Processes contributing to cloud dissipation and formation events on the North Slope of Alaska

Details

• Journal Title:
  Atmospheric Chemistry and Physics
• Personal Author:
  Sedlar, Joseph ; Igel, Adele ; Telg, Hagen
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; GML (Global Monitoring Laboratory) ; CIRES (Cooperative Institute for Research in Environmental Sciences)
• Description:
  Clear-sky periods across the high latitudes have profound impacts on the surface energy budget and lower atmospheric stratification; however an understanding of the atmospheric processes leading to low-level cloud dissipation and formation events is limited. A method to identify clear periods at Utqiaġvik (formerly Barrow), Alaska, during a 5-year period (2014–2018) is developed. A suite of remote sensing and in situ measurements from the high-latitude observatory are analyzed; we focus on comparing and contrasting atmospheric properties during low-level (below 2 km) cloud dissipation and formation events to understand the processes controlling clear-sky periods. Vertical profiles of lidar backscatter suggest that aerosol presence across the lower atmosphere is relatively invariant during the periods bookending clear conditions, which suggests that a sparsity of aerosol is not frequently a cause for cloud dissipation on the North Slope of Alaska. Further, meteorological analysis indicates two active processes ongoing that appear to support the formation of low clouds after a clear-sky period: namely, horizontal advection, which was dominant in winter and early spring, and quiescent air mass modification, which was dominant in the summer. During summer, the dominant mode of cloud formation is a low cloud or fog layer developing near the surface. This low cloud formation is driven largely by air mass modification under relatively quiescent synoptic conditions. Near-surface aerosol particles concentrations changed by a factor of 2 around summer formation events. Thermodynamic adjustment and increased aerosol presence under quiescent atmospheric conditions are hypothesized as important mechanisms for fog formation.
• Keywords:
  Clouds
• Source:
  Atmos. Chem. Phys., 21, 4149–4167
• DOI:
  https://doi.org/10.5194/acp-21-4149-2021
• Document Type:
  Journal Article
• Place as Subject:
  Alaska
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha256:1f0230acd5b0489ba316b9c96ecaac2715440ac6cf48e9b087bdd3e2664a5327
• Download URL:
  https://repository.library.noaa.gov/view/noaa/44740/noaa_44740_DS1.pdf
• File Type:
  [PDF - 4.50 MB ]