1. The MPI MAX-DOAS inversion scheme 2. Cloud classification 3. Results: Aerosol OD: Correlation with AERONET Surface extinction: Correlation with Nephelometer Mixing Layer Height: Correlation with Ceilometer NO2 Surface mixing ratio: Correlation with EMPA Mixing Layer Height: Correlation with Ceilometer Inversion of synthetic NO2 SCDs 4. Conclusions Results of the profile inversion from MPI MiniMAX-DOAS measurements during CINDI Thomas Wagner, Reza Shaigan, Steffen Beirle MPI Mainz, Germany

Aerosol profiles are parametrised by 3 parameters: following the ideas of Li, X., Brauers, T., Shao, M., Garland, R. M., Wagner, T., Deutschmann, T., and Wahner, A.: MAX-DOAS measurements in southern China: retrieval of aerosol extinctions and validation using ground-based in-situ data, Atmos. Chem. Phys., 10, , A) vertical optical depth OD (related to total aerosol amount) B) mixing layer height MLH (important atmospheric parameter) C) fraction of total optical depth in boundary layer (allows to adjust vertical profile, depending e.g. on vertical mixing into free troposphere)f = % Constant extinction in ML, exponential decrease above 1. The MPI MAX-DOAS inversion scheme

f = 1.5 New (since Nov. 2009): f > 1: Profiles with elevated layers Aerosol profiles are parametrised by 3 parameters: following the ideas of Li, X., Brauers, T., Shao, M., Garland, R. M., Wagner, T., Deutschmann, T., and Wahner, A.: MAX-DOAS measurements in southern China: retrieval of aerosol extinctions and validation using ground-based in-situ data, Atmos. Chem. Phys., 10, , The MPI MAX-DOAS inversion scheme

f = 1.1 New (since Nov. 2009): f > 1: Profiles with elevated layers Aerosol profiles are parametrised by 3 parameters: following the ideas of Li, X., Brauers, T., Shao, M., Garland, R. M., Wagner, T., Deutschmann, T., and Wahner, A.: MAX-DOAS measurements in southern China: retrieval of aerosol extinctions and validation using ground-based in-situ data, Atmos. Chem. Phys., 10, , The MPI MAX-DOAS inversion scheme Multi-layer aerosols can not be described by this parametrisation

Modelling of O4 AMFs: Radiative transfer modelling: Backward Monte-Carlo RTM McArTim (Deutschmann, 2009) Surface albedo: 5% Surface altitude of measurement site Pressure and temperature profiles from US standard atmosphere Greenblatt et al. O4 cross section (corrected by +15% to +25%) Single scattering albedo: 0.95 Asymmetry parameter: 0.68 Number of aerosol scenarios: MLH (14): 20, 100, 200, 300, 500, 700, 1000, 1200, 1500, 1750, 2000, 2500, 3000, 5000m OD (10): 0.05, 0.1, 0.2, 0.3, 0.5, 0.7, 1.0, 1.5, 2.0, 3.0 f (11): 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 1.0, 1.1, 1.2, 1.5, 1.8 for 8 elevation angles and 14 SZA / rel. Azimuth angles 1. The MPI MAX-DOAS inversion scheme

Parametrisation of NO 2 profiles in a similar way: A) mixing layer height MLH (important atmospheric parameter) B) fraction f of total VCD in boundary layer (allows to adjust vertical profile, depending e.g. on vertical mixing into free troposphere) However, no absolute tropospheric VCD is varied, because NO 2 AMF depends only on relative profile 1. The MPI MAX-DOAS inversion scheme

Aerosol inversion: Modelled AMFs are fitted to the measured data in the following way: Measurements: -Subtraction of O4 DSCD at 90° for each elevation sequence -Division by O4 VCD => O4 DAMF Model results: -Subtraction of O4 AMF at 90° for each elevation sequence => O4 DAMF Least squares fit: OD, ML (f: fixed) 1. The MPI MAX-DOAS inversion scheme

Result of aerosol fit, Cabauw, Sequence 6 Min: for layer height 0.5km, optical depth: The MPI MAX-DOAS inversion scheme

NO 2 inversion: Modelled AMFs are fitted to the measured data in the following way: Measurements: - Subtraction of NO2 DSCD at 90° for each elevation sequence - Division by (shifted) DSCD at 10° Model results (calculated for specific aerosol scenario): - Subtraction of NO2 AMF at 90° for each elevation sequence => NO2 DAMF - Division by DAMFs at 10° Least squares fit: ML (f: fixed) Aerosol parameter from O4 inversion 1. The MPI MAX-DOAS inversion scheme

Result of NO2 fit, Cabauw sequence sequence 62 Chi2 = 0.05Chi2 = The MPI MAX-DOAS inversion scheme

Classification of the cloud cover using radiance and O4 observations at 90° elevation angle Temporal variation of radiance smooth? yes => Temporal variation of O4 smooth? yes => clear day no => cloudy day O4 absorption largely increased and/or varying rapidly compared to clear day? yes => thick cloud no => thin cloud 2. Cloud classification

Day with clear sky Cabauw Bruxelles 2. Cloud classification

Day with 'thin' clouds Cabauw Bruxelles 2. Cloud classification

Day with 'thick' clouds Cabauw Bruxelles 2. Cloud classification

Classification of the cloud cover using radiance and O4 observations at 90° elevation angle O4 AMF – O4 AMF cloudfree 2. Cloud classification

A) Typical diurnal cycles B) Aerosol OD: Correlation with AERONET data C) Surface extinction: Correlation with WetNephelometer data D) Mixing Layer Height: Correlation with Ceilometer data 3.1 Results: Aerosols

Clear sky cloudy 3.1 Results: Aerosols A) Typical diurnal cycles

mostly cloudy Clear sky 3.1 Results: Aerosols A) Typical diurnal cycles

All coincidences (half hour averages) 3.1 Results: AerosolsB) Correlation with AERONET OD O4 scaling factor = 1.2 f=0.9

Data with layer heigth >= 3km removed 3.1 Results: AerosolsB) Correlation with AERONET OD

Also data with chi2 >= 0.04 removed 3.1 Results: AerosolsB) Correlation with AERONET OD

Days with (unrealistic) rapid variation of the aerosol OD: 3.1 Results: AerosolsB) Correlation with AERONET OD

Data with rapid variation of OD (> 0.5) removed 3.1 Results: AerosolsB) Correlation with AERONET OD

Only data for thin clouds 3.1 Results: AerosolsB) Correlation with AERONET OD

Only data for clear sky Coincidences only in the morning! (with systematically low MAX-DOAS results) 3.1 Results: AerosolsB) Correlation with AERONET OD

Only data for thick clouds 3.1 Results: AerosolsB) Correlation with AERONET OD

Correlation with WetNephelometer data from Paul Zieger 3.1 Results: AerosolsC) Correlation with in-situ extinction

Correlation with WetNephelometer data from Paul Zieger for different layer heights >1500m: Slope  2 <1500m Slope  1

MAX-DOAS aerosol layer height F-value: 0.9 F-value: Results: AerosolsD) Correlation with Ceilometer MLH

all data 3.1 Results: AerosolsD) Correlation with Ceilometer MLH

only clear sky observations and chi2 < Results: AerosolsD) Correlation with Ceilometer MLH

3.2 Results: NO2 A) Typical diurnal cycles B) Mixing ratio: Correlation with EMPA data C) Mixing Layer Height: Correlation with Ceilometer data D) Inversion of synthetic NO2 DSCDs

NO2 mixing ratio for different aerosol f-values thin clouds 3.2 Results: NO2 A) Typical diurnal cycles

thin clouds NO2 mixing ratio for different NO2 f-values 3.2 Results: NO2 A) Typical diurnal cycles

All coincidences (half hour averages, f-value: 0.9) 3.2 Results: NO2B) Correlation with EMPA mixing ratio

All coincidences (half hour averages, f-value: 0.9) Chi2 < Results: NO2B) Correlation with EMPA mixing ratio

Only thin clouds 3.2 Results: NO2B) Correlation with EMPA mixing ratio

clear sky (only early morning data) 3.2 Results: NO2B) Correlation with EMPA mixing ratio

Only thick clouds 3.2 Results: NO2B) Correlation with EMPA mixing ratio

Slope of fitR2R2 All data chi2< thin clouds clear sky thick clouds

On some days the NO2 mixing ratios depend strongly on the assumed (relative) aerosol profile. The mixing ratios derived for an elevated aerosol layer (f>1) agree better with the in-situ data. For these observations also the lowest chi2 is found in the aerosol fit (O4 data) for an assumed elevated aerosol layer 3.2 Results: NO2B) Correlation with EMPA mixing ratio

Lowest chi2 for elevated aerosol layer Better agreement of NO2 mixing ratio for elevated aerosol layer 3.2 Results: NO2B) Correlation with EMPA mixing ratio

3.2 Results: NO2C) Correlation with Ceilometer MLH Slope of fitR2R2 All data chi2< thin clouds clear sky thick clouds Aerosol fit: f=0.9 f=1.1

Fit results for all daily profiles (UV profile 03) F-value Layer height NO2 VCD Chi2 3.2 Results: NO2D) Inversion of synthetic NO2 DSCDs

(UV profile 03, all daily profiles) 3.2 Results: NO2D) Inversion of synthetic NO2 DSCDs

Results for all UV profiles 3.2 Results: NO2D) Inversion of synthetic NO2 DSCDs

-simple MAX-DOAS inversion scheme for UV measurements, based on MC-RTM LUT and least squares fit of simple profile parametrisation -discrimination scheme for clear sky / thin clouds / thick clouds Aerosol inversion: -aerosol OD is reasonable for aerosol f-value of 0.9, clear sky and thin cloud observations; MAX-DOAS aerosol OD about 25% smaller than AERONET -aerosol extinction agrees well with wetnepelometer data for layer heights <1500m -aerosol layer height shows (weak) correlation with ceilometer data only for clear sky 4. Conclusions

NO2 inversion: -NO2 mixing ratio agrees well with in-situ observations for clear sky and thin cloud observations; only weak dependence on aerosol f-value; almost no dependence on NO2 f-value -NO2 layer height shows reasonable correlation with ceilometer data for clear sky and thin cloud data Inversion of synthetic NO2 SCDs -good agreement found for NO2 profiles for low and high aerosol load -for some profiles rather large deviations during the day 4. Conclusions

different scaling factors for the O4 cross section (observations for thin clouds) +20 % seems to be the best choice 3.1 Results: AerosolsB) Correlation with AERONET OD +15 % +20 % +25 %

Correlations for different f-.values (observations for thin clouds) 0.9 seems to be a good choice 3.1 Results: AerosolsB) Correlation with AERONET OD

Aerosol extinction for different aerosol f-values thin clouds 3.1 Results: Aerosols

clear sky cloudy sky 3.1 Results: Aerosols Aerosol extinction for different aerosol f-values

for different aerosol f-values (thin cloud data) 3.2 Results: NO2B) Correlation with EMPA mixing ratio

for different NO2 f-values (thin cloud data) Almost no dependence on NO2 f-value 3.2 Results: NO2B) Correlation with EMPA mixing ratio

Day with better agreement for elevated layer (some periods) Lowest chi2 for elevated aerosol layer Better agreement of NO2 mixing ratio for elevated aerosol layer 3.2 Results: NO2B) Correlation with EMPA mixing ratio

(all data, NO2 f-value: 0.9) 3.2 Results: NO2C) Correlation with Ceilometer MLH

NO2 Chi2 < Results: NO2C) Correlation with Ceilometer MLH

Only thin clouds 3.2 Results: NO2C) Correlation with Ceilometer MLH

Only clear sky 3.2 Results: NO2C) Correlation with Ceilometer MLH

Only thick clouds 3.2 Results: NO2C) Correlation with Ceilometer MLH