Discrete Probability Distributions. Probability Distributions.
Measurements of pollutants and their spatial distributions over the Los Angeles Basin
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Measurements of pollutants and their spatial distributions over the Los Angeles Basin Ross Cheung 1,2 , Olga Pikelnaya 1,2 , Catalina Tsai 1 , Jochen Stutz 1,2 , Dejian Fu 2,3 , and Stanley P. Sander 2,3 5/16/2011 1 Department of Atmospheric and Oceanic Sciences, UCLA 2 Joint Institute for Regional Earth System Science and Engineering, UCLA 3 NASA Jet Propulsion Laboratory, Caltech
description
Measurements of pollutants and their spatial distributions over the Los Angeles Basin. Ross Cheung 1,2 , Olga Pikelnaya 1,2 , Catalina Tsai 1 , Jochen Stutz 1,2 , Dejian Fu 2,3 , and Stanley P. Sander 2,3 5/16/2011. 1 Department of Atmospheric and Oceanic Sciences, UCLA - PowerPoint PPT Presentation
Transcript of Measurements of pollutants and their spatial distributions over the Los Angeles Basin
Measurements of pollutants and their spatial distributions over the
Los Angeles BasinRoss Cheung1,2, Olga Pikelnaya1,2, Catalina
Tsai1, Jochen Stutz1,2, Dejian Fu2,3, and Stanley P. Sander2,3
5/16/2011
1Department of Atmospheric and Oceanic Sciences, UCLA2Joint Institute for Regional Earth System Science and Engineering, UCLA3NASA Jet Propulsion Laboratory, Caltech
Motivation
• Observation of spatial and temporal distribution of trace gases in the LA Basin
• Study pollution transport of criteria pollutants in the LA basin
• Provide data for assimilation into air quality models
• Use inverse modeling to validate emissions inventories
California Laboratory for Atmospheric Remote Sensing (CLARS)Mt. Wilson, CA, in San Gabriel Mountains, with a near full view of the LA basin
Longitude: 34° 13' 28'' NLatitude: 118° 3' 25'' WAltitude: 1706 meters/5597 feet ASLMost of the time above the boundary layer
• UCLA Multi-AXis Differential Optical Absorption Spectrometer (MAX-DOAS)• JPL Near-IR FTS (Fourier Transform Spectrometer) – see talk by Dejian Fu, Tuesday May 17th, 9:10 am
Measurements started in mid-May 2010 and are still continuing
CLARS observatory at Mt. Wilson
Viewing Geometry
Azimuth Angles
147.4°, 160°, 172.5°, 182°, 240.6°
Elevation Angles
-10°, -8°, -6°, -4°, -2°, 0°, 3°, 6°, 90°
Continuous scans in elevation and azimuth. Cycle length: 60-80 minutes
147.4 °
240.6 °
182°
UCLA MAX-DOAS
Scattered sunlight from the sky (positive a)
Scattered sunlight from the basin (negative a)
Spectralon
Wavelength interval (nm)
Trace gases measured
316.4 – 448.2 NO2, HCHO, Glyoxal, O4
463.5 – 591.9 NO2, O4
MAX-DOAS can point in virtually any direction, measures scattered sunlight from sunrise to sunset
Field of view: 0.4°
Acquisition time: ~1 minute
αα
MAX-DOAS at Mt. Wilson
Viewing geometry
Scattering both in atmosphere and off ground
MAX-DOAS measures path-integrated concentration along path s: Slant Column Density (SCD) :
Differential slant column densities (DSCD) obtained by removing zenith SCD:
O4 vertical profile zenithaxisoff SCDSCDDSCD
L
dsscSCD0
αα
MAX-DOAS at Mt. Wilson
Viewing geometry
Scattering both in atmosphere and off ground
MAX-DOAS measures path-integrated concentration along path s: Slant Column Density (SCD) :
Differential slant column densities (DSCD) obtained by removing zenith SCD:
O4 gives important information about atmospheric path length
O4 vertical profile zenithaxisoff SCDSCDDSCD
L
dsscSCD0
-0.06-0.04-0.02 NO2 reference
Retrieved NO2
500 520 540 560 580 600-0.025
-0.02
-0.015
-0.01
-0.005
0
wavelength (nm)
log[
Inte
nsity
]
NO2 reference
NO2 plus residual
460 470 480 490 500 510-0.035
-0.03
-0.025
-0.02
-0.015
-0.01
-0.005
wavelength (nm)
log[
Inte
nsity
]
NO2 reference
NO2 plus residual
420 430 440 450-0.05
-0.045
-0.04
-0.035
-0.03
-0.025
wavelength (nm)
log[
Inte
nsity
]
NO2 reference
NO2 plus residual
320 330 340 350 360 370-0.03
-0.025
-0.02
-0.015
-0.01
wavelength (nm)
log[
Inte
nsity
]
NO2 reference
NO2 plus residual
All figures are in the same viewing direction
Path length is wavelength dependent due to scattering effects
Wavelength Dependence of DSCDDSCD: (5.3 ± 0.3) x 1016
DSCD: (7.4 ± 0.2) x 1016
DSCD: (7.3 ±0.1) x 1016
DSCD: (10 ± 0.2) x 1016
323-362 nm
419-447 nm
464-507 nm
520-588 nm
0
5
10
x 1016
12:00 15:00 18:00 21:00 00:00 03:000
2
4
6
8x 1043
Time (UTC), 5/30/2010
323-362 nm419-447 nm464-507 nm520-588 nm
350-390 nm464-507 nm520-588 nm
Scattering Effects
Obtaining NO2 and O4 DSCDs at different wavelengths adds valuable information on radiative transfer
DSCDs increase with increasing path lengths
Elevation -4o
Azimuth 182o
NO
2 DSC
Dm
olec
/cm
2
O4 D
SCD
mol
ec2 /
cm5
0
5
10
x 1016
12:00 15:00 18:00 21:00 00:00 03:000
2
4
6
8x 1043
Time (UTC), 5/30/2010
323-362 nm419-447 nm464-507 nm520-588 nm
350-390 nm464-507 nm520-588 nm
Scattering Effects
Obtaining NO2 and O4 DSCDs at different wavelengths adds valuable information on radiative transfer
NO2 DSCDs increase close to Mt. Wilson
Elevation -4o
Azimuth 182o
NO
2 DSC
Dm
olec
/cm
2
O4 D
SCD
mol
ec2 /
cm5
No strong RT effects seen in O4
0
2
4
6
8
10x 10
17
NO
2 DS
CD
, mol
ec/c
m2
Azimuth 147º Azimuth 160º Azimuth 172º Azimuth 182º
Azimuth 241º
elevation 6ºelevation 3ºelevation 0ºelevation -2ºelevation -4ºelevation -6ºelevation -8ºelevation -10º0
5
10
15x 10
16
HC
HO
DS
CD
, mol
ec/c
m2
12:00 00:000
5
10
15x 10
43
O4 D
SC
D, m
olec
2 /cm
5
12:00 00:00 12:00 00:00Time (UTC) for May 31st, 2010
12:00 00:00 12:00 00:00
40 viewing directions in 2 wavelengths, every 60-80min
Overview of May 31 data
Looking westward (towards Santa Monica)
Looking eastwards (towards Baldwin Park and West Covina)
NO
2 DSC
Dm
olec
/cm
2
HCHO
DSC
Dm
olec
/cm
2O
4 DSC
Dm
olec
2 /cm
5
Az 160oAz 147o Az 172o Az 182o Az 241o
0
5
10 x 1017
0
5
10 x 1016
15:00 18:00 21:00 00:000
5
10
x 1043
Time (UTC) for May 31st, 2010
elevation 6ºelevation 3ºelevation 0ºelevation -2ºelevation -4ºelevation -6ºelevation -8ºelevation -10º
HCHO
DSC
Dm
olec
/cm
2
DSCDs at 172° Azimuth
O4 surprisingly constant throughout this day
Increase in NO2 later in day – transport of pollution
NO2 above boundary layer relatively constant
NO
2 DSC
Dm
olec
/cm
2O
4 DSC
Dm
olec
2 /cm
5
0
5
10 x 1017
0
5
10 x 1016
15:00 18:00 21:00 00:000
5
10
x 1043
Time (UTC) for May 31st, 2010
elevation 6ºelevation 3ºelevation 0ºelevation -2ºelevation -4ºelevation -6ºelevation -8ºelevation -10º
HCHO
DSC
Dm
olec
/cm
2
DSCDs at 172° AzimuthN
O2 D
SCD
mol
ec/c
m2
O4 D
SCD
mol
ec2 /
cm5
O4 greater in horizontal elevation angles
NO2 and HCHO greatest when looking into boundary layer
Downwards looking Upwards looking
Overview of May 31 data by elevation angle
0
5
10x 10
17
0
5
10
15x 10
16
12:00 00:000
5
10
15 x 1043
12:00 00:00 12:00 00:00Time (UTC) for May 31st, 2010
12:00 00:00 12:00 00:00
Azimuth 147ºAzimuth 160ºAzimuth 172ºAzimuth 182ºAzimuth 241º
NO
2 DSC
Dm
olec
/cm
2
HCHO
DSC
Dm
olec
/cm
2O
4 DSC
Dm
olec
2 /cm
5
Elev. -6o Elev. -4o Elev. -2o Elev. 0o Elev. 3o
0
5
10x 10
17
0
5
10
15x 10
16
12:00 00:000
5
10
15 x 1043
12:00 00:00 12:00 00:00Time (UTC) for May 31st, 2010
12:00 00:00 12:00 00:00
Azimuth 147ºAzimuth 160ºAzimuth 172ºAzimuth 182ºAzimuth 241º
NO
2 DSC
Dm
olec
/cm
2
HCHO
DSC
Dm
olec
/cm
2O
4 DSC
Dm
olec
2 /cm
5
Elev. -6o Elev. -4o Elev. -2o Elev. 0o Elev. 3o
Overview of May 31 data by elevation angle
O4 values increase with elevation angle – increasing path length
241° Azimuth behaves differently from others
0
5
10x 10
17
0
5
10
15x 10
16
12:00 00:000
5
10
15 x 1043
12:00 00:00 12:00 00:00Time (UTC) for May 31st, 2010
12:00 00:00 12:00 00:00
Azimuth 147ºAzimuth 160ºAzimuth 172ºAzimuth 182ºAzimuth 241º
NO
2 DSC
Dm
olec
/cm
2
HCHO
DSC
Dm
olec
/cm
2O
4 DSC
Dm
olec
2 /cm
5
Elev. -6o Elev. -4o Elev. -2o Elev. 0o Elev. 3o
Clear vertical gradient in NO2 and HCHO DSCDs
Diurnal variability in NO2, HCHO
Overview of May 31 data by elevation angle
Quantifying the Effect of Radiative Transfer
Weighing factor for each atmospheric layer’s contribution to absorption and scattering at each elevation angle: Differential Box Air-Mass Factor (DBAMF)
m
jjjiji ChDBAMFDSCD
1
][)(a
DBAMFs calculated with TRACY II Monte- Carlo Radiative Transfer Model
0
1
2
3
4
5
0 10 20 30 40 50
Differential Box Air Mass Factor (DBAMF)
Alti
tude
(km
)
Elevation 6o
Elevation 3o
Elevation 0o
Elevation -2o
Elevation -4o
Elevation -6o
Elevation -8o
Elevation -10o
Weight moves lower in atmosphere with decreasing elevation angle
DBAMFs for May 31st
Quantifying the Effect of Radiative Transfer
Weighing factor for each atmospheric layer’s contribution to absorption and scattering at each elevation angle: Differential Box Air-Mass Factor (DBAMF)
m
jjjiji ChDBAMFDSCD
1
][)(a
DBAMFs calculated with TRACY II Monte- Carlo Radiative Transfer Model
0
1
2
3
4
5
0 10 20 30 40 50
Differential Box Air Mass Factor (DBAMF)
Alti
tude
(km
)
Elevation 6o
Elevation 3o
Elevation 0o
Elevation -2o
Elevation -4o
Elevation -6o
Elevation -8o
Elevation -10o
Weight moves lower in atmosphere with decreasing elevation angle
DBAMFs for May 31st
Quantifying the Effect of Radiative Transfer
Weighing factor for each atmospheric layer’s contribution to absorption and scattering at each elevation angle: Differential Box Air-Mass Factor (DBAMF)
m
jjjiji ChDBAMFDSCD
1
][)(a
DBAMFs calculated with TRACY II Monte- Carlo Radiative Transfer Model
Weight moves lower in atmosphere with decreasing elevation angle
0
1
2
3
4
5
0 10 20 30 40 50
Differential Box Air Mass Factor (DBAMF)
Alti
tude
(km
)
Elevation 6o
Elevation 3o
Elevation 0o
Elevation -2o
Elevation -4o
Elevation -6o
Elevation -8o
Elevation -10o
DBAMFs for May 31st
Retrieval of BL and FT NO2 concentrations
MAX-DOAS @ Mt. Wilson
Ctop
CBL
HM
AX-DOAS = 1550m
HBL
adownward
aupwardConcentration Cj for each atmospheric layer j is:
)()(a
aDBAMFhDSCD
Cj
jj
•NO2 elevated and well-mixed in in boundary layer (BL). •Boundary layer height was determined by Ceilometer at Caltech.•NO2 concentration free troposphere from horizontal elevation scan
0
500
1000Boundary Layer Height
Alti
tude
(met
ers)
0
0.5
1
1.5"Top" layer Mixing Ratio (C
top)
NO
2, ppb
12:00 15:00 18:00 21:00 00:00 03:000
5
10
15
Time/Date (UTC) for May 31st, 2010
NO
2, ppb
Boundary Layer Height Mixing Ratio (CBL
)
160º172º182ºLP-DOAS
NO2 mixing ratios, May 31st
Boundary Layer Height courtesy of C. Haman and B. Lefer, University of Houston
Values in 3 azimuths agree well
0
500
1000Boundary Layer Height
Alti
tude
(met
ers)
0
0.5
1
1.5"Top" layer Mixing Ratio (C
top)
NO
2, ppb
12:00 15:00 18:00 21:00 00:00 03:000
5
10
15
Time/Date (UTC) for May 31st, 2010
NO
2, ppb
Boundary Layer Height Mixing Ratio (CBL
)
160º172º182ºLP-DOAS
NO2 mixing ratios, May 31st
Boundary Layer Height courtesy of C. Haman and B. Lefer, University of Houston
For more on the Long-path DOAS, see talk by Catalina Tsai, Tuesday, May 17th, 1:30 pm
Conclusions and Outlook
• UCLA MAX-DOAS measured spatial and temporal distribution of NO2, HCHO, and O4 (aerosol extinction) during CalNex
• Raw data clearly shows the change of trace gas levels with location and altitude in the LA basin
• Initial radiative transfer calculations result in reasonable boundary layer NO2 mixing ratios
• More detailed radiative transfer calculations are currently performed
• Retrieval of concentration distributions will be performed directly and through an adjoint 3D air quality model (see talk by Dan Chen, Tuesday May 17th 4:10 pm)
Acknowledgements
We would like to thank the NOAA and the California Air Resources Board (CARB) for providing funding, and the NASA Jet Propulsion Laboratory for providing access to the CLARS facility on Mt. Wilson
