IASI greenhouse gases and aerosols data

Validation of the mineral dust product

The detailed evaluation is to be found in Callewaert et al., 2019. Here we only show the major results, with very limited discussion or interpretation.

Aerosol Optical Depth evaluation with AERONET

This figure shows the Pearson correlation coefficient between the AERONET SDA coarse mode AOD and the MAPIR version 4.1 AOD converted to 550nmFigure 1: Map of the 72 AERONET stations that were matched with IASI measurements. The color scale represents the value of the Pearson correlation coefficient between the AERONET SDA coarse mode AOD and the MAPIR AOD converted to 550 nm.

Figure 2: MAPIR AOD, converted to 550 nm, versus the AERONET SDA coarse mode AOD difference distribution. (a) Scatter plot of the AOD difference in function of the AERONET AOD (red dots), for all considered stations combined. Data are split into 10 bins of equal quantity, corresponding binned median (black dots) and interquartile range (IQR, vertical black lines) are shown. (b) AOD difference histogram.

 

Mean altitude evaluation with CALIOP

The mean altitude computed from the MAPIR vertical profiles (as the altitude for which half the aerosols are below and half are above) was compared with the mean altitude from CALIOP (altitude for which half the aerosol extinction is below and half is above) for 40 days in the year 2017. MAPIR on average underestimates the dust aerosol altitude by about 300m. Provided that the vertical sampling of the retrieval is 1km, this is a very good result.

 

Profile evaluation against CATS

Figure 3: Mineral dust profile comparison along the CATS track on 16 February 2017 . The first plot gives the global retrieved AOD by MAPIR together with the pathway of CATS that could be co-located with IASI in time (1 hour) and space (0.25°). The part which corresponds to the plotted profiles below is given in pink. It covers the Sahel region. The second plot shows the dust extinction profiles along the pink track, as measured by CATS. On the third plot, the CATS data smoothed according to Eq. (7) of Callewaert et al (2019) is presented, on those locations where there is a MAPIR profile. Finally, the fourth plot presents the averaged MAPIR profiles along the track.
Figure 4: Same as Figure 3 but with a co-located track on 19 June 2015. The pink track covers Western Sahara

 

References

  • Callewaert, S., Vandenbussche, S., Kumps, N., Kylling, A., Shang, X., Komppula, M., Goloub, P., and De Mazière, M.: The Mineral Aerosol Profiling from Infrared Radiances (MAPIR) algorithm: version 4.1 description and evaluation, Atmos. Meas. Tech., https://doi.org/10.5194/amt-12-3673-2019, 2019.