Vertical structure of particle properties and water content in noctilucent clouds

2008 ◽  
Vol 35 (10) ◽  
Author(s):  
G. Baumgarten ◽  
J. Fiedler
Keyword(s):  
Water Content ◽  
Vertical Structure ◽  
Noctilucent Clouds ◽  
Particle Properties

scholarly journals On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution

2010 ◽  
Vol 10 (2) ◽  
pp. 3605-3625
Author(s):  
G. Baumgarten ◽  
J. Fiedler ◽  
M. Rapp
Keyword(s):  
Particle Size ◽  
Linear Relationship ◽  
Size Distribution ◽  
Eddy Diffusion ◽  
Particle Sizes ◽  
Noctilucent Clouds ◽  
Atmospheric Variability ◽  
Distribution Width ◽  
Particle Properties ◽  
Microphysical Processes

Abstract. Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69° N, 16° E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42±0.02. For the vertically resolved particle properties (Δz=0.15 km) the slope is smaller and only 0.39±0.03. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements.

scholarly journals Changes in the shape of cloud ice water content vertical structure due to aerosol variations

2016 ◽  
Vol 16 (10) ◽  
pp. 6091-6105 ◽  
Author(s):  
Steven T. Massie ◽  
Julien Delanoë ◽  
Charles G. Bardeen ◽  
Jonathan H. Jiang ◽  
Lei Huang
Keyword(s):  
Water Content ◽  
Vertical Structure ◽  
Distribution Functions ◽  
Ozone Monitoring Instrument ◽  
Modis Aod ◽  
Ice Water Content ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Ice ◽  
Ice Water ◽  
Derivatives Of

Abstract. Changes in the shape of cloud ice water content (IWC) vertical structure due to variations in Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depths (AODs), Ozone Monitoring Instrument (OMI) absorptive aerosol optical depths (AAODs), and Microwave Limb Sounder (MLS) CO (an absorptive aerosol proxy) at 215 hPa are calculated in the Tropics during 2007–2010 based upon an analysis of DARDAR IWC profiles for deep convective clouds. DARDAR profiles are a joint retrieval of CloudSat-CALIPSO data. Analysis is performed for 12 separate regions over land and ocean, and carried out applying MODIS AOD fields that attempt to correct for 3-D cloud adjacency effects. The 3-D cloud adjacency effects have a small impact upon our particular calculations of aerosol–cloud indirect effects. IWC profiles are averaged for three AOD bins individually for the 12 regions. The IWC average profiles are also normalized to unity at 5 km altitude in order to study changes in the shape of the average IWC profiles as AOD increases. Derivatives of the IWC average profiles, and derivatives of the IWC shape profiles, in percent change per 0.1 change in MODIS AOD units, are calculated separately for each region. Means of altitude-specific probability distribution functions, which include both ocean and land IWC shape regional derivatives, are modest, near 5 %, and positive to the 2σ level between 11 and 15 km altitude. Similar analyses are carried out for three AAOD and three CO bins. On average, the vertical profiles of the means of the derivatives based upon the profile shapes over land and ocean are smaller for the profiles binned according to AAOD and CO values, than for the MODIS AODs, which include both scattering and absorptive aerosol. This difference in character supports the assertion that absorptive aerosol can inhibit cloud development.

scholarly journals Changes in the shape of cloud ice water content vertical structure due to aerosol variations

2016 ◽  
Author(s):  
Steven T. Massie ◽  
Julien Delanoe ◽  
Charles G. Bardeen
Keyword(s):  
Water Content ◽  
Vertical Structure ◽  
Distribution Functions ◽  
Convective Clouds ◽  
Modis Aod ◽  
Ice Water Content ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Cloud Ice ◽  
Ice Water ◽  
Derivatives Of

Abstract. Changes in the shape of cloud ice water content vertical structure due to aerosol variations are calculated in the Tropics during 2007–2010 based upon an analysis of DARDAR ice water content (IWC) profiles for deep convective clouds. DARDAR profiles are a joint retrieval of CloudSat-CALIPSO data. Our analysis is performed for 12 separate regions over land and ocean, and carried out applying Moderate-Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) fields that attempt to correct for 3D cloud adjacency effects. The 3D cloud adjacency effects have a small impact upon our calculations of aerosol-cloud indirect effects. IWC profiles are averaged for three AOD bins individually for the 12 regions. The IWC average profiles are also normalized to unity at 5 km altitude in order to study changes in the shape of the average IWC profiles as AOD increases. Derivatives of the IWC average profiles, and derivatives of the IWC shape profiles, in percent change per 0.1 change in MODIS AOD units, are calculated separately for each region. Means of altitude-specific probability distribution functions, which include both ocean and land IWC shape regional derivatives, are modest, near 5 %, and positive to the 2σ level between 11 and 15 km altitude.

scholarly journals A ubiquitous ice size bias in simulations of tropical deep convection

2017 ◽  
Author(s):  
McKenna W. Stanford ◽  
Adam Varble ◽  
Ed Zipser ◽  
J. Walter Strapp ◽  
Delphine Leroy ◽  
...  
Keyword(s):  
Water Content ◽  
Deep Convection ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Properties ◽  
Ice Water Content ◽  
High Bias ◽  
Microphysical Processes ◽  
Bin Microphysics ◽  
Ice Water

Abstract. The High Altitude Ice Crystals – High Ice Water Content (HAIC-HIWC) joint field campaign produced aircraft retrievals of total condensed water content (TWC), hydrometeor particle size distributions (PSDs), and vertical velocity (w) in high ice water content regions of mature and decaying tropical mesoscale convective systems (MCSs). The resulting dataset is used here to explore causes of the commonly documented high bias in radar reflectivity within cloud-resolving simulations of deep convection. This bias has been linked to overly strong simulated convective updrafts lofting excessive condensate mass but is also modulated by parameterizations of hydrometeor size distributions, single particle properties, species separation, and microphysical processes. Observations are compared with three Weather Research and Forecasting model simulations of an observed MCS using differing microphysics while controlling for w, TWC, and temperature. Two bulk microphysics schemes (Thompson and Morrison) and one bin microphysics scheme (Fast Spectral Bin Microphysics) are compared. For temperatures between −10 °C and −40 °C and TWC > 1 g m−3 inside updrafts, all microphysics schemes produce median mass diameters (MMDs) that are generally larger than observed, and the precipitating ice species that controls this size bias varies by scheme, temperature, and w. Despite a much greater number of samples, all simulations fail to reproduce observed high TWC conditions (> 2 g m−3) between −20 °C and −40 °C in which only a small fraction of condensate mass is found in relatively large particle sizes greater than 1 mm in diameter. Although more mass is distributed to relatively large particle sizes relative to observed across all schemes when controlling for temperature, w, and TWC, differences with observations for a given particle size vary greatly between schemes. As a result, this bias is hypothesized to partly result from errors in parameterized hydrometeor PSD and single particle properties, but because it is present in all schemes, it may also partly result from errors in parameterized microphysical processes present in all schemes. Because of these ubiquitous ice size biases, microphysical parameterizations inherently produce a high bias in convective reflectivity for a wide range of temperatures, vertical velocities, and TWCs.

scholarly journals On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution

2010 ◽  
Vol 10 (14) ◽  
pp. 6661-6668 ◽  
Author(s):  
G. Baumgarten ◽  
J. Fiedler ◽  
M. Rapp
Keyword(s):  
Particle Size ◽  
Linear Relationship ◽  
Size Distribution ◽  
Eddy Diffusion ◽  
Particle Sizes ◽  
Noctilucent Clouds ◽  
Atmospheric Variability ◽  
Distribution Width ◽  
Particle Properties ◽  
Microphysical Processes

Abstract. Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69° N, 16° E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42±0.02 for mean particle sizes up to 40 nm. For the vertically resolved particle properties (Δz = 0.15 km) the slope is comparable and about 0.39±0.03. For particles larger than 40 nm the distribution width becomes nearly independent of particle size and even decreases in the lower part of the layer. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements.

scholarly journals A ubiquitous ice size bias in simulations of tropical deep convection

2017 ◽  
Vol 17 (15) ◽  
pp. 9599-9621 ◽  
Author(s):  
McKenna W. Stanford ◽  
Adam Varble ◽  
Ed Zipser ◽  
J. Walter Strapp ◽  
Delphine Leroy ◽  
...  
Keyword(s):  
Water Content ◽  
Deep Convection ◽  
Particle Sizes ◽  
Size Distributions ◽  
Particle Properties ◽  
Ice Water Content ◽  
High Bias ◽  
Microphysical Processes ◽  
Bin Microphysics ◽  
Ice Water

Abstract. The High Altitude Ice Crystals – High Ice Water Content (HAIC-HIWC) joint field campaign produced aircraft retrievals of total condensed water content (TWC), hydrometeor particle size distributions (PSDs), and vertical velocity (w) in high ice water content regions of mature and decaying tropical mesoscale convective systems (MCSs). The resulting dataset is used here to explore causes of the commonly documented high bias in radar reflectivity within cloud-resolving simulations of deep convection. This bias has been linked to overly strong simulated convective updrafts lofting excessive condensate mass but is also modulated by parameterizations of hydrometeor size distributions, single particle properties, species separation, and microphysical processes. Observations are compared with three Weather Research and Forecasting model simulations of an observed MCS using different microphysics parameterizations while controlling for w, TWC, and temperature. Two popular bulk microphysics schemes (Thompson and Morrison) and one bin microphysics scheme (fast spectral bin microphysics) are compared. For temperatures between −10 and −40 °C and TWC  >  1 g m−3, all microphysics schemes produce median mass diameters (MMDs) that are generally larger than observed, and the precipitating ice species that controls this size bias varies by scheme, temperature, and w. Despite a much greater number of samples, all simulations fail to reproduce observed high-TWC conditions ( >  2 g m−3) between −20 and −40 °C in which only a small fraction of condensate mass is found in relatively large particle sizes greater than 1 mm in diameter. Although more mass is distributed to large particle sizes relative to those observed across all schemes when controlling for temperature, w, and TWC, differences with observations are significantly variable between the schemes tested. As a result, this bias is hypothesized to partly result from errors in parameterized hydrometeor PSD and single particle properties, but because it is present in all schemes, it may also partly result from errors in parameterized microphysical processes present in all schemes. Because of these ubiquitous ice size biases, the frequently used microphysical parameterizations evaluated in this study inherently produce a high bias in convective reflectivity for a wide range of temperatures, vertical velocities, and TWCs.

scholarly journals Evaluating CloudSat ice water content retrievals using a cloud-resolving model: Sensitivities to frozen particle properties

2008 ◽  
Vol 113 ◽  
Author(s):  
Christopher P. Woods ◽  
Duane E. Waliser ◽  
Jui-Lin Li ◽  
Richard T. Austin ◽  
Graeme L. Stephens ◽  
...  
Keyword(s):  
Water Content ◽  
Particle Properties ◽  
Cloud Resolving Model ◽  
Ice Water Content ◽  
Ice Water
Sign in / Sign up

Export Citation Format

Share Document