jae h. kim 1 , sunmi na 1 , and mike newchurch 2

Jae H. KimJae H. Kim11, Sunmi Na, Sunmi Na11, and Mike Newchurch, and Mike Newchurch22

1; Department of Atmospheric Science, Pusan Nat’l University1; Department of Atmospheric Science, Pusan Nat’l University2; Department of Atmospheric Science, University of Alabama, Huntsville2; Department of Atmospheric Science, University of Alabama, Huntsville

Evaluation of Tropospheric Ozone Derived from SEvaluation of Tropospheric Ozone Derived from Scan Angle Geometry Method (SAM)can Angle Geometry Method (SAM)

Weighting function of Diff

Tropospheric ozone scaling factor x Diff + 30DU (scaling factor = 6.7)

ProblemDiff can not directly apply to TOMS because measurements do not occurs simultaneous both at nadir and at high scan position.

hightotalnadirtotalDiff ,,

Scan-Angle MethodScan-Angle Method

Algorithm

- Orbital drift causes FOV at nadir position to overlap closely with the FOV at high scan position about two days later.

- Select a box with 15 degree longitude and 2 degree latitude

avghightotavgnadirtotavemonthlyDiff ,,,,

Scan-Angle MethodScan-Angle Method

How to apply to TOMS

-Diff is sum of retrieval efficiency difference and stratospheric ozone difference between two scan positions.

=> this method can only applicable where daily stratospheric ozone variation is relatively small and smooth => tropics.

Scan-Angle MethodScan-Angle Method

ADEOS-EP SAM

EP-only SAM

Improvement

SAM & Aerosol IndexSAM & Aerosol Index

The correlation between diff & AI

Comparison Comparison (Dec-Jan-Feb)(Dec-Jan-Feb)

SAMSAM

GEOS-CHEMGEOS-CHEM

CCDCCD

Fire CountsFire Counts

Carbon MonoxideCarbon Monoxide

Comparison Comparison (Mar-Apr-May)(Mar-Apr-May)

SAMSAM

GEOS-CHEMGEOS-CHEM

CCDCCD

Fire CountsFire Counts

Carbon MonoxideCarbon Monoxide

Comparison Comparison (Jun-Jul-Aug)(Jun-Jul-Aug)

SAMSAM

GEOS-CHEMGEOS-CHEM

CCDCCD

Fire CountsFire Counts

Carbon MonoxideCarbon Monoxide

Comparison Comparison (Sep-Oct-Nov)(Sep-Oct-Nov)

Carbon MonoxideCarbon Monoxide

Fire CountsFire Counts

CCDCCD

GEOS-CHEMGEOS-CHEM

SAMSAM

ComparisonComparison

Abidjan (5ºN 4 º W)

ComparisonComparison

Madras (13 º N 80 º E)

ComparisonComparison

Bangkok (14 º N 101 º E)

EvaluationEvaluation

The correlation between the SAM results and CO is higher for the December-February period corresponding to the northern burning season.

The correlation between the CCD results and CO is higher during the October-November period corresponding to the southern burning season.

The correlation between the SAM and CCD results shows a disagreement for December-February period, the northern burning season.

• Tropospheric ozone signal can be detected by using TOMS error depending on scan angle geometery.

• Number of data sampling give an improvement for ozone derivation from SAM => Multiangle Scanning Spectrometer may be able to provide tropospheric ozone derivation with a better temporal and spatial resolution.

• The SAM observes the elevated ozone over northern equatorial Africa during the northern burning season (Dec-Feb), which is consistent with fire counts and CO measurements. However, the feature is not reported by the CCD results. On the contrary, the CCD shows elevated ozone always over southern Africa.

• The seasonal variation of ozone distribution from SAM agrees well with those from MOZAIC and GEOS-CHEM at Abidjan, Madras, and Bangkok. However, not from CCD.

ConclusionsConclusions