1. NRT Tropospheric and UTLS Ozone From OMI/MLS
Mark A. Olsen
UMBC/GEST
(At NASA/GSFC)
Mark Schoeberl
NASA/GSFC
START08 Workshop
January 9, 2008

2. MLS Stratospheric O3 Column Map made from MLS measurement points shown
MLS and OMI Ozone Data
Both MLS and OMI are on the Aura platform providing concurrent stratospheric ozone (MLS) and total column ozone (OMI) measurements.
Level 2 (along-track) MLS data reported at 316, 215, 147, 100 hPa and higher.
Tropospheric column ozone given by OMI column - MLS column as by Ziemke et al. [2006].
Both provide daily global coverage (14 orbits) but longitudinal resolution of MLS is ~25° compared to ~0.25° for OMI.
Data between tracks is interpolated. Assumes no structure between tracks.
MLS Stratospheric O3 Column Map made from MLS measurement points shown

3. High Resolution Stratospheric Ozone Maps
To increase the effective resolution of the MLS data, forward trajectories mapped from the previous 6 days on to the orbit track. Theoretical Improvement: 6 days of trajectory mapping gives ~ 2-3° horizontal resolution.
High-resolution (1° x 1.25°) stratospheric ozone maps from MLS used with OMI column data to produce tropospheric ozone residual (TOR).

4. Comparison to Ziemke et al. Low Resolution TOR
June Trop. Column Ozone
June Ziemke et al. [2006]
Monthly Mean
Differences between this product and Ziemke’s TOR.
High resolution stratospheric column
Tropopause height is computed using PV in the extra tropics.
Even with monthly average, much more structure is seen using the high-res stratospheric column ozone.

5. Air pollution transport?
Case Comparison
6 day average
Air pollution transport?
Ziemke et al. 2006 80
ppbv
Mean tropospheric ozone mixing ratio used to eliminate topographic effects.
This day shows a high ozone region off the U. S. east coast.
The fold identification scheme (white) shows that this feature appears to be due to a stratospheric ozone fold, not pollution.
Daily ozone mean mixing ratios are usually high - much higher than the 6 day average.

6. Improved Time Synchronization
In the previous example the all data is assumed to asynoptic - measurement times are ignored. This can create problems with rapid moving events like folds.
Synoptic TOR
Use OMI L2G with measurement time stamp
Forward trajectories are grouped in time for target day (1/10th day resolution)
Tropopause is time interpolated from 6 hour DAS fields
Product has same zonal mean as asynoptic TOR
Fold TOR anomalies are greatly reduced

7. Time Synchronized Product
Tropospheric Column
Not Time Synchronized
Time Synchronized

8. June 26, 2005 Mean Tropospheric Mixing Ratio Tropopause Pressure
(From OMI column -
Hi-Res Strat. Column)
Note: Only 150°E to 0°
Tropopause
Pressure
Anomaly

9. June 26, 2005 Mean Tropospheric Mixing Ratio Tropopause Pressure
(From OMI column -
Hi-Res Strat. Column)
Note: Only 150°E to 0°
Tropopause
Pressure
Anomaly

10. More Mean Trop. Ozone and STE
June 28, 2005
July 1, 2005
Mean tropospheric ozone maxima tend to occur near locations of significant ozone STE.
However, not all STE maxima are associated with distinct maxima in the tropospheric ozone field. (Meteorology? Other???)

11. PV-Theta Mapping
Currently assessing new product that uses stratospheric ozone mapped to PV and theta in the extratropics rather than trajectory mapping. (Trajectory mapping still used in tropics).
PV and theta mapping from DAS and MLS ozone near target day
Evaluation of this product with sondes and comparisons to trajectory mapping only is currently incomplete.

12. Mean Tropospheric Mixing Ratio
PV-Theta Product
Mean Tropospheric Mixing Ratio
In NH, overall structure is similar although small differences exist.
Gradients near fronts appear to be more well-defined.
Greatest differences seen in SH.

13. Comparisons 215 hPa ozone; June 30, 2005 Tropics are “flat” Simple
Interpolation
SH not
so good!
PV-theta is used when LMS
depth exceeds 1.8 km

14. NRT Capability
MLS team plans to start producing NRT ozone for testing and interface purposes in Jan 08.
Online production stream in NRT in Feb 08.
How “Near to Real Time” is still uncertain. High resolution stratospheric ozone maps: less than 3 hours after availability of MLS data.
Currently checking availability of NRT OMI ozone data to produce high resolution tropospheric ozone in the same timeframe.

15. Products Overview
High resolution (1° x 1.25°) stratospheric ozone from MLS with trajectories.
Two levels below HIAPER ceiling (215 and 147 hPa).
Likely available with no more than two days lag (hopefully not more than one).
Tropospheric ozone column and mean mixing ratio at same resolution. Time frame dependant on OMI data availability.
Possibility of advecting stratospheric ozone field as passive tracer in model for forecasting purposes?
Best case scenario: Both mean tropospheric ozone and UTLS ozone can be used for forecasting/flight planning.
Worst case scenario: these can be used in post-flight analysis.