Warmly Welcome Dr. Lucian Sfîcă to the Editorial Board of JASR
2024-06-20
Convective Phenomenes in the Context of Meso-β-scale Convective Structures
Authors
-
Livshits Evgeny
Independent researcher, Frankfurt am Main, 60326, Germany.
-
Petrov Vasiliy
Independent researcher, Stafford, ST17 9XX, UK.
DOI:
https://doi.org/10.30564/jasr.v7i3.6278Abstract
This review article presents the results of radar studies of convective phenomena in Moldavia and the North Caucasus using Eulerian (ECS) and Lagrangian (LCS) coordinate systems. Application of the Lagrangian approach allowed us to exclude the influence of the tropospheric displacement and to obtain integral grid patterns of thunderstorm-hail processes. These structures are especially well manifested at small wind shears (up to 1 m/sec/km). At large shears, the mesh structures are transformed predominantly into linear structures. The methodology for obtaining integral pictures of radio echoes of thunderstorm processes is described. Intersections of linear elements, which we call facets, occur at nodes. The latter plays a particularly important role in the dynamics and kinematics of convective storms. The development of storms occurs along the facets and at the nodes of meso-β-scale convective structures (MMCS), which explains the mechanisms of splitting and merging of storms: in the first case the facets diverge, in the second case they converge. The relations of motion vectors for different types of storms are obtained. It is shown that the direction of the radio echo canopy coincides with the storm motion trajectory; the evolution vector (propagation) for the most powerful storms deviates from the storm displacement direction by 80°–135°. The structure of the updated band within which the Flanking Line is formed for supercells and multicells is studied. Mnemonic rules have been derived that allow one to infer from instantaneous patterns of anvil orientation and the mutual location of storms whether they are converging or diverging, and to identify left- or right-moving storms. A hypothesis on the internal structure of the cold front of the 2nd kind is stated. The main conclusion of the work is that the evolution of storms is determined by the configuration of meso-β-scale convective structures. This explains various convective phenomena from unified positions. The results are applicable in works on modification of convective cloudiness, for ultra-short-term forecasts of dangerous phenomena, storm warnings of the population, rescue services, etc.
Keywords:
Convective storm; Motion vectors and their relations; Storm merging and splitting; Meso-β-scale convective structures; Feeder cells; Flanking LineReferences
[1] Starostin, A.N., Livshits, E.M., Shvetsov, V.S. 1983. Mesoscale structure of radio echo fields of convective clouds in Moldova. Meteorology and Hydrology.10, 55–59. [In Russian].
[2] Livshits, E.M., 2023. Dynamics and kinematics of convective storms on elements of meso-β-scale convective structures. М. 324. [In Russian].
[3] Abshaev, M.T., Abshaev, A.M., Barekova, M.V., Malkarova, A.M. 2014. Guidelines for organizing and conducting anti-hail operations. Nalchik. 500. [In Russian].
[4] Livshits, E.M., Petrov, V.I. 2021. Radar detection of the location of the feeding cloud line. Part I. Main motion vectors and their relation in severe hail storms. Proceedings of the All-Russian Open Conference on FO and AB on Hydrometeorological Processes. Nalchik. 192–198. [In Russian].
[5] Livshits, E.M., Petrov, V.I., 2021. Radar detection of the location of the feeding cloud line. Part II. Results of the study. Proceedings of the All-Russian Open Conference on FC and AI on Hydrometeorological Processes. Nalchik. 198–204. [In Russian].
[6] Hitschfeld, W., 1960. The motion and erosion of convective storms in severe vertical wind shear. Journal of the Atmospheric Sciences. 17(3), 270–282. DOI: https://doi.org/10.1175/1520-0469(1960)017%3C0270:TMAEOC%3E2.0.CO;2
[7] Newton, C.W., Fankhauser, J.C., 1964. On the movements of convective storms, with emphasis on size discrimination in relation to water budget requirements. Journal of Applied Meteorology and Climatology. 3(6), 651–668. DOI: https://doi.org/10.1175/1520-0450(1964)003%3C0651:OTMOCS%3E2.0.CO;2
[8] Fujita, T., Grandoso, H., 1968. Split of a thunderstorm into anticyclonic and cyclonic storms and their motion as determined from numerical model experiments. Journal of the Atmospheric Sciences. 25, 416–439. DOI: https://doi.org/10.1175/1520-0469(1968)025%3C0416:SOATIA%3E2.0.CO;2
[9] Charba, J., Sasaki, Y., 197I. Structure and movement of the severe thunderstorms of 3 April 1964 as revealed from radar and surface mesonetwork data analysis. Journal of the Meteorological Society of Japan. Ser. II. 49(3), 191–214. DOI: https://doi.org/10.2151/JMSJ1965.49.3_191
[10] Haglund, G.T., 1969. A study of a severe local storm of 16 April 1967. ESSA Technical Memorandum. ERLTM-NSSL 44. National Severe Storms Laboratory: Norman, OK. pp. 54.
[11] Marwitz, J.D., 1972. The structure and motion of severe hailstorms. Part I: Supercell storms. Journal of Applied Meteorology and Climatology. 11(1),166–179. DOI: https://doi.org/10.1175/1520-0450(1972)011%3C0166:TSAMOS%3E2.0.CO;2
[12] Burgess, D.W., Lemon, L.R., Achtemeier, G.L., 1976. Severe storm splitting and left-moving storm structure. The Union City Tornado of 24 May 1973, NOAA Technical Memorandum. ERL NSSL-80, National Severe Storms Laboratory: Norman, OK. pp. 53–66.
[13] Bluestein, H.B., Sohl, C.J., 1979. Some observations of a splitting severe thunderstorm. Monthly Weather Review. 107(7), 861–873. DOI: https://doi.org/10.1175/1520-0493(1979)107<0861:SOOASS>2.0.CO;2
[14] Lemon, L.R., Burgess, D.W., 1980. Magnitude and implications of high speed outflow at severe storm summits. Preprints, 19th Conf. on Radar Meteorology, Miami Beach, FL, Amer. Meteor. Soc. 364–368.
[15] Kubesh, R.J., Musil, D.J., Farley, R.D., et al., 1988. The 1 August 1981 CCOPE storm: observations and modeling results. Journal of Applied Meteorology and Climatology. 27(3), 216–243. DOI: https://doi.org/10.1175/1520-0450(1988)027%3C0216:TAMSOA%3E2.0.CO;2
[16] Brown, R.A., 1992. Initiation and evolution of updraft rotation within an incipient supercell thunderstorm. Journal of the Atmospheric Sciences. 49(21), 1997–2031. DOI: https://doi.org/10.1175/1520-0469(1992)049<1997:IAEOUR>2.0.CO;2
[17] Burgess, D.W., Curran, E.B., 1985. The relationship of storm type to environment in Oklahoma on 26 April 1984. Preprints, 14th Conf. on Severe Local Storms, Indianapolis, IN, Amer. Meteor. Soc. 208–211.
[18] Conway, J.W., Weisman, M.L., 1988. An investigation into the splitting and propagation of the 13 June 1984 Denver hailstorms. Preprints, 15th Conf. on Severe Locof Storms, Baltimore, MD, Amer. Meteor. Soc. 276–279.
[19] Browning, K.A., Ludlam, F. H., 1960. Radar analysis of a hailstorm. Tech. Note No. 5. Dept. of Meteorology. Imperial College. London. 106.
[20] Bluestein, H.B., Parker, S.S., 1993. Modes of isolated, severe convective storm formation along the dry line. Monthly Weather Review. 121(5), 1354–1372. DOI: https://doi.org/10.1175/1520-0493(1993)121<1354:MOISCS>2.0.CO;2
[21] Browning, K.A., Foote, G.B., 1976. Airflow and hail growth in supercеll storms and some umplications for hail suppression. Quarterly Journal of the Royal Meteorological Society, 102(433), 499–533. DOI: https://doi.org/10.1002/QJ.49710243303
[22] Chalon, J.-P., Fankhauser, J.C., Eccles, P.J. 1976. Structure of an evolving hailstorm. Part I: general characteristic and cellular structure. Monthly Weather Review. 104(5), 564–575. DOI: https://doi.org/10.1175/1520-0493(1976)104<0564:SOAEHP>2.0.CO;2
[23] Chisholm, A.J., 1973. Alberta Hailstorms Part I: Radar case studies and airflow models. Alberta Hailstorms. Meteorological Monographs. American Meteorological Society: Boston, MA. pp. 1–36. DOI: https://doi.org/10.1007/978-1-935704-32-4
[24] Chisholm, A.J., Renick, J.H., 1972. The kinematics of multicell and supercell Alberta hailstorms. Alberta Hail Studies 1972. Research Council of Alberta. Hail Studies Report. 72–2, 24 –31.
[25] Fankhauser, J.C., 1982. Hailstorms of the Central High Plains. Vol. 2. Part I: 22 June 1976 case study — a complex multicellular hail and rainstorm. Chap. 13: Large-scale influences, radar echo structure and mesoscale circulations. C. Knight. P. Squires. Eds. Colorado Assoc. University Press.
[26] Foot, G.B., Frank, H.W., 1983. Case study of a hailstorm in Colorado. Part III: Airflow from triple-doppler measurements. Journal of the Atmospheric Sciences. 40(3), 686–707. DOI: https://doi.org/10.1175/1520-0469(1983)040<0686:CSOAHI>2.0.CO;2
[27] Westcott, N.E., Kennedy, P.C., 1989. Cell development and merger in an Illinois thunderstorm observed by doppler radar. Journal of the Atmospheric Sciences. 46(1), 117–131. DOI: https://doi.org/10.1175/1520-0469(1989)046<0117:CDAMIA>2.0.CO;2
[28] Klose, B., Klose, H., 2015. Meteorologie. Eine interdisziplinaere Einfuerung in die Physik der Atmosphaere. Springer Spektrum Berlin: Heidelberg. DOI: https://doi.org/10.1007/978-3-662-43578-6
[29] Lemon, L.R., Doswell, C.A. III., 1979. Severe thunderstorm evolution and mesocyclone structure as related to tornadogenesis. Monthly Weather Review. 107 (9), 1184–1197. DOI: https://doi.org/10.1175/1520-0493(1979)107<1184:STEAMS>2.0.CO;2
[30] Moller, A.R., Doswell III C.A., Foster, M.P., et al., 1994. The operational recognition of supercell thunderstorm environments and storm structures. Weather and Forecasting. 9(3), 327–347. DOI: https://doi.org/10.1175/1520-0434(1994)009<0327:TOROST>2.0.CO;2
[31] Vasiloff, S.V., Brandes, E.A., Davies-Jones, R.P., 1986. An investigation of the transition from multicell to supercell storms. Journal of Climate and applied Meteorology. 25(7), 1022–1036. DOI: https://doi.org/10.1175/1520-0450(1986)025<1022:AIOTTF>2.0.CO;2
[32] Davies-Jones, R., Doswell III, C.A., Brooks H.E., 1994. Comments on “initiation and evolution of updraft rotation within an incipient supercell thunderstorm”. Journal of the Atmospheric Sciences. 51(2), 326–331. DOI: https://doi.org/10.1175/1520-0469(1994)051<0326:COAEOU>2.0.CO;2
[33] Starostin A., Abdoullaev S., Nunes A.B., 2000. Storm evolution in nonlinear mesoscale convective systems. XI Brazilian Meteorological Congress.1990–1995.[In Portuguese]
[34] Heymsfield, A. J., Jameson, A.R., Frank, H.W., 1980. Hail growth mechanisms in a Colorado storm. Part II: Hail formation processes. Journal of the Atmospheric Sciences. 37(8), 1779–1807. DOI: https://doi.org/10.1175/1520-0469(1980)037<1779:HGMIAC>2.0.CO;2
[35] Tessendorf ,S.A., Miller, L.J., Wiens, K.C., et al., 2005. The 29 June 2000 supercell observed during STEPS. Part I: Kinematics and Microphysics. Journal of the Atmospheric Sciences. 62(12), 4127–4150. DOI: https://doi.org/10.1175/JAS3585.1
[36] Cheng, L., Rogers, D.C., 1988. Hailfalls and hailstorm feeder clouds—an alberta case study. Journal of the Atmospheric Sciences. 45(23), 3533–3545. DOI: https://doi.org/10.1175/1520-0469(1988)045%3C3533:HAHFCA%3E2.0.CO;2
[37] Gilbert, D.B., Boe, B.A., Krauss ,T.W., 2016. Twenty seasons of airborne hail suppression in Alberta, Canada. The Journal of Weather Modification. 48(1), 68–93. DOI: https://doi.org/10.54782/jwm.v48i1.551
[38] Mazur, R.J., Weaver, J.F., Van der Haar, T.H., 2007. Observations of inflow feeder clouds and their relation to severe thunderstorm. 22 Conference on Weath. Analysis and Forecast. 18.
[39] Levizzani, V., Amorati, R., Meneguzzo, F., 2002. A review of satellite based rainfall estimation methods. Environmental Science, Geography. 1–66. DOI: https://www.researchgate.net/publication/252272255
[40] Mecikalski, J.R., Williams, J.K., Jewett, C.P., et al., 2015. Probabilistic 0 – 1h convective initiation nowcasts that combine geostationary satellite observations and numerical weather prediction model data. Journal of Applied Meteorology and Climatology. 54(5), 1039–1059. DOI: https://doi.org/10.1175/JAMC-D-14-0129.1
[41] Krauss, T.W., Renick, J., 2021. The New Alberta Hail Suppression Project. The Journal of Weather Modification. 29(1), 100–105. DOI: https://doi.org/10.54782/jwm.v29i1.474
[42] Krauss, T.W., Marwitz, J.D., 1984. Precipitation process within an alberta supercell hailstorm. Journal of the Atmospheric Sciences. 41(6), 1025–1035. DOI: https://doi.org/10.1175/1520-0469(1984)041<1025:PPWAAS>2.0.CO;2
[43] Abshaev, M.T., Abshaev, A.M., Malkarova A.M., et al., 2022. Protection of agricultural plants from hailstorms in the North Caucasus. Meteorology and Hydrology. 7, 11–27. [In Russian].
[44] Abshaev, M.; Abshaev, A.; Sinkevich, A.; et al., 2019. Characteristics of the Supercell Cb Thunderstorm and Electrical Discharges on 19 August 2015, North Caucasus: A Case Study. Preprints. 2019120033. DOI: https://doi.org/10.20944/preprints201912.0033.v1
[45] Skamarock, W.C., Klemp, J.B., Dudhia, J., et al., 2021. A Description of the Advanced Research WRF Model Version 4.3 (No. NCAR/TN-556+STR). DOI: https://doi.org/10.5065/1dfh-6p97
[46] Hersbach, H., Bell, B., Berrisford P., et al., 2020. The ERA5 global reanalysis. Quarterly Journal of the Royal Meteorological Society. 146, 1999–2049. DOI: https://doi.org/10.1002/qj.3803
[47] Lindsey, D.T, Bunkers, M.J., 2005. Observations of a severe, left-moving supercell on 4 May 2003. Weather and Forecasting. 20(1), 15–22. DOI: https://doi.org/10.1175/WAF-830.1
[48] Setvak, M., Bedka, K., Lindsey, D.T., et al., 2013. A-train observations of deep convective storm tops. Atmospheric Research. 123, 229–248. DOI: https://doi.org/10.1016/j.atmosres.2012.06.020
[49] Minnachmetov, R.M., Starostin, A.N., 1989. Radar observations of cell convection in the atmospheric boundary layer. Active impact on atmospheric processes in Moldova. Kishinev “Shtiyintsa”. 55–61. [In Russian].
[50] Banghoff, J.R., Sorber, J.D., Stensrud, D.J., et al., 2019. A 10-Year warm-season climatology of horisontal convective rolls and cellular convection in Central Oklahoma. Monthly Weather Review. 148(1). 21–42. DOI: https://doi.org/10.1175/MWR-D-19-0136.1
[51] Minnachmetov, R.M., Starostin, A.N., 1986. Spatial and temporal structure of the thunderstorm process on June 28, 1982. Active influence on the atmospheric processes in Moldova. Kishinev. 29–43. [In Russian].
[52] Starostin, A.N., 1992. Classification of types of cumulonimbus cloud evolution. Active influence on atmospheric processes in Moldova. Kishinev. 58–74. [In Russian].
[53] Livshits, E.M., Petrov, V.I., 2021. Splitting of convective storms. Part II. organization of the mesoscale structure of the thunderstorm process. Hydrometeorology and Ecology. 66, 648–670. [In Russian]. DOI: https://doi.org/10.33933/2713-3001-2021-65-648-670
[54] Livshits, E.M., Petrov, V.I., 2022. Merging of convective storms and their typing. Hydrometeorology and Ecology. 69, 620–643. [In Russian]. DOI: https://doi.org/10.33933/2713-3001-2022-69-620-643
[55] Livshits, E.M., Petrov, V.I., 2023. A special type of multicell storms developing in the nodes of meso-β-scale convective structures. Scientific and Practical Journal “Notes of a Scientist”. 6, 175–189. [In Russian].
[56] Stull, R., 2016. Practical Meteorology: An Algebra-based Survey of Atmosphere Science. Vancouver, Canada: The University of British Columbia. 924.
[57] Charba, J., Sasaki, Y., 1971. Structure and movement of the severe thunderstorms of 3 April 1964 as revealed from radar and surface mesonet work data analysis. Journal of the Meteorological Society of Japan. Ser. II. 49(3), 191–214. DOI: https://doi.org/10.2151/jmsj1965.49.3_191
[58] Wang, C.-С., Chen T.-J. G., Yang, S.-С., et al., 2009. Wintertime supercell thunderstorms in a subtropical environment: numerical simulation. Monthly Weather Review. 137(7), 2175–2202. DOI: https://doi.org/10.1175/2008MWR2616.1
[59] Bocheva, L., Dimitrova, T., Penchev, R., et al., 2018. Severe convective supercell outbreak over western Bulgaria on July 8, 2014. Quarterly Journal of the Hungarian Meteorological Service. 122(2), 101–216. DOI: https://doi.org/10.28974/idojaras.2018.2.5
[60] Livshits, E.M, Petrov, V.I., 2021. The splitting of convective storms. Part I. dynamics and kinematics. Journal of Hydrometeorology and Ecology. 65, 648–670. [In Russian]. DOI: https://doi.org/10.33933/2713-3001-2021-65-648-670
[61] Livshits, E.M., Petrov, V.I., 2023. To the question of wind shear with height and its influence on the dynamics and kinematics of convective storms. Scientific and Practical Journal “Science and Production”. 2, 75–87. [In Russian].
[62] Abshaev, M.T., 1982. Structure and dynamics of development of thunderstorm-hail processes of the North Caucasus. Proc. VGI. 53, 6–22. [In Russian].
[63] Livshits, E.M., Petrov, V.I., 2023. Renewal Band Structure in Deep Convective Storms. Russian Meteorology and Hydrology. 48(8), 722–732. DOI: https://doi.org/10.3103/S1068373923080101
[64] Westcott, N.E., 1994. Merging of convective clouds: Cloud initiation, bridging and subsequent growth. Monthly Weather Review. 122(5), 780–790. DOI: https://doi.org/10.1175/1520-0493(1994)122<0780:MOCCCI>2.0.CO;2
[65] Fu, D., Guo, X., 2011. Cloud-resolving simulation study on the merging processes and effects of topography and environmental winds. Journal of the Atmospheric Sciences. 69(4), 1232–1249. DOI: https://doi.org/10.1175/JAS-D-11-049.1
[66] Tao, W.-K., Simpson, J., 1989. A further study of cumulus interactions and mergers: three-dimensional simulations with trajectory analyses. Journal of the Atmospheric Sciences. 46(19), 2974–3004. DOI: https://doi.org/10.1175/1520-0469(1989)046<2974:AFSOCI>2.0.CO;2
[67] Lin, Y.-L., Joyce, L.E., 2001. A further study of the mechanisms of cell regeneration, propagation, and development within two-dimensional multicell storms. Journal of the Atmospheric Sciences. 58(20), 2957–2988. DOI: https://doi.org/10.1175/1520-0469(2001)058<2957:AFSOTM>2.0.CO;2
[68] Lee, B.D., Jewett, B.F., Wilhelmson, R.B., 2006. The 19 April 1996 Illinois tornado outbreak. Part I: Cell evolution and supercell isolation. Weather Forecasting. 21(4), 433–448. DOI: https://doi.org/10.1175/WAF944.1
[69] Carey, L.D., Petersen, W.A., Rutledge, S.A., 2003. Evolution of cloud-to-ground lightning and storm structure in the Spencer, South Dakota, tornadic supercell of 30 May 1998. Montly Weather Review. 131(8), 1811–1831. DOI: https://doi.org/10.1175//2566.1
[70] Gauthier, M., Petersen, W.A., Carey, L., 2010. Cell mergers and their impact on cloud-to-ground lightning over the Houston area. Atmospheric Research. 96(4), 626–632. DOI: https://doi.org/10.1016/j.atmosres.2010.02.010
[71] Lu, J., Qie, X., Jiang, R., 2021. Lightning activity during convective cell mergers in a squall line and corresponding dynamical and thermodynamical characteristics. Atmospheric Research. 256, 105555. DOI: https://doi.org/10.1016/j.atmosres.2021.105555
[72] Sinkevich, A.A., Krauss, T.V., 2010. Impacts on clouds in Saudi Arabia, statistical evaluation of the results. Meteorology and Hydrology. 6, 26–37. [In Russian].
[73] Sinkevich, A.A., Dovgalyuk, Yu. A., Veremey, N.E., et al., 2018. Convective cloud merger. St. Petersburg. Amirit Ltd. 280. [In Russian].
[74] Krauss, T.W., Sinkevich, A.A., Ghulam, A.S., 2011. Effects of feeder cloud merging on storm development in Saudi Arabia. Journal of King Abdulaziz University-Meteorology Environment and Arid Land Agriculture Sciences. 22(2), 23–39.
[75] Simpson, J., Keenan, T.D., Ferrier, B., et al., 1993. Cumulus mergers in the maritime continent region. Meteorology and Atmospheric Physics. 51, 73–99. DOI: https://doi.org/10.1007/BF01080881
[76] Sinkevich, A., Krauss, T., 2014. Changes in thunderstorm characteristics due to feeder cloud merging. Atmospheric Research. 142, 124–132. DOI: https://doi.org/10.1016/j.atmosres.2013.06.007
[77] Stalker, J.R., Knupp, K.R., 2003. Cell merger potential in multicell thunderstorms of weakly sheared environments: Cell separation distance versus planetary boundary layer depth. Monthly Weather Review. 131. P. 1678–1695. DOI: https://doi.org/10.1175//2556.1
[78] Bluestein, H. B., 1986. Visual aspects of the flanking line in severe thunderstorms. Monthly Weather Review. 114 (4), 788–795. DOI: https://doi.org/10.1175/1520-0493(1986)114<0788:VAOTFL>2.0.CO;2
[79] Appayeva Zh. Yu., Cherednik, E.A., 2018. Peculiarities of distribution of the main radar characteristics of single-cell hail clouds of the North Caucasus. Reports of the Third International Scientific Conference with elements of scientific school. Stavropol, 35–39. [In Russian].
[80] Lemon, L.R., 1976. The flanking line, a severe thunderstorm intensification source. Journal of the Atmospheric Sciences. 33(4), 686–694. DOI: https://doi.org/10.1175/1520-0469(1976)033<0686:TFLAST>2.0.CO;2
[81] Henderson, T.J., 1968. 6000 thunderstorms and what they indicate. Proc. Intern. Conf. Cloud Physics, Toronto. 555–558
[82] Browning, K.A., Fankhauser, J.C., Chalon, J.P., et al., 1976. Structure of an evolving hailstorm, part v; synthesis and implications for hail growth and hail suppression. Monthly Weather Review. 104(5), 603–610. DOI: https://doi.org/10.1175/1520-0493(1976)104%3C0603:SOAEHP%3E2.0.CO;2
[83] Hoeller, H., Bring,i V.N., Hubbert, J., et al., 1994. Life cycle and precipitation formation in a hybrid-type hailstorm revealed by polarimetric and doppler radar measurements. Journal of the Atmospheric Sciences. 51 (17), 2500–2522. DOI: https://doi.org/10.1175/1520-0469(1994)051<2500:LCAPFI>2.0.CO;2
[84] LaDue, J.G., LaDue, D.S., 2008. Convective Storm Classification: is it in Need of Change? Еnvironmental Science. 1–10.
Downloads
How to Cite
Evgeny, L., & Vasiliy , P. (2024). Convective Phenomenes in the Context of Meso-β-scale Convective Structures. Journal of Atmospheric Science Research, 7(3), 1–38. https://doi.org/10.30564/jasr.v7i3.6278
Issue
Article Type
Review
License
Copyright © 2024 Livshits E.M., Petrov V.I.
This is an open access article under the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.
