Variability of CH 2 O during ICARTT: Implications for GOME/OMI
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005 Airborne measurements of spectral direct...
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Transcript of Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005 Airborne measurements of spectral direct...
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Airborne measurements of spectral direct aerosol radiative forcing - a new aerosol gradient method applied to data
collected in INTEX/ITCT/ICARTT, 2004
J. Redemann(1), P. Pilewskie(2), P. Russell(4), J. Livingston(3), S. Howard(1), J.
Pommier(1), B. Schmid(1), W. Gore(4), J. Eilers(4), M. Wendisch(5)
(1) Bay Area Environmental Research Institute, Sonoma, USA, (2) University of Colorado, Boulder, USA,
(3) SRI International, Menlo Park, USA, (4) NASA Ames Research Center, Moffett Field, USA,
(5) Institute for Tropospheric Research, Leipzig, Germany
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Contents
Description of the airborne instrumentation
used in this study
Methodology for an observationally-based
estimate of aerosol radiative effects
Comparison of results to ground-based
methods
Summary
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Jetstream-31 (J31) in ITCT-INTEXIntercontinental Transport and Chemical Transformation-Intercontinental
Chemical Transport Experiment
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Methodology for radiative effect studies from AOD gradientsMethodology for radiative effect studies from AOD gradients
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Methodology for studying aerosol radiative forcing from horizontal AOD gradients
Measure simultaneous change in spectral aerosol optical depth
(AATS-14) and spectral net irradiance (SSFR) →
Fnet/AOD = aerosol radiative forcing efficiency
Observationally-based estimate of aerosol radiative effect
Advantage over ground-based methods – quasi-instantaneous –
because of short horizontal distances
Need to check (and correct for) effects of changing solar zenith
angle and changing column water vapor contents
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
18.25 18.3 18.35 18.4
0.08
0.09
0.1ICARTT 21. 7.2004 JRF12-R21Jul04.AB 18.25-18.37 UT
Alti
tud
e (
km) GPS alt
Press alt
18.25 18.3 18.35 18.40
0.5
UT
AO
D s
cre
en
ed
0.3535
0.38
0.4526
0.4994
0.5194
0.6044
0.6751
0.7784
0.8645
1.0191
1.2413
1.5578
2.1393
18.25 18.3 18.35 18.4860
880
900
920
940
UT
Do
wn
-we
llin
g F
lux
350-700nm350-1700nm
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
J31 Flight 12, 21 July 2004
Slope yields measure Slope yields measure of forcing efficiency, of forcing efficiency, i.e. forcing=f(AOD)i.e. forcing=f(AOD)
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Full spectrum of Full spectrum of absoluteabsolute and and relativerelative forcing efficiency forcing efficiency
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
DateFlight Index
Case Index
incr./decr.Distance
[km] cos()
cos()/
07/17/04 JRF10 1 ↓ 0.016 (25.2%) 15.32 0.016 0.50% 0.31
07/21/04 JRF12 2 ↑ 0.134 (41.5%) 30.24 0.134 0.50% 0.04
07/22/04 JRF13 3 ↓ 0.069 (14.7%) 13.23 0.069 0.31% 0.05
07/23/04 JRF14 4 ↑ 0.201 (40.0%) 22.49 0.201 0.47% 0.02
07/23/04 JRF14 5 ↓ 0.070 (11.0%) 7.99 0.070 0.17% 0.02
07/23/04 JRF14 6 ↑ 0.039 (5.1%) 6.84 0.039 0.13% 0.03
07/29/04 JRF16 7 ↓ 0.143 (38.1%) 18.69 0.143 0.22% 0.02
07/29/04 JRF16 8 ↑ 0.378 (91.3%) 28.38 0.378 0.67% 0.02
07/29/04 JRF16 9 ↓ 0.177 (35.1%) 6.46 0.177 0.01% 0.00
08/02/04 JRF19 10 ↓ 0.245 (124.6%) 42.85 0.245 0.67% 0.03
08/02/04 JRF19 11 ↑ 0.219 (111.8%) 44.70 0.219 1.09% 0.05
08/03/04 JRF21 12 ↑ 0.095 (25.5%) 33.06 0.095 2.19% 0.23
08/07/04 JRF22 13 ↓ 0.02 (27.6%) 64.35 0.020 1.99% 1.00
08/08/04 JRF24 14 ↑ 0.036 (66.5%) 108.30 0.036 2.05% 0.58
Summary of 14 gradient casesSummary of 14 gradient cases
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
RR22-statistic – univariate vz. multivariate regressor model-statistic – univariate vz. multivariate regressor model
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
350-700nm net flux change for 10 ICARTT cases, assuming ssa=0.9-1, g=0.65-0.7
Conversion from instantaneous to 24h-average forcing efficiency
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Bush and Bush and Valero, 2003 Valero, 2003 ACE-AsiaACE-Asia
Previous methodologies for aerosol radiative forcing studiesPrevious methodologies for aerosol radiative forcing studies
Flu
x 40
0-70
0nm
F
lux
400-
700n
m
[Wm
[Wm
-2]]
GMT on Day 106
AOD (500nm)
Flu
x 40
0-70
0nm
F
lux
400-
700n
m
[Wm
[Wm
-2]]
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Comparison of 24h-avg. forcing efficiencies at the surface to previous work
Author 24h-ARFE @ surface
[Wm-2]
Spectral range region comments
This work 45.8±13.1
82.9±23.1
0.35 – 0.7m
0.35 – 1.67m
Gulf of Maine airborne
Kim et al., 2005 69 - 90 (non-dust)
91 - 104 (dust)
0.3 – 4.0m Korean peninsula + East China Sea
surface
Kim et al., 2005 55 - 76 0.3 – 4.0m East Asia surface
Meywerk and Ramanathan, 1999
48* (84 at noon) 0.4 – 0.7m East Asia, INDOEX-1
ship
Bush and Valero, 2002
38.5±4.0
72.2±5.5
0.4 – 0.7m
0.3 – 3.81m
Kaashidhoo, INDOEX
surface
Bush and Valero, 2003
42.2±4.8
73.0±9.6
0.4 – 0.7m
0.3 – 3.81m
Gosan,
ACE-Asia
surface
* Converted from reported value at solar noon
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Summary
1. In INTEX/ICARTT/ITCT, we observed a total of 14 horizontal AOD gradients, with 10 gradients well suited for an analysis using the gradient forcing method.
2. More than half of the AOD gradients (at a wavelength of 499 nm) were greater than 0.1 and extended over distances less than 40 km.
3. We found cos()/«1 && nm>0.05 to be necessary criteria for the gradient forcing method.
4. Within the 10 case studies we found a high variability in the derived instantaneous aerosol forcing efficiencies (forcing per unit optical depth) for the visible wavelength range (350-700nm), with a mean of -79.6Wm-2 and a standard deviation of 21.8Wm-2(27%).
5. The mean instantaneous forcing efficiency for the visible plus near-IR wavelength range (350-1670nm) was derived to be ‑135.3Wm-2 with a standard deviation of 36.0Wm-2(27%).
6. An analytical conversion of the instantaneous forcing efficiencies to 24h-average values based on a 2-stream approximation yielded -45.8±13.1Wm-2 (mean±std) for the visible and -82.9±23.1Wm-2 (mean±std) for the visible plus near-IR wavelength range, respectively.
Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005Redemann, ICARTT workshop, Durham, NH, Aug.9-12, 2005
Acknowledgements
Funding for the J-31 aircraft modifications through NASA RSP, TCP + SSP, and for ICARTT measurements and data analysis through NOAA ACCP are gratefully acknowledged.