SABER H 2 O RETRIEVAL: CURRENT STATUS AND FUTURE PLANS A.G. Feofilov 1,2, A.A. Kutepov 1,2, W.D. Pesnell 1, R.A. Goldberg 1 SABER Team Meeting, June 15,16, 2009, Hampton, VA 1 - NASA GSFC, Greenbelt, MD 2 – Catholic University of America, Washington, DC

Outline H 2 O non-LTE model Sensitivity study New validation approach Obstacles: “up-down” differences in radiance and temperature profiles Updated non-LTE model H 2 O VMR retrievals Conclusions and future plans

Non-LTE model of H 2 O radiative transitions V-V, V-T processes O1DO1D

Oxygen photochemical scheme [Yankovsky & Manuilova, 2006]

Quantum yield of O 2 (X,v=1) production per one act of O 3 photodissociation 

H 2 O radiance in 6.3µm band: LTE and NLTE Non-LTE LTE

Best case scenario H 2 O non-LTE model Pressure, temperature, VMRs of other constituents 6.6  m radiance Retrieved H 2 O VMR

Real life H 2 O non-LTE modelSensitivity study Comparisons with correlative H 2 O dataset 6.6  m radiance Set of parameters to be validated Retrieved H 2 O VMR Updated H 2 O non-LTE model Pressure, temperature, VMRs of atmospheric gases Validation, correction

Sensitivity study V-T rates V-V rates Net quantum yield  for O 2 (X,v=1) pumping from O 3 photolysis Temperature 5 test atmospheres (polar/midlatitude summer/winter + tropics) Varying the single rate, comparing the population of H 2 O(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 O 2 (X,v=1) production:OK Radiances, temperatures, other gases:???

“Up-down” differences in radiance and temperature Only downward scans were selected

Validating the H 2 O non-LTE model Selecting the correlative H 2 O dataset (ACE-FTS) Finding the simultaneous common volume measurements Using the ACE-FTS H 2 O VMR in forward radiance calculation with different sets of non-LTE model parameters 63 variants x 40 test atmospheres = 2520 runs Comparing the calculated SABER radiance with measured radiance Selecting the set that provide the minimal deviation of radiance in 60-85km altitude range

Updating the H 2 O non-LTE model Minimum  2 corresponds to: k V-V {H 2 O-O 2 }=1.2 x cm 3 s -1 k V-T {O 2 -O}=3.3 x cm 3 s -1 k V-T {H 2 O-M}=1.4 x current rates This is our updated H 2 O 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 system at ALOMAR (69.2°N)

Conclusions The methodology for non-LTE model validation has been developed. Gain switching effects have been found in temperature and H 2 O channels of SABER that resulted in re-analysis of Level 0/1 data performed by SABER team. The H 2 O non-LTE model has been validated for downward scans using the overlapping measurements performed by ACE-FTS and SABER. The H 2 O 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 H 2 O dataset (suggestions?). Implement updated non-LTE H 2 O model to SOPC Begin H 2 O VMR retrievals