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Tobias Kremer, Elmar Schömer, Christian Euler, and Michael Riemer

and start to transition into midlatitude cyclones ( Jones et al. 2003 ; Evans et al. 2017 ). An ET case therefore appears to be a well-suited testbed to demonstrate the applicability of our clustering approach. In addition, our clustering results can be compared with results of a previous study that has investigated the ET of Karl focusing on airstreams associated with latent heat release near the inner core ( Euler et al. 2019 ). In the current study, however, we will consider the more general

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

and subtropics ( Medina et al. 2019 ; Webster et al. 2011 ) or during time periods when the tropics are strongly influenced by the more predictable extratropical circulation ( Davis et al. 2013 ; van der Linden et al. 2017 ). The sobering performance of current NWP systems in the tropics have substantial socioeconomic implications, as the majority of developing countries are located in this area. Their populations are especially vulnerable to weather disasters and often underserved by

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

ground to 22 km above mean sea level. Shallow convection is parameterized using the Tiedtke scheme. Details on parameterizations can be found in Doms et al. (2011) . The setup follows the operational COSMO-DE setup with 461 by 421 grid points centered over Germany at 50°N, 10°E. The only major deviation from the current operational setup is a change of the tuning parameter tur_len in the boundary layer scheme to 500 m. As discussed in the introduction, a smaller value was applied as an ad hoc

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Kevin Bachmann, Christian Keil, George C. Craig, Martin Weissmann, and Christian A. Welzbacher

, Fig. 2 ) encompassing 461 × 421 grid points with a horizontal grid spacing of 0.025° or 2.8 km. The vertical coordinates are identical to the idealized setup, and the same parameterizations as in the idealized setup are applied. We use an asymptotic vertical mixing length of the boundary layer turbulence scheme of 500 m, as in the idealized configuration, but in contrast to the current operational value of 150 m. This facilitates not only direct comparisons to the idealized setup, but also removes

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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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Tobias Selz, Lucas Fischer, and George C. Craig

. 1999 ), increasing exponents with height ( Tjemkes and Visser 1994 ; Kahn et al. 2011 ), boundary layer versus free troposphere ( Cho et al. 2000 ; Pressel and Collins 2012 ), and anisotropic scaling ( Lovejoy et al. 2010 ). The implications of the different observed exponents for the existence of universal power laws are not clear, since the data used in each case are limited, and the results may not be comparable. It is, however, interesting to consider whether distinct physical mechanisms may

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Marlene Baumgart, Paolo Ghinassi, Volkmar Wirth, Tobias Selz, George C. Craig, and Michael Riemer

convection-permitting simulations on very large, preferably global, domains and for long lead times. Such an approach is computationally extremely costly, but has recently been performed for a single case by Judt (2018) . This approach, however, is currently not feasible to be applied to a large number of cases with several ensemble members to ensure the robustness of the results. Using coarser resolution with a deterministic scheme to parameterize convection, upscale error growth turns out to be much

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Christian Euler, Michael Riemer, Tobias Kremer, and Elmar Schömer

counterintuitive to see air masses from the boundary layer at the initial positions when looking at downward motions of air parcels in the inner core. The fact that air parcels from the same region are part of the inner-core convection ( Figs. 6d,f,h ) indicates that air parcels in the inner core of Karl perform a rollercoaster-like movement while circulating upward inside the core. Since the seeding of the trajectories in the inner core is a snap-shot of the current state at seeding time, some of those air

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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

1. Introduction Numerical atmospheric models generally consider terrestrial hydrological processes as only being vertical, in order to estimate the surface heat fluxes for constraining the atmospheric lower boundary condition. This is, for example, the case for the Weather Research and Forecasting (WRF) Model ( Skamarock and Klemp 2008 ) coupled with the Noah land surface model (LSM; Chen and Dudhia 2001 ). In this approach, the lateral redistribution of soil moisture according to the

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Marlene Baumgart, Michael Riemer, Volkmar Wirth, Franziska Teubler, and Simon T. K. Lang

across the boundary of the integration domain [second term in Eq. (5) ]. Not explicitly included in the barotropic framework of Boer (1984) , the third term in Eq. (5) constitutes an error source due to the divergence of the quasi-horizontal (adiabatic) flow. The remaining terms describe the influence of nonconservative processes (term 4), the boundary contribution due to changes in the integration area (term 5), and the residual (term 6). We evaluate the PV error tendency equation on an

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