Group 4 - Aerosol optical properties and Arctic Haze

  • Dina, Bjørn, Sigrid, Eemeli, Dominik
  • Maria, Olga

Aerosol chemical composition

  • Dina Stabell

Goals

  • Change in chemical composition
  • Compare models to observations

Data

  • Observational data from EBAS (For now: sea salt, SO$_4$, trying to get: NH$_4$, NO$_3$, organic aerosol and black carbon).
  • Model data: from the CMIP6 r1i1p1f1 run (For now: NorESM2-LM, Later: CESM2, CESM2_WACCAM, BCC-ESM1, GFDL-CM4 and GFDL_ESM4)

Difficulties

  • Finding all the observational data
  • Is the pyaerocom concss sea salt?
  • What is the pyaerocom concso4?

Relative Humidity (RH): Models vs Observations

-Sigrid J. Bakke

Motivation

  • We are interested in Optical properties
  • Optical properties (models vs measurements) are compared for same RH.
    • So if the RH is wrong in one of them, we are comparing the wrong optical properties
    • Thus, important to know how well RH is modelled

Goal

  • Compare modelled RH to observed RH
    • How well models represent observations
    • (to see if the model perform differently depending on region, seasonality, statistic etc.)

Data

  • Model data: CMIP6 (CESM2, CanESM5, IPSL-CM6A-LR) and ATRAS
  • Obs data: stations at Svalbard, hopefully expand to other locations

Optical properties: Dry scattering and hygroscopicity

-Eemeli Holopainen

  • Search for inconsistencies in the models according to scattering of dry cases
  • How does the different models capture scattering?
  • How do models represent the hygroscopic growth between 0 and 40 RH?
  • Do these by comparing the data between the models and measurements?

Data used:

  • Models: CAM5-Atras, CAM5, GEOS-Chem, ECMWF, GEOS5-Globase, MERRAero, OSLO-CTM3, CAM5-Oslo, TM5-AP3
  • Measurements: EBAS scattering coefficients 550nm

Challenges:

  • Pyaerocom does not have the data available
  • consistencies in the model outputs

Aerosol optical hygroscopic growth

-Dominic Heslin-Rees

  • Hygroscopic growth
  • Light scattering enhancement factor [$f(RH, \lambda)$]

Research Questions

  • Discrepancies between model and Obserbvations
  • Differences between surface and vertical column (at pressure level) in model output
  • Reasons for discrepancies

Data

  • Model data (CAM, Atras, Chem, ECMWF, Globase, Oslo CTM3 \& TM5)
  • In situ groud based measurements from Zeppelin, Barrow \& (Hyytiälä)

Preliminary results

  • Models overestimate [$f(RH, \lambda)$] (e.g. for Atras at Barrow):

Problems

  • The datasets are not matching (e.g. Zeppelin has 3 months in 2008 \& model = 2010)

Thank you