# Presentation: 195816

## Quantifying the science impact of instrument and missions designs: The ozone case

**Presented by Annmarie Eldering**
**Jet Propulsion Laboratory**
**California Institute of Technology**
- Aura Science Team Meeting
- October 29, 2008, Columbia, MD
- Contributors: Kevin Bowman, Meemong Lee, Zheng Qu, Mathew Yeates, Paul Hamer, Changsub Shim, John Worden
- JPL Clearance: N/A
- Last Modified:	5/27/2008

**National Aeronautics and Space Administration**

- www.nasa.gov** ****	****	****	****	****	****	****	****Jet Propulsion Laboratory****	****1****	****	****	****	****	****	****	****California Institute of Technology****	****	****	****	****	**** ****	****	****	****Pasadena, CA**

## Outline:

**Outline:**

- Motivtion: Measuring tropospheric pollution and air quality from space for GEO-CAPE
- Approach: Evaluation of possible approaches for ozone – focused on 825 hPa
- Conclusion
- There are instrument designs that can measure boundary layer ozone
- Use of uv/vis and high spectral resolution IR wavelengths together are needed to have low bias and low rms in 825 hPa ozone
- Narrowing IR window reduces sensitivity slightly
- GEOS-CHEM adjoint being used to quantify spatial and temporal relationships

## Exploiting OSSEs in the Mission Design Process

- Assimilation System

- Reference
- model
- fields

- Spatio-temporal
- sampling

- Instrument
- model

- Compare
- science
- metrics

- -

**Exploiting OSSEs in the Mission Design Process**

## Our experiments

**Our experiments**

- First phase focused on getting the right instrument sensitivity
- In second phase, will study mission design in more detail
- How we compare instrument & mission ideas:
-  Averaging kernels - are they sensitive in the region of interest?
-  Bias statistics - does the bias meet the requirements?
-  Maps of characteristics - will the spatial characteristics meet science goals?
-  Assimilate into model - assess ability to capture features of interest
-  Air quality forecast - test ideas against forecast skill

## Instrument designs evaluated

**Instrument designs evaluated**

- Using instrument designs in the realm of EOS capabilities.
- First plots focus on 6 combinations
- IR: 970-1080 cm-1
- UV/vis: 312-344 nm

**better**

**IR instruments**

**UV instruments**

## Simulated retrievals used to derive metrics

- OSSE: The ozone case

**Simulated retrievals used to derive metrics**

- Pdf of truth – retrieved
- Used to derive bias (mean value of pdf)
- - And rms (rms of distribution)

## Can we design an instrument to measure O3 to 5ppb at 825 hPa??

**Can we design an instrument to measure O3 to 5ppb at 825 hPa??**

**UV only**

**IR only**

## Combinations

**Combinations**

**Combo - high noise, low res**

**Combo - low noise, high res**

## Looking over the range of cases

**Looking over the range of cases**

- Lower spectral resolution IR instrument (used alone or in combination with UV/vis) have large bias and rms
-  Combined high-spectral resolution IR and uv/vis have low bias and rms

**bias**

**Rms**

## Comparing statistics: varying width of IR window

- UV only

- OSSE: The ozone case

- IR only

- UV + IR

- Narrow window
- 1043-1075

- wider window
- 970-1080

## Preparing to include 3.6 microns

- Need to perform radiative transfer calculations with both solar terms and thermal emission

- OSSE: The ozone case

## Verifying RT calculations in LIDORT

- OSSE: The ozone case

- Wavenumber (2778 cm-1 = 3.6 microns)

## Next Steps

-  Complete characterizations of 3.6 micron window
-  combine with UV/vis and IR
-  break down UV/vis into more specific bands (as Kelly Chance has outlined)

- OSSE: The ozone case

## Sensitivity between states or parameters

- The sensitivity between states can be calculated this way

- or that way

## Sensitivity Analysis: August 1st, 2006, sensitivity of NY ozone at 2:30 pm to its precursors  

- target region

- region of maximum sensitivity of boundary layer ozone in
- New  York to free tropospheric NOx

- The sensitivity of ozone in NY to free tropospheric NOx on 7/29/06 over Chicago is roughly half of the sensitivity to local NOx on 08/01/06

## How sensitive is ozone to local NOx?

- Boundary layer ozone is sensitive
- to local  NOx up to 3 days before

- Strong diurnal variation

- Highest sensitivity to
-  morning NOx

## Does knowing free tropospheric ozone improve boundary layer ozone prediction?

- The maximum sensitivity of ozone in NY to free tropospheric
- ozone is roughly .2 two days before.

**Does knowing free tropospheric ozone improve boundary layer ozone prediction?**

## Does knowing ozone today improveozone predictability for the following day?

- The sensitivity of ozone to ozone on 07/31/08 is about half of ozone on 08/01/08

## Conclusions

**Conclusions**

- It is critical to assess how effectively we can answer science questions with proposed mission
- We have toolset for quickly making a relative comparison of nadir viewing instruments designs for atmospheric composition
- Analysis suggests that boundary level ozone can be measured with UV/vis paired with high spectral resolution (0.06) IR with good noise characteristics
- Mission design (footprint size, frequency of measurements) to be evaluated in geostationary framework
- Measurement requirements must have more detail - a single number is not enough

## BACKUP

- OSSE: The ozone case

## Sampling the field + retrievals

**Sampling the field + retrievals**

- Can select orbit parameters and footprints, profiles then selected from field.
- Generate radiance, apply instrument function, and use linearized optimal estimation to generate simulated retrievals and error characterization (as well as averaging kernels).

- Orbiter-2D

## Comparing requirements to simulated performance

**Comparing requirements to simulated performance**

- Focus on the ozone requirements from the NRC white paper - JANZ
- All figures for 825 hPa

- Yellow box marks requirement

- Mean bias @ 825hPa for all simulated instruments

**Notes:**
Meant to give an overview of the different ways that we look at the data that we produce

## Where do we go from here?

**Where do we go from here?**

- Important science questions with societal impacts push us towards a new way of measuring ozone (GEO-CAPE)
- Improve air quality forecast skill
- Quantify impacts of pollution transport on regional to continental scales
- Monitor pollution emissions

- Current measurements fall short for these science goals
- Limited sensitivity to the lower layers of the atmosphere
- Observations at best twice per day

## Suggestions in the literature

**Suggestions in the literature**

- Simulations based on existing instrument configurations (TES+OMI) show that combination of UV/vis and IR should have better sensitivity to the boundary layer.

- We have extended this to test in wide range of atmospheric conditions, range of mission designs, and in end-use science applications

## Using OSSEs to more fully evaluate possible approaches (getting to the right design for the INSTRUMENT and the MISSION):

**Using OSSEs to more fully evaluate possible approaches (getting to the right design for the INSTRUMENT and the MISSION):**

## Measuring ozone from Space

**Measuring ozone from Space**

-  We have a long history of space based measurements
-  Many nadir viewing approaches, key for tropospheric measurements
- Total column ozone from SBUV, TOMS, and OMI based on uv/vis
-  GOME, SCIAMACHY, GOME-2
- Infrared sounder measurements
- AIRS total column
- TES - profiles with ability to differentiate the upper and lower troposphere
- IASI  - total columns and some thick layer vertical information