Relative humidity and its effect on aerosol optical depth in the vicinity of convective clouds

被引:52
作者
Altaratz, O. [1 ]
Bar-Or, R. Z. [1 ]
Wollner, U. [1 ]
Koren, I. [1 ]
机构
[1] Weizmann Inst Sci, Dept Environm Sci & Energy Res, IL-76100 Rehovot, Israel
来源
ENVIRONMENTAL RESEARCH LETTERS | 2013年 / 8卷 / 03期
基金
以色列科学基金会;
关键词
aerosols; clouds; aerosol humidification; RADIATIVE PROPERTIES; SEA-SALT; INVIGORATION; MICROPHYSICS; THICKNESS; PARAMETER; POLLUTION; IMPACT; DUST; RAIN;
D O I
10.1088/1748-9326/8/3/034025
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The hygroscopic growth of aerosols is controlled by the relative humidity (RH) and changes the aerosols' physical and hence optical properties. Observational studies of aerosol-cloud interactions evaluate the aerosol concentration using optical parameters, such as the aerosol optical depth (AOD), which can be affected by aerosol humidification. In this study we evaluate the RH background and variance values, in the lower cloudy atmosphere, an additional source of variance in AOD values beside the natural changes in aerosol concentration. In addition, we estimate the bias in RH and AOD, related to cloud thickness. This provides the much needed range of RH-related biases in studies of aerosol-cloud interaction. Twelve years of radiosonde measurements (June-August) in thirteen globally distributed stations are analyzed. The estimated non-biased AOD variance due to day-to-day changes in RH is found to be around 20% and the biases linked to cloud development around 10%. Such an effect is important and should be considered in direct and indirect aerosol effect estimations but it is inadequate to account for most of the AOD trend found in observational studies of aerosol-cloud interactions.
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页数:6
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