EGU21-11992
https://doi.org/10.5194/egusphere-egu21-11992
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

AEROCOM/AEROSAT: an intercomparison of AAOD & SSA in model and satellite data

Nick Schutgens1, Qirui Zhong1, and the AEROCOM/AEROSAT teams*
Nick Schutgens and Qirui Zhong and the AEROCOM/AEROSAT teams
  • 1Vrije Universiteit Amsterdam, Earth sciences, Amsterdam, Netherlands (n.a.j.schutgens@vu.nl)
  • *A full list of authors appears at the end of the abstract

Absorbing aerosol has the capacity to warm the climate, but the amount of warming is highly uncertain. AAOD (Absorptive Aeorosl Optical Depth) is an optical measure of the abundance of this absorbing aerosol, comprising mineral dust, black and brown carbon and can be retrieved from satellite measurements providing an almost global view on absorbing aerosol.

In this study we evaluate AEROCOM models with satellite observations of AAOD and SSA (Single Scattering Albedo) and interpret the discrepancies. Over source regions, diversity in model AAOD is mostly due to emissions even though models employ different assumptions regarding the imaginary refractive index. On the one hand this suggests emissions to be a major error source, on the other hand it suggests that the AEROCOM ensemble as a whole may have a bias with regards to MAC (Mass Absorption Coefficient). We show that in the models AAOD scales almost linearly with emissions (either black carbon or dust) and this allows the use of observations as a constraint.  In contrast, model diversity in AOD is shown to depend in almost equal measure on emissions, lifetimes and MECs (Mass Extinction Coefficient). We also analyse mineral dust and black carbon lifetimes by considering the contrast in AAOD over source regions and over outflow regions, and again provide observations constraints.

While the older Phase II models generally underestimate AAOD, Phase III models tend to straddle the observations, with some models over-estimating and other models underestimating AAOD. Emissions seem to be the driving factor in this difference. The amount of diversity is larger in the Phase III than Phase II models.

This study was conducted using four satellite datasets of AAOD and SSA. These datasets were extensively evaluated with AERONET. Dearth of observations prevents global assesment of the satellite retrievals. However, we show that model evaluation is relatively independent of the chosen dataset, even though we identify significant biases between the datasets.

AEROCOM/AEROSAT teams:

Nick Schutgens, Oleg Dubovik, Otto Hasekamp, Omar Torres, Hiren Jethva, Peter J.T. Leonard, Jens Redemann, Yohei Shinozuka, Yves Balkanski, Nicolas Bellouin, Tommi Bergman, Huisheng Bian, Gabriele Curci, Zak Kipling, Alf Kirkevåg, Harri Kokkola, Marianne Tronstad Lund, Gunnar Myhre, Samuel Remy, Twan van Noije, Dirk Jan Leo Olivie, Joyce E. Penner, Toshihiko Takemura, Kai Zhang, Jialei Zhu, Ramiro Checa-Garcia, Xiaohong Liu, Hitoshi Matsui, Tero Mielonen, David Neubauer, Ragnhild Bieltvedt Skeie, Svetlana Tsyro, Gerrit de Leeuw, Stefan Kinne, Thomas Popp, Michael Schulz, and Philip Stier

How to cite: Schutgens, N. and Zhong, Q. and the AEROCOM/AEROSAT teams: AEROCOM/AEROSAT: an intercomparison of AAOD & SSA in model and satellite data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11992, https://doi.org/10.5194/egusphere-egu21-11992, 2021.

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