Post on 28-Jan-2016
description
transcript
Xiong Liu (xliu@cfa.harvard.edu)
Harvard-Smithsonian Center for Astrophysics
K. Chance, C.E. Sioris, R.J.D. Spurr, T.P. Kurosu, R.V. Martin, M. Fu, J.A. Logan, I. Megretskaia, P.I. Palmer, M.J.
Newchurch, D.J. Jacob, R. Chatfield, P.K. Bhartia
2nd GEOS-HCEM Users’ Meeting
Harvard University, April 4, 2005
Cross-Evaluation of GEOS-CHEM and GOME
Tropospheric Column Ozone
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Outline
GOME Tropospheric Column Ozone Retrieval
Tropopause, Sampling GEOS-CHEM data
GOME vs. GEOS-CHEM Tropospheric Column Ozone
Evaluation of both GOME and GEOS-CHEM with MOZAIC and Ozonesonde Observations
Summary
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GOME Tropospheric Column Ozone Retrieval
Ozone profile and tropospheric ozone: directly retrieved from GOME Ultraviolet radiance spectra with the LIDORT model
Rodgers’ optimal estimation with v8-TOMS climatological a priori Wavelength range: 289-307 nm, 326-340 nm Perform extensive wavelength and radiometric calibrations and improve
radiative transfer simulations to reduce the fitting precision to < 0.2% NCEP/NCAR tropopause: divide the troposphere and stratosphere Spatial resolution: 960×80 km2 ; Global coverage: 3 days in the equator Retrieval characterization:
A priori influence: ~15% in the tropics to ~50% at high-latitudes Precision: ~6% (1.5 DU) in the tropics to ~12% (3 DU) at high-
latitudes Smoothing error: ~12% (3 DU) in the tropics to ~25% (6 DU) at
high-latitudes
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Tropopause, GEOS-CHEM Sampling and Adjustment NCEP tropopause: thermal
tropopause ECMWF dynamic tropopause: 2.5
pvu Global tropopause: minimum
between NCEP and dynamic tropopause
GEOS-CHEM: v6.13, 2.5º × 2 º Different spatial and vertical
resolutions GEOS-CHEM Adjustment
Sampling GEOS-CHEM data
Apply GOME retrieval averaging kernels
Integrate to the same tropopause
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GOME vs. GEOS-CHEM
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GOME vs. GEOS-CHEM (09/96-08/97)
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GOME vs. GEOS-CHEM
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GOME vs. GEOS-CHEM
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GOME vs. GEOS-CHEM Poor correlation:
central America, equatorial remote Pacific, tropical North Africa and Atlantic, North high latitudes
Large positive bias of 6-12 DU: central America, tropical North Africa, Southeast Asia
Comparisons with MOZAIC/ozonesonde: use the same tropopause and surface pressure with correction
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Comparison vs. Mozaic/Ozonesonde-Central America
GOME GEOS-CHEM
R Bias R Bias
San C 0.67 2.5 0.87 8.8
Bogota 0.38 2.8 0.0 8.3
Parama. 0.42 -6.0 0.33 0.6
Caracas 0.57 0.8 0.54 8.7
Puerto R 0.20 3.2 0.40 11.1
Mexico 0.85 -1.6 -0.2 6.9
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Comparison vs. Mozaic/Ozonesonde-Southeast Asia
GOME GEOS-CHEM
R Bias R Bias
Kuala L 0.64 2.5 0.83 7.3
Madras 0.88 -2.8 0.89 7.5
Bangkok 0.83 -2.4 0.94 7.2
Hanoi 0.84 -1.0 0.93 9.6
Naha 0.62 2.8 0.86 7.5
Delhi 0.66 -4.5 0.74 6.6
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Comparison vs. Mozaic/Ozonesonde-N. Africa & Mid East
GOME GEOS-CHEM
R Bias R Bias
Lagos+ 0.16 -3.1 0.92 -1.1
Dakar -0.37 -3.8 0.81 5.2
Dubai+ 0.73 -5.1 0.86 5.3
Tela viv 0.96 -1.5 0.94 1.4
Teheran 0.95 -0.7 0.94 5.4
Ankara 0.95 -0.2 0.92 0.7
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Comparison vs. Mozaic/Ozonesonde-North Europe
GOME GEOS-CHEM
R Bias R Bias
Vienna 0.80 0.2 0.94 0.5
Frank. 0.42 1.5 0.94 0.8
Brussels 0.34 -0.4 0.89 -1.2
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Summary
The overall structures in Tropospheric Column Ozone (TCO) are similar: wave-1 pattern in the tropics and nearly zonally-bands of high TCO at ~30ºN/S. The seasonality is similar at most regions.
GEOS-CHEM TCO is higher than GOME TCO by ~6-12 DU at some tropical regions (e.g., central America, North Africa and North Atlantic, and southeast Asia). Poor correlation occurs at some tropical regions and northern high-latitudes.
Comparisons with MOZAIC and ozonesonde observations show that most of the positive biases over central America and Southeast Asia are from GOES-CHEM TCO except at Paramaribo and Delhi.
GEOS-CHEM better captures the seasonality at North Africa, Dubai, northern Europe, and slightly better at southeast Asia.
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