupling and presents the first climatological analysis of cloud-surface coupling across five geographically diverse regions. Results reveal consistent coupling thresholds and similar average frequencies across all sites, with coupled clouds accounting for 68% of cases and decoupled clouds for 32%. Thermodynamic and dynamic analyses highlight distinct differences between these regimes: coupled clouds form in warmer environments where vertical motions directly link the surface to the cloud base, promoting boundary layer cloud development. In contrast, decoupled clouds occur in drier and colder conditions, with vertical motions within the boundary layer remaining detached from the cloud base. A detailed seasonal and diurnal analysis at the SGP site further reveals notable similarities between coupled clouds in summer and those observed in the Amazon region. These findings enhance our understanding of cloud-surface interactions and provide a foundation for future research on cloud formation and evolution.
ABSTRACT: Planetary boundary layer (PBL) processes regulate land-atmosphere interactions, influencing cloud formation and evolution, convection initiation, and air quality. Over land, surface fluxes drive convective cloud development, creating a coupled cloud-surface system. However, the coupling state of continental clouds remains underexplored due to complex land-atmosphere interactions. However, the coupling states between these clouds and the surface remain uncertain, particularly over continental regions where complex thermodynamic processes complicate their characterization. This study leverages data from the Atmospheric Radiation Measurement (ARM) program to investigate cloud-surface coupling and presents the first climatological analysis of cloud-surface coupling across five geographically diverse regions. Results reveal consistent coupling thresholds and similar average frequencies across all sites, with coupled clouds accounting for 68% of cases and decoupled clouds for 32%. Thermodynamic and dynamic analyses highlight distinct differences between these regimes: coupled clouds form in warmer environments where vertical motions directly link the surface to the cloud base, promoting boundary layer cloud development. In contrast, decoupled clouds occur in drier and colder conditions, with vertical motions within the boundary layer remaining detached from the cloud base. A detailed seasonal and diurnal analysis at the SGP site further reveals notable similarities between coupled clouds in summer and those observed in the Amazon region. These findings enhance our understanding of cloud-surface interactions and provide a foundation for future research on cloud formation and evolution.
