Assimilation of Aura HIRDLS O3 profile data in the new NCEP GSI system

1
Assimilation of Aura HIRDLS O3 profile data in
the new NCEP GSI system

• Shuntai Zhou and Craig S. Long
• NOAA/NCEP/Climate Prediction Center
• Acknowledgements Russ Treadon (NCEP/EMC) and
  HIRDLS Team

2
Introduction

• Ozone assimilation in NCEP GFS
• Comparisons of HIRDLS ozone with MLS and SBUV/2
• HIRDLS ozone assimilation experiments
• control SBUV/2
• experiments SBUV/2 HIRDLS (100-1 hPa)

3
Ozone assimilation in NCEP GFS

• SBUV/2 ozone has been assimilated since 1997.
• Current operation NOAA-16 and -17 SBUV/2 version
  8
• Near future NOAA-18 SBUV/2, OMI, (MLS, HIRDLS,
  GOME-2)
• Future NPOESS OMPS
• New GSI system (Nov. 27, 2007)
• --- 3DVar with FOTO (First-Order Time
  extrapolation to Observation) option

4
Coincident observation comparison (lat/lon lt 1
deg., t lt 1.5 hr) 20060510
5
Coincident observation comparison (lat/lon lt 1
deg., t lt 1.5 hr) 20060510
HIRDLS ozone profile is similar to that of MLS,
but with finer vertical structure.
6
Vertical resolutions of the 64-layer GFS model,
SBUV/2 and HIRDLS
Data not assimilated
version 6
Data assimilated
7
12Z 3 hrs
Local day time Local nigh time
8
ppm
9
ppm
10
ppm
11
Total ozone difference
DU
12
Total ozone difference
DU
13
Total ozone difference
DU
14
Summary

• HIRDLS assimilated total ozone is less than
  SBUV/2, because HIRDLS partial column O3 (100-1
  hPa) has a low bias compared with SBUV/2 data.
• The low bias is not uniformly distributed
  vertically. In tropics, HIRDLS O3 profile show
  high bias in the lower stratosphere and low bias
  above.
• V003 data have reduced significantly the low bias
  in V002 data.