[1] Four different simulations of a winter period in Central Europe are carried out to investigate the principle effect of anthropogenic heat release from the highly industrialized and populated Ruhrarea region (Germany) on regional climate conditions. The results reveal a permanent warming due to anthropogenic heat emissions over affected areas ranging from 0.15 K over land area with an additional 2 W m À2 anthropogenic heat flux up to 0.5 K over the Ruhrarea with additional 20 W m À2 anthropogenic heat flux. The temperature effects induced by anthropogenic heat not only depend on the amount of added heat but also on orographical factors. No significant variations are found for precipitation.

SummaryThe problem of polar and subpolar inversions is attacked. Thus a literature review of the exploration of the polar lower atmosphere is presented together with an attempt to classify these inversions, according to the participating processes, such as subsidence, advection and radiation. These physical processes are incorporated into a simple inversion model, giving the heights of inversion and cloud base, the radiative cooling rates and the vertical profiles of the thermodynamic quantities and the turbulent fluxes. The model is applied to a period with subsidence inversion over the Norwegian Sea during summer. The case study shows a good agreement between the results of the steady-state model and the mean observed thermodynamic structure of the atmospheric boundary layer. Zusammenfassung Die Struktur der subpolaren Inversionen in der atmosphiirischen GrenzschichtDie Erforschung der polaren und subpolaren atmosphfirischen Grenzschicht wird in einer Literaturiibersicht dargestellt. Anhand der bei der Entstehung beteiligten Prozesse wie grot~skaliges Absinken, Advektion und Strahlung wird eine Einteilung der Inversionen vorgenommen. Mit einem einfachen Modell, das diese Prozesse berticksichtigt, wird eine sommerliche Inversionslage fiber der Norwegischen See untersucht. Das Modell liefert die H6hen yon Inversion und Wotkenbasis, die Strahlungsabktihlung und die Vertikalproffle der thermodynamischen Zustandsgr6gen und der turbulenten Fliisse. Die Modellergebnisse zeigen eine gute (Ybereinstimmung mit den Beobachtungen.

The mechanism of localized inertial wave excitation and its efficiency is investigated for an annular cavity rotating with $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\Omega _0$. Meridional symmetry is broken by replacing the inner cylinder with a truncated cone (frustum). Waves are excited by individual longitudinal libration of the walls. The geometry is non-separable and exhibits wave focusing and wave attractors. We investigated laboratory and numerical results for the Ekman number $E\approx 10^{-6}$, inclination $\alpha =5.71^\circ $ and libration amplitudes $\varepsilon \leq 0.2$ within the inertial wave band $0 < \omega < 2\Omega _0$. Under the assumption that the inertial waves do not essentially affect the boundary-layer structure, we use classical boundary-layer analysis to study oscillating Ekman layers over a librating wall that is at an angle $\alpha \neq 0$ to the axis of rotation. The Ekman layer erupts at frequency $\omega =f_{*}$, where $f_{*}\equiv 2 \Omega _0 \sin \alpha $ is the effective Coriolis parameter in a plane tangential to the wall. For the selected inclination this eruption occurs for the forcing frequency $\omega /\Omega _0=0.2$. For the librating lids eruption occurs at $\omega /\Omega _0=2$. The study reveals that the frequency dependence of the total kinetic energy $K_{\omega }$ of the excited wave field is strongly connected to the square of the Ekman pumping velocity $w_{{E}}(\omega )$ that, in the linear limit, becomes singular when the boundary layer erupts. This explains the frequency dependence of non-resonantly excited waves. By the localization of the forcing, the two configurations investigated, (i) frustum libration and (ii) lids together with outer cylinder in libration, can be clearly distinguished by their response spectra. Good agreement was found for the spatial structure of low-order wave attractors and periodic orbits (both characterized by a small number of reflections) in the frequency windows predicted by geometric ray tracing. For ‘resonant’ frequencies a significantly increased total bulk energy was found, while the energy in the boundary layer remained nearly constant. Inertial wave energy enters the bulk flow via corner beams, which are parallel to the characteristics of the underlying Poincaré problem. Numerical simulations revealed a mismatch between the wall-parallel mass fluxes near the corners. This leads to boundary-layer eruption and the generation of inertial waves in the corners.

A modified profile method for determing the vertical deposition (or/and exhalation) fluxes of NO, NO2, ozone, and HN03 in the atmosphere surface layer is presented. This method is based on the generally accepted niicrometeorological ideas of the transfer of momentum, sensible heat and matter near the Earth's surface and the chemical reactions among these trace gases. The analysis (aerodynamic profile method) includes a detailed determination of the micrometeorological quantities (such as the friction velocity, the fluxes of sensible and latent heat, the roughness length and the zero plane displacement), and of the height-invariant fluxes of the composed chemically conservative trace gases with "group" concentrations c 1 = NO + NO2 + HNO3, c 2 = NO2 +O3 + 3/2 . HNO3, and c 3 = NO - O3 - 1/2 . HNO3. The fluxes of the "individual" species are finally determined by the numerical solution of a system of coupled nonlinear ordinary differential equations for the concentrations of ozone and HN O3 ("decoding" method). The parameterization of the fluxes is based on the flux-gradient relationships in the turbulent region of the atmospheric surface layer. The model requires only the vertical profile data of wind velocity, temperature and humidity and concentrations of NO, NO2, ozone, and HNO3. The method has been applied to vertical profile data obtained at Jülich (September 1984) and collected in the BIATEX joint field experiment LOVENOX (Halvergate, U.K., September 1989)

A nocturnal low-level jet characterized by a distinct inertial oscillation lasting from around sunset until sunrise the next day was observed during the coastal experiment PUKK. The phenomenon appeared over an area of at least 40 km in diameter; it thus had a mesoscale extension. We were able not only to observe this fine case but also to simulate it by an integrated dynamical PBL model.