assessing the need for a o4 scaling factor for max -doas...
TRANSCRIPT
Mathematical formulation of the problem
Selection of well suited days during MADCAT
Available supporting data sets
Results, interpretation & outlook
Assessing the need for a O4 scaling factor for MAX-DOAS measurements during the MAD-CAT
campaign in Maing Germany, Summer 2013
T. Wagner, J. Remmers, R.Shaiganfar, J. Lampel, Y. Wang, S. Beirle, S. Dörner
Max-Planck-Institute for Chemistry, Mainz, Germany
measuredAMFVCDSCD
VCD
measured optical depth (of the O4 aborption at 360 nm) O4 aborption cross section SCD slant column density of O4 VCD vertical column density of O4 AMF Air mass factor
Are measurements and simulations in agreement for well defined situations, or is a scaling factor needed?
simulatedmeasured AMFAMF?
Are measurements and simulations in agreement for well defined situations, or is a scaling factor needed?
measuredAMFVCDSCD
VCD
measured optical depth (of the O4 aborption at 360 nm) O4 aborption cross section SCD slant column density of O4 VCD vertical column density of O4 AMF Air mass factor
simulatedmeasured AMFAMF?
Spectral analysis
T & p profiles
Different data sets, temperature dependence
Radiative transfer simulations
Two selected days
Clear days during MADCAT
Available data sets
Spectroscopy
MAX-DOAS measurements (4 azimuth directions)
Different O4 cross sections, including temperature dependence
AMF calculations & O4 VCD calculations
Ceilometer backscatter profiles (above 150m)
AOD from AERONET sun photometer
Surface measurements of pm2.5 and pm10
Temperature and pressure profiles from ECMWF
Surface measurements of temperature, pressure, rel. humidity
Standard O4 analysis at 360 nm
-wavelength range: 352 – 387 nm (two O4 bands)-Fraunhofer reference spectrum (FRS): 08.07., 10:05:35, SZA: 32.37°, elevation angle: 90°-calibration: using NDSC high resolution solar spectrum -cross sections:-O3, Bogumil et al., 223K-NO2 Vandaele, 298K-BrO, Fleischmann, 223K-O4, Thalmann, 293K-Ring 1-Ring 2 (Ring 1 -4)-polynomial of 5th order-intensity offset (second order polynomial)-measured spectrum is allowed to shift (versus FRS and cross sections)
Standard O4 analysis at 360 nm
Fit result for north-east direction, 08.07.2013, 11:21:54, elevation angle: 6°, SZA: 27.6°
Results for different spectral ranges
Fit result for north-east direction, 08.07.2013, 11:21:54, elevation angle: 6°, SZA: 27.6°
352-387nm:
O4 bands at 360nm and 380 nm
345-377nm:
O4 band at 360nm
335-377nm:
O4 bands at 340nm and 360nm
Influence of the wavelength range:Two other wavelength ranges are tested:-345-377nm: only the O4 band at 360nm-335-377nm: two O4 bands at 340nm and 360nm
Influence of the wavelength range:Two other wavelength ranges are tested:-345-377nm: only the O4 band at 360nm-335-377nm: two O4 bands at 340nm and 360nm
Influence of the wavelength range:Two other wavelength ranges are tested:-345-377nm: only the O4 band at 360nm-335-377nm: two O4 bands at 340nm and 360nm
0.8
0.9
1
1.1
1.2
3:36 6:00 8:24 10:48 13:12 15:36 18:00Time (08.07.2013)
Rat
io fo
O4
DS
CD
s (s
eque
ntia
l ref
.)
ratio_335_377nmratio_345_377nmRatio (340 & 360) / (360 & 380)Ratio (360) / (360 & 380)
1.00
0.97
The ratios are close to unity. The deviations of the results for 335 – 377nm can be explained by the wavelength dependence of the AMF.
Influence of the O4 cross section:-Greenblatt et al. (only interpolated)-Hermans et al.
The ratios of the O4 dSCDs are close to unity (especially if the Greenblatt et al cross section is allowed to shift)
0.8
0.9
1
1.1
1.2
2:24 4:48 7:12 9:36 12:00 14:24 16:48 19:12Time (08.07.2013)
Rat
io b
etw
een
O4D
SC
Ds
(fixe
d re
fere
nce)
ratio_burk_Thalratio_burkshift_Thalratio_Her_Thal
1.07
1.02
0.97
Only 293K
Only 203K
Both temperatures
Both temperatures, 293K orthogonalised
Both temperatures, 203K orthogonalised
Effect of the temperature dependence
Fit results for different combinations of O4 cross sections (original or orthogonalised)
7.68e-4
8.06e-4
7.65e-4
7.65e-4
7.65e-4
Effect of the temperature dependenceLarge difference are found for the retrieved O4 dSCDs:
colder effective temperatures in the morning
If low temperature cross section is used, the O4 dSCDs are underestimated by 30%
Effect of the temperature dependenceLarge differences are found for the retrieved O4 dSCDs (also forsequential FRS):
colder effective temperature in the morning
If low temperature cross section is used, the O4 dSCDs are underestimated by 30%
ECMWF
Surface measurements
O4 profile
temperature profile
18.06.2013
Profiles of pressuretemperaturehumidity
Calculation of the O4 VCDs for May to August 2013(based only on the surface pressure and temperature)
1.15
1.2
1.25
1.3
1.35
21.4 11.5 31.5 20.6 10.7 30.7 19.8 8.9
Time
O4
VC
D [1
043
mol
ec5/
cm²]
16.08. 08.07.
integration is performed between 150m and 30 km with a vertical resolution of 20m
RTM calculations are performed with MCARTIM (1)
-same t & p, and O4 profiles as used for determination of O4 VCD-vertical discretisation (150m =0m in RTM grid):-0m – 500m: 20m-500m – 2000m: 100m-2km – 12km: 200m-12km – 25km: 1km-25km – 45km: 2km-45km – 100km: 5km-100km – 1000km: 900km
-surface albedo: 5%, aerosol optical properties are varied-aerosol extinction profiles are derived from Ceilometer and AERONET AOD
Determination of aerosol extinction profiles1 8 .0 6 . , 0 8 :0 0 to 1 1 :0 0
- 1 .0 0 E + 0 9
0 .0 0 E + 0 0
1 .0 0 E + 0 9
2 .0 0 E + 0 9
3 .0 0 E + 0 9
0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0A lt i t u d e [m ]
atte
nuat
ed b
acks
catte
r sig
nal
8 : 3 09 : 3 01 0 : 3 08 _ 1 1 h
1 8 .0 6 . , 0 8 :0 0 to 1 1 :0 0
0
0 .1
0 .2
0 .3
0 .4
0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0a lt itu d e [m ]
Extin
ctio
n [1
/km
]
s lo p e _ 1 8 0 _ 2 4 0 md o u b le s lo p e _ 1 8 0 _ 2 4 0 mc o n s t
Extrapolation, smoothing, scaling to AERONET AOD
0
0 .1
0 .2
0 .3
0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0 5 0 0 0 6 0 0 0a lt itu d e [m ]
Extin
ctio
n [1
/km
]
s lo p e _ 1 8 0 _ 2 4 0 ms lo p e _ 1 8 0 _ 2 4 0 mo r ig in a lw ith e x tin c tio n c o rre c tio n
0 8 .0 7 ., 0 4 :0 0 to 0 7 :0 0
Raw profiles from Ceilometer (1 hour averages)18.06., 8:00 – 11:00
Correction of aerosol self-extinction‘
Determination of aerosol extinction profiles
18.06., 08:00 to 11:00 18.06., 11:00 – 14:00 18.06., 14:00 – 19:00
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
08.07., 04:00 to 07:00 08.07., 07:00 – 11:00 08.07., 11:00 – 19:00
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
0
0.1
0.2
0.3
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240mslope_180_240moriginalwith extinction correction
Comparison of profiles without (blue) and with (magenta) extinction correction. Both profile versions are scaled to the same total AOD determined from the sun photometer.
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (08.07.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3
07:00 - 11:0004:00 - 07:0011:00 - 19:00
RTM results (AMF for 1° elevation, north-east direction)
Influence of time of day (T, p, O4, aerosol profiles)
08.07.2013
RTM results (AMF for 1° elevation, north-east direction)
Influence of extrapolation of aerosol profile below 180m
08.07.2013
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (08.07.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3
linearly extrapolated below 180mconstant below 180mlinearly extrap., double slope below 180m
RTM results (AMF for 1° elevation, north-east direction)
Influence of aerosol optical properties
08.07.2013
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (08.07.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3elev_3
HG, asymmetry parameter 0.68HG, asymmetry parameter 0.60HG, asymmetry parameter 0.75HG, asymmetry parameter 0.85
RTM results (AMF for 1° elevation, north-east direction)
Influence of aerosol optical properties
08.07.2013
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (08.07.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3
Single scattering albedo 0.95Single scattering albedo 0.90Single scattering albedo 1.00
RTM results (AMF for 1° elevation, north-east direction)
Influence of surface albedo
08.07.2013
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (08.07.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3
Surface albedo: 0.05Surface albedo: 0.03Surface albedo: 0.10
Comparison result for one azimuth direction
The RTM results systematically underestimate the measured AMF. Similar results for all azimuth directions and low elevation angles
08.07.2013, 3° elevation towards north-east
0
1
2
3
4
5
6
7
3:00 7:00 11:00 15:00 19:00Time (08.07.2013)
O4
DA
MF
measurementssimulations 4h – 7hsimulations 7h – 11hsimulations 11h – 19h
measurementssimulations 4h – 7hsimulations 7h – 11hsimulations 11h – 19h
O4 AMF
O4 DAMF
0
1
2
3
4
5
6
7
3:00 7:00 11:00 15:00 19:00Time (18.06.2013)
O4
DAM
F
s
On the morning of 18.06 RTM results are higher than measured O4 dSCDs
What is the reason?
O4 AMF
O4 DAMF
Aerosol concentration measured by in situ instruments
In the morning of 18.06. high aerosol load was found close to the surface
0
10
20
30
40
50
3:00 7:00 11:00 15:00 19:00Time
pm2.
5 [µ
g/m
³]
blue: 18.06.red: 08.07.
ZitadelleParcusstrasseWI Ringkirche
0
10
20
30
40
50
60
70
3:00 7:00 11:00 15:00 19:00Time
pm 1
0 [µ
g/m
³]
blue: 18.06.red: 08.07.
ParcusstrasseZitadelleMombachWI Schierst.WI Sued
Modified aerosol extinction profile for morning of 18.06. 2013
The values below 180m are set to three times the values of the profile with linear extrapolation below 180m. The total AOD is changed from 0.38 (average value) to 0.41 (close to maximum during that period).
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 1000 2000 3000 4000 5000 6000altitude [m]
Ext
inct
ion
[1/k
m]
slope_180_240m
double slope_180_240m
const
three times extinction_AOD041
RTM results (AMF for 1° elevation, north-east direction)
Results for the modified profile are much smaller
18.06.2013
0
1
2
3
4
5
6
03:00 07:00 11:00 15:00 19:00Time (18.06.2015)
O4
AM
F (1
°)
elev_3elev_3elev_3Reihe4
linearly extrapolated below 180mconstant below 180mlinearly extrap., double slope below 180m3 times extinction below 180m, AOD 0.41
0
1
2
3
4
5
6
7
3:00 7:00 11:00 15:00 19:00Time (18.06.2013)
O4
DAM
F
s
measurementssimulations 8h – 11hsimulations 11h – 14hsimulations 14h – 19h
Profile inversions using parameterised methodComparison to Ceilometer
0
1000
2000
3000
4000
3:00 7:00 11:00 15:00 19:00Time
heig
ht [m
]
18.06. shape factor: 0.8sclaing factor: 0.8
0
1000
2000
3000
4000
3:00 7:00 11:00 15:00 19:00T ime
heig
ht [m
]08.07.
shape factor: 0.8scaling factor: 0.8
0
0.2
0.4
0.6
0.8
3:00 7:00 11:00 15:00 19:00Time
AO
D (3
60 n
m)
Reihe1Reihe2Reihe3Reihe4
fact: 0.7fact: 0.8fact: 0.9AERONET
18.06. shape factor: 0.8
0
0.2
0.4
0.6
0.8
3:00 7:00 11:00 15:00 19:00Time
AO
D (3
60 n
m)
Reihe1Reihe2Reihe3Reihe4
fact: 0.7fact: 0.8fact: 0.9AERONET
08.07. shape factor: 0.8
Profile inversions using parameterised methodComparison to Ceilometer
0
1000
2000
3000
4000
3:00 7:00 11:00 15:00 19:00Time
heig
ht [m
]
18.06. shape factor: 0.8sclaing factor: 0.8
0
1000
2000
3000
4000
3:00 7:00 11:00 15:00 19:00T ime
heig
ht [m
]08.07.
shape factor: 0.8scaling factor: 0.8
Comparison of aerosol extinction / pm2.5 & pm10 on both days
0
10
20
30
40
50
3:00 7:00 11:00 15:00 19:00Time
pm2.
5 [µ
g/m
³]
blue: 18.06.red: 08.07.
ZitadelleParcusstrasseWI Ringkirche
0
10
20
30
40
50
60
70
3:00 7:00 11:00 15:00 19:00Time
pm 1
0 [µ
g/m
³]
blue: 18.06.red: 08.07.
ParcusstrasseZitadelleMombachWI Schierst.WI Sued
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
3:00 7:00 11:00 15:00 19:00time
Ext
inct
ion
[1/k
m]
Reihe10Reihe118.06.201308.07.2013 MAX-DOAS aerosol extinction
(AOD / layer height)
Surface in situ measurements
Summary
-measured O4 AMFs (and dAMFs) on 08.07.2013 are by about 20% larger than simulated ones (on 18.06. differences are smaller)-RTM uncertainties or choice of cross sections and fit settings can not explain these differences
-for the selected days the calculation of the O4 VCD is very accurate (but changes of the O4 VCD are > 10% during the MADCAT period due to pressure and temperature variations)-temperature dependence of O4 cross section is large (30% change of O4 dSCD for 100K temperature difference), but can not explain the observed differences on the selected days.
-the need for scaling factor remains unexplained
-all steps should be repeated by other participants (using also measurements from other instruments)
I will send out email with detailed information soon.