Multi-Layer Arctic Mixed-Multi-Layer Arctic Mixed-Phase Clouds Simulated by a Phase Clouds Simulated by a

Cloud-Resolving Model:Cloud-Resolving Model: Comparison with ARM Comparison with ARM

Observations and Sensitivity Observations and Sensitivity ExperimentsExperiments

Yali LuoYali Luo

State Key Lab of Severe Weather (LaSW)State Key Lab of Severe Weather (LaSW)Chinese Academy of Meteorological SciencesChinese Academy of Meteorological Sciences

Co-authorsCo-authors: Kuan-Man Xu (: Kuan-Man Xu (LaRCLaRC), Hugh Morrison (), Hugh Morrison (NCARNCAR), Greg ), Greg McFarquhar (McFarquhar (U IllinoisU Illinois), Zhien Wang (), Zhien Wang (U WyomingU Wyoming), Gong Zhang (), Gong Zhang (U U

IllinoisIllinois))

Polar Cloud Working Group Breakout Session II, 4th Pan-GCSS MeetingPolar Cloud Working Group Breakout Session II, 4th Pan-GCSS MeetingJune 4June 4thth 2008; Toulouse, France 2008; Toulouse, France

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OutlineOutline1.1. IntroductionIntroduction2.2. Large-scale background and Large-scale background and

observationsobservations3.3. Model and simulationsModel and simulations4.4. Comparing Baseline results Comparing Baseline results

with observationswith observations5.5. Results from sensitivity Results from sensitivity

experimentsexperiments

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IntroductionIntroductionThe UCLA/CAMS CRM is used to simulate the The UCLA/CAMS CRM is used to simulate the

multiple-layer mixed-phase stratiform (MPS) multiple-layer mixed-phase stratiform (MPS) clouds that occurred during a 3.5-day sub-period clouds that occurred during a 3.5-day sub-period of the M-PACE (14Z 5 Oct - 02Z 9 Oct)of the M-PACE (14Z 5 Oct - 02Z 9 Oct)

The large-scale forcing data used is the same as The large-scale forcing data used is the same as that for the ARM inter-comparison of model that for the ARM inter-comparison of model simulationssimulations

Baseline results are compared to the M-PACE Baseline results are compared to the M-PACE observations observations

Sensitivity experiments are conducted to explore Sensitivity experiments are conducted to explore the possible mechanisms for the formation and the possible mechanisms for the formation and evolution of the multiple-layer MPS cloudsevolution of the multiple-layer MPS clouds

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OutlineOutline1.1. IntroductionIntroduction2.2. Large-scale background and Large-scale background and

observationsobservations3.3. Model and simulationsModel and simulations4.4. Comparing Baseline results with Comparing Baseline results with

observationsobservations5.5. Results from sensitivity Results from sensitivity

experimentsexperiments6.6. ConclusionsConclusions

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Large-scale backgroundLarge-scale background

201 km360 km

Toolik Lake

High pressure over the pack ice to the northeast of the Alaska coast

North Slope of North Slope of Alaska (NSA)Alaska (NSA)

Barrow

Midlevel low pressure system drifted along the northern Alaska coast

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Observations of Observations of Cloud Cloud propertiesproperties

Occurrences and Occurrences and locations of locations of mixed-phase mixed-phase cloud layers cloud layers

Liquid water pathLiquid water pathBulk cloud Bulk cloud

microphysical microphysical propertiesproperties

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Other observations usedOther observations usedAerosol properties Aerosol properties (for (for

microphysics calculation)microphysics calculation)Surface precipitation rate, Surface precipitation rate,

temperature, moisture temperature, moisture (for (for model evaluation; produced by model evaluation; produced by the ARM analysis)the ARM analysis)

88

OutlineOutline1.1. IntroductionIntroduction2.2. Large-scale background and Large-scale background and

observationsobservations3.3. Model and simulationsModel and simulations4.4. Comparing Baseline results with Comparing Baseline results with

observationsobservations5.5. Results from sensitivity Results from sensitivity

experimentsexperiments6.6. Conclusions Conclusions

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UCLA/CAMS CRMUCLA/CAMS CRM(University of California at Los (University of California at Los Angeles/Chinese Academy of Angeles/Chinese Academy of

Meteorological Sciences)Meteorological Sciences)Anelastic dynamic framework Anelastic dynamic framework Third-order turbulence closureThird-order turbulence closure -four-stream radiative transfer scheme-four-stream radiative transfer schemeTwo-moment microphysics Two-moment microphysics parameterizationparameterization

Krueger, S. K., 1988: Numerical simulation of tropical cumulus clouds and their interaction with the subcloud layer. J. Atmos. Sci., 45, 2221-2250.

Luo, Y., etc., 2008: Arctic mixed-phase clouds simulated by a cloud-resolving model: Comparison with ARM observations and sensitivity to microphysics parameterizations. J. Atmos. Sci., 65, 1285-1303.

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Large-scale forcing dataLarge-scale forcing data

Klein, S., A. Fridlind, R. McCoy, G. McFarquhar, S. Menon, H. Morrison, S. Xie, J. J. Yio, and M. Zhang (2006), Arm Cloud Parameterization and Modeling Working Group – GCSS Polar Cloud Working Group model intercomparison. Procedures for ARM CPMWG Case 5/GCSS Polar Cloud WG SCM/CRM/LES Intercomparison Case f2004: ARM Mixed-phase Arctic Cloud Experiment (M-PACE): October 5-22, 2004.

Xie, S., S. A. Klein, M. Zhang, J. J. Yio, R. T. Cederwall, and R. McCoy (2006), Developing large-scale forcing data for single-column and cloud-resolving models from the Mixed-Phase Arctic Cloud Experiment, J. Geophys. Res., 111, D19104, doi:10.1029/2005JD006950.

Large-scale advection of temperature and moistureSurface fluxes of latent and sensible heatSkin temperatureSurface broadband albedo

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List of simulationsList of simulations1.1. BaselineBaseline: standard baseline simulation: standard baseline simulation2.2. noLSforcingnoLSforcing: neglecting large-scale advective : neglecting large-scale advective

forcingforcing3.3. noSfcFlxnoSfcFlx: neglecting surface fluxes of latent and : neglecting surface fluxes of latent and

sensible heatsensible heat4.4. noLWradnoLWrad: neglecting longwave radiative : neglecting longwave radiative

cooling/heatingcooling/heating5.5. noIcenoIce: neglecting ice-phase microphysical : neglecting ice-phase microphysical

processesprocesses6.6. IN50thIN50th ：： decreasing IFN concentration from 0.16/L decreasing IFN concentration from 0.16/L

to 0.003/Lto 0.003/L7.7. IN50IN50 ：： increasing IFN concentration from 0.16/L increasing IFN concentration from 0.16/L

to 8/Lto 8/L

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OutlineOutline1.1. IntroductionIntroduction2.2. Large-scale background and Large-scale background and

observationsobservations3.3. Model and simulationsModel and simulations4.4. Comparing Baseline results with Comparing Baseline results with

observationsobservations5.5. Results from sensitivity Results from sensitivity

experimentsexperiments6.6. Conclusions Conclusions

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Baseline Results: Baseline Results: Time-height Time-height distribution of distribution of horizontal-averagedhorizontal-averaged LWC (shades) and IWC (lines)LWC (shades) and IWC (lines)

Time (hrs from 14Z October 5, 2004)

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Baseline Results: Baseline Results: Occurrences of Occurrences of multiple-layer MPS cloudsmultiple-layer MPS clouds

1- layer (%) 2-layer (%) 3-layer (%)

MMCR-MPL 10/06 49 41 9CRM 12-36 h 29 64 7MMCR-MPL 10/07 66 31 3CRM 36-60 h 63 36 1MMCR-MPL 10/08 90 10 0CRM 60-84 h 66 34 0

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Baseline Results: Baseline Results: Histograms ofHistograms of cloud-base cloud-base height, cloud-top height and cloud physical height, cloud-top height and cloud physical

thickness of the thickness of the 1st1st MPS cloud layer MPS cloud layer

ObservationsCRM Baseline Cloud Base

Height

Cloud Top

Height

Cloud Physical

Thickness

Lower!

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Baseline Results: Baseline Results: Histograms ofHistograms of cloud-base cloud-base height, cloud-top height and cloud physical height, cloud-top height and cloud physical

thickness of the thickness of the 2nd2nd MPS cloud layer MPS cloud layer

ObservationsCRM Baseline Cloud Base

Height

Cloud Top

Height

Cloud Physical

Thickness

Too homogeneous in the horizontal!

Thicker!

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Baseline Results: Baseline Results: Vertical profiles ofVertical profiles of in-cloud in-cloud LWCLWC

CRM BaselineAircraft Obs.Subperiod A

Subperiod B

Subperiod C

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Baseline Results: Baseline Results: Vertical profiles Vertical profiles ofof in-cloud in-cloud nncc

CRM BaselineAircraft Obs.

Subperiod A

Subperiod B

Subperiod C

?

?

CCN activation parameterization

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Baseline Results: Baseline Results: Vertical profiles ofVertical profiles of in-cloud in-cloud IWCIWC

Aircraft Obs. CRM BaselineSubperiod A

Subperiod B

Subperiod C but a few times smaller than observations.

Reproduced the larger IWCs below 1.5 km;

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Baseline Results: Baseline Results: Vertical profiles Vertical profiles of of in-cloudin-cloud n nii

CRM BaselineAircraft Obs.

Subperiod A

Subperiod B

Subperiod C

Differ by one order of

magnitude!

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Baseline Results: Baseline Results: Surface Surface precipitationprecipitation

Dashed line: CRM Baseline

Solid line: Observations

delayed underestimated

11

22

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Summary of baseline resultsSummary of baseline resultsThe Baseline simulation reproduces the dominance of single- The Baseline simulation reproduces the dominance of single- and double-layer MPS clouds revealed by the MMCR-MPL and double-layer MPS clouds revealed by the MMCR-MPL observations and qualitatively captures the major characteristics observations and qualitatively captures the major characteristics in the vertical distributions of LWC, nc, ISWC and nis and their in the vertical distributions of LWC, nc, ISWC and nis and their interperiod differences suggested by the aircraft observations. interperiod differences suggested by the aircraft observations. However, However, The simulated first MPS cloud layer is too low and nc within the The simulated first MPS cloud layer is too low and nc within the

lower layer decreases with height, in contrast to the relatively lower layer decreases with height, in contrast to the relatively constant nc revealed by the observations. These could be due to constant nc revealed by the observations. These could be due to uncertainties associated with the parameterizations (e.g., uncertainties associated with the parameterizations (e.g., turbulence, droplet activation, radiation), and the forcing data.turbulence, droplet activation, radiation), and the forcing data.

The simulated second cloud layer is too thick with too large LWC, The simulated second cloud layer is too thick with too large LWC, causing too strong LW cooling and negative biases in temperature. causing too strong LW cooling and negative biases in temperature.

Both simulated cloud layers contain too few ice crystal numbers Both simulated cloud layers contain too few ice crystal numbers and too small ice crystal masses, indicating missing of ice and too small ice crystal masses, indicating missing of ice enhancement mechanisms in the microphysics scheme and enhancement mechanisms in the microphysics scheme and resulting in the underestimate of surface precipitation rates.resulting in the underestimate of surface precipitation rates.

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OutlineOutline1.1. IntroductionIntroduction2.2. Large-scale background and Large-scale background and

observationsobservations3.3. Model and simulationsModel and simulations4.4. Comparing Baseline results Comparing Baseline results

with observationswith observations5.5. Results from sensitivity Results from sensitivity

experimentsexperiments

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Time-height distribution of LWC Time-height distribution of LWC and ISWC :and ISWC : Baseline vs. noLSadvBaseline vs. noLSadv

noSfcFlx

Baseline noLSadv

T advection qv advection

cooling moistening

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Time-height distribution of LWC Time-height distribution of LWC and ISWC :and ISWC : Baseline vs. noSfcFlxBaseline vs. noSfcFlx

BaselinenoSfcFlx

LH: 185 W m-2

SH: 35 W m-2

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Time-height distribution of LWC Time-height distribution of LWC and ISWC:and ISWC: Baseline vs. noLWradBaseline vs. noLWrad

Baseline noLWrad

LW radiative cooling/heating in Baseline

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Time-height distribution of LWC Time-height distribution of LWC and ISWC:and ISWC: Baseline vs. noIce and Baseline vs. noIce and

IN50thIN50thBaseline noIce

The temporally averaged LWP is increased by a factor of 3 in

noIce compared to the Baseline, suggesting depletion

of liquid droplets by ice crystals in Baseline.

IN50th

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Time-height distribution of LWC Time-height distribution of LWC and ISWC:and ISWC: Baseline vs. IN50Baseline vs. IN50

Baseline IN50

No MPS clouds are formed in IN50 experiment (while magnitude of the vertically integrated ice and snow mass increases by a factor of 6).

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Summary of sensitivity Summary of sensitivity experimentsexperiments

LW radiative cooling

LW radiative warming

Surface fluxes of latent and sensible heat

LS advection

Bergeron process

Bergeron process

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End.End.Thanks for your Thanks for your

attention!attention!

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Summary of sensitivity Summary of sensitivity experimentsexperiments

LW radiative cooling

LW radiative warming

Surface fluxes of latent and sensible heat

LS advection

Bergeron process

Bergeron process

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Time-height distribution of LWC Time-height distribution of LWC and ISWC :and ISWC : Baseline vs. noMicLatBaseline vs. noMicLat

Baseline noMicLat

Heating/cooling due to phase change in Baseline

a larger magnitude of LWC in the interior of the MPS cloud layers

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Observations of Observations of Aerosol Aerosol propertiesproperties

observed and fitted dry aerosol size distribution

Aerosol composition: ammonium bisurfate (NH4HSO4) with an insoluble fraction of 30%

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Observations of Observations of Ice nulcei (IN) Ice nulcei (IN) number concentrationnumber concentration

Active IN acting in deposition, condensation-freezing, and immersion-freezing modes:

a mean of 0.16 L-1

Contact-freezing IN:a function of temperature (Meyers et al., 1992)

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Field measurements:Field measurements:Profiles of the sample numbers for liquid water content (solid lines) and ice water content (dashed lines), respectively, in each height bin of 400 m during the three missions that the UND Citation took on October 5 (a), October 6 (b), and October 8 (c), 2004.

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Baseline Results: Baseline Results: Temperature and Temperature and moisturemoisture

CRM Baseline

Baseline-Analysis

water vapor mixing ratio

temperature

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Baseline Results: Baseline Results: Time series of Time series of LWPLWP

Baseline (79 g m-2)MWR retrieval

(81 g m-2)

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Results from sensitivity tests:Results from sensitivity tests: eddy eddy kinetic energykinetic energy