Search Results

You are looking at 1 - 10 of 556 items for :

  • Anthropogenic effects x
  • Journal of the Atmospheric Sciences x
  • User-accessible content x
Clear All
Baolin Jiang, Bo Huang, Wenshi Lin, and Suishan Xu

1. Introduction The annual discharge of anthropogenic aerosols into the atmosphere is considerable, but the effects of those aerosols on weather and climate remain very uncertain ( IPCC 2007 ). Aerosols can absorb and reflect solar radiation, thereby reducing the surface temperature and planetary boundary layer height, but they also act as cloud condensation nuclei (CCN) or ice nuclei, affecting cloud microphysics and subsequent precipitation rates, and increasing cloud coverage, albedo, and

Full access
Andrew R. Jongeward, Zhanqing Li, Hao He, and Xiaoxiong Xiong

attribution more reliably than any single source can suggest where the strengths of one data type can augment the deficiencies of others. This work expands on previous studies by considering the anthropogenic effects downwind of any significant anthropogenic sources. This paper is presented as follows. Section 2 describes the data products employed for this work. Section 3 contains results of AOD trend analysis from satellite and surface observational datasets. Section 4 discusses the attribution of

Full access
James G. Hudson and Stephen Noble

1. Introduction Low stratus clouds that predominate the east sides of oceans provide a majority of the indirect aerosol effect (IAE; Warren et al. 1988 ; Platnick and Twomey 1994 ; Kogan et al. 1996 ), which remains the largest climate uncertainty ( Alley et al. 2007 ). The high radiative temperatures and large albedo contrasts with the underlying ocean provide substantial global cooling that can be increased by the advection and injection of anthropogenic cloud condensation nuclei (CCN

Full access
Dandan Zhao, Jinyuan Xin, Chongshui Gong, Xin Wang, Yongjing Ma, and Yining Ma

1. Introduction Aerosol is an important component of the atmosphere, and the study of aerosol has become a specific issue in basic and applied science ( Hansen et al. 2000 ; Haywood and Boucher 2000 ; IPCC 2001 ; Lee et al. 2007b ; Luo et al. 2000 ; Penner et al. 2001 ; Stocker et al. 2014 ). Large amounts of particulate matter can be inhaled by humans, resulting in health effects ( Fujii et al. 2001 ). Furthermore, the direct radiation effect of aerosols drives important changes in which

Full access
M. Kanakidou, S. Myriokefalitakis, N. Daskalakis, G. Fanourgakis, A. Nenes, A. R. Baker, K. Tsigaridis, and N. Mihalopoulos

reduced inorganic (IN) or organic (ON) forms by natural (e.g., soils, lightning, plants, bacteria, viruses) and anthropogenic sources (e.g., industries, transportation, domestic wood burning) ( Neff et al. 2002 ; Dentener et al. 2006 ; Galloway et al. 2008 ; references therein). Recent observations and modeling studies have shown that ON is a significant fraction of total nitrogen (TN) deposition; however, the chemical characterization of this fraction remains a challenge ( Cornell 2011 ; Cape et

Full access
Stacey Kawecki, Geoffrey M. Henebry, and Allison L. Steiner

. 2006 ). We include the direct and indirect radiative effects of aerosols with anthropogenic emissions and online chemistry to predict CN. In this version of the model, the chemistry module calculates the number and mass of aerosols that will activate as CCN based on hygroscopicity and supersaturation (Köhler curves), and provides this prognostic CCN to the microphysics module. Gas-phase chemistry is simulated with the Regional Acid Deposition Model, version 2, (RADM2) chemical mechanism ( Stockwell

Full access
Matthew W. Christensen, James A. Coakley Jr., and William R. Tahnk

1. Introduction The use of ship tracks to study how clouds respond to elevated concentrations of particles has yielded a number of insights fundamental to the aerosol indirect radiative forcing of climate. Ships under way beneath marine stratus and stratocumulus provide a source of cloud condensation nuclei (CCN). The CCN enter the clouds, increase droplet number concentrations, and reduce droplet radii. The effects manifest themselves as distinctive lines in imagery of reflected sunlight at

Full access
Philip A. Durkee, Kevin J. Noone, and Robert T. Bluth

). While the early observations in the TIROS images were limited to the visible region of the spectrum, recent measurements at near-IR wavelengths reveal more extensive signatures of ship effects on clouds ( Coakley et al. 1987 ). These new observations of ship tracks from space have prompted interest in the processes that form ship tracks. The fundamental motivation for investigating the ship track phenomenon is to understand the basic atmospheric problem of how anthropogenic aerosols modify the

Full access
Pengfei Tian, Lei Zhang, Xianjie Cao, Naixiu Sun, Xinyue Mo, Jiening Liang, Xuetao Li, Xingai Gao, Beidou Zhang, and Hongbin Wang

was close to that of the anthropogenic aerosols. Thus, the mixed-type aerosols are effective in both scattering and absorbing solar radiation over SACOL. The BOA, TOA, and ATM aerosol radiative effects of the anthropogenic, mixed-type, and dust aerosols over SACOL were estimated using the SBDART radiative transfer model. The results are shown in Fig. 8a . To better analyze the properties of mixed-type aerosols, we included only those observations with an SSA curvature of greater than 0.1, which

Full access
Guoxing Chen, Wei-Chyung Wang, and Jen-Ping Chen

only directly reduce the shortwave radiation reaching the surface but also indirectly modify the cloud microphysical properties, resulting in an enhancement in cloud albedo that further reduces the surface insolation. The purpose of the present study is to investigate to what extent the anthropogenic aerosols affect the cloud microphysical properties and their subsequent effects on the surface radiation balance over the SEP within the context of the biases mentioned above. One unique aspect of the

Full access