Preface to special section on East Asian Studies of Tropospheric Aerosols: An International Regional Experiment (EAST‐AIRE)

Abstract

[1] Papers published in this special section report findings from the East Asian Study of Tropospheric Aerosols: An International Regional Experiment (EAST-AIRE). They are concerned with (1) the temporal and spatial distributions of aerosol loading and precursor gases, (2) aerosol single scattering albedo (SSA), (3) aerosol direct radiative effects, (4) validation of satellite products, (5) transport mechanisms, and (6) the effects of air pollution on ecosystems. Aerosol loading is heaviest in mideastern China with a mean aerosol optical depth (AOD) of 0.5 and increasing to 0.7 around major cities that reduced daily mean surface solar radiation by $30-40 W m À2 , but barely changed solar reflection at the top of the atmosphere. Aerosol loading, particle size and composition vary considerably with location and season. The MODIS AOD data from Collection 5 (C5) agree much better with ground data than earlier releases, but considerable discrepancies still exist because of treatments of aerosol SSA and surface albedo. Four methods are proposed/adopted to derive the SSA by means of remote sensing and in situ observation, which varies drastically with time and space. The nationwide means of AOD, Å ngström exponent, and SSA (0.5 mm) in China are 0.69 ± 0.17, 1.06 ± 0.26, and 0.89 ± 0.04, respectively. Measurements of trace gases reveal substantial uncertainties in emission inventories. An analysis of aircraft measurements revealed that dry convection is an important mechanism uplifting pollutants over northern China. Model simulations of nitrogen deposition and impact of ozone pollution on net primary productivity indicate an increasing threat of air pollution on the ecosystem.

Absorbing aerosol in the troposphere of the Western Arctic during the 2008 ARCTAS/ARCPAC airborne field campaigns

“…To evaluate the validity of this assumption, the MAE values calculated using the ARCTAS data can be compared to MAE values for brown carbon from INTEX-A as well as those computed by Yang et al (2009) during EAST-AIRE (Li et al, 2007). Note that the Yang et al absorbing mass values are based on EC/OC measurements using the Sunset Labs technique (Huebert et al, 2004a;Kline et al, 2004), while their absorption measurements at 470, 520 and 660 nm use a corrected 7-wavelength aethalometer Bond et al, 1999).…”

Individual Particle Analysis of Atmospheric Aerosols at Nam Co, Tibetan Plateau

“…Recently, climate change has become a crucial issue receiving tremendous attention worldwide (IPCC, 2007;Li et al, 2007). Especially, the TP has been regarded as a sensitive region to global climate change owing to its special landform, ecosystem, and monsoon circulation.…”

A long-term study of aerosol modulation of atmospheric and surface solar heating over Pune, India

“…Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) (Huebert et al, 2003), the Asian Atmospheric Particle Environment (APEX) (Nakajima et al, 2003), the East Asian Study of Tropospheric Aerosols: An International Regional Experiment (EAST-AIRE) (Li et al, 2007) and cloud-free aerosol radiative forcing across China (Li et al, 2010). In recent years, many studies have been undertaken to assess the impact of aerosols on the climate in the Indian region Ramanathan et al, 2001b;Moorthy et al, 2005;Ramachandran, 2005aRamachandran, , 2005bTripathi et al, 2005;Pant et al, 2006;Niranjan et al, 2007;Babu et al, 2007;Sreekanth et al, 2007;Dey and Tripathi, 2008).…”