Irion et al., May 3, 2005 Page 1

Ozone validation for AIRS V4

Fredrick W. Irion, Michael R. GunsonJet Propulsion Laboratory

California Institute of Technology

Michael J. Newchurch University of Alabama at Huntsville

Sunmi NaPusan National University

AIRS Science Team MeetingMay 3, 2005

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Channel changes between v3 and v4

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AIRS-TOMS comparison between v3 and v4

AIRS - TOMSAIRS

% ± 1V3.0.8 V4.0.0

all regions9.51 ± 6.68(N = 56229)

1.65 ± 6.42(N = 62381)

> 99% land15.28 ± 7.69(N = 8349)

3.83 ± 9.09(N = 10096)

> 99% ocean7.91 ± 5.40(N = 41939)

0.99 ± 5.38(N = 46051)

Average AIRS O3 column difference from TOMS for Sept. 6, 2002 using Version 3.0.8 (left panel), and for Version 4.0.0 (right panel).

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Latitudinal AIRS-TOMS comparison

N.B. TOMS may be in absolute error by -2 to -4% around 50°N or S.

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AIRS-TOMS difference vsskin temperature for v3 and v4

(AIRS - TOMS) / AIRS vs. retrieved skin temperature for Sept. 6, 2002, 50°S - 50°N, using Version 3.0.8 (left panel), and for Version 4.0.0 (right panel).

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Focus day comparisons for

total column between

AIRS v4 and TOMS v8

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Brewer/Dobson comparisons

AIRS-Brewer comparisons over Arosa, Switzerland (left panel) and AIRS-Dobson comparisons over Boulder, CO and Mauna Loa, Hawaii (middle and right panels). The upper panels show total ozone retrievals, the middle panels show relative differences, and the bottom panels are histograms of the relative differences.

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Ozonesonde comparisons

Average (AIRS - Sonde) / Sonde profiles for V4.0.0 (left panel) and standard deviations (right panel). “N” refers to the number of AIRS retrievals. Several AIRS observations may be matched up to a single ozonesonde. AIRS observations are made with 2 hours and 100 km of ozonesonde launch. The San Cristobal observations uses a different type of sonde; the comparatively larger difference with AIRS is being investigated.

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Umkehr comparisonsN.B. Umkehr measurements are made over a range of solar zenith angles during the day.

N = number of AIRS comparisons (not days)

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Effect of changing trapezoid levels

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Conclusions• Average (AIRS-TOMS)/TOMS column differences vary

from -2 to +4% with a standard deviation of ~7%.• Dobson comparisons:

– show slightly higher columns over land in summer – sampling issue of tropospheric pollution?

• Ozonesonde comparisons:– AIRS 20-70% high in troposphere,– ~10% low in stratosphere.

• Umkehr comparisons:– positive bias in upper stratosphere/lower mesosphere

• Changes in trapezoid levels only make small changes in retrievals.