# Presentation: 357540

## Improvements in Calibration and Retrievals for OH and HO2 

- H. Pickett, T. Canty, V. Perun, W. Read, A. Lambert, N. Livesey
- Jet Propulsion Laboratory, California Institute of Technology

- Aura Science Team Meeting, 9/06

## THz Level 1b Calibration Changes

|  | OLD (V1.5X) | NEW (V2.1) |
| --- | --- | --- |
| Phase 1: Fit DLLO and Gain for orbit sized time intervals.
Output has T(A) units, but Tsys not yet removed. (DLLO is ~300K for 10% LLO power change.) | Divide day into 14 intervals. When intervals are not synchronized with LLO relock there are large changes in radiance at the interval boundary. Gain is assumed constant for each interval. 
(2 parameter fit for each channel.) | Divide day into intervals of 230-240 MAFs with LLO relock at interval boundary. Last two intervals overlap but are both full length.  Gain has sin(Φ) and cos(Φ) dependence with Φ = 2π / (number of MAFs). 
(4 parameter fit for each channel.)  |
| Phase 2: Remove zeros. Output is fully calibrated radiance. | Use both cold and target views to determine zeros by quadratic interpolation similar to GHz procedure.
Using target views improves precision, but gain errors have effect for cold views as well as warm views.  | Use only cold views to determine zeros by quadratic interpolation.
Precision is reduced, but errors in gain have little effect for views with ~0K and 4/3 the effect for continuum [T(A) = ~160K vs. 240K for target].  |
| Fault recognition | Test (1) LLO power and (2) presence of cold view at specified angle | Test (1) LLO power, (2) presence of cold view, (3) moon in cold view, (4) absolute Yaw angle less than 1 degree, and (5) radiance in range .  |

- Aura Science Team Meeting, 9/06

## Channel 1

- Channel 25

- Aura Science Team Meeting, 9/06

## THz Level 2gp Retrieval Changes

|  | OLD (V1.5X) | NEW (V2.1) |
| --- | --- | --- |
| Vertical Resolution | 3 / decade above 0.1 hPa (64 km) and
6 / decade below. OH Profiles frequently had negative excursions far in excess of precision. | Uniformly 6 / decade.  OH profiles are smoother and have fewer negative excursions.  Retrieval needed extra degrees of freedom to fit radiances. |
| Convergence limits | Iteration limit was 4.  Not all fits converged. | Iteration limit set to 8. Many more fits converge. |
| Fault recognition | Did not always recognize bad radiances | Code and configuration fixed so that bad radiances are handled better. |

- Aura Science Team Meeting, 9/06

## Slide 5

- Aura Science Team Meeting, 9/06

## HO2 Changes

|  | OLD (V1.5X) | NEW (V2.1) |
| --- | --- | --- |
| Vertical Resolution | 3 / decade above 0.1 hPa (46 km) and 6 / decade below. HO2 profiles are jagged. Negative precision flag on above 0.1 hPa | Resolution unchanged. Tikhonov smoothing to 5 km FWHM in vertical and 3 profiles (4.5 degrees) FWHM in horizontal. Need to implement negative precision flag that works correctly in presence of smoothing |

- Aura Science Team Meeting, 9/06

## HOx for Sept 23, 2004 

- Mdl_C is JPL02 kinetics, Smith & Stewart O+OH, and a 20% increase in OH+HO2
- OH is zonal average over lat = [24,44]
- HO2 is zonal average over lat =  [-60,60] for 2 days

- Aura Science Team Meeting, 9/06

## HOx for Sept 20, 2005 

- Mdl_C is JPL02 kinetics, Smith & Stewart O+OH, and a 20% increase in OH+HO2
- OH is zonal average over lat = [24,44]
- HO2 is zonal average over lat =  [-60,60] for 2 days

- Aura Science Team Meeting, 9/06