Microphysical characteristics of some convective clouds over Oklahoma

Poellot, Michael R.; Pflaum, John C.

doi:10.1016/0169-8095(89)90041-0

Cited by 8 publications

(4 citation statements)

References 7 publications

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“…The statistics of aircraft observations by Borovikov et al (1963) show that characteristic values for dense cumulus congestus and cumulonimbus are 0.5-3 g m 23 . In cumulus clouds with very strong updrafts, LWC can be up to 5 g m 23 or more (Poellot and Pflaum 1989;Musil and Smith 1989). Recent aircraft observations by Prabha et al (2011) in the Indian monsoon region show the horizontally averaged LWC in premonsoon and monsoon convection clouds in the range of 0.5-2 g m 23 , with typical values between 1 and 1.5 g m 23 in midtroposphere.…”

Section: Evaluation Of the Parameterization With Observations A Micrmentioning

confidence: 96%

Evaluation of Microphysics Parameterization for Convective Clouds in the NCAR Community Atmosphere Model CAM5

Song

Zhang

2012

Journal of Climate

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A physically based two-moment microphysics parameterization scheme for convective clouds is implemented in the NCAR Community Atmosphere Model version 5 (CAM5) to improve the representation of convective clouds and their interaction with large-scale clouds and aerosols. The explicit treatment of mass mixing ratio and number concentration of cloud and precipitation particles enables the scheme to account for the impact of aerosols on convection. The scheme is linked to aerosols through cloud droplet activation and ice nucleation processes and to stratiform cloud parameterization through convective detrainment of cloud liquid/ice water content (LWC/IWC) and droplet/crystal number concentration (DNC/CNC). A 5-yr simulation with the new convective microphysics scheme shows that both cloud LWC/IWC and DNC/CNC are in good agreement with observations, indicating the scheme describes microphysical processes in convection well. Moreover, the microphysics scheme is able to represent the aerosol effects on convective clouds such as the suppression of warm rain formation and enhancement of freezing when aerosol loading is increased. With more realistic simulations of convective cloud microphysical properties and their detrainment, the mid-and low-level cloud fraction is increased significantly over the ITCZ-southern Pacific convergence zone (SPCZ) and subtropical oceans, making it much closer to the observations. Correspondingly, the serious negative bias in cloud liquid water path over subtropical oceans observed in the standard CAM5 is reduced markedly. The large-scale precipitation is increased and precipitation distribution is improved as well. The long-standing precipitation bias in the western Pacific is significantly alleviated because of microphysicsthermodynamics feedbacks.

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Section: Evaluation Of the Parameterization With Observations A Micrmentioning

confidence: 96%

Evaluation of Microphysics Parameterization for Convective Clouds in the NCAR Community Atmosphere Model CAM5

Song

Zhang

2012

Journal of Climate

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“…Continental cumulus clouds exhibit significantly higher liquid water contents: Poellot and Pflaum [1989] measured averages in the range 0.3-1.19 g m −3 , depending on temperature level and updraft velocity, and peak values up to 4.4 g m −3 . In the absence of temperature and pressure information, the units of g m −3 in which liquid water content of convective clouds is typically reported in the literature cannot be readily converted to the more convenient g kg −1 .…”

Section: A5 Cloud Processing and Cf 3 C(o)f Lifetimementioning

confidence: 98%

Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO‐1234yf

et al. 2014

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Currently, HFC‐134a (1,1,1,2‐tetrafluoroethane) is the most common refrigerant in automobile air conditioners. This high global warming potential substance (100 year GWP of 1370) will likely be phased out and replaced with HFO‐1234yf (2,3,3,3‐tetrafluoropropene) that has a 100 year GWP of 4. HFO‐1234yf will be oxidized to produce trifluoroacetic acid (TFA) in clouds. TFA, a mildly toxic substance with detrimental effects on some aquatic organisms at high concentrations (≥100μgL−1), would be transported by rain to the surface and enter bodies of water. We investigated the dry and wet deposition of TFA from HFO‐1234yf over the contiguous USA using the Advanced Research Weather Research and Forecasting model (ARW) with interactive chemical, aerosol, and cloud processes (WRF/Chem) model. Special focus was placed on emissions from three continental USA regions with different meteorological characteristics. WRF/Chem simulated meteorology, cloud processes, gas and aqueous phase chemistry, and dry and wet deposition between May and September 2006. The model reproduced well the multimonth total sulfate wet deposition (4% bias) and its spatial variability (r = 0.86) observed by the National Atmospheric Deposition Program. HFO‐1234yf emissions were obtained by assuming the number of automobile air conditioners to remain unchanged, and substituting HFO‐1234yf, mole‐per‐mole for HFC‐134a. Our estimates of current HFC‐134a emissions were in agreement with field data. Average TFA rainwater concentration was 0.89μgL−1, with peak values of 7.8μgL−1, for the May–September 2006 period over the contiguous USA. TFA rainwater concentrations over the dry western USA were often significantly higher, but wet‐deposited TFA amounts remained relatively low at such locations.

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“…There is a typographical error in equations numbered ( 10) and (11). with liquid water content greater than 1 g m − 3 was often observed (Paluch et al, 1995) and in addition, Poellot and Pflaum (1989) have even reported values of 5 g m − 3 in particular cumuli with very high updraughts.…”

Section: Comparison With Other Relationsmentioning

confidence: 94%

Influence of drizzle on Z–M relationships in warm clouds

Pujol¹,

Georgis²,

Sauvageot³

2007

Atmospheric Research

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This paper addresses the sensitivity of the relationships between radar reflectivity (Z) and liquid water content (M) for liquid water clouds to microphysical drizzle parameters by means of simulated radar observation at a frequency of 3 GHz of modeled cumulus clouds. A power law relationship for non drizzling clouds with water content as high as 3 gm − 3 : Z c = 0.026 M c 1.61 is numerically derived and agreed with previous empirical relationships relative to cumulus and stratocumulus. This relationship is then used to explore the influence of drizzle on the correlation between radar reflectively and water content. Due to their large diameters with respect to cloud droplets, drizzle sized drops dominate radar reflectivity but do not carry the cloud water content so that reflectivity and liquid water content are expected to be not correlated in clouds containing drizzle. It is shown that for congestus or extreme congestus cumuli, microphysical conditions for which the Z c -M c relationship can be used with a tolerance of 5 and 10% are provided whereas for humilis or mediocris cumuli, the presence of drizzle breaks down the Z c -M c relationship whatever the situations.

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Microphysical characteristics of some convective clouds over Oklahoma

Cited by 8 publications

References 7 publications

Evaluation of Microphysics Parameterization for Convective Clouds in the NCAR Community Atmosphere Model CAM5

Evaluation of Microphysics Parameterization for Convective Clouds in the NCAR Community Atmosphere Model CAM5

Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO‐1234yf

Influence of drizzle on Z–M relationships in warm clouds

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