Validation of AIRS Version 5 Ozone Retrievals AIRS Science Team - - PowerPoint PPT Presentation

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Validation of AIRS Version 5 Ozone Retrievals AIRS Science Team Meeting - March 28, 2007 Bill Irion - Jet Propulsion Laboratory Michael Newchurch - U. Alabama at Huntsville Sunmi Na - Pusan National University With thanks to Sung-Yung Lee,

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Validation of AIRS Version 5 Ozone Retrievals

Bill Irion - Jet Propulsion Laboratory Michael Newchurch - U. Alabama at Huntsville Sunmi Na - Pusan National University

With thanks to Sung-Yung Lee, Annmarie Eldering, Greg Osterman, John Blaisdell, Chris Barnet, Murty Divakarla, Jennifer Wei, Wallace McMillan, Steve Friedman and SHADOZ

AIRS Science Team Meeting - March 28, 2007

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Irion et al. AIRS Science Team Meeting 2 “Validation of AIRS V5 ozone” 3/28/2007

The problem with Version 4 ozone

Like ECMWF, V4 AIRS is too high in troposphere and too low in lower stratosphere; column OK to first order. AIRS/Sonde

Correction: matchup is within 100 km and 6 hrs.

ECMWF/Sonde Relative difgerences of AIRS & ECMWF vs ozonesondes

Standard deviations shown. Pressures

ffset for

clarity.

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Irion et al. AIRS Science Team Meeting 3 “Validation of AIRS V5 ozone” 3/28/2007

Simplified Version 4 algorithm for ozone

Regression Cloud Clearing

(Constrained)

Physical Retrieval

First guess

Profiles and columns

Damping parameter

(“noise propagation threshold”)

Training by ECMWF Cloud-cleared radiances L1B AIRS 3x3

bservation +

AMSU Channel selection Cloud-cleared radiances and uncertainties

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Irion et al. AIRS Science Team Meeting 4 “Validation of AIRS V5 ozone” 3/28/2007

Changes in algorithm from V4 to V5 ozone

Regression Cloud Clearing

(Constrained)

Physical Retrieval

First guess

Profiles and columns

Training by ECMWF Cloud-cleared radiances L1B AIRS 3x3

bservation +

AMSU Cloud-cleared radiances and uncertainties Decreased damping parameter Expanded channel selection

Climatology

First guess

SLIDE 5

Irion et al. AIRS Science Team Meeting 5 “Validation of AIRS V5 ozone” 3/28/2007

Channel selection changes

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Irion et al. AIRS Science Team Meeting 6 “Validation of AIRS V5 ozone” 3/28/2007

First O3 guess from climatology

Monthly zonal-mean climatology from combined ozonesonde, SAGE II and (at high

latitudes) MLS measurements and used as a priori for TOMS Version 8 retrievals.

McPeters, R. D., J. A. Logan, and G. J. Labow (2003), Ozone Climatological Profiles for Version 8 TOMS and SBUV Retrievals, Eos Trans. AGU, 87 (52), Fall Meet. Suppl., Abstract A21D-0998; McPeters, R.D., G. J. Labow, and J. A. Logan (2007), Ozone climatological profiles for satellite retrieval algorithms, J. Geophys. Res., 112, D05308, doi:10.1029/2005JD006823.

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Irion et al. AIRS Science Team Meeting 7 “Validation of AIRS V5 ozone” 3/28/2007

AIRS V4 and V5 total O3 comparison

November 5, 2004

V5 ozone decreases along tropics and high southern latitudes.

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Irion et al. AIRS Science Team Meeting 8 “Validation of AIRS V5 ozone” 3/28/2007

AIRS V4 and V5 comparison vs surface temperature

Large decreases in V5 in high latitude cold regions.

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Irion et al. AIRS Science Team Meeting 9 “Validation of AIRS V5 ozone” 3/28/2007

V3 V4 V5 total ozone comparisons with OMI

AIRS column ozone V3–>V4–>V5 show increasing agreement with OMI.

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Irion et al. AIRS Science Team Meeting 10 “Validation of AIRS V5 ozone” 3/28/2007

Zonal comparisons with OMI over Focus Days

Irion et al. AIRS Sci Team Meeting 10 “Validation of AIRS V5 ozone” 3/25/2007

Versions 4 and 5 AIRS

zone columns show

comparable biases w.r.t OMI, except bias substantially lowered in southern high latitudes. Need to compare to ground-based Dobson/Brewer measurements.

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Irion et al. AIRS Science Team Meeting 11 “Validation of AIRS V5 ozone” 3/28/2007

Average zonal bias over all Focus Days

AIRS Version 5 - OMI bias symmetric across equator.

AIRS positive bias also seen against Brewer/Dobson measurements - see Murty Divakarla’s presentation on Thursday

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Irion et al. AIRS Science Team Meeting 12 “Validation of AIRS V5 ozone” 3/28/2007

Sonde comparisons with and without regression

What does a climatology for the first guess do to the profile?

Retrievals using regression in red Retrievals using climatology in blue Same channels and damping for both

Generally improved agreement in mid-to-lower troposphere and lower

stratosphere. Mixed results

in upper troposphere.

V5 AIRS-Sonde Average Relative Bias Regression 1st guess Climatology 1st guess

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Irion et al. AIRS Science Team Meeting 13 “Validation of AIRS V5 ozone” 3/28/2007

Layer comparison with TES

Pre-release TES Version 3 retrievals courtesy of Greg Osterman and Annmarie Eldering

At high ozone mixing ratios @ 273 mb 50°-60°N AIRS V4 is high w.r.t. TES while V5 is low.

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Irion et al. AIRS Science Team Meeting 14 “Validation of AIRS V5 ozone” 3/28/2007

AIRS-TES bias at 273 mb coincident with lower tropopause height

TES and AIRS show increased ozone, but AIRS mixing ratios lower than TES. Would shifting first guess mixing ratio profile up or down with tropopause pressure change this? Need to carefully look at information content and spectral fits.

Irion et al. AIRS Sci Team Meeting 14 “Validation of AIRS V5 ozone” 3/25/2007

AIRS 1st guess at 273mb less suited to lowered tropopause?

O3 @ 273 mb Tropopause Pressure

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Irion et al. AIRS Science Team Meeting 15 “Validation of AIRS V5 ozone” 3/28/2007

Ideas to try for Version 6

Re-evaluate trapezoid levels?
Shift a priori mapping up or down with

retrieved tropopause pressure?

Based on tests deciding new damping

factor…

 Dynamically modify damping factor with skin temperature or tropopause height?

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Irion et al. AIRS Science Team Meeting 16 “Validation of AIRS V5 ozone” 3/28/2007

Thanks for your time!

We’ll be watching like…uh, you know.