Overview of Ozone Assimilation at NCEP

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Overview of Ozone Assimilation at NCEP

• Craig S. Long Shuntai Zhou
• Alvin Miller, Jeannette Wild,
• Lawrence Flynn, Shobha Kundragunta,
• Trevor Beck

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Current Status - Operations

• NCEP has been assimilating ozone in global model
  since 1997
• SBUV/2 NOAA-11, NOAA-14, NOAA-16
• Utilizes all 12 Umkehr layers
• Always assimilating just one satellite
• Benefits deduction of temperatures from channels
  sensitive to ozone.
• Longwave and shortwave radiation calculations
• UV forecasting
• Boundary conditions for AQ forecasts
• Production loss terms

3
Research

• Current operational NOAA-16 ozone products less
  accurate
• Switch to improved products could cause shock
  to model
• Assessing using both NOAA-16 and NOAA-17 ozone
  products to minimize shock
• Differences
• Impacts
• Transition from one to other
• NOAA-N (18) to be launched tomorrow (May 11)
• Need to transition from NOAA-16 to NOAA-18
• Begin using OMI ozone data products (total and
  profile)
• Assess impacts
• Work toward using total ozone in NRT
• Validation against ozonesonde, MLS, HIRDLS(?)

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Compare NOAA-16 and NOAA-17 SBUV/2 total and
profile O3

• NOAA-16 ascending (200 pm) vs NOAA-17 descending
  (1000 am)
• Time difference concern Movement of features
• Issues
• NOAA-16 operation ozone products are not best
  possible (calibration issues).
• NOAA-17 operation ozone products considered to be
  better of two.
• Inter-satellite differences should be lt 1 for
  TO3 and lt 5 for profile O3
• If ozone data differ too much GFS forecasts
  (thermal, dynamic fields) will be adversely
  impacted
• Appropriate weights must be determined,
  transition new data into GFS
• Match up observations to compare TO3 and profile
  O3 April 2005
• Within 1 Lat and 1 Lon
• Within 6 hours of each other
• About 130 match-ups per day
• Compare
• Total Ozone
• Profile Ozone
• Zonal Mean total and profile ozone
• Findings
• Total ozone NOAA-16 biased high (2) compared
  to NOAA-17
• Profile ozone differences do not vary with
  latitude or TO3 amount

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Orbits of NOAA-16 and NOAA-17 at 6 hr intervals
NOAA-16
NOAA-17
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Distribution of Total Ozone Differences
Within 2 Good
N16 gt N17
N17 gt N16
Larger Differences Need More Investigation
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NOAA-16 NOAA-17 Ozone Profile Comparisons
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OMI White NOAA-16 SBUV/2 - Red
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Day 338 2004
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OMI (24 hr) and GFS (12Z) Total Ozone
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Zonal Mean OMI GFS Total Ozone and Differences
OMI - GFS
5 DU