Vaughan Phillips
Universitetslektor
Effects from Time Dependence of Ice Nucleus Activity for Contrasting Cloud Types
Författare
Other contributions
- Akash Deshmukh
Summary, in English
The role of time-dependent freezing of ice nucleating particles (INPs) is evaluated with the “Aerosol–Cloud” (AC) model in 1) deep convection observed over Oklahoma during the Midlatitude Continental Convective Cloud Experiment (MC3E), 2) orographic clouds observed over North California during the Atmospheric Radiation Measurement (ARM) Cloud Aerosol Precipitation Experiment (ACAPEX), and 3) supercooled, stratiform clouds over the United Kingdom, observed during the Aerosol Properties, Processes And Influences on the Earth’s climate (APPRAISE) campaign. AC uses the dynamical core of the WRF Model and has hybrid bin–bulk microphysics and a 3D mesoscale domain. AC is validated against coincident aircraft, ground-based, and satellite observations for all three cases. Filtered concentrations of ice (.0.1–0.2 mm) agree with those observed at all sampled levels. AC predicts the INP activity of various types of aerosol particles with an empirical parameterization (EP), which follows a singular approach (no time dependence). Here, the EP is modified to represent time-dependent INP activity by a purely empirical approach, using our published laboratory observations of time-dependent INP activity. In all simulated clouds, the inclusion of time dependence increases the predicted INP activity of mineral dust particles by 0.5–1 order of magnitude. However, there is little impact on the cloud glaciation because the total ice is mostly (80%–90%) from secondary ice production (SIP) at levels warmer than about 2368C. The Hallett–Mossop process and fragmentation in ice–ice collisions together initiate about 70% of the total ice, whereas fragmentation during both raindrop freezing and sublimation contributes ,10%. Overall, total ice concentrations and SIP are unaffected by time-dependent INP activity. In the simulated APPRAISE case, the main causes of persistence of long-lived clouds and precipitation are predicted to be SIP in weak embedded convection and reactivation following recirculation of dust particles in supercooled layer cloud.
Avdelning/ar
- Institutionen för naturgeografi och ekosystemvetenskap
- MERGE: ModElling the Regional and Global Earth system
- BECC: Biodiversity and Ecosystem services in a Changing Climate
- eSSENCE: The e-Science Collaboration
- LTH profilområde: Aerosoler
Publiceringsår
2023-08-15
Språk
Engelska
Sidor
2013-2039
Publikation/Tidskrift/Serie
Journal of Atmospheric Sciences
Volym
80
Fulltext
Dokumenttyp
Artikel i tidskrift
Förlag
Amer Meteorological Soc
Ämne
- Meteorology and Atmospheric Sciences
Nyckelord
- Ice crystals
- Clouds
- Time dependence
- primary ice
- secondary ice
- layer clouds
- orographic clouds
- thunderstorm
- numerical cloud model
Status
Published
Projekt
- Mechanisms for the Ice Nucleus Aerosols and their Indirect Effects: Cloud Modelling
- Secondary ice production: An empirical formulation and organization of mechanisms among simulated cloud-types
- Mechanisms for the Influence from Ice Nucleus Aerosols on Clouds and their Indirect Effects: Cloud Modelling
ISBN/ISSN/Övrigt
- ISSN: 1520-0469