NRT Tropospheric and UTLS Ozone From OMIMLS

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NRT Tropospheric and UTLS Ozone From OMI/MLS

• Mark A. Olsen
• UMBC/GEST
• (At NASA/GSFC)
• olsen_at_code613-3.gsfc.nasa.gov
• Mark Schoeberl
• NASA/GSFC

START08 Workshop January 9, 2008
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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
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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).

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Comparison to Ziemke et al. Low Resolution TOR
June Trop. Column Ozone
June Ziemke et al. 2006
Monthly Mean

• Differences between this product and Ziemkes
  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.

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Case Comparison
6 day average
Air pollution transport?
Ziemke et al. 2006
80
0
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.

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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

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Time Synchronized Product
Tropospheric Column
Time Synchronized
Not Time Synchronized
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June 26, 2005
Mean Tropospheric Mixing Ratio
(From OMI column - Hi-Res Strat. Column)
Note Only 150E to 0
Tropopause Pressure Anomaly
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June 26, 2005
Mean Tropospheric Mixing Ratio
(From OMI column - Hi-Res Strat. Column)
Note Only 150E to 0
Tropopause Pressure Anomaly
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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???)

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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.

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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.

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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
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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.

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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.