# Presentation: 632615

## How well can we measure the vertical profile of tropospheric aerosol extinction?

**Siberian smoke over Oklahoma as seen from Twin Otter on May 27, 2003**
- Photo courtesy of Roy Woods

**How well can we measure the vertical profile of tropospheric aerosol extinction?**
- B. Schmid, R. Ferrare, C. Flynn, R. Elleman, D. Covert, A. Strawa, E. Welton, D. Turner,
- H. Jonsson, J. Redemann, J. Eilers, K. Ricci, A. Hallar, M. Clayton, J. Michalsky,
- A. Smirnov, B. Holben, J. Barnard

- Paper submitted to AIOP JGR special issue, Feb 3, 2005

## ARM Aerosol IOP – May 2003

**Focus on data obtained in vertical profiles over SGP CF**
**Altitudes: ~90 – 5600 m **

**CIRPAS Twin Otter**

**ARM Aerosol IOP – May 2003**

## How do we measure the vertical profile of aerosol extinction?

- Photo courtesy Yin-Nan Lee, BNL

**How do we measure the vertical profile of aerosol extinction?**
**unaltered aerosol ****	****@ ambient concentration **
**	****	****	****@ thermodynamic state**

**Airborne:**
** ****Nephelometer+PSAP**
** ****Cavity-Ring-Down (Cadenza) **
** ****Sunphotometry (AATS-14)**

**Ground based:**
** ****Raman Lidar (CARL)**
** ****MPLNET**
** ****MPLARM**** **

## NASA Ames Airborne Tracking SunphotometerAATS-14: 354-2139 nmAerosol Optical Depth and H2O columnAerosol Extinction and H2O density in suitable profiles

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## Conclusions: Current Effort

- Looking at results from 6 field campaigns, airborne in-situ measurements of extinction tend to be biased slightly low (mean of 17%) when compared to airborne sunphotometer extinction.
- Lidar measurements of extinction from 6 field campaigns show no or positive biases.
- Systematic errors in measuring ambient aerosol extinction profiles with current state-of-the-art instrumentation are 15-20% in the visible. Random errors are considerably larger.
- Raman Lidar measurements in AIOP biased high (29 Mm-1  UV 54%). We expect better agreement from a “healthier” Raman lidar.

## Summary of Achievements: Current ARM ST EffortVertically resolved aerosol optical properties over the ARM SGP sitePI: Schmid, Co-I: Pilewskie, Strawa, Russell, Bergstrom, Redemann

- PI instrumental in planning and executing AIOP. Platform Scientist Twin Otter.
- Twin Otter data used in 10 publications for AIOP JGR special issue.
- PI and Co-I’s have contributed directly to 7 of the 10 publications:

**Aerosol Indirect Effect Studies at Southern Great Plains during the May 2003 Intensive Operations Period. **Feingold et al. (with Pilewskie).
**Comparison of methods for deriving aerosol asymmetry parameter.  **Andrews et al. (with Schmid)
**Evaluation of Daytime Measurements of Aerosols and Water Vapor made by an Operational Raman Lidar over the Southern Great Plains. **Ferrare et al. (with Schmid, Redemann),
**How well can we measure the vertical profile of aerosol extinction? **Schmid et al. (with Strawa, Redemann)
**A comparison of aerosol optical properties obtained from in-situ measurements and retrieved from Sun and sky radiance observations during the May 2003 ARM aerosol intensive observation period. **Ricchiazzi et al. (with Schmid)
**Comparison of In-Situ and Remote Aerosol Optical Property Measurements During the DOE Aerosol IOP. **Strawa et al. (with Schmid), close to submission,
**Elevated injection height, long-range transport, and evolution of a Siberian forest fire smoke plume. **Colarco et al. (with Schmid) close to submission

## Aerosol Extinction profiles =355 nm 

**Aerosol Extinction profiles ********=355 nm **
**Unnoticed loss of sensitivity leading up to AIOP**
**Automated algorithms had to be modified to reduce impact of sensitivity loss, but 54% bias remains**
**Major upgrades/mods were performed after AIOP resulting in significantly better performance than during any other time.**

## Micro Pulse Lidars

- First validation in AIOP over SGP
- Would like larger dataset for validation

- Deployed at:
- SGP
- NSA (pol.)
- AMF (pol.)
- TWP Manus
- TWP Nauru
- TWP Darwin
- & several spares

## Proposed SGP Lidar Validation IOP

**Goal: Validate CARL, MPL and IAP Aerosol Extinction Profiles**
-  AATS-14 aboard a profiling aircraft
-  10 days, 20 flight hours
-  Profiles 300 – 23,000 ft altitude
-  Sep 2005, IOP (after NASA CALIPSO validation experiment)
-  Dec. 10, 2004 Endorsed by AWG
-  Feb. 28, 2005 Pre-proposal submitted
-  Mar. 18, 2005 (?) Pre-proposal approved

**AATS-14 on Sky Research J-31**

## Proposed future ST effortsTask 1:

**Aerosol Best Estimate (ABE) Product – Sensitivity Study**
- Aerosol extinction, o, g at all times and heights above all ACRF
- Inputs for BBHRP &  Shortwave QME
- Currently for SGP only
- How much detail is required? (varies by site?  use of resources)
- Collaborators (Turner, Ferrare, Mlawer)

## Proposed future ST effortsTask 2:

**Vertically resolved aerosol and cloud radiative properties over SGP**
- Radiometric AIOP aircraft data set underused
- Observation-based quantification of effect of aerosol & clouds on radiation
- Radiative closure (in-situ  RTM  radiation)
- BBHRP test cases
- Collaborators: Pilewskie, Mlawer

## Proposed future ST effortsTask 3:

- Proposed future ST effortsTask 3:

- Integrated analysis of data from proposed Lidar Validation IOP (if approved before submission of full ST proposal)
- Collaborators: Ferrare, Turner, Flynn