Title: Developments Of OPTRAN And Preparation For Its Use To High Spectral Resolution Sounder
1Developments Of OPTRAN AndPreparation For Its
Use ToHigh Spectral Resolution Sounder
- Yoshihiko Tahara (UCAR, JMA, NCEP)
- Paul van Delst (CIMSS, NCEP)
- John C. Derber (NCEP)
- Larry M. McMillin (NESDIS)
- Xiaozhen Xiong (NESDIS)
- Thomas J. Kleespies (NESDIS)
2OPTRAN Meets Hardship
- Absorption coefficient prediction
- A large number of equations
- 2,140,200 equations for AIRS 2378 channels
- Hard to validate all
- Numerous coefficients
- 98 Mbytes for AIRS 2378 channels
- A lot of computer resources
- Hard to introduce high spectral resolution
sensors - Hard to keep updated
- Hard to be more developed
- More absorbers, more predictors, more layers, etc
3New Prediction Form
- Coefficients traced over 300 layers by
polynomials - Equations reduced by a factor of 1/300
- Coefficients reduced more than 95
- 1 additional atmospheric predictor introduced
- No vertical interpolation
4Weight to Generate Trans Coef
- Impossible to transfer all information from 300
equations to one - Weight enables to transfer the essential
information.
NOAA/HIRS Ch 3
ln Abs CoefError
Trans Error
Weight
Trans
5Atmospheric Predictors
- 17 atmospheric predictors
- 2 new predictors
- Q/T2 for wet continuum
- P1/4 for ozone
6Choice of Predictors
- 21778 predictor set possibilities for each gas
and channel - Transmittance calculation error is monitored to
select the best. - Stability index is introduced to monitor
computation stability
Validated best predictors
Less than 24 hrs to find best sets for 500 chs
using 10 CPUs on IBM SP4
7LBL Transmittances
- UMBC atmospheric profiles (for generating
coefficients) - 48 profiles
- 101 levels (0.005 -- 1100 hPa)
- CIMSS atmospheric profiles (for independent
verification) - 32 profiles
- 101 levels (0.005 -- 1100 hPa)
- Transmittances (Infrared)
- LBLRTM Ver 6.12 with HITRAN2000 AER updates
- 6 angles for each atmos profile
- Sep 2002 AIRS SRFs for AIRS
- Central frequencies generated based upon the SRFs
8Dependent ComparisonNOAA16/HIRS3
S.D.
Bias
9Independent ComparisonNOAA16/HIRS3
S.D.
Bias
10Dependent ComparisonAqua/AIRS
S.D.
Bias
11Independent ComparisonAqua/AIRS
S.D.
Bias
12Design of NWP Experiment
- Start up Oct 1st -- Oct 7th, 2002
- Experiment Oct 8th -- Nov 7th, 2002
- 8-day forecast Every 00 UTC initial in the
experimental period - Control run OPTRAN used in the NCEP
operational NWP system - Test run New OPTRAN with recalculated bias
correction tables - Trans coef CIMSS 45-layer profile set is used
for BOTH OPTRAN to generate transmittance
coefficients - NWP system NCEP global system implemented in
Oct, 2002 - Resolution reduced to T170L42
- Sat. channels The same as the operational
except too high peak channels NOAA14/HIRS2MSU,
NOAA15/AMSU, NOAA16/HIRS3AMSU -
13SSI with New OPTRAN
00z Oct 1, 2002
00z Oct 8, 2002
14NOAA16/HIRS3 Tb Comparisons
- No Bias Correction
- 21z Oct 7, 2002 to21z Nov 7, 2002
- Global (90S - 90N)
- No use forCh 1,16,17,18 19
- of samples
S.D. Tb error
Mean Tb error
15- NOAA16/HIRS
- Tb Scan Angle Comp
- 21z Oct 8 - 21z Nov 7
- Red - New OPTRAN
- Blue - Orig OPTRAN
Ch8 - SD
Ch8 - Mean
Ch2 - SD
Ch2 - Mean
16NOAA16/HIRS3 Ch.8
CNTL RUN -- OLD OPTRAN
TEST RUN -- NEW OPTRAN
17NOAA16/HIRS3 Tb Comparisons
- After Bias Cor
- 21z Oct 7, 2002 to21z Nov 7, 2002
- Global (90S - 90N)
- No use forCh 1,16,17,18 19
- of samples
S.D. Tb error
Mean Tb error
18NOAA16/AMSU Tb Comparisons
- No Bias Correction
- 21z Oct 7, 2002 to21z Nov 7, 2002
- Global (90S - 90N)
- No use forCh 12, 13 and 14
- of samples
S.D. Tb error
Mean Tb error
19NOAA16/AMSU Tb Scan Angle Comp 21z Oct 8 - 21z
Nov 7 Red - New OPTRAN Blue - Orig OPTRAN
20NOAA16/AMSU Tb Comparisons
- After Bias Cor
- 21z Oct 7, 2002 to21z Nov 7, 2002
- Global (90S - 90N)
- No use forCh 12, 13 and 14
- of samples
S.D. Tb error
Mean Tb error
21Impacts on AnalysisMean Diff (8 - 15 Oct)
T 500hPa
TPW
T 200hPa
O3MR 10hPa
22Impact on AnalysisZonal Mean Diff (8 - 15 Oct)
23Impacts of New OPTRAN on Global Fcst
NH 1000 Z
SH 1000 Z
SH 500 Z
NH 500 Z
24Impacts of New OPTRAN on Global Fcst
Trop 850 Vct Wind
Trop 200 Vct Wind
25AIRS Real-time Tb Comparisons(Preliminary, 20 -
24 Feb)
Ch 28 656.1 SD 0.76 MN 0.16
Ch 253 722.1 SD 0.39 MN 0.29 (clr sky)
Ch 1082 1036.5 SD 0.63 MN 0.33 (clr sky)
Ch 1756 1524.4 SD 1.22 MN 0.44 (clr sky)
26AIRS Real-time Tb Comparison(Preliminary, 20 -
24 Feb)
S.D.
Bias
Num
27Conclusion
- Equations and coefficients in OPTRAN are reduced
significantly --gt New sensors are welcome. - Offline validation shows new OPTRAN has
- Around 0.1 deg or less SDs for most channels
- 0.2 0.3 deg SDs for ozone channels
- NWP experiment shows new OPTRAN has
- Better Tb calculation for ozone channels
- Small SD increase in no bias correction Tbs for
some IR chs,and small SD decrease for some MW
chs - Angle dependent variation for low peak IR chs
- Same SDs for bias corrected Tbs
- Some consistent changes in analysis fields
- Positive impact on SH forecast, neutral on NH and
Trop - Good results from AIRS preliminary study