Task 220

Retrievals and Analyses of Global Aerosol Properties

Principal Investigator(s):

S-H. Wang


S. Tsay

Last Updated:

October 26, 2012 15:25:48

Description of Problem

Aerosols affect Earth’s energy budget by scattering and absorbing radiation (the “direct effect”) and by modifying microphysical and radiative properties of clouds (the “indirect effect”). The complex spatial, temporal, chemical composition, physical size and shape, and optical characteristics of atmospheric aerosols cause large uncertainties in the estimation of aerosol effects on climate. To lessen the uncertainties, remote sensing and in-situ measurements as observational approach providing essential information. The NASA/GSFC SMART-COMMIT (Surface-sensing Measurements for Atmospheric Radiative Transfer – Chemical, Optical, and Microphysical Measurement of In-situ Troposphere) mobile observatory has conducted more than 10 worldwide field campaigns in the past 10 years. The surface remote sensing and in-situ technologies were applied to study aerosol properties using SMART-COMMIT database. We integrate surface radiation measurement, satellites data, and radiative transfer model to understand the global aerosol properties and regional radiative impact of aerosols.

Scientific Objectives and Approach

Our specific objectives are:

• Develop a synergistic process to study aerosol vertical distributions of optical properties and their effects on solar heating using data derived from ground-based remote-sensing measurements (AERONET and MPLNET) and radiative transfer simulations.

• To understand and characterize the aerosol optical and radiative properties captured during the past SMART-COMMIT fields campaigns.

• Investigate aerosol radiative effects using theoretical and observational approaches


A synergy of using remote-sensing measurements (e.g., MPLNET, AERONET, and the MODIS) and radiative transfer simulations was developed to better understanding the relationships of the aerosol vertical distribution, transport mechanism, optical properties and radiative effects, as well as regional-to-global climatic impacts [Wang et al., 2010a]. The synergistic methodology has also been successfully applied to the NASA NAMMA filed campaign. Furthermore, by integrating with longwave radiation measurements and simulations [Hansell et al., 2010], we have demonstrated the capability in investigating radiation and aerosol interaction from observational point of view. Wang et al. [2010b] present an evidence of aerosol and cloud interaction based on the measurements (e.g., cloud water chemistry and lidar profiling) carried out in northern Taiwan. The mixture of anthropogenic and dust particle influences strongly on the characteristics of bulk cloud condensation nuclei (CCN). Extremely low liquid water content measurements during the dust-laden event influence not only the dissipating stage of the cloud, but also suppress cloud droplet sizes as a result of relatively high CCN loading.

An intense Asian dust storm (21 March 2010) was observed during the 7-SEAS/Dongsha experiment. The dust storm migrated from the Gobi deserts to the West Pacific in 3 days, and its spatiotemporal evolution was evident in the MODIS aerosol retrievals (Fig. 1). For the first time, the characterization of Asian dust storm transported to the northern South China Sea has been explored by the comprehensive in situ measurements. Figure 2 depicts a dramatic increase of PM2.5 concentration, dust mass fraction, lidar depolarization ratio, decrease of aerosol humidification factor, and a change of aerosol optical properties due to the dust intrusion. The results also suggest that the dust particles were mixed with anthropogenic and marine aerosols, and transported near the surface. An important implication of these results is that the Asian dust transported to northern South China Sea may have influence on marine ecosystems [Wang et al. 2011].

Refereed Journal Publications

Wang, S.-H., S.-C. Tsay, N.-H. Lin, N. C. Hsu, S. W. Bell, C. Li, Q. Ji, M.-J. Jeong, R. A. Hansell, E. J. Welton, and B. N. Holben (2011), First detailed observations of long-range transported dust over the northern South China Sea. Submitted to Atmos. Environ.

Wang, S.-H., N.-H. Lin, M.-D. Chou, S.-C. Tsay, E. J. Welton, N. C. Hsu, D. M. Giles, G.-R. Liu, and B. N. Holben (2010a), Profiling transboundary aerosols over Taiwan and assessing their radiative effects, J. Geophys. Res., 115, D00K31, doi:10.1029/2009JD013798.

Wang, S.-H., N.-H. Lin, C.-F. Ouyang, J.-L. Wang, J. R. Campbell, C.-M. Peng, C.-T. Lee, G.-R. Sheu, and S.-C. Tsay (2010b), Impact of Asian dust and continental pollutants on cloud chemistry observed in northern Taiwan during the experimental period of ABC/EAREX 2005, J. Geophys. Res., 115, D00K24, doi:10.1029/2009JD013692.

Chen, Shu-Hua, Sheng-Hsiang Wang, and Mark Waylonis (2010), Modification of Saharan air layer and environmental shear over the eastern Atlantic Ocean by dust-radiation effects, J. Geophys. Res., 115, D21202, doi: 10.1029/2010JD014158.

Sheu, G.-R., N.-H. Lin, J.-L Wang, C.-T. Lee, C.-F. Ou Yang, and S.-H. Wang (2010), Temporal distribution and potential sources of atmospheric mercury measured at a high-elevation background station in Taiwan. Atmos. Environ., doi: 10.1016/j.atmosenv.2010.04.009.

Hansell, R. A., S.-C. Tsay, Q. Ji, N. C. Hsu, M. J. Jeong, S.-H. Wang, J. S. Reid, K. N. Liou, and S. C. Ou (2010), An Assessment of Surface Longwave Direct Radiative Effect of Airborne Saharan Dust during the NAMMA field campaign. J. Atmos. Sci., 67, 1048-1065.

Other Publications and Conferences

Wang, S.-H. (2011), Remote Sensing, In-situ Measurement, and Model Simulation of Atmospheric Aerosols over Asian Region: Toward a Better Understanding of
Aerosol-Radiation-Climate Interactions, NCU, Taiwan. (4 January 2011)

Wang, S.-H., N.-H. Lin, M.-D. Chou, S.-C. Tsay, D. Giles, E. J. Welton, and B. Holben (2010), Profiling transboundary aerosols over Taiwan and assessing radiative effects. AGU 2010 Western Pacific Geophysics Meeting, Taipei, Taiwan. (22–25 June 2010)

Wang, S.-H., N.-H. George Lin, Si-Chee Tsay, Shaun W. Bell, Can Li, Q. Jack Ji, Richard A. Hansell, Ferret Kuo, Eric Chia, Jense Chiu, N. Christina Hsu, Brent N. Holben, and E. Judd Welton (2010), Dongsha Experiment of NASA COMMIT Observatory and EZlidar: Preliminary Data & Discussions. Dongsha experiment data workshop, NCU, Taiwan. (15 June 2010)

Wang, S.-H. et al. (2010), Deployment of NASA/GSFC SMART-COMMIT Mobile Observatory: Measuring an Asian super dust storm in 2010!!, Aerosol Updates, NASA/GSFC, Maryland, USA. (April 2010)

Task Figures

Fig. 1 – Composite MODIS-Aqua aerosol Deep-Blue and Dark-Target retrievals of AOT around 0530 UTC.

Fig. 2 – Time series of (a) wind, T, P, and RH, (b) PM2.5 mass and number concentrations, (c) dust mass fraction and aerosol humidification factor, (d) total, dust, and background particle scattering coefficients, (e) normalized lidar relative backscatter (0-500 m above ground is shown), and (f) the corresponding lidar depolarization ratio, at Dongsha on 21 March 2010.