Classification and Synoptic Analysis of Subtropical Cyclones within the Northeastern Atlantic Ocean

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Since more research is needed on subtropical cyclones (STCs) formed within the North Atlantic eastern basin, this survey analyzes them from a synoptic point of view, on a climatological basis, with the main aims of studying their common features, complementing other studies of these storms in the North Atlantic, and aiding the forecasting community. Fifteen cases of STCs were identified during the period 1979-2011 by applying a set of criteria from two databases. Composite analysis reveals that an extratropical depression acts as a precursor when it is isolated from the westerlies and then suffers a deepening when becoming subtropical instead of decaying through occlusion. This process is accompanied by an atmospheric circulation, within the North Atlantic, whose main feature is characterized by notable departures from the climatological pattern with a statistically significant anomalous high pressure to the north of the STCs. Three conceptual models of synoptic pattern of subtropical cyclogenesis are derived and show that these departures appeared because the westerly circulation moves poleward and/ or the flow has a great meridional component, with the possibility of a blocked flow pattern occurring. Moreover, the identified STCs predominantly formed in a highly sheared (>10 m s^-1) environment with low sea surface temperature values (<25 degrees C), which differs from the dominant features of STCs in the North Atlantic, especially within its western region. Finally, a recent (2010) STC, identified by the authors, is synoptically discussed in order to achieve a better interpretation of the general results.
© 2015 American Meteorological Society. Comments from three anonymous reviewers and the editor, to whom the authors are grateful, greatly improved this manuscript. We highly appreciate the data of subtropical cyclones provided by Dr. Mark P. Guishard from The Pennsylvania State University. We thank Dr. Robert E. Hart from The Florida State University for providing us the cyclone phase diagrams as well. We are also grateful to Dr. Francisco Doblas Reyes from the Catalán Institute of Climate Sciences for his valuable comments and recommendations. This work was supported under a MECD Grant (Spanish government), the MINECO projects CGL2011-25327 and PCIN-2014-013-C07-04 (Spanish government), and by the U.S. National Science Foundation under Grant ATM1322532. Discussions with D. Iñigo Gomara and Dr. David Barriopedro from Complutense University of Madrid about RWB and blockings, respectively, are also appreciated.
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Beven, J. L., 2006: Tropical cyclone report: Tropical Storm Delta, 22–28 November 2005. National Hurricane Center, 12 pp. Bjerknes, J., and H. Solberg, 1922: Life cycle of cyclones and the polar front theory of atmospheric circulation. Geophys. Norv., 3, 1–18. Browning, S. A., and I. D. Goodwin, 2013: Large-scale influences on the evolution of winter subtropical maritime cyclones affecting Australia’s East Coast. Mon. Wea. Rev., 141, 2416– 2431, doi:10.1175/MWR-D-12-00312.1. Case, R. A., 1990: Preliminary tropical cyclone report: Tropical Storm Edouard, 02–11 August 1990. National Hurricane Center. [Available online at storm_wallets/atlantic/atl1990-prelim/edouard/.] Charney, J. G., 1947: The dynamics of long waves in a baroclinic westerly current. J. Meteor., 4, 135–161, doi:10.1175/ 1520-0469(1947)004,0136:TDOLWI.2.0.CO;2. Charney, J. G., and A. Eliassen, 1964: On the growth of the hurricane depression. J. Atmos. Sci., 21, 68–75, doi:10.1175/1520-0469(1964)021,0068: OTGOTH.2.0.CO;2. Davis, C. A., and L. F. Bosart, 2003: Baroclinically induced tropical cyclogenesis. Mon. Wea. Rev., 131, 2730–2747, doi:10.1175/ 1520-0493(2003)131,2730:BITC.2.0.CO;2. Dee, D. P., and Coauthors, 2011: The ERA-Interim reanalysis: Configuration and performance of the data assimilation system. Quart. J. Roy. Meteor. Soc., 137, 553–597, doi:10.1002/ qj.828. Doblas Reyes, F. J., M. J. Casado, and M. A. Pastor, 2002: Sensitivity of the Northern Hemisphere blocking frequency to the detection index. J. Geophys. Res., 107 (D2), doi:10.1029/ 2000JD000290. Dvorak, V. F., 1975: Tropical cyclone intensity analysis and forecasting from satellite imagery. Mon. Wea. Rev., 103, 420–430, doi:10.1175/1520-0493(1975)103,0420:TCIAAF.2.0.CO;2. Eady, E. T., 1949: Long waves and cyclone waves. Tellus, 1, 33–52, doi:10.1111/j.2153-3490.1949.tb01265.x. Emanuel, K. A., 1986: An air–sea interaction theory for tropical cyclones. Part I: Steady-state maintenance. J. Atmos. Sci., 43, 585– 605, doi:10.1175/1520-0469(1986)043,0585:AASITF.2.0.CO;2. Emanuel, K. A., 1988: Toward a general theory of hurricanes. Amer. Sci., 76, 370–379. Evans, J. L., 1993: Sensitivity of tropical cyclone intensity to sea surface temperature. J. Climate, 6, 1133–1140, doi:10.1175/ 1520-0442(1993)006,1133:SOTCIT.2.0.CO;2. Evans, J. L., and M. P. Guishard, 2004: A proposed potential vorticity mechanism for sub-tropical cyclogenesis and tropical transition. Preprints, 26th Conf. on Hurricanes and Tropical Meteorology, Miami, FL, Amer. Meteor. Soc., P1.90. [Available online at pdf.] Evans, J. L., and Evans, J. L., 2009: Atlantic subtropical storms. Part I: Diagnostic criteria and composite analysis. Mon. Wea. Rev., 137, 2065–2080, doi:10.1175/2009MWR2468.1. Evans, J. L., and A. Braun, 2012: A climatology of subtropical cyclones in the South Atlantic. J. Climate, 25, 7328–7340, doi:10.1175/ JCLI-D-11-00212.1. Franklin, J. L., 2006: Tropical cyclone report: Hurricane Vince, 8–11 October 2005. National Hurricane Center, 9 pp. González Alemán, J. J., F. Valero, and F. Martín León, 2014: How to detect a subtropical cyclone. 33nd Scientific Conf. of the Spanish Meteorological Association, Oviedo, Spain. [Available online (in Spanish) at 33-Oviedo/TabajosCompletosJornadas/4.analisis_y_prediccion_ del_tiempo/Oral_GonzalezAleman.pdf.] Gray, W. M., 1968: Global view of the origin of tropical disturbances and storms. Mon. Wea. Rev., 96, 669–700, doi:10.1175/ 1520-0493(1968)096,0669:GVOTOO.2.0.CO;2. Guishard, M. P., E. A. Nelson, J. L. Evans, R. E. Hart, and D. G. O’Connell, 2007: Bermuda subtropical storms. Meteor. Atmos. Phys., 97, 239–253, doi:10.1007/s00703-006-0255-y. Guishard, M. P., J. L. Evans, and R. E. Hart, 2009: Atlantic subtropical storms. Part II: Climatology. J. Climate, 22, 3574–3594, doi:10.1175/ 2008JCLI2346.1. Gyakum, J. R., 1983a: On the evolution of the QE II storm. I: Synoptic aspects. Mon. Wea. Rev., 111, 1137–1155, doi:10.1175/ 1520-0493(1983)111,1137:OTEOTI.2.0.CO;2. Gyakum, J. R., 1983b: On the evolution of the QE II storm. II: Dynamic and thermodynamic structure. Mon. Wea. Rev., 111, 1156–1173, doi:10.1175/1520-0493(1983)111,1156:OTEOTI.2.0.CO;2. Hart, R. E., 2003: A cyclone phase space derived from thermal wind and thermal asymmetry. Mon. Wea. Rew., 131, 585–616, doi:10.1175/1520-0493(2003)131,0585:ACPSDF.2.0.CO;2 Hebert, P. H., and K. O. Poteat, 1975: A satellite classification technique for subtropical cyclones. NOAA Tech. Memo. NWS SR-83, 25 pp. [Available online at noaa_documents/NWS/NWS_SR/TM_NWS_SR_83.pdf.] Holland, G. J., A. H. Lynch, and L. M. Leslie, 1987: Australian eastcoast cyclones. Part I: Synoptic overview and case study. Mon. Wea. Rev., 115, 3024–3036, doi:10.1175/1520-0493(1987)115,3024: AECCPI.2.0.CO;2. Holton, J. R., 2004: An Introduction to Dynamic Meteorology. Academic Press, 535 pp. Hoskins, B. J., M. E. McIntyre, and A. W. Robertson, 1985: On the use and significance of isentropic potential vorticity maps. Quart. J. Roy. Meteor. Soc., 111, 877–946, doi:10.1002/ qj.49711147002. Jarvinen, B. R., C. J. Neumann, and M. A. S. Davis, 1984: A tropical cyclone data tape for the North Atlantic basin, 1886–1983: Contents, limitations, and uses. NOAA Tech. Memo. NWS NHC 22, 21 pp. [Available online at pdf/NWS-NHC-1988-22.pdf.] Knapp, K. R., M. C. Kruk, D. H. Levinson, H. J. Diamond, and C. J. Neumann, 2010: The International Best Track Archive for Climate Stewardship (IBTrACS): Unifying tropical cyclone data. Bull. Amer. Meteor. Soc., 91, 363–376, doi:10.1175/2009BAMS2755.1. Kuo, H. L., 1965: On formation and intensification of tropical cyclones through latent heat release by cumulus convection. J. Atmos. Sci., 22, 40–63, doi:10.1175/1520-0469(1965)022,0040: OFAIOT.2.0.CO;2. Landsea, C. W., 2007: Counting Atlantic tropical cyclones back to 1900. Eos, Trans. Amer. Geophys. Union, 88, 197–202. Mauk, R. G., and J. S. Hobgood, 2012: Tropical cyclone formation in environments with cool SST and high wind shear over the northeastern Atlantic Ocean. Wea. Forecasting, 27, 1433– 1448, doi:10.1175/WAF-D-11-00048.1. McBride, J. L., and R. Zehr, 1981: Observational analysis of tropical cyclone formation. Part II: Comparison of non-developing versus developing systems. J. Atmos. Sci., 38, 1132–1151, doi:10.1175/ 1520-0469(1981)038,1132:OAOTCF.2.0.CO;2. Nieto, R., and Coauthors, 2005: Climatological features of cutoff low systems in the Northern Hemisphere. J. Climate, 18, 3085– 3103, doi:10.1175/JCLI3386.1. Nolan, D. S., and E. D. Rappin, 2008: Increased sensitivity of tropical cyclogenesis to wind shear in higher SST environments. Geophys. Res. Lett., 35, L14805, doi:10.1029/2008GL034147. Ooyama, K., 1969: Numerical simulation of the life-cycle of tropical cyclones. J. Atmos. Sci., 26, 3–40, doi:10.1175/ 1520-0469(1969)026,0003:NSOTLC.2.0.CO;2. Otkin, J. A., and J. E. Martin, 2004: A synoptic climatology of the subtropical kona storm. Mon. Wea. Rev., 132, 1502–1517, doi:10.1175/1520-0493(2004)132,1502:ASCOTS.2.0.CO;2. Raymond, D. J., 1992: Nonlinear balance and potential-vorticity thinking at large Rossby number. Quart. J. Roy. Meteor. Soc., 118, 987–1015, doi:10.1002/qj.49711850708. Romero, R., 2001: Sensitivity of a heavy-rain-producing western Mediterranean cyclone to embedded potential-vorticity anomalies. Quart. J. Roy. Meteor. Soc., 127, 2559–2597, doi:10.1002/ qj.49712757805. Rotunno, R., and K. A. Emanuel, 1987: An air–sea interaction theory for tropical cyclones. Part II: Evolutionary study using a nonhydrostatic axisymmetric numerical model. J. Atmos. Sci., 44, 542–561, doi:10.1175/1520-0469(1987)044,0542: AAITFT.2.0.CO;2. Steward, S. R., 2001: Tropical cyclone report: Hurricane Karen, 12– 15 October 2001. National Hurricane Center, 10 pp. Thorncroft, C. D., B. J. Hoskins, and M. E. McIntyre, 1993: Two paradigms of baroclinic-wave life-cycle behaviour. Quart. J. Roy. Meteor. Soc., 119, 17–55, doi:10.1002/qj.49711950903.