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Peter Vogel, Peter Knippertz, Andreas H. Fink, Andreas Schlueter, and Tilmann Gneiting

organization and coupling to larger-scale circulations. The most important example of such a coupling on weather time scales are equatorial waves, classically referring to planetary-scale solutions of the shallow water equations for the tropics ( Matsuno 1966 ; Wheeler and Kiladis 1999 ). The coupling relies on a wave-induced modification of environmental conditions for convection such as convergence, stability, moisture availability, and shear ( Schlueter et al. 2019a , b ). Although a relatively high

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Georgios Fragkoulidis and Volkmar Wirth

Rhines , P. , 2015 : Dynamical meterology—Rossby waves. Encyclopedia of Atmospheric Sciences , 2nd ed. G. R. North, J. Pyle, and F. Zhang, Eds., Academic Press, 404–416, https://doi.org/10.1016/B978-0-12-382225-3.00346-7 . 10.1016/B978-0-12-382225-3.00346-7 Rossby , C. G. , 1940 : Planetary flow patterns in the atmosphere . Quart. J. Roy. Meteor. Soc. , 66 , 68 – 97 . Röthlisberger , M. , O. Martius , and H. Wernli , 2018 : Northern Hemisphere Rossby wave initiation events on the

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Paolo Ghinassi, Georgios Fragkoulidis, and Volkmar Wirth

, https://doi.org/10.1175/JAS3491.1 . 10.1175/JAS3491.1 Chang , E. K. M. , and I. Orlanski , 1993 : On the dynamics of a storm track . J. Atmos. Sci. , 50 , 999 – 1015 , https://doi.org/10.1175/1520-0469(1993)050<0999:OTDOAS>2.0.CO;2 . 10.1175/1520-0469(1993)050<0999:OTDOAS>2.0.CO;2 Charney , J. G. , and P. G. Drazin , 1961 : Propagation of planetary-scale disturbances from the lower into the upper atmosphere . J. Geophys. Res. , 66 , 83 – 109 , https://doi.org/10.1029/JZ066i001p

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

-00304.1 Charney , J. , 1955 : The use of the primitive equations of motion in numerical prediction . Tellus , 7 , 22 – 26 , https://doi.org/10.3402/tellusa.v7i1.8772 . 10.3402/tellusa.v7i1.8772 Charney , J. , and P. G. Drazin , 1961 : Propagation of planetary-scale disturbances from the lower into the upper atmosphere . J. Geophys. Res. , 66 , 83 – 109 , https://doi.org/10.1029/JZ066i001p00083 . 10.1029/JZ066i001p00083 Chen , G. , J. Lu , D. A. Burrows , and L. R. Leung , 2015

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Christian Barthlott and Corinna Hoose

. Moreover, the environmental conditions in the planetary boundary layer for convection initiation and at the cloud base remain unchanged. The obvious effect of this modification is on the stability of the atmosphere by directly increasing or decreasing the lapse rate. Given that the cloud base remains more or less unaffected, the convective available energy (CAPE) will be larger for the runs with decreased temperature values. This is due to the higher level of equilibrium as rising air parcels transect

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Stephan Rasp, Tobias Selz, and George C. Craig

1. Introduction Diabatic processes in the atmosphere, especially the release of latent heat through condensation and freezing, have been shown to have a large impact on atmospheric dynamics by modifying the upper-tropospheric potential vorticity (PV) distribution. Warm conveyor belts (WCB) are the predominant diabatically influenced phenomena in the midlatitudes. They are defined as broad airstreams that originate from the boundary layer of the cyclone’s warm sector and subsequently rise along

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Mirjam Hirt, Stephan Rasp, Ulrich Blahak, and George C. Craig

perturbations in the free troposphere present also during the night. However, the PSP was developed with the convective boundary layer in mind and many of its assumptions (notably vertically correlated eddies) are not valid for free tropospheric turbulence. In order to improve the physical integrity of the scheme and simultaneously reduce unrealistic precipitation, we limit the perturbations to the planetary boundary layer height H PBL . We determine H PBL as the height at which the bulk Richardson

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Andreas Schlueter, Andreas H. Fink, Peter Knippertz, and Peter Vogel

precipitation and their representation in numerical weather prediction (NWP) models over northern tropical Africa. Equatorial waves are a potential source of predictability in the tropics, as they can be considered preferred eigenmodes of the tropical atmosphere. These waves can couple with deep convection and subsequently modulate rainfall on the synoptic to subseasonal time scale throughout the tropics ( Wheeler and Kiladis 1999 ). Equatorial waves interacting with precipitation are thus called

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Joël Arnault, Thomas Rummler, Florian Baur, Sebastian Lerch, Sven Wagner, Benjamin Fersch, Zhenyu Zhang, Noah Kerandi, Christian Keil, and Harald Kunstmann

noticeable in a 100 × 100 km 2 domain, but not in a 500 × 2500 km 2 domain. WRF-Hydro also produced daily discharge moderately close to observations according to the Nash–Sutcliffe model efficiency coefficient (NSE; Nash and Sutcliffe 1970 ): 0.27 in the case of Senatore et al. (2015) , 0.43 in the case of Arnault et al. (2016) , and 0.02 in the case of Kerandi et al. (2018) . The above studies show that the representation of terrestrial water flow indeed impacts the surface fluxes and planetary

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Hilke S. Lentink, Christian M. Grams, Michael Riemer, and Sarah C. Jones

) and http://www.cosmo-model.org for more details on the computational methods]. The model is set up with a horizontal resolution of 0.025° (about 2.5 km at 35°N) and 57 vertical levels up to 30-km height, with an enhanced vertical resolution in the planetary boundary layer. Shallow convection is parameterized using the mass-flux scheme of Tiedtke (1989) , while middle and high convection are explicitly computed. For all parameterized processes, the default setup of COSMO is used ( Doms et al

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