# Presentation: 804897

## Developments Of ‘OPTRAN’ AndPreparation For Its Use ToHigh 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)**

## OPTRAN 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**

## New 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**

## Weight to Generate Trans Coef 

**Impossible to transfer all information from 300 equations to one**
**Weight enables to transfer the essential information.**

**Trans**

**ln Abs Coef****Error**

**Trans**
**Error**

_**NOAA/HIRS Ch 3**_

**Weight**

## Atmospheric Predictors

**Atmospheric Predictors**

**17 atmospheric predictors**
**2 new predictors**
**Q/T****2**** for wet continuum**
**P****1/4**** for ozone**

## Choice 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**

## LBL 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**

## Dependent ComparisonNOAA16/HIRS3

**Dependent Comparison****NOAA16/HIRS3**

**S.D.**

**Bias**

## Independent ComparisonNOAA16/HIRS3

**Independent Comparison****NOAA16/HIRS3**

**S.D.**

**Bias**

## Dependent ComparisonAqua/AIRS

**Dependent Comparison****Aqua/AIRS**

**S.D.**

**Bias**

## Independent ComparisonAqua/AIRS

**Independent Comparison****Aqua/AIRS**

**S.D.**

**Bias**

## Design 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/HIRS2+MSU, NOAA15/AMSU, NOAA16/HIRS3+AMSU**
**	****	****	**

## SSI with New OPTRAN

**00z Oct 1, 2002**

**00z Oct 8, 2002**

## NOAA16/HIRS3   Tb Comparisons

**NOAA16/HIRS3   Tb Comparisons**

**No Bias Correction**
**21z Oct 7, 2002****     to****21z Nov 7, 2002**
**Global (90S - 90N)**
**No use for****Ch 1,16,17,18 & 19**
**# of samples**

**S.D. Tb error**

**Mean Tb error**

## NOAA16/HIRS
Tb Scan Angle Comp

21z Oct 8 - 21z Nov 7

Red - New OPTRAN
Blue - Orig OPTRAN

**Tb Scan Angle Comp**
**21z Oct 8 - 21z Nov 7**
**Red - New OPTRAN**
**Blue - Orig OPTRAN**

**Ch8 - SD**

**Ch2 - SD**

**Ch2 - Mean**

**Ch8 - Mean**

## NOAA16/HIRS3 Ch.8

**CNTL RUN -- OLD OPTRAN**

**TEST RUN -- NEW OPTRAN**

## NOAA16/HIRS3   Tb Comparisons

**NOAA16/HIRS3   Tb Comparisons**

**After Bias Cor**
**21z Oct 7, 2002****     to****21z Nov 7, 2002**
**Global (90S - 90N)**
**No use for****Ch 1,16,17,18 & 19**
**# of samples**

**S.D. Tb error**

**Mean Tb error**

## NOAA16/AMSU   Tb Comparisons

**NOAA16/AMSU   Tb Comparisons**

**No Bias Correction**
**21z Oct 7, 2002****     to****21z Nov 7, 2002**
**Global (90S - 90N)**
**No use for****Ch 12, 13 and 14**
**# of samples**

**S.D. Tb error**

**Mean Tb error**

## NOAA16/AMSU

**Tb Scan Angle Comp**
**21z Oct 8 - 21z Nov 7**
**Red - New OPTRAN**
**Blue - Orig OPTRAN**

## NOAA16/AMSU   Tb Comparisons

**NOAA16/AMSU   Tb Comparisons**

**After Bias Cor**
**21z Oct 7, 2002****     to****21z Nov 7, 2002**
**Global (90S - 90N)**
**No use for****Ch 12, 13 and 14**
**# of samples**

**S.D. Tb error**

**Mean Tb error**

## Impacts on AnalysisMean Diff (8 - 15 Oct)

**Impacts on Analysis****Mean Diff (8 - 15 Oct)**

**T 500hPa**

**T 200hPa**

**TPW**

**O3MR 10hPa**

## Impact on AnalysisZonal Mean Diff (8 - 15 Oct)

## Impacts of New OPTRAN on Global Fcst 

**Impacts of New OPTRAN on Global Fcst **

**NH**
**1000 Z**

**SH**
**1000 Z**

**SH**
**500 Z**

**NH**
**500 Z**

## Impacts of New OPTRAN on Global Fcst

**Impacts of New OPTRAN on Global Fcst**

**Trop**
**850 Vct Wind**

**Trop**
**200 Vct Wind**

## AIRS 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)**

## AIRS Real-time Tb Comparison(Preliminary, 20 - 24 Feb)

**S.D.**

**Num**

**Bias**

## Conclusion

**Equations and coefficients in OPTRAN are reduced significantly --> 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**