Profiling Transboundary Aerosols over Taiwan and Assessing Their Radiative Effects

A synergistic process was developed to study the vertical distributions of aerosol optical properties and their effects on solar heating using data retrieved from ground-based radiation measurements and radiative transfer simulations. Continuous MPLNET and AERONET observations were made at a rural site in northern Taiwan from 2005 to 2007. The aerosol vertical extinction profiles retrieved from ground-based lidar measurements were categorized into near-surface, mixed, and two-layer transport types, representing 76% of all cases. Fine-mode (Angstrom exponent, alpha, approx.1.4) and moderate-absorbing aerosols (columnar single-scattering albedo approx.0.93, asymmetry factor approx.0.73 at 440 nm wavelength) dominated in this region. The column-integrated aerosol optical thickness at 500 nm (tau(sub 500nm)) ranges from 0.1 to 0.6 for the near-surface transport type, but can be doubled in the presence of upper-layer aerosol transport. We utilize aerosol radiative efficiency (ARE; the impact on solar radiation per unit change of tau(sub 500nm)) to quantify the radiative effects due to different vertical distributions of aerosols. Our results show that the ARE at the top-of-atmosphere (-23 W/ sq m) is weakly sensitive to aerosol vertical distributions confined in the lower troposphere. On the other hand, values of the ARE at the surface are -44.3, -40.6 and -39.7 W/sq m 38 for near-surface, mixed, and two-layer transport types, respectively. Further analyses show that the impact of aerosols on the vertical profile of solar heating is larger for the near-surface transport type than that of two-layer transport type. The impacts of aerosol on the surface radiation and the solar heating profiles have implications for the stability and convection in the lower troposphere.

[1]  Oleg Dubovik,et al.  Non‐spherical aerosol retrieval method employing light scattering by spheroids , 2002 .

[2]  Nobuo Sugimoto,et al.  Vertical distribution and optical properties of aerosols observed over Japan during the Atmospheric Brown Clouds–East Asia Regional Experiment 2005 , 2007 .

[3]  Ellsworth J. Welton,et al.  Measurements of aerosol vertical profiles and optical properties during INDOEX 1999 using micropulse lidars , 2002 .

[4]  P. Lin,et al.  Effects of aerosols on the surface solar radiation in a tropical urban area , 2006 .

[5]  Kyu-Tae Lee,et al.  Parameterizations for the Absorption of Solar Radiation by Water Vapor and Ozone , 1996 .

[6]  Alexander Smirnov,et al.  Cloud-Screening and Quality Control Algorithms for the AERONET Database , 2000 .

[7]  Ellsworth J. Welton,et al.  Global monitoring of clouds and aerosols using a network of micropulse lidar systems , 2001, SPIE Asia-Pacific Remote Sensing.

[8]  E. Vermote,et al.  Operational remote sensing of tropospheric aerosol over land from EOS moderate resolution imaging spectroradiometer , 1997 .

[9]  J. Herman,et al.  Radiative impacts from biomass burning in the presence of clouds during boreal spring in southeast Asia , 2003 .

[10]  Michael D. King,et al.  Aerosol properties over bright-reflecting source regions , 2004, IEEE Transactions on Geoscience and Remote Sensing.

[11]  D. Jacob,et al.  Asian chemical outflow to the Pacific in spring: Origins, pathways, and budgets , 2001 .

[12]  Sally A. McFarlane,et al.  Vertical distribution and radiative effects of mineral dust and biomass burning aerosol over West Africa during DABEX , 2008 .

[13]  J. Seinfeld.  Atmospheric Chemistry and Physics of Air Pollution , 1986 .

[14]  Y. Kaufman,et al.  Passive remote sensing of tropospheric aerosol and atmospheric , 1997 .

[15]  E. Kassianov,et al.  Surface shortwave aerosol radiative forcing during the Atmospheric Radiation Measurement Mobile Facility deployment in Niamey, Niger , 2009 .

[16]  D. Jaffe,et al.  Long‐range transport of Asian pollution to the northeast Pacific: Seasonal variations and transport pathways of carbon monoxide , 2004 .

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

[18]  E. Vermote,et al.  Second‐generation operational algorithm: Retrieval of aerosol properties over land from inversion of Moderate Resolution Imaging Spectroradiometer spectral reflectance , 2007 .

[19]  Chih-Wei Chiang,et al.  Optical properties of tropospheric aerosols based on measurements of lidar, sun-photometer, and visibility at Chung-Li (25°N, 121°E) , 2007 .

[20]  N. Lin,et al.  Rainwater chemistry at a high‐altitude station, Mt. Lulin, Taiwan: Comparison with a background station, Mt. Fuji , 2008 .

[21]  V. Ramaswamy,et al.  Global sensitivity studies of the direct radiative forcing due to anthropogenic sulfate and black carbon aerosols , 1998 .

[22]  R. Draxler.  Boundary layer isentropic and kinematic trajectories during the August 1993 North Atlantic Regional Experiment Intensive , 1996 .

[23]  Michael D. King,et al.  A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements , 2000 .

[24]  Alexander Smirnov,et al.  How well do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare? , 2006 .

[25]  N. C. Strugnell,et al.  First operational BRDF, albedo nadir reflectance products from MODIS , 2002 .

[26]  Jean-François Léon,et al.  Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust , 2006 .

[27]  Anthony J. Baran,et al.  Physical and optical properties of mineral dust aerosol during the Dust and Biomass-burning Experiment , 2008 .

[28]  Tatsuro Tsukamoto,et al.  Characterization of Asian dust and Siberian smoke with multi‐wavelength Raman lidar over Tokyo, Japan in spring 2003 , 2004 .

[29]  Brent N. Holben,et al.  Lidar Observations of Tropospheric Aerosols Over Northeastern South Africa During the Arrex and Safari-2000 Dry Season Experiments , 2003 .

[30]  Alexander Smirnov,et al.  Aeronet's Version 2.0 quality assurance criteria , 2006, SPIE Asia-Pacific Remote Sensing.

[31]  Roland B. Stull,et al.  Mean Boundary Layer Characteristics , 1988 .

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

[33]  Chea-Yuan Young,et al.  Influence of Asian dust storms on air quality in Taiwan. , 2006, The Science of the total environment.

[34]  Alexander Smirnov,et al.  Columnar aerosol optical properties at AERONET sites in central eastern Asia and aerosol transport to the tropical mid‐Pacific , 2005 .

[35]  James D. Spinhirne,et al.  Compact Eye Safe Lidar Systems , 1995 .

[36]  Michael Q. Wang,et al.  An inventory of gaseous and primary aerosol emissions in Asia in the year 2000 , 2003 .

[37]  Alexis K.H. Lau,et al.  Analysis of aerosol vertical distribution and variability in Hong Kong , 2008 .

[38]  Michael D. King,et al.  Deep Blue Retrievals of Asian Aerosol Properties During ACE-Asia , 2006, IEEE Transactions on Geoscience and Remote Sensing.

[39]  T. Eck,et al.  Variability of Absorption and Optical Properties of Key Aerosol Types Observed in Worldwide Locations , 2002 .

[40]  J. Woo,et al.  Estimate of radiative forcing of Asian biomass‐burning aerosols during the period of TRACE‐P , 2007 .

[41]  Alexander Smirnov,et al.  Ground-Based Lidar Measurements of Aerosols During ACE-2 Instrument Description, Results, and Comparisons with Other Ground-Based and Airborne Measurements , 2000 .

[42]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.