# Presentation: 051955

## Measurement-based Aerosol Radiative Effects within the Context of CCSP and IPCC

**Hongbin Yu, Yoram Kaufman**
**February 10, 2006**

##  Background

-  Presently the IPCC assessments are largely model-based (the models are evaluated using satellite and surface measurements).
- In recent years, a great deal of effort has gone into improving measurements and data sets:
- It is feasible to shift the estimate of aerosol radiative effects from** ****largely model-based**** **to** ****increasingly measurement-based**.

**MISR**

##  CCSP

- CCSP, an interagency program, was established to coordinate and integrate scientific research on global change & climate change.
- CCSP is generating 21 synthesis & assessment products to (1) support policymaking & adaptive management; and (2) contribute to IPCC FAR.
_**Product 2.3**_**:** Aerosol Properties and Their Impacts on Climate *(lead by NASA, Phil DeCola)*
- In-situ measurements of aerosol properties and direct forcing *(Bates et al.)*
- _Satellite measurements of aerosol direct effect_ *(Kaufman, Chin, Feingold)*
- Aerosol indirect effects *(Penner et al.)*

##  Specific Goals

**Assess the global aerosol distribution and direct radiative effect using satellites supplemented by chemical transport models.**** **
**Assess the anthropogenic component, using satellite data and models.**
**Evaluate these assessments against surface network data and field experiments; and compare them to model estimates.**

**“****A review of measurement-based assessments of the aerosol direct effect and forcing”**, ***accepted to ***_***Atmospheric Chemistry and Physics***_

## 11 observations  (MODIS, CERES, MISR, POLDER, SeaWiFS, MO_MI_GO, ......)

_***Possible reasons for the discrepancies:***_
**	******** ****Optical depth**** *****(cloud contamination in satellites; low biases of models --- sources, humidification, ......*****)  **
**	****** **Large discrepancies exist in *****Forcing Efficiency****** (forcing normalized by optical depth), *****which may result from model biases, such as ****high absorption, weak backscattering (large size), too bright surface.**** **

**11 observations****  *****(MODIS, CERES, MISR, POLDER, SeaWiFS, MO_MI_GO, ......)***
**5 models****  (GOCART, GISS, ......)**

**M****/****O****=0.64**

**M****/****O****=0.58**

**natural + anthrop.**

## Regional Assessments

**Regional Assessments**

**Measurements**

**Models**

**Remer & Kaufman, Atmos. Chem. Phys., 6, 237-253, 2006**

_**OCEAN, TOA**_

## Over ocean, the anthropogenic contribution to MODIS AOD is about 21%. MODIS and models are consistent in anthropogenic AOD. (Kaufman et al., GRL, 2005)

** ****Natural + **
** ****Anthropogenic**

** ****Anthropogenic**

**MODIS measured aerosol size parameters can be used to distinguish anthropogenic aerosols from natural aerosols**

**total**

**Anthrop.**

## Clear-sky DCF =   x  ff     x     faf    x   Ea

**Using as many measurements as possible, we estimate the TOA forcing of ****-1.3 ****± 0.8**** W/m****2****  ****for cloud-free conditions (LAND + OCEAN)****.**
** **
**9 models give ****-0.6 W/m****2**** *****(Michael Schulz)***** **

**Fine-mode fraction**

**Anthrop. fraction in fine- mode**

**Forcing efficiency **

## We need GLAS and Calipso!!!!  And to know aerosol absorption better!!

- Estimating the _DIRECT FORCING_ in the presence of clouds:
**We need GLAS and Calipso!!!!  And to know aerosol absorption better!!**

## Aerosol-Cloud Interactions as Inferred from MODIS Measurements

- Kaufman, Y. J., I. Koren, L. A. Remer, D. Rosenfeld, and Y. Rudich, 2005: _**The Effect of Smoke, Dust and Pollution Aerosol on Shallow Cloud Development Over the Atlantic Ocean,**_ *Proc. Nat. Acad. Sci.*,102(32), pp.11207-11212.
- Koren, I., Y. J. Kaufman, D. Rosenfeld, L. A. Remer, and Y. Rudich, 2005: _**Aerosol Invigoration and Restructuring of Atlantic Convective Clouds.**_ *Geophys. Res. Lett.*, 32, LI4828, doi: 10.1029/2005GL023187.

***adding new observational evidence for aerosol impacts on clouds**** ****in IPCC FAR.***

## Dust

**Total TOA Solar Forcing **
**=    Cloud modifications  (fraction, Nc, LWP) **
** ****+   Direct effect**