# Presentation: 533610

## Airborne sunphotometer measurements of aerosol in ACE-Asia and their comparisons to correlative measurements

- Beat Schmid et al.
- BAER Institute, Sonoma, CA
- Presented by
- Michael Box
- University of New South Wales, Sydney

**Notes:**
Title slide (I simplified the title)

## Co-authors

- Hsu, C, Welton, E, *GEST/UMBC, NASA Goddard Space Flight Center, Greenbelt, MD*
- Redemann, J, *Bay Area Environmental Research, Institute, Sonoma, CA *
- Livingston, J , *SRI, International, Menlo Park, CA*
- Russell P,  *NASA, Ames Research Institute, Moffett Field, CA*
- Wang, J, Flagan, R, Seinfeld, J, *California Institute of Technology, Pasadena, CA*
- Bates, D, *University of, Miami, Coral Gables, FL *
- Jonsson, H, *CIRPAS, Marina, CA*

**Notes:**
Co-authors (I only show those contributing to this talk, it makes the list more appealing)

## Make Observations to Improve Models of Aerosol Concentrations and Impacts.

- _[Slide 16](file:///ColoCollegeSeminarOct01#Slide 16)_

**Make Observations to Improve Models of Aerosol Concentrations and Impacts.**

**Notes:**
Obvious

## Satellite, Ship and Aircraft Platforms in ACE-Asia

**Notes:**
Obvious

## Groundbased observations 

- Lidars, aerosol chemistry & physics, optical properties, and radiation

## AATS-6

**AATS-6**

**AATS-14**

**NASA Ames Airborne Sunphotometers (AATS)**
**AOD (350-1558 nm) and H****2****O**

**C-130**

**Twin Otter**

**Notes:**
AATS-6 was flown on the C-130 and AATS-14 on the Twin Otter

## ACE-Asia C-130 Flight Tracks

**C-130**

**Ron Brown**

**Twin Otter**

**Notes:**
This may take a second to load. Don’t panic. All flight tracks of the C-130 in ACE-Asia. Shows coverage.

## Validation

**Validation of SeaWiFS AOD (Hsu et al. algo) with Aircraft**
**Sun photometer**

- Flying low over the ocean

**Notes:**
Low level legs were coordinated with many different satellite overpasses. Here we show one example. SeaWiFS using the algo by Hsu et al compared to AATS-14 on three different dates. 4/12 also has result from standard retrieval which is worse than Hsu et al. algo.

## AATS vertical profiles during ACE-Asia

- AATS-14
- AATS-6

**Notes:**
Shows location of all 26 AATS-14 and 26 AATS-6 vertical profiles

## Slide 10

**Notes:**
Vertical profile from AATS-14. 13 wavelengths from 353 to 1558 nm. Spectrum is monotonic (wavelength in order). Left is AOD which should decrease monotonically as you climb. Dashed lines are smoothed spline fits. A differentiation of these yields spectral extinction (right panel). Two aerosol layers and a clean layer are visible. Notice wavelength dependence. Large particles in the upper layer (dust) and low (sea salt) smaller particles elsewhere (pollution).

## In situ measurement of Extinction =

- Absorption
- Particle Soot Absorption Photometer (PSAP, =550nm)
- noisy (averaging)
- low RH
- Corrections
- scattering contribution
- inlet-cutoff (Da=8m)*
- correct to ambient RH*

- Scattering
- Nephelometers
-  = 450, 550, 700 nm, low RH
-  = 550 nm, RH=20,60,85%
- Corrections
- light source
- angular truncation (7°-170°)
- inlet-cutoff (Da=8m)*
- correct to ambient RH

- +

- *correction not required or done

**Notes:**
How to get extinction from in-situ measurements. No need to explain corrections.

## Closure between airborne sunphotomter and in-situ

**Notes:**
Comparison of in situ extinction and AOD with AATS-14. In the left panel AATS-14 AOD is added to the integrated extinction from in-situ so they start out at the same value.

## Closure between airborne sunphotomter and in-situ for 9 profiles

**Notes:**
Statistical summary of comparisons just mentioned for 9 profiles processed so far. Left layer AOD right extintion. Slopes are similar. In-situ underestimates extinction by 15%. Need to do more profiles and stratify data by aerosol type.

## In situ measurement of size distribution and computation of extinction

- Twin DMA, * D*=15-1000 nm (close to ambient RH)
- Aerodynamic Particle Sizer, *D*=0.5 - 8 m (drier than ambient RH),
- adjust to ambient RH
- compute extinction, needs *m*

- }

- needs composition

- Wang et al. 2002, JGR (submitted)

**Notes:**
Another way to get extinction from in-situ 

## Wang et al. subm. JGR, 2002

**Notes:**
Comparison of extinction from AATS-14, computed from size distribution (predicted) and also lidar on the R/V Brown. See next slide.

## Closure experiment with airborne sunphotometer and lidar on ship

**Ron Brown**

**Twin Otter**

- R/V Ron Braun

- CIRPAS Twin Otter

**Notes:**
We did 3 rendez-vous with Twin Otter and ship.

## Slide 17

**Notes:**
Vertical profile at ship location. Explanation see earlier.

## Slide 18

**Notes:**
Comparison of extinction profile over ship between AATS-14 and ship lidar (MPL). Red MPL extinction-to-backscatter ratio (Lidar Ratio) constant with altitude.  Blue implied lidar ratio to get agreement between AATS-14 and MPL extinction. Implied lidar ratio is not unrealistic.