Supplementary material to "Modelling the relationship between liquid water content and cloud droplet number concentration observed in low clouds in the summer Arctic and its radiative effects"

Abstract. Low clouds persist in the summer Arctic with important consequences for the radiation budget. In this study, we simulate the linear relationship between liquid water content (LWC) and cloud droplet number concentration (CDNC) observed during an aircraft campaign based out of Resolute Bay, Canada conducted as part of the NETCARE study in July 2014. Using a single column model, we find that autoconversion can explain the observed linear relationship between LWC and CDNC. Of the three schemes we examined, the autoconversion scheme using continuous drizzle (Khairoutdinov and Kogan, 2000) appears to best reproduce the observed linearity in the tenuous-cloud regime (Mauritsen et al., 2011), while a scheme with a threshold for rain (Liu and Daum, 2004) best reproduces the linearity at higher CDNC. An offline version of the radiative transfer model used in the Canadian Atmospheric Model version 4.3 is used to compare the radiative effects of the modelled and observed clouds. We find that there is no significant difference in the upward longwave fluxes at the top of the atmosphere from the three autoconversion schemes (p = 0.05), but that all three schemes differ at p = 0.05 from the calculations based on observations. In contrast, the downward longwave and shortwave fluxes at the surface for all three schemes do not differ significantly (p = 0.01) from the observation-based radiative calculations.

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Modelling the relationship between liquid water content and cloud droplet number concentration observed in low clouds in the summer Arctic and its radiative effects

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-29-2020 ◽

2020 ◽

Vol 20 (1) ◽

pp. 29-43

Author(s):

Joelle Dionne ◽

Knut von Salzen ◽

Jason Cole ◽

Rashed Mahmood ◽

W. Richard Leaitch ◽

...

Keyword(s):

Linear Relationship ◽

Water Content ◽

Liquid Water ◽

Cloud Droplet ◽

Liquid Water Content ◽

Number Concentration ◽

Radiative Effect ◽

Low Clouds ◽

Cloud Radiative Effect ◽

Cloud Droplet Number Concentration

Abstract. Low clouds persist in the summer Arctic with important consequences for the radiation budget. In this study, we simulate the linear relationship between liquid water content (LWC) and cloud droplet number concentration (CDNC) observed during an aircraft campaign based out of Resolute Bay, Canada, conducted as part of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments study in July 2014. Using a single-column model, we find that autoconversion can explain the observed linear relationship between LWC and CDNC. Of the three autoconversion schemes we examined, the scheme using continuous drizzle (Khairoutdinov and Kogan, 2000) appears to best reproduce the observed linearity in the tenuous cloud regime (Mauritsen et al., 2011), while a scheme with a threshold for rain (Liu and Daum, 2004) best reproduces the linearity at higher CDNC. An offline version of the radiative transfer model used in the Canadian Atmospheric Model version 4.3 is used to compare the radiative effects of the modelled and observed clouds. We find that there is no significant difference in the upward longwave cloud radiative effect at the top of the atmosphere from the three autoconversion schemes (p=0.05) but that all three schemes differ at p=0.05 from the calculations based on observations. In contrast, the downward longwave and shortwave cloud radiative effect at the surface for the Wood (2005b) and Khairoutdinov and Kogan (2000) schemes do not differ significantly (p=0.05) from the observation-based radiative calculations, while the Liu and Daum (2004) scheme differs significantly from the observation-based calculation for the downward shortwave but not the downward longwave fluxes.

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Exploring satellite-derived relationships between cloud droplet number concentration and liquid water path using a large-domain large-eddy simulation

10.5194/dach2022-252 ◽

2021 ◽

Author(s):

Sudhakar Dipu ◽

Matthias Schwarz ◽

Annica Ekman ◽

Edward Gryspeerdt ◽

Tom Goren ◽

...

Keyword(s):

Liquid Water ◽

Cloud Droplet ◽

Number Concentration ◽

Liquid Water Path ◽

Large Domain ◽

Water Path ◽

Large Eddy ◽

Cloud Droplet Number Concentration ◽

Les Model ◽

The Relationship

<div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>Important aspects of the adjustments to aerosol-cloud interactions can be examined using the relationship between cloud droplet number concentration (Nd) and liquid water path (LWP). Specifically, this relation can constrain the role of aerosols in leading to thicker or thinner clouds in response to adjustment mechanisms. This study investigates the satellite retrieved relationship between Nd and LWP for a selected case of mid-latitude continental clouds using high-resolution Large-eddy simulations (LES) over a large domain in weather prediction mode. Since the satellite retrieval uses adiabatic assumption to derive the Nd (NAd), we have also considered NAd from the LES model for comparison. The NAd-LWP relationship in the satellite and the LES model show similar, generally positive, but non-monotonic relations. This case over continent thus behaves differently compared to previously-published analysis of oceanic clouds, and the analysis illustrates a regime dependency (marine and continental) in the NAd-LWP relation in the satellite retrievals. The study further explores the impact of the satellite&#160;retrieval assumptions on the Nd-LWP relationship. When considering the relationship of the actually simulated cloud-top Nd, rather than NAd, with LWP, the result shows a much more nonlinear relationship. The difference is much less pronounced, however, for shallow stratiform than for convective clouds. Comparing local vs large-scale statistics from satellite data shows that continental clouds exhibit only a weak nonlinear Nd-LWP relationship. Hence a regime based Nd-LWP analysis is even more relevant when it comes to continental clouds.</p> </div> </div> </div>

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Supplementary material to "On the Relationship Between Cloud Water Composition and Cloud Droplet Number Concentration"

10.5194/acp-2020-247-supplement ◽

2020 ◽

Author(s):

Alexander B. MacDonald ◽

Ali Hossein Mardi ◽

Hossein Dadashazar ◽

Mojtaba Azadi Aghdam ◽

Ewan Crosbie ◽

...

Keyword(s):

Cloud Droplet ◽

Cloud Water ◽

Number Concentration ◽

Water Composition ◽

Cloud Droplet Number Concentration ◽

Supplementary Material ◽

The Relationship

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An investigation into the relationship between liquid water content and cloud number concentration in the stratiform clouds over north China

Atmospheric Research ◽

10.1016/j.atmosres.2013.12.004 ◽

2014 ◽

Vol 139 ◽

pp. 137-143 ◽

Cited By ~ 8

Author(s):

Jin-Fang Yin ◽

Dong-Hai Wang ◽

Guo-Qing Zhai ◽

Huan-Bin Xu

Keyword(s):

Water Content ◽

Liquid Water ◽

North China ◽

Liquid Water Content ◽

Number Concentration ◽

Stratiform Clouds ◽

The Relationship

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A depolarisation lidar based method for the determination of liquid-cloud microphysical properties

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-9917-2014 ◽

2014 ◽

Vol 7 (9) ◽

pp. 9917-9992 ◽

Cited By ~ 1

Author(s):

D. P. Donovan ◽

H. Klein Baltink ◽

J. S. Henzing ◽

S. R. de Roode ◽

A. P. Siebesma

Keyword(s):

Water Content ◽

Multiple Scattering ◽

Liquid Water ◽

Cloud Droplet ◽

Optimal Estimation ◽

Liquid Water Content ◽

Cloud Base ◽

Base Region ◽

Large Eddy Simulation Model ◽

Inversion Procedure

Abstract. The fact that polarisation lidars measure a depolarisation signal in liquid clouds due to the occurrence of multiple-scattering is well-known. The degree of measured depolarisation depends on the lidar characteristics (e.g. wavelength and receiver field-of-view) as well as the cloud macrophysical (e.g. liquid water content) and microphysical (e.g. effective radius) properties. Efforts seeking to use depolarisation information in a quantitative manner to retrieve cloud properties have been undertaken with, arguably, limited practical success. In this work we present a retrieval procedure applicable to clouds with (quasi-)linear liquid water content (LWC) profiles and (quasi-)constant cloud droplet number density in the cloud base region. Thus limiting the applicability of the procedure allows us to reduce the cloud variables to two parameters (namely the derivative of the liquid water content with height and the extinction at a fixed distance above cloud-base). This simplification, in turn, allows us to employ a fast and robust optimal-estimation inversion using pre-computed look-up-tables produced using extensive lidar Monte-Carlo multiple-scattering simulations. In this paper, we describe the theory behind the inversion procedure and successfully apply it to simulated observations based on large-eddy simulation model output. The inversion procedure is then applied to actual depolarisation lidar data corresponding to a range of cases taken from the Cabauw measurement site in the central Netherlands. The lidar results were then used to predict the corresponding cloud-base region radar reflectivities. In non-drizzling condition, it was found that the lidar inversion results can be used to predict the observed radar reflectivities with an accuracy within the radar calibration uncertainty (2–3 dBZ). This result strongly supports the accuracy of the lidar inversion results. Results of a comparison between ground-based aerosol number concentration and lidar-derived cloud droplet number densities are also presented and discussed. The observed relationship between the two quantities is seen to be consistent with the results of previous studies based on aircraft-based in situ measurements.

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

10.5194/acp-2015-1057 ◽

2016 ◽

Author(s):

V. Anil Kumar ◽

G. Pandithurai ◽

P. P. Leena ◽

K. K. Dani ◽

P. Murugavel ◽

...

Keyword(s):

High Altitude ◽

Indirect Effects ◽

Cloud Droplet ◽

Droplet Size Distribution ◽

Liquid Water Content ◽

Number Concentration ◽

Effective Radius ◽

Aerosol Indirect Effects ◽

Cloud Droplet Number Concentration ◽

Aerosol Effects

Abstract. The effect of aerosols on cloud droplet number concentration and droplet effective radius are investigated from ground-based measurements over a high-altitude site where in clouds pass over the surface. First aerosol indirect effect AIE estimates were made using i) relative changes in cloud droplet number concentration (AIEn) and ii) relative changes in droplet effective radius (AIEs) with relative changes in aerosol for different LWC values. AIE estimates from two different methods reveal that there is systematic overestimation in AIEn as compared to that of AIEs. Aerosol indirect effects (AIEn and AIEs) and Dispersion effect (DE) at different liquid water content (LWC) regimes ranging from 0.05 to 0.50 gm-3 were estimated. The analysis demonstrates that there is overestimation of AIEn as compared to AIEs which is mainly due to DE. Aerosol effects on spectral dispersion in droplet size distribution plays 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 which offsets the AIE by 30%.

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