• Barnes, H. C., J. P. Zagrodnik, L. A. McMurdie, A. K. Rowe, and R. A. Houze Jr., 2018: Kelvin–Helmholtz waves in precipitating midlatitude cyclones. J. Atmos. Sci., 75, 27632785, https://doi.org/10.1175/JAS-D-17-0365.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Bergeron, T., 1935: On the physics of cloud and precipitation. Proc. Fifth Assembly UGGI, Lisbon, Portugal, Union Géodésique et Géophysique Internationale, 156–178.

  • Bergmaier, P. T., and B. Geerts, 2016: Airborne radar observations of lake-effect snow bands over the New York Finger Lakes. Mon. Wea. Rev., 144, 38953914, https://doi.org/10.1175/MWR-D-16-0103.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Blestrud, D., 2018: Idaho Power Company Crouch sounding data [IPC], version 1.0. UCAR/NCAR Earth Observing Laboratory, accessed 16 January 2018, https://doi.org/10.5065/D67S7MJ9.

    • Crossref
    • Export Citation
  • Chen, S., P. Bartello, M. K. Yau, P. A. Vaillancourt, and K. Zwijsen, 2016: Cloud droplet collisions in turbulent environment: Collision statistics and parameterization. J. Atmos. Sci., 73, 621636, https://doi.org/10.1175/JAS-D-15-0203.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Choularton, T. W., and S. J. Perry, 1986: A model of the orographic enhancement of snowfall by the seeder-feeder mechanism. Quart. J. Roy. Meteor. Soc., 112, 335345, https://doi.org/10.1002/qj.49711247204.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chu, X., L. Xue, B. Geerts, and B. Kosovicì, 2018: The impact of boundary layer turbulence on snow growth and precipitation: Idealized large eddy simulations. Atmos. Res., 204, 5466, https://doi.org/10.1016/j.atmosres.2018.01.015.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Conrick, R., C. F. Mass, and Q. Zhong, 2018: Simulated Kelvin–Helmholtz waves over terrain and their microphysical implications. J. Atmos. Sci., 75, 27872800, https://doi.org/10.1175/JAS-D-18-0073.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Damiani, R., and S. Haimov, 2006: A high-resolution dual-Doppler technique for fixed multiantenna airborne radar. IEEE Trans. Geosci. Remote Sens., 44, 34753489, https://doi.org/10.1109/TGRS.2006.881745.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Field, P. R., and et al. , 2017: Secondary ice production: Current state of the science and recommendations for the future. Ice Formation and Evolution in Clouds and Precipitation: Measurement and Modeling Challenges, Meteor. Monogr., No. 58, Amer. Meteor. Soc., https://doi.org/10.1175/AMSMONOGRAPHS-D-16-0014.1.

    • Crossref
    • Export Citation
  • Finlon, J. A., G. M. McFarquhar, R. M. Rauber, D. M. Plummer, B. F. Jewett, D. Leon, and K. R. Knupp, 2016: A comparison of X-band polarization parameters with in situ microphysical measurements in the comma head of two winter cyclones. J. Appl. Meteor. Climatol., 55, 25492574, https://doi.org/10.1175/JAMC-D-16-0059.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • French, J. R., and A. Majewksi, 2017: UW King Air hydrometeor size spectra data, version 1.0. UCAR/NCAR Earth Observing Laboratory, accessed 22 December 2017, https://doi.org/10.5065/D6GT5KXK.

    • Crossref
    • Export Citation
  • French, J. R., and et al. , 2018: Precipitation formation from orographic cloud seeding. Proc. Natl. Acad. Sci. USA, 115, 11681173, https://doi.org/10.1073/pnas.1716995115.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Friedrich, K., and et al. , 2020: Quantifying snowfall from orographic cloud seeding. Proc. Natl. Acad. Sci. USA, 117, 51905195, https://doi.org/10.1073/pnas.1917204117.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Geerts, B., and Q. Miao, 2005: The use of millimeter Doppler radar echoes to estimate vertical air velocities in the fair-weather convective boundary layer. J. Atmos. Oceanic Technol., 22, 225246, https://doi.org/10.1175/JTECH1699.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Geerts, B., R. Damiani, and S. Haimov, 2006: Finescale vertical structure of a cold front as revealed by an airborne Doppler radar. Mon. Wea. Rev., 134, 251271, https://doi.org/10.1175/MWR3056.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Geerts, B., Q. Miao, and Y. Yang, 2011: Boundary layer turbulence and orographic precipitation growth in cold clouds: Evidence from profiling airborne radar data. J. Atmos. Sci., 68, 23442365, https://doi.org/10.1175/JAS-D-10-05009.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grabowski, W. W., and L. P. Wang, 2013: Growth of cloud droplets in a turbulent environment. Annu. Rev. Fluid Mech., 45, 293324, https://doi.org/10.1146/annurev-fluid-011212-140750.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Grasmick, C., and B. Geerts, 2020: Detailed dual-Doppler structure of Kelvin–Helmholtz waves from an airborne profiling radar over complex terrain. Part I: Dynamic structure. J. Atmos. Sci., 77, 17611782, https://doi.org/10.1175/JAS-D-19-0108.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Haimov, S., and A. Rodi, 2013: Fixed-antenna pointing-angle calibration of airborne Doppler cloud radar. J. Atmos. Oceanic Technol., 30, 23202335, https://doi.org/10.1175/JTECH-D-12-00262.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hallett, J., and S. C. Mossop, 1974: Production of secondary ice particles during the riming process. Nature, 249, 2628, https://doi.org/10.1038/249026a0.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Herzegh, P. H., and P. V. Hobbs, 1980: The mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones. II: Warm-frontal clouds. J. Atmos. Sci., 37, 597611, https://doi.org/10.1175/1520-0469(1980)037<0597:TMAMSA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Houser, J. L., and H. B. Bluestein, 2011: Polarimetric Doppler radar observations of Kelvin–Helmholtz waves in a winter storm. J. Atmos. Sci., 68, 16761702, https://doi.org/10.1175/2011JAS3566.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Houze, R. A., Jr., and S. Medina, 2005: Turbulence as a mechanism for orographic precipitation enhancement. J. Atmos. Sci., 62, 35993623, https://doi.org/10.1175/JAS3555.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Jackson, R. C., and G. M. McFarquhar, 2014: An assessment of the impact of antishattering tips and artifact removal techniques on bulk cloud ice microphysical and optical properties measured by the 2D cloud probe. J. Atmos. Oceanic Technol., 31, 21312144, https://doi.org/10.1175/JTECH-D-14-00018.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kalesse, H., W. Szyrmer, S. Kneifel, P. Kollias, and E. Luke, 2016: Fingerprints of a riming event on cloud radar Doppler spectra: Observations and modeling. Atmos. Chem. Phys., 16, 29973012, https://doi.org/10.5194/acp-16-2997-2016.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Keeler, J. M., B. F. Jewett, R. M. Rauber, G. M. McFarquhar, R. M. Rasmussen, L. Xue, C. Liu, and G. Thompson, 2016: Dynamics of cloud-top generating cells in winter cyclones. Part II: Radiative and instability forcing. J. Atmos. Sci., 73, 15291553, https://doi.org/10.1175/JAS-D-15-0127.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Keppas, S. C., J. Crosier, T. W. Choularton, and K. N. Bower, 2018: Microphysical properties and radar polarimetric features within a warm front. Mon. Wea. Rev., 146, 20032022, https://doi.org/10.1175/MWR-D-18-0056.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., 1995: The influence of supersaturation fluctuations on droplet size spectra formation. J. Atmos. Sci., 52, 36203634, https://doi.org/10.1175/1520-0469(1995)052<3620:TIOSFO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., and I. P. Mazin, 2003: Supersaturation and time of phase relaxation in mixed clouds (theoretical consideration). Russ. Meteor. Hydrol., 28, 524.

    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., and T. Leisner, 2020: Review of experimental studies of secondary ice production. Atmos. Chem. Phys., 20, 11 76711 797, https://doi.org/10.5194/acp-20-11767-2020.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., J. W. Strapp, G. A. Isaac, and A. N. Nevzorov, 1998: The Nevzorov airborne hot-wire LWC–TWC probe: Principle of operation and performance characteristics. J. Atmos. Oceanic Technol., 15, 14951510, https://doi.org/10.1175/1520-0426(1998)015<1495:TNAHWL>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Korolev, A. V., and et al. , 2017: Mixed-phase clouds: Progress and challenges. Ice Formation and Evolution in Clouds and Precipitation: Measurement and Modeling Challenges, Meteor. Monogr., No. 58, Amer. Meteor. Soc., https://doi.org/10.1175/AMSMONOGRAPHS-D-17-0001.1.

    • Crossref
    • Export Citation
  • Lance, S., C. A. Brock, D. Rogers, and J. A. Gordon, 2010: Water droplet calibration of a cloud droplet probe and in-flight performance in liquid, ice and mixed-phase clouds during ARCPAC. Atmos. Meas. Tech., 3, 16831706, https://doi.org/10.5194/amt-3-1683-2010.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lawson, R. P., D. O’Connor, P. Zmarzly, K. Weaver, B. Baker, Q. Mo, and H. Jonsson, 2006: The 2D-S (stereo) probe: Design and preliminary tests of a new airborne, high-speed, high-resolution particle imaging probe. J. Atmos. Oceanic Technol., 23, 14621477, https://doi.org/10.1175/JTECH1927.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mahalov, A., M. Moustaoui, and V. Grubisic, 2011: A numerical study of mountain waves in the upper troposphere and lower stratosphere. Atmos. Chem. Phys., 11, 51235139, https://doi.org/10.5194/acp-11-5123-2011.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Majewski, A., and J. R. French, 2020: Supercooled drizzle development in response to semi-coherent vertical velocity fluctuations within an orographic-layer cloud. Atmos. Chem. Phys., 20, 50355054, https://doi.org/10.5194/acp-20-5035-2020.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Mazin, I., 1986: Relation of cloud phase structure to vertical motion. Sov. Meteor. Hydrol., N11, 2735.

  • Medina, S., and R. A. Houze, 2015: Small-scale precipitation elements in midlatitude cyclones crossing the California Sierra Nevada. Mon. Wea. Rev., 143, 28422870, https://doi.org/10.1175/MWR-D-14-00124.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Miao, Q., B. Geerts, and M. LeMone, 2006: Vertical velocity and buoyancy characteristics of coherent echo plumes in the convective boundary layer, detected by a profiling airborne radar. J. Appl. Meteor. Climatol., 45, 838855, https://doi.org/10.1175/JAM2375.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Moeng, C. H., 1984: A large-eddy-simulation model for the study of planetary boundary-layer turbulence. J. Atmos. Sci., 41, 20522062, https://doi.org/10.1175/1520-0469(1984)041<2052:ALESMF>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Murphy, A. M., R. M. Rauber, G. M. McFarquhar, J. A. Finlon, D. M. Plummer, A. A. Rosenow, and B. F. Jewett, 2017: A microphysical analysis of elevated convection in the comma head region of continental winter cyclones. J. Atmos. Sci., 74, 6991, https://doi.org/10.1175/JAS-D-16-0204.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pinsky, M., and A. Khain, 1998: Some effects of cloud turbulence on water–ice and ice–ice collisions. Atmos. Res., 47–48, 6986, https://doi.org/10.1016/S0169-8095(98)00041-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pinsky, M., A. Khain, and M. Shapiro, 1999: Collisions of small drops in a turbulent flow. Part I: Collision efficiency. Problem formulation and preliminary results. J. Atmos. Sci., 56, 25852600, https://doi.org/10.1175/1520-0469(1999)056<2585:COSDIA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pinsky, M., A. Khain, and M. Shapiro, 2000: Stochastic effects of cloud droplet hydrodynamic interaction in a turbulent flow. Atmos. Res., 53, 131169, https://doi.org/10.1016/S0169-8095(99)00048-4.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Plummer, D. M., G. M. McFarquhar, R. M. Rauber, B. F. Jewett, and D. C. Leon, 2014: Structure and statistical analysis of the microphysical properties of generating cells in the comma head region of continental winter cyclones. J. Atmos. Sci., 71, 41814203, https://doi.org/10.1175/JAS-D-14-0100.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Plummer, D. M., G. M. McFarquhar, R. M. Rauber, B. F. Jewett, and D. C. Leon, 2015: Microphysical properties of convectively generated fall streaks within the stratiform comma head region of continental winter cyclones. J. Atmos. Sci., 72, 24652483, https://doi.org/10.1175/JAS-D-14-0354.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rauber, R. M., and A. Tokay, 1991: An explanation for the existence of supercooled water at the top of cold clouds. J. Atmos. Sci., 48, 10051023, https://doi.org/10.1175/1520-0469(1991)048<1005:AEFTEO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rauber, R. M., J. Wegman, and J. Plummer, 2014: Stability and charging characteristics of the comma head region of continental winter cyclones. J. Atmos. Sci., 71, 15591582, https://doi.org/10.1175/JAS-D-13-0253.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rauber, R. M., and et al. , 2015: The role of cloud-top generating cells and boundary layer circulations in the finescale radar structure of a winter cyclone over the Great Lakes. Mon. Wea. Rev., 143, 22912318, https://doi.org/10.1175/MWR-D-14-00350.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rosenow, A. A., D. M. Plummer, R. M. Rauber, G. M. McFarquhar, B. F. Jewett, and D. Leon, 2014: Vertical velocity and physical structure of generating cells and convection in the comma head region of continental winter cyclones. J. Atmos. Sci., 71, 15381558, https://doi.org/10.1175/JAS-D-13-0249.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rutledge, S. A., and P. Hobbs, 1983: The mesoscale and microscale structure and organization of clouds and precipitation in midlatitude cyclones. VIII: A model for the “seeder-feeder” process in warm-frontal rainbands. J. Atmos. Sci., 40, 11851206, https://doi.org/10.1175/1520-0469(1983)040<1185:TMAMSA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sauer, J. A., D. Muñoz-Esparza, J. M. Canfield, K. R. Costigan, R. R. Linn, and Y. Kim, 2016: A large-eddy simulation study of atmospheric boundary layer influence on stratified flows over terrain. J. Atmos. Sci., 73, 26152632, https://doi.org/10.1175/JAS-D-15-0282.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tessendorf, S. A., and et al. , 2019: A transformational approach to winter orographic weather modification research: The SNOWIE project. Bull. Amer. Meteor. Soc., 100, 7192, https://doi.org/10.1175/BAMS-D-17-0152.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Thompson, G., P. R. Field, R. M. Rasmussen, and W. D. Hall, 2008: Explicit forecasts of winter precipitation using an improved bulk microphysics scheme. Part II: Implementation of a new snow parameterization. Mon. Wea. Rev., 136, 50955115, https://doi.org/10.1175/2008MWR2387.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Trier, S. B., R. Sharman, and T. P. Lane, 2012: Influences of moist convection on a cold-season outbreak of clear-air turbulence (CAT). Mon. Wea. Rev., 140, 24772496, https://doi.org/10.1175/MWR-D-11-00353.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • University of Wyoming Research Flight Center, 1995: University of Wyoming Cloud Radar (WCR). University of Wyoming College of Engineering, Dept. of Atmospheric Science, accessed 4 June 2020, https://doi.org/10.15786/M2237S.

    • Crossref
    • Export Citation
  • University of Wyoming Research Flight Center, 2017a: Flight level data from the University of Wyoming King Air during the Seeded and Natural Orographic Wintertime clouds-the Idaho Experiment (SNOWIE) project, version 1.0. University of Wyoming College of Engineering, Dept. of Atmospheric Science, accessed 24 September 2020, https://doi.org/10.15786/M2MW9F.

    • Crossref
    • Export Citation
  • University of Wyoming Research Flight Center, 2017b: Wyoming cloud radar data from the University of Wyoming King Air during the University of Wyoming King Air during the Seeded and Natural Orographic Wintertime clouds-the Idaho Experiment (SNOWIE) project, version 1.0. University of Wyoming College of Engineering, Dept. of Atmospheric Science, accessed 18 September 2020, https://doi.org/10.15786/M2CD4J.

    • Crossref
    • Export Citation
  • Wang, Z., and et al. , 2012: Single aircraft integration of remote sensing and in situ sampling for the study of cloud microphysics and dynamics. Bull. Amer. Meteor. Soc., 93, 653668, https://doi.org/10.1175/BAMS-D-11-00044.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Yamaguchi, T., and G. Feingold, 2012: Large-eddy simulation of cloudy boundary layer with the Advanced Research WRF Model. J. Adv. Model. Earth Syst., 4, M09003, https://doi.org/10.1029/2012MS000164.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 321 321 321
Full Text Views 43 43 43
PDF Downloads 45 45 45

Detailed Dual-Doppler Structure of Kelvin–Helmholtz Waves from an Airborne Profiling Radar over Complex Terrain. Part II: Evidence for Precipitation Enhancement from Observations and Modeling

View More View Less
  • 1 a Department of Atmospheric Sciences, University of Wyoming, Laramie, Wyoming
  • | 2 b Department of Atmospheric Sciences, University of Illinois at Urbana–Champaign, Urbana, Illinois
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

Kelvin–Helmholtz (KH) waves are a frequent source of turbulence in stratiform precipitation systems over mountainous terrain. KH waves introduce large eddies into otherwise laminar flow, with updrafts and downdrafts generating small-scale turbulence. When they occur in cloud, such dynamics influence microphysical processes that impact precipitation growth and fallout. Part I of this paper used dual-Doppler, 2D wind and reflectivity measurements from an airborne cloud radar to demonstrate the occurrence of KH waves in stratiform orographic precipitation systems and identified four mechanisms for triggering KH waves. In Part II, we use similar observations to explore the effects of KH wave updrafts and turbulence on cloud microphysics. Measurements within KH wave updrafts reveal the production of liquid water in otherwise ice-dominated clouds, which can contribute to snow generation or enhancement via depositional and accretional growth. Fallstreaks beneath KH waves contain higher ice water content, composed of larger and more numerous ice particles, suggesting that KH waves and associated turbulence may also increase ice nucleation. A large-eddy simulation (LES), designed to model the microphysical response to the KH wave eddies in mixed-phase cloud, shows that depositional and accretional growth can be enhanced in KH waves, resulting in more precipitation when compared to a baseline simulation. While sublimation and evaporation occur in KH downdrafts, persistent supersaturation with respect to ice allows for a net increase in ice mass. These modeling results and observations suggest that KH waves embedded in mixed-phase stratiform clouds may increase precipitation, although the quantitative impact remains uncertain.

Significance Statement

This study investigates how the turbulence caused by Kelvin–Helmholtz (KH) waves embedded in deep clouds affect precipitation growth. To answer this question, we used a Doppler radar on board a research aircraft to locate KH waves inside of clouds. These waves often break, and produce fallstreaks, which may descend down to the surface. Aircraft measurements from within these fallstreaks confirmed that they contain larger, more numerous ice particles. This evidence of enhanced precipitation coincided with turbulence and supercooled liquid water produced by the KH waves. Modeled KH waves show that some of the precipitation enhancement is caused by accretion and deposition within updrafts, but further research is needed to understand the role of turbulence and ice initiation in KH waves.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Coltin Grasmick, cgrasmic@uwyo.edu

This article has a companion article which can be found at http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-19-0108.1.

Abstract

Kelvin–Helmholtz (KH) waves are a frequent source of turbulence in stratiform precipitation systems over mountainous terrain. KH waves introduce large eddies into otherwise laminar flow, with updrafts and downdrafts generating small-scale turbulence. When they occur in cloud, such dynamics influence microphysical processes that impact precipitation growth and fallout. Part I of this paper used dual-Doppler, 2D wind and reflectivity measurements from an airborne cloud radar to demonstrate the occurrence of KH waves in stratiform orographic precipitation systems and identified four mechanisms for triggering KH waves. In Part II, we use similar observations to explore the effects of KH wave updrafts and turbulence on cloud microphysics. Measurements within KH wave updrafts reveal the production of liquid water in otherwise ice-dominated clouds, which can contribute to snow generation or enhancement via depositional and accretional growth. Fallstreaks beneath KH waves contain higher ice water content, composed of larger and more numerous ice particles, suggesting that KH waves and associated turbulence may also increase ice nucleation. A large-eddy simulation (LES), designed to model the microphysical response to the KH wave eddies in mixed-phase cloud, shows that depositional and accretional growth can be enhanced in KH waves, resulting in more precipitation when compared to a baseline simulation. While sublimation and evaporation occur in KH downdrafts, persistent supersaturation with respect to ice allows for a net increase in ice mass. These modeling results and observations suggest that KH waves embedded in mixed-phase stratiform clouds may increase precipitation, although the quantitative impact remains uncertain.

Significance Statement

This study investigates how the turbulence caused by Kelvin–Helmholtz (KH) waves embedded in deep clouds affect precipitation growth. To answer this question, we used a Doppler radar on board a research aircraft to locate KH waves inside of clouds. These waves often break, and produce fallstreaks, which may descend down to the surface. Aircraft measurements from within these fallstreaks confirmed that they contain larger, more numerous ice particles. This evidence of enhanced precipitation coincided with turbulence and supercooled liquid water produced by the KH waves. Modeled KH waves show that some of the precipitation enhancement is caused by accretion and deposition within updrafts, but further research is needed to understand the role of turbulence and ice initiation in KH waves.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Coltin Grasmick, cgrasmic@uwyo.edu

This article has a companion article which can be found at http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-19-0108.1.

Save