Evaluating and constraining ice cloud parameterizations in CAM5 using aircraft measurements from the SPARTICUS campaign

Abstract. This study uses aircraft measurements of relative humidity and ice crystal size distribution collected in synoptic cirrus during the SPARTICUS (Small PARTicles In CirrUS) field campaign to evaluate and constrain ice cloud parameterizations in the Community Atmosphere Model version 5. The probability density function (PDF) of ice crystal number concentration (Ni) derived from high frequency (1 Hz) measurements features a strong dependence on ambient temperature. As temperature decreases from −35 °C to −62 °C, the peak in the PDF shifts from 10–20 L−1 to 200–1000 L−1, while the ice crystal number concentration shows a factor of 6–7 increase. Model simulations are performed with two different in-situ ice nucleation schemes. One of the schemes can reproduce a clear increase of Ni with decreasing temperature, by using either an observation based ice nuclei spectrum or a classical theory based spectrum with a relatively low (5–10%) maximum freezing ratio for dust aerosols. The simulation with the other scheme, which assumes a high maximum freezing ratio (100%), shows much weaker temperature dependence of Ni. Simulations are also performed to test empirical parameters related to water vapor deposition and the auto-conversion of ice crystals to snow. Results show that a value between 0.05 and 0.1 for the water vapor deposition coefficient and 250 μm for the critical ice crystal size can produce good agreements between model simulation and the SPARTICUS measurements in terms of ice crystal number concentration and effective radius. The climate impact of perturbing these parameters is also discussed.

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Evaluating and constraining ice cloud parameterizations in CAM5 using aircraft measurements from the SPARTICUS campaign

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-4963-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 4963-4982 ◽

Cited By ~ 35

Author(s):

K. Zhang ◽

X. Liu ◽

M. Wang ◽

J. M. Comstock ◽

D. L. Mitchell ◽

...

Keyword(s):

Water Vapor ◽

Vapor Deposition ◽

Model Simulation ◽

Strong Dependence ◽

Critical Diameter ◽

Climate Impact ◽

Ice Crystals ◽

Aircraft Measurements ◽

Ice Crystal ◽

Ice Cloud

Abstract. This study uses aircraft measurements of relative humidity and ice crystal size distribution collected during the SPARTICUS (Small PARTicles In CirrUS) field campaign to evaluate and constrain ice cloud parameterizations in the Community Atmosphere Model version 5. About 200 h of data were collected during the campaign between January and June 2010, providing the longest aircraft measurements available so far for cirrus clouds in the midlatitudes. The probability density function (PDF) of ice crystal number concentration (Ni) derived from the high-frequency (1 Hz) measurements features a strong dependence on ambient temperature. As temperature decreases from −35 °C to −62 °C, the peak in the PDF shifts from 10–20 L−1 to 200–1000 L−1, while Ni shows a factor of 6–7 increase. Model simulations are performed with two different ice nucleation schemes for pure ice-phase clouds. One of the schemes can reproduce a clear increase of Ni with decreasing temperature by using either an observation-based ice nuclei spectrum or a classical-theory-based spectrum with a relatively low (5–10%) maximum freezing ratio for dust aerosols. The simulation with the other scheme, which assumes a high maximum freezing ratio (100%), shows much weaker temperature dependence of Ni. Simulations are also performed to test empirical parameters related to water vapor deposition and the autoconversion of ice crystals to snow. Results show that a value between 0.05 and 0.1 for the water vapor deposition coefficient, and 250 μm for the critical diameter that distinguishes ice crystals from snow, can produce good agreement between model simulation and the SPARTICUS measurements in terms of Ni and effective radius. The climate impact of perturbing these parameters is also discussed.

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Observing cirrus halos to constrain in-situ measurements of ice crystal size

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-7-1295-2007 ◽

2007 ◽

Vol 7 (1) ◽

pp. 1295-1325 ◽

Cited By ~ 2

Author(s):

T. J. Garrett ◽

M. B. Kimball ◽

G. G. Mace ◽

D. G. Baumgardner

Keyword(s):

Crystal Size ◽

In Situ Measurements ◽

Ice Crystals ◽

Ice Crystal ◽

Optical Extinction ◽

Airborne Measurements ◽

Ice Cloud ◽

Ice Crystal Size ◽

High Concentrations

Abstract. In this study, characteristic optical sizes of ice crystals in synoptic cirrus are determined using airborne measurements of ice crystal size distributions, optical extinction and water content. The measurements are compared with coincident visual observations of ice cloud optical phenomena, in particular the 22° and 46° halos. In general, the scattering profiles derived from the in-situ cloud probe measurements are consistent with the observed halo characteristics. It is argued that this implies that the measured ice crystals were small, probably with characteristic optical radii between 10 and 20 μm. There is a current contention that in-situ measurements of high concentrations of small ice crystals reflect artifacts from the shattering of large ice crystals on instrument inlets. Significant shattering cannot be entirely excluded using this approximate technique, but it is not indicated. On the basis of the in-situ measurements, a parameterization is provided that relates the optical effective radius of ice crystals to the temperature in mid-latitude synoptic cirrus.

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review of "A water vapor modulated aerosol impact on ice crystal size"

10.5194/acp-2017-548-rc2 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Water Vapor ◽

Crystal Size ◽

Ice Crystal ◽

Ice Crystal Size

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An Effective Radius Retrieval for Thick Ice Clouds Using GOES

Journal of Applied Meteorology and Climatology ◽

10.1175/2007jamc1612.1 ◽

2008 ◽

Vol 47 (4) ◽

pp. 1222-1231 ◽

Cited By ~ 15

Author(s):

Daniel T. Lindsey ◽

Louie Grasso

Keyword(s):

Crystal Size ◽

Difficult Problem ◽

Effective Radius ◽

Ice Crystal ◽

Ice Clouds ◽

Ice Cloud ◽

Satellite Retrieval ◽

Microphysical Properties ◽

Ice Crystal Size ◽

Shortwave Infrared

Abstract Satellite retrieval of cirrus cloud microphysical properties is an important but difficult problem because of uncertainties in ice-scattering characteristics. Most methods have been developed for instruments aboard polar-orbiting satellites, which have better spatial and spectral resolution than geostationary sensors. The Geostationary Operational Environmental Satellite (GOES) series has the advantage of excellent temporal resolution, so that the evolution of thunderstorm-cloud-top properties can be monitored. In this paper, the authors discuss the development of a simple ice cloud effective radius retrieval for thick ice clouds using three bands from the GOES imager: one each in the visible, shortwave infrared, and window infrared portion of the spectrum. It is shown that this retrieval compares favorably to the MODIS effective radius algorithm. In addition, a comparison of the retrieval for clouds viewed simultaneously from GOES-East and GOES-West reveals that the assumed ice-scattering properties perform very well. The algorithm is then used to produce maps of mean ice cloud effective radius over the continental United States. A real-time version of this retrieval is currently running and may be used to study the evolution of thunderstorm-top ice crystal size in rapidly evolving convection.

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Supplementary material to "A water vapor modulated aerosol impact on ice crystal size"

10.5194/acp-2017-548-supplement ◽

2017 ◽

Author(s):

Bin Zhao ◽

Kuo-Nan Liou ◽

Yu Gu ◽

Jonathan H. Jiang ◽

Qinbin Li ◽

...

Keyword(s):

Water Vapor ◽

Crystal Size ◽

Ice Crystal ◽

Supplementary Material ◽

Ice Crystal Size

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Model emulation to understand the joint effects of ice-nucleating particles and secondary ice production on deep convective anvil cirrus

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-17315-2021 ◽

2021 ◽

Vol 21 (23) ◽

pp. 17315-17343

Author(s):

Rachel E. Hawker ◽

Annette K. Miltenberger ◽

Jill S. Johnson ◽

Jonathan M. Wilkinson ◽

Adrian A. Hill ◽

...

Keyword(s):

Temperature Dependence ◽

Production Efficiency ◽

Crystal Size ◽

Particle Production ◽

Number Concentration ◽

Mixed Phase ◽

Ice Crystals ◽

Ice Crystal ◽

Ice Crystal Size ◽

Ice Production

Abstract. Ice crystal formation in the mixed-phase region of deep convective clouds can affect the properties of climatically important convectively generated anvil clouds. Small ice crystals in the mixed-phase cloud region can be formed by heterogeneous ice nucleation by ice-nucleating particles (INPs) and secondary ice production (SIP) by, for example, the Hallett–Mossop process. We quantify the effects of INP number concentration, the temperature dependence of the INP number concentration at mixed-phase temperatures, and the Hallett–Mossop splinter production efficiency on the anvil of an idealised deep convective cloud using a Latin hypercube sampling method, which allows optimal coverage of a multidimensional parameter space, and statistical emulation, which allows us to identify interdependencies between the three uncertain inputs. Our results show that anvil ice crystal number concentration (ICNC) is determined predominately by INP number concentration, with the temperature dependence of ice-nucleating aerosol activity having a secondary role. Conversely, anvil ice crystal size is determined predominately by the temperature dependence of ice-nucleating aerosol activity, with INP number concentration having a secondary role. This is because in our simulations ICNC is predominately controlled by the number concentration of cloud droplets reaching the homogeneous freezing level which is in turn determined by INP number concentrations at low temperatures. Ice crystal size, however, is more strongly affected by the amount of liquid available for riming and the time available for deposition growth which is determined by INP number concentrations at higher temperatures. This work indicates that the amount of ice particle production by the Hallett–Mossop process is determined jointly by the prescribed Hallett–Mossop splinter production efficiency and the temperature dependence of ice-nucleating aerosol activity. In particular, our sampling of the joint parameter space shows that high rates of SIP do not occur unless the INP parameterisation slope (the temperature dependence of the number concentration of particles which nucleate ice) is shallow, regardless of the prescribed Hallett–Mossop splinter production efficiency. A shallow INP parameterisation slope and consequently high ice particle production by the Hallett–Mossop process in our simulations leads to a sharp transition to a cloud with extensive glaciation at warm temperatures, higher cloud updraughts, enhanced vertical mass flux, and condensate divergence at the outflow level, all of which leads to a larger convectively generated anvil comprised of larger ice crystals. This work highlights the importance of quantifying the full spectrum of INP number concentrations across all mixed-phase altitudes and the ways in which INP and SIP interact to control anvil properties.

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comments on "A water vapor modulated aerosol impact on ice crystal size" by Zhao, et. al.

10.5194/acp-2017-548-rc1 ◽

2017 ◽

Author(s):

Anonymous

Keyword(s):

Water Vapor ◽

Crystal Size ◽

Ice Crystal ◽

Ice Crystal Size

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Characterization of Arctic mixed-phase cloud properties at small scale and coupling with satellite remote sensing

10.5194/acp-2017-93 ◽

2017 ◽

Cited By ~ 3

Author(s):

Guillaume Mioche ◽

Olivier Jourdan ◽

Julien Delanoë ◽

Christophe Gourbeyre ◽

Guy Febvre ◽

...

Keyword(s):

Remote Sensing ◽

Crystal Size ◽

Mixed Phase ◽

Ice Crystals ◽

Small Scale ◽

Vertical Profiles ◽

Liquid Droplets ◽

Ice Crystal ◽

High Concentration ◽

Ice Crystal Size

Abstract. This study aims to characterize the microphysical and optical properties of ice crystals and supercooled liquid droplets within low-level Arctic mixed-phase clouds (MPC). We compiled and analyzed cloud in situ measurements from 4 airborne campaigns (18 flights, 71 vertical profiles in MPC) over the Greenland Sea and the Svalbard region. Cloud phase discrimination and representative vertical profiles of number, size, mass and shapes of ice crystals and liquid droplets are assessed. The results show that the liquid phase dominates the upper part of the MPC with high concentration of small droplets (120 cm−3, 15&tinsp;μm), and averaged LWC around 0.2 g m−3. The ice phase is found everywhere within the MPC layers, but dominates the properties in the lower part of the cloud and below where ice crystals precipitate down to the surface. The analysis of the ice crystal morphology highlights that irregulars and rimed are the main particle habit followed by stellars and plates. We hypothesize that riming and condensational growth processes (including the Wegener-Bergeron-Findeisein mechanism) are the main growth mechanisms involved in MPC. The differences observed in the vertical profiles of MPC properties from one campaign to another highlight that large values of LWC and high concentration of smaller droplets are possibly linked to polluted situations which lead to very low values of ice crystal size and IWC. On the contrary, clean situations with low temperatures exhibit larger values of ice crystal size and IWC. Several parameterizations relevant for remote sensing or modeling are also determined, such as IWC (and LWC) – extinction relationship, ice and liquid integrated water paths, ice concentration and liquid water fraction according to temperature. Finally, 4 flights collocated with active remote sensing observations from CALIPSO and CloudSat satellites are specifically analyzed to evaluate the cloud detection and cloud thermodynamical phase DARDAR retrievals. This comparison is valuable to assess the sub-pixel variability of the satellite measurements as well as their shortcomings/performance near the ground.

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