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Julian F. Quinting and Sarah C. Jones

packets (RWPs) (e.g., Harr et al. 2008 ; Reynolds et al. 2009 ; Anwender et al. 2010 ; Pantillon et al. 2013 ). Hence, it is of interest to investigate the excitation and modification of Rossby waves through TCs over various ocean basins in order to quantify how and to what extent recurving TCs impact the weather patterns in downstream regions. A key factor for the modification of the extratropical flow pattern through a transitioning TC is the reduction of potential vorticity (PV) through

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Maxi Boettcher and Heini Wernli

. C. , I. T. Sears , and L. K. Locke , 2008 : The great coastal gale of 2007 from coastal storms program buoy 46089. Proc. OCEANS 2008, Quebec, QC, Canada, Institute of Electrical and Electronics Engineers, 1516–1522 . Dacre , H. F. , and S. L. Gray , 2009 : The spatial distribution and evolution of North Atlantic cyclones . Mon. Wea. Rev. , 137 , 99 – 115 . Davies , H. C. , C. Schär , and H. Wernli , 1991 : The palette of fronts and cyclones within a baroclinic wave

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Gabriel Wolf and Volkmar Wirth

reconstruction for the above wave packet on 7 August 2002. On that date, there is a wave signal over North America and the western part of the North Atlantic Ocean. It is quite apparent from the previous figure that this wave signal should be considered as one single wave packet—any split must be considered as spurious. Figure 7a shows the result using the Hilbert transform. The southerly and northerly wind maxima (red and blue contours) occur in pairs, with larger spacing in between (this feature is also

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Gabriel Wolf and Volkmar Wirth

have the same strength | F| but that differ in their meridional component. Figure 3 indicates a coherent RWP starting west of 135°W at the beginning of August and propagating all the way across the Atlantic Ocean toward Asia. As in Fig. 2 , the troughs still appear as relative maxima in Fig. 3 despite the use of the semigeostrophic coordinate transformation. Fig . 3. Evolution of the RWP associated with the Elbe flooding by the use of the wave activity flux F at 300 hPa. (bottom) The

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Andrea Schneidereit, Silke Schubert, Pavel Vargin, Frank Lunkeit, Xiuhua Zhu, Dieter H. W. Peters, and Klaus Fraedrich

train. As this wave train is apparent throughout the troposphere ( Orsolini and Nikulin 2006 ), the large-scale flow seems to play an important role in European heat waves. Model simulations indicate that the anomalous circulation during the summer of 2010 over eastern Europe can be ascribed primarily to natural internal atmospheric variability rather than to climate change or ocean boundary conditions like sea surface temperature or sea ice extent ( Dole et al. 2011 ), reflecting changes in the

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Volkmar Wirth, Michael Riemer, Edmund K. M. Chang, and Olivia Martius

concomitant momentum flux convergence acts to sharpen the jet ( Chang 2001 , 2005b ). Apparently, much of the mean flow modification occurs in the vicinity of the RWP. Most of the events with significant growth and decay of hemispheric total eddy kinetic energy can be traced back to a single RWP, especially when the RWP propagates across the highly baroclinic region in the south Indian Ocean. The final stage of the RWP life cycle is usually associated with Rossby wave breaking ( Fig. 9 ), that is, the

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Franziska Teubler and Michael Riemer

Rossby’s early notion of the displacement of PV contours. An illustration of a high-amplitude Rossby wave pattern along the midlatitude jet is provided in Fig. 1 in terms of PV on an isentropic level intersecting the midlatitude tropopause. An RWP apparently extends from the North Pacific Ocean into Europe and is identified by the undulation of the strong PV gradient between the stratospheric, high-PV air and the tropospheric, low-PV air. Clearly associated with the wave pattern are high and low

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Andrea Schneidereit, Dieter H. W. Peters, Christian M. Grams, Julian F. Quinting, Julia H. Keller, Gabriel Wolf, Franziska Teubler, Michael Riemer, and Olivia Martius

the North Pacific Ocean, in particular, and farther downstream in the Atlantic–European sector, and to understand their contribution to the amplification of the anticyclones. Furthermore, tendency equations of eddy kinetic energy K e and Ertel’s PV ( Ertel 1942 ) are evaluated to quantify the forcing mechanisms of ridges. The standard approaches of Plumb (1985) and Takaya and Nakamura (1997) are used to diagnose wave activity fluxes. Also, classical EP flux calculations ( Andrews et al. 1987

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Julia H. Keller, Sarah C. Jones, and Patrick A. Harr

and Lackmann 1995 ; Riemer et al. 2008 ; Scheck et al. 2011a ) the development of a midlatitude Rossby wave train. Hence, the impact of a transitioning TC on the midlatitude flow is not limited to the immediate vicinity of the cyclone itself. The triggered Rossby wave train may propagate far downstream, eventually enhancing the potential for downstream cyclogenesis on the opposite side of the ocean basin ( Agustí-Panareda et al. 2004 ; Harr and Dea 2009 ; Riemer and Jones 2010 ). The potential

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Olivia Martius and Heini Wernli

. Gill , A. E. , 1980 : Some simple solutions for heat-induced tropical circulation . Quart. J. Roy. Meteor. Soc. , 106 , 447 – 462 . Gill , A. E. , 1982 : Atmosphere–Ocean Dynamics . Academic Press, 645 pp . Held , I. M. , and A. Y. Hou , 1980 : Nonlinear axially symmetric circulations in a nearly inviscid atmosphere . J. Atmos. Sci. , 37 , 515 – 533 . Held , I. M. , and P. Phillips , 1990 : A barotropic model of the interaction between the Hadley cell and a Rossby wave . J

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