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Improving the representation of supercooled liquid water in the HARMONIE-AROME weather forecast model Cover

Improving the representation of supercooled liquid water in the HARMONIE-AROME weather forecast model

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Volume 72 (2020): Issue 1
By: ,   and    
Open Access
|Jan 2020
Figures & tables

Figures & Tables

Fig. 1.

(a) Skew-T plot of the initial profile and (b) time-height cross-section of the vertical velocity forcing used for the orographic lifting case in MUSC.

Fig. 2.

(a) Skew-T plot of the freezing drizzle case, blue lines represent the operational forecast from HARMONIE-AROME and initial profile used in MUSC, while red lines represent the radiosonde profile taken from MET-Norway’s site at Blindern, Oslo at 1150 UTC. (b) time-height cross-section of the vertical velocity forcing applied to the MUSC experiments for the freezing drizzle case.

Table 1.

List of MUSC 1 D experiments and the microphysical processes studied.

ExperimentProcess alteredPreviousNewCTRLHeterogeneous ice nucleationCode mistakeBug fixBR74Autoconversion (cloud to rain)Khairoutdinov and Kogan (2000)Berry and Reinhardt (1974)ACCRain accreting cloud waterVariable efficiency (OCND2)Variable efficiency (Thompson)C86Heterogeneous ice nucleationMeyers et al. (1992)Cooper (1986)BiggFreezing of water dropsNoneBigg (1954)GCWGraupel collecting cloud waterFerrier (1994) for dry growth; Musil (1970) and Nelson (1983) for wet growthCober and List (1993)SCWSnow collecting cloud waterFarley et al. (1989)Wang and Ji (2000)RCSRain collecting snowFerrier (1994); Eff = 1.0New variable collection efficiencyRCGRain collecting graupelFerrier (1994); Eff = 1.0New variable collection efficiencyHPHydrometeor propertiesLocatelli and Hobbs (1974)Thompson et al. (2008)Y-INTRain inverse exponential Y-intercept parameter8 × 106 m−4 (Marshal-Palmer)Variable intercept parameter (Thompson et al 2004)
Fig. 3.

Results from the control run (CTRL) for the orographic lift case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) cloud ice, (h) snow, and (i) cloud droplets.

Fig. 4.

Results from the Bigg experiment for the orographic lift case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) cloud ice, (h) snow, and (i) cloud droplets.

Fig. 5.

Results from experiment SCW for the orographic lift case. Time-height cross-sections of mixing ratios of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) rain, (h) snow, and (i) cloud droplets.

Fig. 6. Plot of the collection efficiency for rain collecting snow/graupel with terminal velocity ratio (snow/graupel to rain).

Table 2.

List of coefficients for mass and velocity-diameter relations for CTRL and HP experiments.

SpeciesCTRLHPSnowa = 0.02, b = 1.9, c = 5.1, d = 0.27a = 0.069, b = 2, c = 40, d = 0.55Graupela = 19.6, b = 2.8, c = 124, d = 0.66a = 19.6, b = 2.8, c = 442, d = 0.89
Fig. 7.

Results from the Y-INT experiment for the orographic lift case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) rain, (h) snow, and (i) cloud droplets.

Fig. 8.

Results from the control experiment (CTRL) for the freezing drizzle case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) rain, (h) snow, and (i) cloud droplets.

Fig. 9.

Results from the ACC experiment for the freezing drizzle case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain.

Fig. 10. Results from experiment Y-INT for the freezing drizzle case. Time-height cross-sections of (a) relative humidity with respect to ice saturation, mixing ratios of (b) cloud ice, (c) cloud droplets, (d) graupel, (e) snow, and (f) rain. Budget plots with time-evolutions of the sum of sources and sinks for (g) rain, (h) snow, and (i) cloud droplets.

DOI: https://doi.org/10.1080/16000870.2019.1697603 | Journal eISSN: 3035-9554
Journal RSS Feed
Language: English
Page range: 1697603 - 1697603
Published on: Jan 1, 2020
Published by: Stockholm University Press
In partnership with: Paradigm Publishing Services
Keywords:
cloud microphysics,
supercooled liquid water,
numerical modelling,
HARMONIE-AROME,
atmospheric icing forecast

© 2020 Bjørg Jenny Kokkvoll Engdahl, Gregory Thompson, Lisa Bengtsson, published by Stockholm University Press
This work is licensed under the Creative Commons Attribution 4.0 License.

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