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Ultrafine atmospheric aerosols, clou...

Pierce, Jeffrey Robert.

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Ultrafine atmospheric aerosols, clouds and climate.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Ultrafine atmospheric aerosols, clouds and climate./
作者:	Pierce, Jeffrey Robert.
面頁冊數:	308 p.
附註:	Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1786.
Contained By:	Dissertation Abstracts International69-03B.
標題:	Atmospheric Sciences. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3305803
ISBN:	9780549525172

Ultrafine atmospheric aerosols, clouds and climate.
Pierce, Jeffrey Robert.

Ultrafine atmospheric aerosols, clouds and climate. - 308 p.

Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1786.

Thesis (Ph.D.)--Carnegie Mellon University, 2008.

Changes in atmospheric aerosol due to anthropogenic emissions are the most uncertain factors that have contributed to recent climate change. Much of this uncertainty is from the effect that particles have on cloud radiative properties, the aerosol indirect effect. Particles on which cloud droplets form are called cloud condensation nuclei (CCN). Particles larger than about 80--100 nm dry diameter typically act as CCN in stratus clouds. In order to predict how cloud radiative properties have changed since pre-industrial times, the CCN concentrations in both present-day and pre-industrial times must be known. Much of the uncertainty in CCN predictions is from uncertainty in the sources of ultrafine particles (particles with diameter smaller than 100 nm) as well as the processes that grow these particles to CCN sizes. This thesis explores various aspects of the how uncertainties in ultrafine particles affect predictions of CCN.

ISBN: 9780549525172Subjects--Topical Terms:

1019179
Atmospheric Sciences.

Ultrafine atmospheric aerosols, clouds and climate.
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502 $a Thesis (Ph.D.)--Carnegie Mellon University, 2008.
520 $a Changes in atmospheric aerosol due to anthropogenic emissions are the most uncertain factors that have contributed to recent climate change. Much of this uncertainty is from the effect that particles have on cloud radiative properties, the aerosol indirect effect. Particles on which cloud droplets form are called cloud condensation nuclei (CCN). Particles larger than about 80--100 nm dry diameter typically act as CCN in stratus clouds. In order to predict how cloud radiative properties have changed since pre-industrial times, the CCN concentrations in both present-day and pre-industrial times must be known. Much of the uncertainty in CCN predictions is from uncertainty in the sources of ultrafine particles (particles with diameter smaller than 100 nm) as well as the processes that grow these particles to CCN sizes. This thesis explores various aspects of the how uncertainties in ultrafine particles affect predictions of CCN.
520 $a First, we explore the uncertainty in CCN due to uncertain sea-salt emissions and also the affect of recently quantified ultrafine sea-salt on CCN. In the Southern Ocean, uncertainty in sea-salt emissions contributed to uncertainties in CCN(0.2%) by a factor of 2. Ultrafine sea-salt aerosol increased CCN(0.2%) in remote marine regions by more than 20%.
520 $a Next, we look at how primary carbonaceous particles affect CCN as well as how uncertainties in their chemical properties affect CCN. The addition of primary carbonaceous aerosol increased CCN(0.2%) concentrations by 65--90% in the globally averaged surface layer. A sensitivity study showed that approximately half of this increase occurs even if all carbonaceous aerosols are completely insoluble.
520 $a To study the growth of ultrafine particles to CCN sizes, we develop the Probability of Ultrafine Growth (PUG) model. It was found in most cases that condensation is the dominant growth mechanism and coagulation with larger particles is the dominant sink mechanism for ultrafine particles. We found that the probability of a 30 nm ultrafine particle generating a 100 nm CCN varies from <0.1% to &sim;90% in different parts of the atmosphere. For a given mass of primary ultrafine aerosol, an uncertainty of a factor of two in the median emission diameter can lead to an uncertainty in the number of CCN generated as high as a factor for eight.
520 $a Next, we develop a method for parameterizing sub-grid scale aerosol dynamics of freshly-emitted aerosol. This approach is based on the calculation of the probability that a given particle emitted inside a computational grid cell will survive and be available for transfer outside the cell. The method for applying the sub-grid coagulation parameterization to a CTM is discussed.
520 $a In order to elucidate the computational burden of simulating aerosol nucleation in 3-D models, we derive the pseudo-steady-state approximation (PSSA) for sulfuric acid vapor and tested it in a box model with size-resolved aerosol microphysics. The associated errors in prediction of the sulfuric acid vapor concentration and particle concentrations are small. The PSSA model was faster than a model that explicitly solves for the sulfuric acid vapor concentration in 97% of the tests, more than ten times faster in 91% of the points, and more than 100 times faster in 69% of the tests.
520 $a Next, we evaluate the sensitivity of CCN(0.2%) concentrations to changes in the nucleation rates. The difference in predicted nucleation rates in simulations using a binary nucleation parameterization and a ternary nucleation parameterization was six orders of magnitude, globally. The global CCN(0.2%) concentration was 12% higher when the ternary parameterization was used instead of the binary parameterization. The sensitivity of CCN(0.2%) to changes in nucleation rate increased both when the primary particle emissions were reduced and when the SOA formation rates were increased. In our pre-industrial simulations, the sensitivity of CCN(0.2%) to the nucleation rates were similar to the present day simulations.
520 $a We found that the proposed ion-aerosol clear-air mechanism cannot explain trends in cosmic ray/cloud correlations. The ion-induced nucleation rate changed by 15--20%, globally, using two separate ion-induced nucleation schemes between the maximum and minimum solar activity. The change in CCN(0.2%) between the solar maximum and minimum was less than 0.1% in using either ion-induced nucleation scheme.
520 $a Finally, we presented the development and testing of the Aerosol Parameter Estimation (APE) model. APE is an inverse model that solves the aerosol general dynamic equation to determine best estimates for the size-dependent condensation rate and size-dependent wall-loss rate as a function of time.
590 $a School code: 0041.
650 4 $a Atmospheric Sciences. $3 1019179
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