Aerosol direct radiative effect at the top of the atmosphere over cloud free ocean derived from four years of MODIS data

A four year record of MODIS spaceborne data provides a new measurement tool to assess the aerosol direct radiative effect at the top of the atmosphere. MODIS derives the aerosol optical thickness and microphysical properties from the scattered sunlight at 0.55–2.1 μm. The monthly MODIS data used here are accumulated measurements across a wide range of view and scattering angles and represent the aerosol's spectrally resolved angular properties. We use these data consistently to compute with estimated accuracy of ±0.6 Wm −2 the reflected sunlight by the aerosol over global oceans in cloud free conditions. The MODIS high spatial resolution (0.5 km) allows observation of the aerosol impact between clouds that can be missed by other sensors with larger footprints. We found that over the clear-sky global ocean the aerosol reflected 5.3±0.6 Wm −2 with an average radiative efficiency of −49±2 Wm −2 per unit optical thickness. The seasonal and regional distribution of the aerosol radiative effects are discussed. The analysis adds a new measurement perspective to a climate change problem dominated so far by models.

[1]  B. Holben,et al.  Validation of MODIS aerosol optical depth retrieval over land , 2002 .

[2]  Thomas P. Charlock,et al.  Analysis of Broadband Solar Radiation and Albedo over the Ocean Surface at COVE , 2002 .

[3]  Yoram J. Kaufman,et al.  Aerosol-cloud interaction-Misclassification of MODIS clouds in heavy aerosol , 2005, IEEE Transactions on Geoscience and Remote Sensing.

[4]  Sundar A. Christopher,et al.  Shortwave Aerosol Radiative Forcing from MODIS and CERES observations over the oceans , 2002 .

[5]  Brent N. Holben,et al.  An analysis of potential cloud artifacts in MODIS over ocean aerosol optical thickness products , 2005 .

[6]  O. Boucher,et al.  Estimation of the aerosol perturbation to the Earth's Radiative Budget over oceans using POLDER satellite aerosol retrievals , 2000 .

[7]  Bruce A. Wielicki,et al.  Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II; Validation , 2003 .

[8]  B. Holben,et al.  MODIS observation of aerosols and estimation of aerosol radiative forcing over southern Africa during SAFARI 2000 , 2003 .

[9]  S. Christopher,et al.  Shortwave aerosol radiative forcing over cloud‐free oceans from Terra: 1. Angular models for aerosols , 2005 .

[10]  Yoram J. Kaufman,et al.  Aerosol distribution in the Northern Hemisphere during ACE‐Asia: Results from global model, satellite observations, and Sun photometer measurements , 2004 .

[11]  Yoram J. Kaufman,et al.  Shortwave aerosol radiative forcing over cloud‐free oceans from Terra: 2. Seasonal and global distributions , 2005 .

[12]  D. F. Young,et al.  Angular Distribution Models for Top-of-Atmosphere Radiative Flux Estimation from the Clouds and the Earth's Radiant Energy System Instrument on the Tropical Rainfall Measuring Mission Satellite. Part II; Validation , 2003 .

[13]  B. Holben,et al.  A spatio‐temporal approach for global validation and analysis of MODIS aerosol products , 2002 .

[14]  E. Vermote,et al.  The MODIS Aerosol Algorithm, Products, and Validation , 2005 .

[15]  M. Chou,et al.  A Solar Radiation Model for Use in Climate Studies , 1992 .

[16]  Lorraine Remer,et al.  A critical examination of the residual cloud contamination and diurnal sampling effects on MODIS estimates of aerosol over ocean , 2005, IEEE Transactions on Geoscience and Remote Sensing.

[17]  Natividad Manalo-Smith,et al.  Top-of-Atmosphere Direct Radiative Effect of Aerosols over Global Oceans from Merged CERES and MODIS Observations , 2005 .

[18]  J. Privette,et al.  Africa burning: A thematic analysis of the Southern African Regional Science Initiative (SAFARI 2000) , 2003 .

[19]  H. Neckel,et al.  Improved data of solar spectral irradiance from 0.33 to 1.25μ , 1981 .

[20]  Yoram J. Kaufman,et al.  Direct radiative effect of aerosols as determined from a combination of MODIS retrievals and GOCART simulations , 2004 .

[21]  H. Neckel,et al.  Improved data of solar spectral irradiance from 0.33 to 1.25 microns , 1981 .

[22]  Yoram J. Kaufman,et al.  Distinguishing tropospheric aerosols from thin cirrus clouds for improved aerosol retrievals using the ratio of 1.38‐μm and 1.24‐μm channels , 2002 .

[23]  M. Chin,et al.  Aerosol anthropogenic component estimated from satellite data , 2005 .

[24]  T. Eck,et al.  Comparison of Moderate Resolution Imaging Spectroradiometer (MODIS) and Aerosol Robotic Network (AERONET) remote-sensing retrievals of aerosol fine mode fraction over ocean , 2005 .

[25]  Ziauddin Ahmad,et al.  An Iterative Radiative Transfer Code For Ocean-Atmosphere Systems , 1982 .

[26]  A. Smirnov,et al.  AERONET-a federated instrument network and data archive for aerosol Characterization , 1998 .

[27]  Young-Joon Kim,et al.  An overview of ACE‐Asia: Strategies for quantifying the relationships between Asian aerosols and their climatic impacts , 2003 .

[28]  D. Tanré,et al.  Remote sensing of aerosol properties over oceans using the MODIS/EOS spectral radiances , 1997 .

[29]  Max J. Suarez,et al.  A solar radiation parameterization (CLIR-AD-SW) for atmospheric studies , 1999 .

[30]  M. Chin,et al.  A review of measurement-based assessments of the aerosol direct radiative effect and forcing , 2005 .

[31]  Yoram J. Kaufman,et al.  MODIS Cloud screening for remote sensing of aerosols over oceans using spatial variability , 2002 .

[32]  B. Holben,et al.  Validation of MODIS aerosol retrieval over ocean , 2002 .