Characteristics for the sources and sinks of gravity waves in an orographic heavy snowfall event

Abstract

The characteristics of the mesoscale gravity waves during a snowfall event on November 30, 2018 over the Ili Valley and the northern slope of the Tianshan Mountains are analyzed based on the Weather Research and Forecasting model simulation. The vertical distribution of Ro is similar to that of the residual of the nonlinear balance equation (\mathrm{\Delta }NBE), with their high-value areas located over the leeward slope and the fluctuations extending upwardly with time, indicating the characteristics of strong ageostrophy and non-equilibrium of atmospheric motions. In addition, the Ro and \mathrm{\Delta }NBE are first developed in the lower layers over the leeward slope, revealing that the generation of the gravity waves is closely related to the topography. Thus, the topographic uplifting greatly affects this snowfall, and the ageostrophic motion in the whole troposphere and the lower stratosphere, as well as the unbalanced motions between convergence and divergence over the peak and the leeward slope are conductive to the development of the inertia-gravity waves. In terms of the horizontal scale of the gravity waves, the Barnes’ band-pass filter is applied to separate the mesoscale waves and the synoptic-scale basic flow. The vertical distributions of the vorticity and divergence perturbations have a phase difference of π/2, indicating the polarization state of gravity waves. The analyses on the sources and sinks of gravity waves by the non-hydrostatic wave equation show that the main forcing term for orographic gravity waves is the second-order nonlinear term, whose magnitude mainly depends on the nonlinear thermal forcing. This term is mainly related to the vertical transport of potential temperature perturbations. During the snowfall, the potential temperature perturbations are mainly caused by the topographic relief and the release of condensation latent heat. Therefore, the gravity waves in this snowfall are caused by the topographic forcing and condensation latent heating.

Graphical abstract

Keywords

gravity wave / Fourier transform / nonlinear balance equation / non-hydrostatic wave equation

References

[1] Berckmans J, Woollings T, Demory M E, Vidale P L, Roberts M. ( 2013). Atmospheric blocking in a high resolution climate model: influences of mean state, orography and eddy forcing. Atmos Sci Lett, 14( 1): 34– 40

[2] Blumen W. ( 1972). Geostrophic adjustment. Rev Geophys, 10( 2): 485– 528

[3] Bosart L F, Bracken W E, Seimon A. ( 1998). A study of cyclone mesoscale structure with emphasis on a large-amplitude inertia-gravity wave. Mon Weather Rev, 126( 6): 1497– 1527

[4] Bruintjes R T, Clark T L, Hall W D. ( 1994). Interactions between topographic airflow and cloud/precipitation development during the passage of a winter storm in Arizona. J Atmos Sci, 51( 1): 48– 67

[5] Cahn A. ( 1945). An investigation of the free oscillations of a simple current system. J Atmos Sci, 2( 2): 113– 119

[6] Clark T L, Hauf T H, Kuettner J P. ( 1986). Convectively forced internal gravity waves: results from two-dimensional numerical experiments. Q J R Meteorol Soc, 112( 474): 899– 925

[7] Eliassen A, Palm E. ( 1960). On the transfer of energy in stationary mountain waves. Geofys Publ, 22( 3): 1– 23

[8] Ford R. ( 1994). Gravity wave radiation from vortex trains in rotating shallow water. J Fluid Mech, 281( 25): 81– 118

[9] Fritts D C, Alexander M J. ( 2003). Gravity wave dynamics and effects in the middle atmosphere. Rev Geophys, 41( 1): 1003

[10] Garvert M F, Smull B, Mass C. ( 2007). Multiscale mountain waves influencing a major orographic precipitation event. J Atmos Sci, 64( 3): 711– 737

[11] Guan X F Sun W G Li M J Xie C Y Zhang X Q ( 2016). Climate change in north Xinjiang and its response to Arctic Oscillation during the period of 1965–2012. Arid Zone Res, 33( 04): 681− 689 (in Chinese)

[12] Guo X Guo X L Fu D H Niu S J ( 2013). Relationship between bell-shaped terrain dynamic forcing, mountain wave propagation, and orographic clouds and precipitation. Chin J Atmos Sci, 37( 4): 786− 800 (in Chinese)

[13] Holton J R, Haynes P H, McIntyre M E, Douglass A R, Rood R B, Pfister L. ( 1995). Stratosphere–troposphere exchange. Rev Geophys, 33( 4): 403– 439

[14] Houze R A Jr. ( 2012). Orographic effects on precipitating clouds. Rev Geophys, 50( 1): RG1001

[15] Howard L N. ( 1961). Note of a paper of John W. Miles. J Fluid Mech, 10( 4): 509– 512

[16] Kanehama T, Sandu I, Beljaars A, van Niekerk A, Lott F A. ( 2019). Which orographic scales matter most for medium-range forecast skill in the Northern Hemisphere winter?. J Adv Model Earth Syst, 11( 12): 3893– 3910

[17] Kaplan M L, Karyampudi V M. ( 1992). Meso-bata scale numerical simulations of terrain drag-induced along-stream circulations. Part II: concentration of potential vorticity within dryline bulges. Meteorol Atmos Phys, 49( 1−4): 157– 185

[18] Kaplan M L, Koch S E, Lin Y L, Weglarz R P, Rozumalski R A. ( 1997). Numerical simulations of a gravity wave event over CCOPE. Part I: the role of geostrophic adjustment in mesoscale jetlet formation. Mon Weather Rev, 125( 6): 1185– 1211

[19] Kim Y J, Eckermann S D, Chun H Y. ( 2003). An overview of the past, present and future of gravity-wave drag parameterization for numerical climate and weather prediction models. Atmos-ocean, 41( 1): 65– 98

[20] Koch S E, Dorian P B. ( 1988). A mesoscale gravity wave event observed during CCOPE. Part III: wave environment and probable source mechanisms. Mon Weather Rev, 116( 12): 2570– 2592

[21] Lindzen R S. ( 1974). Wave-CISK in the tropics. J Atmos Sci, 31( 1): 156– 179

[22] Lindzen R S, Tung K K. ( 1976). Banded convective activity and ducted gravity waves. Mon Weather Rev, 104( 12): 1602– 1617

[23] Liu L Ding Z Y Chang Y Chen M Q ( 2012). Application of parameterization of orographic gravity wave drag in WRF model to mechanism analysis of a heavy rain in warm sector over south China. J Meteor Sci, 40( 02): 232− 240 (in Chinese)

[24] Ma S P Ran L K Cao J ( 2021). Diagnosis and analysis of vertical motion during complex topographical heavy snowfall. Chin J Atmos Sci, 45( 5): 1127− 1145 (in Chinese)

[25] Maddox R A. ( 1980). An objective technique for separating macroscale and mesoscale features in meteorological data. Mon Weather Rev, 108( 8): 1108– 1121

[26] Mastrantonio G, Einaudi F, Fua D, Lalas D P. ( 1976). Generation of gravity waves by jet streams in the atmosphere. J Atmos Sci, 33( 9): 1730– 1738

[27] Medina S, Smull B F, Houze J R R A Jr, Steiner M. ( 2005). Cross-barrier flow during orographic precipitation events: results from MAP and IMPROVE. J Atmos Sci, 62( 10): 3580– 3598

[28] Miles J W. ( 1961). On the stability of heterogeneous shear flows. J Fluid Mech, 10( 4): 496– 508

[29] O’sullivan D, Dunkerton T J. ( 1995). Generation of inertia–gravity waves in a simulated life cycle of baroclinic instability. J Atmos Sci, 52( 21): 3695– 3716

[30] Pandya R E, Durran D R, Weisman M L. ( 2000). The influence of convective thermal forcing on the three-dimensional circulation around squall lines. J Atmos Sci, 57( 1): 29– 45

[31] Plougonven R, Zhang F Q. ( 2007). On the forcing of inertia–gravity waves by synoptic-scale flows. J Atmos Sci, 64( 5): 1737– 1742

[32] Ran L K, Chen C S. ( 2016). Diagnosis of the forcing of inertial-gravity waves in a severe convection system. Adv Atmos Sci, 33( 11): 1271– 1284

[33] Rossby C G. ( 1938). On the mutual adjustment of pressure and velocity distributions in certain simple current systems II. J Mar Res, 1( 3): 239– 263

[34] Sandu I van Niekerk A Shepherd T G Vosper S B Zadra A Bacmeister J Beljaars A Brown A R Dörnbrack A McFarlane N Pithan F Svensson G ( 2019). Impacts of orography on large-scale atmospheric circulation. Clim Atmosph Sci 2: 10

[35] Shang S S, Lian L Z, Ma T, Zhang K, Han T. ( 2018). Spatiotemporal variation of temperature and precipitation in northwest China in recent 54 years. Arid Zone Res, 35( 01): 68– 76

[36] Siler N, Roe G, Durran D. ( 2013). On the dynamical causes of variability in the rain-shadow effect: a case study of the Washington Cascades. J Hydrometeorol, 14( 1): 122– 139

[37] Skamarock W C Klemp J B Dudhia J Gill D O Liu Z Q Berner J Wang W Powers J G Duda M G Huang X Y ( 2019). A description of the advanced research WRF Version 4. NCAR Tech. Note NCAR/TN-556+STR.

[38] Song I S, Chun H Y, Lane T P. ( 2003). Generation mechanisms of convectively forced internal gravity waves and their propagation to the stratosphere. J Atmos Sci, 60( 16): 1960– 1980

[39] Sun Y H Li Z C Shou S W ( 2012). A mesoscale analysis of the snowstorm event of 3–5 March 2007 in Liaoning Province. Acta Meteorol Sin, 70( 5): 936− 948 (in Chinese)

[40] van Niekerk A, Shepherd T G, Vosper S B, Webster S. ( 2016). Sensitivity of resolved and parametrized surface drag to changes in resolution and parametrization. Q J R Meteorol Soc, 142( 699): 2300– 2313

[41] Vosper S B, van Niekerk A, Elvidge A, Sandu I, Beljaars A. ( 2020). What can we learn about orographic drag parametrisation from high-resolution models? A case study over the Rocky Mountains.. Q J R Meteorol Soc, 146( 727): 979– 995

[42] Wang S G, Zhang F Q. ( 2010). Source of gravity waves within a vortex-dipole jet revealed by a linear model. J Atmos Sci, 67( 5): 1438– 1455

[43] Wang X Chu C J Mou H ( 2020). Spatial pattern and interannual variation characteristics of snow disaster in Xinjiang. Arid Zone Res, 37( 6): 1488− 1495 (in Chinese)

[44] Yang R, Liu Y, Ran L K, Zhang Y L. ( 2018). Simulation of a torrential rainstorm in Xinjiang and gravity wave analysis. Chin Phys B, 27( 5): 059201

[45] Zhang F Q, Koch S E, Davis C A, Kaplan M. ( 2000). A survey of unbalanced flow diagnostics and their application. Adv Atmos Sci, 17( 2): 165– 183

[46] Zhang F Q, Davis C A, Kaplan M L, Koch S E. ( 2001). Wavelet analysis and the governing dynamics of a large-amplitude mesoscale gravity-wave event along the east coast of the United States. Q J R Meteorol Soc, 127( 577): 2209– 2245

[47] Zhang F Q. ( 2004). Generation of mesoscale gravity waves in upper-tropospheric jet-front systems. J Atmos Sci, 61( 4): 440– 457

[48] Zhang J B Deng Z F ( 1987). Introduction to Xinjiang Precipitation. Beijing: Meteorological Press (in Chinese)

[49] Zhu M Yu Z H Lu H C ( 1999). The effect of meso-scale lee wave and its application. Acta Meteorol Sin, 57( 6): 705− 714 (in Chinese)

Acknowledgments

This work was supported by the National Key Research and Development Project (No. 2018YFC1507104), Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA17010105), The Key Scientific and Technology Research and Development Program of Jilin Province (No. 20180201035SF), and National Natural Science Foundation of China (Grant No. 41775140). We thank Nanjing Hurricane Translation for reviewing the English language quality of this paper.

RIGHTS & PERMISSIONS

2022 Higher Education Press