CMIP6 evaluation of AOD against ground-based observations and MERRA2

Franziska Hellmuth
franziska.hellmuth@geo.uio.no
Group 2
Paul Glantz, Ksenia Tabakova, Jonas Gliss
My results of Aerosol optical depth will take your breath

Motivation
Fig. 1: Glantz et al.,2014 Climatological seasonal cycles of all‐sky AOT averaged for the Svalbard area (75°N–82°N, 10°W–40°E) in 20 global climate models participating in the CMIP5 project. The climatological cycles are based on the period 1980–2004 of the CMIP5's “historical” experiment. Information on individual models can be found at http://cmip‐pcmdi.llnl.gov/cmip5.
  • Seasonal variation over Svalbard area
  • Lowest AOD during summer
  • CMIP5 against remote sensing
    • $\rightarrow$ underestimation during spring
    • $\rightarrow$ overestimation during winter
What is the performance of the models in the IPCC CMIP6 project in terms of AOD simulated over
- Svalbard region?
- Arctic?

Observations, Re-Analysis, historical simulation of CMIP6

AERONET (AERosol RObotic NETwork)

  • Sunphotometer at Arctic Station lat > 66$^{\circ}$N (total 14)

MERRA2 (Modern-Era Retrospective analysis for Research and Applications 2)

  • satellite reanalysis since 1980
  • horizontal resolution: 0.5 - 0.625 $^{\circ}$
CMIP6 Models
GFDL-CM4 E3SM-1-0
CanESM5 MIROC-ES2L
NorESM2-LM CNRM-CM6-1
CESM2-WACCM IPSL-CM6A-LR
GFDL-ESM4 CESM2
Fig. 2: Sunphotometer and Hornsund Site Manager Piotr Lebkowski. MERRA2 Project. WCRP CMIP6.

Validation of AOD from MERRA2 with AERONET

Fig. 3: Monthly mean correlation for 2006-2014. (middle) Aeronet to MERRA2 at Arctic stations. (right) MERRA2 Arctic mean to MERRA2 at stations.

Evaluation of Arctic AOD from CMIP6 to MERRA2

Fig. 4: AOD monthly mean at 550nm for the Arctic region (1980 -2014).

AOD evaluation for Svalbard Region

Fig. 5: Correlation of monthly mean AOD Nordic Sea west of Svalbard and Hornsund (left, middle). (right) CMIP6 evaluation for Nordic Sea west of Svalbard.

AOD zonal evaluation

Fig. 6: Zonal average of AOD for 1980-89, 1990-99, 2000-09. Evaluation for CanESM5, NorESM2-LM, GFDL-ESM.

Conclusion & Future Work

AERONET - MERRA2

  • MERRA2 is higher than AERONET AOD
  • MERRA2 'stations' compare well to Arctic AOD average

MERRA2 - CMIP6

  • Arctic
    • CanESM5 overestimates during spring, too low during summer
    • still underestimation during spring
  • Svalbard region
    • CanESM5 within MERRA2 variability

Zonal average

  • overestimation in NH (CanESM5)
  • overestimation in SH (NorESM2-LM)
  • $\rightarrow$ compare all models, correlate the ones which fit will $\rightarrow$ Why do they fit better?
Thank you!