Atmosphere-Surface Exchanges

Wednesday, November 8, 2017 -
09:00 to 10:00


-          Role call

-          Presentation: How vegetation drives shortwave energy fluxes in a changing tundra landscape -- from observations to 3D radiation modeling (Schaepman-Strub) – 20min

-          Discussion (ALL) – 30min


IASOA Atmosphere-Surface Exchanges (Flux) Working Group

November 8, 2017


Attendees: Sara Morris, Gabriela Schaepman, Allison McComiskey, Chris Fairall, David Cook, Taneil Uttal

Introduction of group members: overview of how IASOA can “work for you”, example of creating a flux product file useful to research in both observations and modeling communities (standardize files), if/when to submit these types of files to archives like Fluxnet or Ameriflux (or NCEI for NOAA datasets)


Presentation: How vegetation drives shortwave energy fluxes in a changing tundra landscape – from observations to 3D radiation modeling (Schaepman):

  • Overview of Siberian tundra research site
    • Kytalyk: a NE Siberian tundra research site (similar to Barrow vegetation, but more continental environment)
    • 10m a.s.l., 71N 147E
    • INTERACT site: international network for terrestrial research and monitoring in the Arctic
    • Measurements: CO2 and CH4 fluxes, meteo-tower, eddy covariance, SW/LW radiation, heat fluxes, met measurements
    • Need to discuss calibration schedule of these instruments and standardize instrumentation
  • Research questions:
    • 1) What are drivers of vegetation change? How are vegetation traits changing?
    • 2) Assessment and prediction of biodiversity – from plot to landscape to pan-Arctic scale
    • 3) How do changes in biodiversity feedback to ecosystem functioning, permafrost, and climate?
  • Research methods
    • Experimental, observations, physical modeling, and integration
  • Vegetation Feedbacks to Climate through Energy Fluxes
    • How energy fluxes are different across different site
    • How do above-ground radiation and soil fluxes vary with vegetation type
    • How does shrub density influence albedo and transmittance
    • How does patchiness of vegetation types influence SW radiation at landscape scale
  • Assess energy fluxes (SW/LW)
    • Comparison of SW and LW fluxes against soil temp
    • Comparison of albedo and heat fluxes (impact of sedges vs shrubs)
  • Phenological Camera capturing changes in surface layer
  • Assess energy fluxes both above and below ground in areas of sedges vs shrubs
    • Snow melt occurs are different timing depending on sedge or shrub area
  • Discussion of results
    • Shrubs absorb more SW radiation and transmit more to the ground surface
    • Shading of sedges mostly by litter
    • Heat flux below sedges much higher  than below dwarf shrubs
    • Processes at very local scale, posing challenges to land surface models that do not model processes at these scales
  • 3D Radiative Transfer Modeling – DART model
    • Discrete anisotropic radiative transfer
    • Can manipulate plant area to assess impact on SW radiation
      • Branches are important absorbers
      • Increasing shrub density does not decrease albedo
      • Albedo insensitive to total plant area
    • Drivers of SW radiation at landscape scale
      • Hydrologic changes in Arctic landscape might be important
  • Can we predict ecosystem responses to environmental change based on traits of species?
    • Permafrost thawing and soil fertilization impacts


Discussion of Schaepman Presentation:

  • How are we collaborating internationally with regard to Arctic flux measurements/parameters?
    • IASC, MOSAiC, T-MOSAiC (terrestrial MOSAiC)
  • Are there measurement protocols?
    • Not currently
    • Can assess previous Arctic sites (Tiksi, Eureka) and how their Fluxtower are set up
      • Datagrams
  • Arctic Council activities (SAON)?
  • Link to satellite data community?


Action Items:

  • Discussion of where to submit/archive flux product files (NCEI, Ameriflux, Fluxnet, etc.), IASOA initiative?? (Uttal, ALL)
  • Evaluate other models (beside DART) to analyze (Uttal, Schaepman)
  • Literature review of energy flux methods (Uttal, Morris, Persson)
Research Group: