Droplet Spectral Broadening in Marine Stratus

Hudson, James G.; Yum, Seong Soo

doi:10.1175/1520-0469(1997)054<2642:dsbims>2.0.co;2

Cited by 93 publications

(108 citation statements)

References 52 publications

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“…6b shows the observed variation of σ with CCN concentration, for fixed mean radius for three narrow ranges 4-4.5, 4.5-5, and 5-5.5 µm, in which σ increases with N ccn . This observation is similar to that reported by previous investigators through aircraft measurements (Hudson and Yum, 1997;Miles et al, 2000;Pandithurai et al, 2012). Hudson and Yum (1997) demonstrated that standard deviation of cloud droplet spectra will be higher at higher CCN concentration from the ASTEX experiment of 1992.…”

Section: Dispersion Effectsupporting

confidence: 92%

“…This observation is similar to that reported by previous investigators through aircraft measurements (Hudson and Yum, 1997;Miles et al, 2000;Pandithurai et al, 2012). Hudson and Yum (1997) demonstrated that standard deviation of cloud droplet spectra will be higher at higher CCN concentration from the ASTEX experiment of 1992. In general, clean maritime clouds have larger droplet size and larger σ , while polluted continental clouds have smaller drops with smaller σ .…”

Section: Dispersion Effectsupporting

confidence: 91%

“…Hudson and Yum (1997) reported that the spectral width (σ ) of cloud droplet spectra was greater with higher N ccn from the Atlantic Stratocumulus Transition Experiment (ASTEX) conducted in 1992. They also observed that this small σ difference can be noticed if cloud parcels with droplets of same mean diameter were considered.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats

et al. 2016

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Abstract. The effect of aerosols on cloud droplet number concentration and droplet effective radius is investigated from ground-based measurements over a high-altitude site where clouds pass over the surface. First aerosol indirect effect (AIE) estimates were made using (i) relative changes in cloud droplet number concentration (AIE n ) and (ii) relative changes in droplet effective radius (AIE s ) with relative changes in aerosol for different cloud liquid water contents (LWCs). AIE estimates from two different methods reveal that there is systematic overestimation in AIE n as compared to that of AIE s . Aerosol indirect effects (AIE n and AIE s ) and dispersion effect (DE) at different LWC regimes ranging from 0.05 to 0.50 g m −3 were estimated. The analysis demonstrates that there is overestimation of AIE n as compared to AIE s , which is mainly due to DE. Aerosol effects on spectral dispersion in droplet size distribution play an important role in altering Twomey's cooling effect and thereby changes in climate. This study shows that the higher DE in the medium LWC regime offsets the AIE by 30 %.

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Section: Dispersion Effectsupporting

confidence: 92%

Section: Dispersion Effectsupporting

confidence: 91%

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Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats

et al. 2016

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“…Most of them employed observational data to establish a statistical relationship between the cloud droplet number concentration and the relative dispersion. Some of these statistical relationships showed a positive correlation between them, i.e., e increased with the increase of cloud droplet number concentration (CN) (Martin et al 1994;Hudson and Yum 1997;Miles et al 2000;Liu and Daum 2002;Liu et al 2006b), while others revealed a negative correlation (Pawlowska et al 2006;Ma et al 2010;Lu et al 2012). Furthermore, some of these studies have also shown that e converges at high cloud droplet number concentration (Zhao et al 2006;Lu et al 2007).…”

Section: Introductionmentioning

confidence: 98%

Skewness of cloud droplet spectrum and an improved estimation for its relative dispersion

Liu

2016

Meteorol Atmos Phys

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The relative dispersion of the cloud droplet spectrum is a very important parameter in describing and modeling cloud microphysical processes. Based on the definition of skewness as well as theoretical and data analyses, a linear fitting relationship (a = 2.91e-0.59) between skewness (a) and relative dispersion (e) is established and a new method is developed to estimate the relative dispersion of the cloud droplet spectrum. The new method does not depend on any assumption of a particular distribution for the cloud droplet spectrum and has broader applicability than the previous methods. Comparisons of the three methods for the relative dispersion with the observed data supported the following conclusions. (1) The skewness of the cloud droplet spectrum is asymmetrically distributed. An assumption of zero skewness in quantifying the relative dispersion inevitably results in relatively large deviations from the observations. Errors of the estimated relative dispersion due to the omission of the skewness term are not solely related to the skewness, but rather to the product of the skewness and relative dispersion. (2) The use of the assumption that the cloud droplet spectrum takes a gamma distribution is similar to the assumption that the skewness is twice the relative dispersion. This leads to a better accuracy in estimating the relative dispersion than that with zero skewness assumption. (3) Comparisons with observations show that the new method is more accurate than the one under gamma distribution assumption and is the best among all the three methods. (4) It is believed that finding a better correlation between the skewness and the relative dispersion would further reduce the deviations for the estimated relative dispersion.

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“…Given that the production of drizzle is a sign of enhanced coalescence within the cloud then one would expect a greater reduction in aerosol number when drizzle drops are formed, but it is coalescence itself that is mainly responsible for the fall in aerosol number concentration. Quantitative estimates of the rate of reduction of aerosol mass and number are difficult to make because of the considerable doubt still remaining about the influence of aerosols on the growth of cloud droplets (Hudson and Yum, 1997). In this analysis it is assumed that the number of dissolved aerosol particles, all of which are identical, in a drizzle dro s of radius rd formed from the coalescence of cloud droplets of radius rc is equal to ('d/rc) .…”

mentioning

confidence: 99%

The effect of drizzle on the redistribution of aerosol in the boundary layer: estimation of the scale of the effect during ACE-2 using aircraft data

Wood¹,

Johnson²,

Osborne³

1998

Journal of Aerosol Science

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Droplet Spectral Broadening in Marine Stratus

Cited by 93 publications

References 52 publications

Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats

Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats

Skewness of cloud droplet spectrum and an improved estimation for its relative dispersion

The effect of drizzle on the redistribution of aerosol in the boundary layer: estimation of the scale of the effect during ACE-2 using aircraft data

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