May 4, 2005, GFDL

TOA Direct Radiative Effect of Aerosols

Norman G. LoebHampton University/NASA Langley Research Center, VA

Natividad Manalo-SmithAnalytical Services and Materials, Hampton, VA

- Do models and observations provide consistent estimates of the total (natural+anthropogenic) direct radiative effect of aerosols (DREA)?

- What are the uncertainties in the observations and how can they be reduced?

- What is the seasonal and interannual variability in the DREA?

- What observations are needed to determine the natural and anthropogenic components of the total DREA?

Introduction

All

0 20 40 60 80 100

0.64

4-μ m

Aer

osol

Opt

ical

Dep

th

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

NOAA-SSFMOD04-SSF

Intersection

0 20 40 60 80 1000.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

All

Cloud Fraction (%)0 20 40 60 80 100

No.

of C

ER

ES

FO

Vs w

ith A

eros

ol

0.0

5.0e+5

1.0e+6

1.5e+6

2.0e+6

2.5e+6

NOAA-SSFMOD04-SSF

Intersection

Cloud Fraction (%)0 20 40 60 80 100

0.0

5.0e+5

1.0e+6

1.5e+6

2.0e+6

2.5e+6

0.644-μm Aerosol Optical Depth vs Cloud Fraction (JJA 2000)

-5.1-4.6-3.2SH-5.7-6.4-4.4NH

-5.4-5.5-3.8GlobalChou_2002MOD04NOAA-SSF

SW Direct Effect of Aerosols (W m-2)

Annual Average Clear-Sky SW Direct Radiative Effect: Comparison with Chou et al. (2002)

JAN, 2001 APR, 2001

JUL, 2001 OCT, 2001

Global Direct Radiative Effect of Aerosols(CERES+MOD04+MOD43)

CERES Minus Aeronet (W m-2)Aerosol Direct Effect (W m-2)

Rel

ativ

e Fr

eque

ncy

(%)

Direct Radiative Effect of Aerosols Over Land (Comparison with Aeronet-Derived Values)

Aeronet-derived DREA provided by Stefan Kinne

- Global ocean clear-sky SW direct radiative effect of aerosolsestimated to be -5.5 W m-2 (MOD04) and -3.8 W m-2 (NOAA-SSF).

- Large regional and global uncertainty due to cloud mask differences, especially near desert regions.-> CALIPSO should help with this.

- The DREA has pronounced seasonal cycle in the Northern Hemisphere and large year-to-year fluctuations between 30°-60°N.

- No systematic trend in deseasonalized anomalies of the DREA is observed over the 46-month time series considered

Summary