SABER H2O RETRIEVAL: CURRENT STATUS AND FUTURE PLANS

A.G. Feofilov1,2, A.A. Kutepov1,2,

W.D. Pesnell1, R.A. Goldberg1

SABER Team Meeting, June 15,16, 2009, Hampton, VA

1 - NASA GSFC, Greenbelt, MD2 – Catholic University of America, Washington, DC

Outline

• H2O non-LTE model

• Sensitivity study

• New validation approach

• Obstacles: “up-down” differences in radiance and temperature profiles

• Updated non-LTE model

• H2O VMR retrievals

• Conclusions and future plans

Non-LTE model of H2O

radiative transitionsV-V, V-T processes

O1D

Oxygen photochemical scheme

[Yankovsky & Manuilova, 2006]

Quantum yield of O2(X,v=1) production per one act of O3 photodissociation

H2O radiance in 6.3µm band: LTE and NLTE

Non-LTE

LTE

Best case scenario

H2O non-LTE model Pressure, temperature,VMRs of other constituents

6.6 m radiance

Retrieved H2O VMR

Real life

H2O non-LTE model Sensitivity study

Comparisons with correlative H2O dataset

6.6 m radiance

Set of parameters to be validated

Retrieved H2O VMR

Updated H2O non-LTE model

Pressure, temperature,VMRs of atmospheric gases

Validation,correction

Validation,correction

Sensitivity study

• V-T rates• V-V rates• Net quantum yield for O2(X,v=1) pumping from O3 photolysis• Temperature

• 5 test atmospheres (polar/midlatitude summer/winter + tropics)• Varying the single rate, comparing the population of H2O(010) to its reference value• Selecting the most important rates and processes

Sensitivity study for midlatitude winter case

Ready for non-LTE model validation?

• Three most important V-V and V-T rates: OK

• Updated quantum yield for O2(X,v=1) production: OK

• Radiances, temperatures, other gases: ???

“Up-down” differences in radiance and temperature

Only downward scans were selected

Validating the H2O non-LTE model

Selecting the correlative H2O dataset (ACE-FTS)

Finding the simultaneous common volume measurements

Using the ACE-FTS H2O VMRin forward radiance calculation

with different sets of non-LTE model parameters63 variants x 40 test atmospheres = 2520 runs

Comparing the calculated SABERradiance with measured radiance

Selecting the set that provide the minimal deviation of radiance

in 60-85km altitude range

Updating the H2O non-LTE model

Minimum 2 corresponds to:

kV-V{H2O-O2}=1.2 x 10-12 cm3s-1

kV-T{O2-O}=3.3 x 10-12 cm3s-1

kV-T{H2O-M}=1.4 x current rates

This is our updated H2O model.It might change after T,P, and radiances are corrected.

Retrievals with updated non-LTE model

Comparisons in numbers

MLS, HALOE, and WVMS at Lauder (45°S) and Mauna Loa (19.5°N)

Microwave monitoring systemat ALOMAR (69.2°N)

Conclusions

• The methodology for non-LTE model validationhas been developed.

• Gain switching effects have been found in temperature and H2O channels of SABER that resulted in re-analysisof Level 0/1 data performed by SABER team.

• The H2O non-LTE model has been validated for downward scans using the overlapping measurements performed by ACE-FTS and SABER.

• The H2O VMRs retrieved with the updated non-LTE model are in agreement with other measurements.

Future plans

• Obtain new T, P, and radiances with gain switching issues fixed.

• Re-do the non-LTE model update using the 2 minimum search approach. Use ACE-FTS data possibly supplemented by other H2O dataset (suggestions?).

• Implement updated non-LTE H2O model to SOPC

• Begin H2O VMR retrievals