A new parameterization of H2SO4/H2O aerosol composition: Atmospheric implications
A new parameterization of H2SO4/H2O aerosol composition: Atmospheric implications
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H2SO4/H2O 气溶胶成分的新参数化：对大气的影响
DOI：
10.1029/97gl01879
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发表时间：
1997
影响因子：
5.2
通讯作者：
P. Hamill
中科院分区：
文献类型：
--
作者：
A. Tabazadeh;O. B. Toon;S. Clegg;P. Hamill
硫酸水溶液的一个热力学模型的近期结果被用于推导一个关于硫酸气溶胶成分随温度和相对湿度变化的新参数化方案。该公式在185至260K的温度范围内、相对湿度高于1%时有效。还给出了一个与硫酸模型一致的计算过冷水的蒸气压的表达式。我们表明，Steele和Hamill[1981]的公式在低温下低估了硫酸水溶液上方的水的分压，低估幅度高达12%。这种差异导致在大约190K时，气溶胶中硫酸浓度相应地被低估了约6%（重量百分比）。此外，通常用于估算过冷水上方水蒸气压的关系式与我们推导出的表达式相差高达10%。综合误差可能导致平流层中硫酸溶液液滴上方的水活度被低估20%，这对平流层硫酸气溶胶中异相反应速率的参数化有影响。还讨论了气溶胶成分对硫酸溶液液滴均相冰核形成速率的影响。该参数化方案也可用于在各种环境条件下（例如飞机尾气中或火山羽流中）硫酸溶液液滴的均相气相成核计算。
Recent results from a thermodynamic model of aqueous sulfuric acid are used to derive a new parameterization for the variation of sulfuric acid aerosol composition with temperature and relative humidity. This formulation is valid for relative humidities above 1% in the temperature range of 185 to 260 K. An expression for calculating the vapor pressure of supercooled liquid water, consistent with the sulfuric acid model, is also presented. We show that the Steele and Hamill [1981] formulation underestimates the water partial pressure over aqueous H2SO4 solutions by up to 12% at low temperatures. This difference results in a corresponding underestimate of the H2SO4 concentration in the aerosol by about 6% of the weight percent at approximately 190 K. In addition, the relation commonly used for estimating the vapor pressure of H2O over supercooled liquid water differs by up to 10% from our derived expression. The combined error can result in a 20% underestimation of water activity over a H2SO4 solution droplet in the stratosphere, which has implications for the parameterization of heterogeneous reaction rates in stratospheric sulfuric acid aerosols. The influence of aerosol composition on the rate of homogeneous ice nucleation from a H2SO4 solution droplet is also discussed. This parameterization can also be used for homogeneous gas phase nucleation calculations of H2SO4 solution droplets under various environmental conditions such as in aircraft exhaust or in volcanic plumes.