COSMO Model Research Articles

Quantum Calculations in Solution for Large to Very Large Molecules: A New Linear Scaling QM/Continuum Approach.

We present a new implementation of continuum solvation models for semiempirical Hamiltonians that allows the description of environmental effects on very large molecular systems. In this approach based on a domain decomposition strategy of the COSMO model (ddCOSMO), the solution to the COSMO equations is no longer the computational bottleneck but becomes a negligible part of the overall computation time. In this Letter, we analyze the computational impact of COSMO on the solution of the SCF equations for large to very large molecules, using semiempirical Hamiltonians, for both the new ddCOSMO implementation and the most recent, linear scaling one, based on the fast multipole method. A further analysis is on the simulation of the UV/visible spectrum of a light-harvesting pigment-protein complex. All of the results show how the new ddCOSMO algorithm paves the way to routine computations for large molecular systems in the condensed phase.

On the time‐splitting errors of one‐dimensional advection schemes in numerical weather prediction models; a comparative study

A one‐dimensional flux‐form advection scheme with a new correction of time‐splitting errors is implemented in the numerical weather prediction (NWP) model COSMO of the German Meteorological Service. The advection scheme is applied for calculating the transport of all prognostic humidity variables in COSMO. Moreover, the advective transport of passive tracers is investigated. With the modified COSMO configuration, several realistic case‐studies are performed and compared with the operational COSMO version. The main focus of these investigations is on the behaviour of the new advection scheme in regions with strong deformational flow fields, such as steep orographical terrain and meteorological fronts.The numerical results of these case‐studies indicate that the modified COSMO model yields results similar to the operational version. The observed differences between the two model versions are minimized when the advection scheme of the operational COSMO model is applied with a numerically expensive Strang splitting approach. At the same time, the results of the new advection scheme are barely affected by the application of Strang splitting. Since, in addition to this, the new advection scheme behaves numerically more stably than the original scheme, it is an attractive alternative for calculating the transport of scalar quantities in NWP models.

The dichotomous structure of the warm conveyor belt

The warm conveyor belt (WCB) of an extratropical cyclone generally splits into two branches. One branch (WCB1) turns anticyclonically into the downstream upper-level tropospheric ridge, while the second branch (WCB2) wraps cyclonically around the cyclone centre. Here, the WCB split in a typical North Atlantic cold-season cyclone is analysed using two numerical models: the Met Office Unified Model and the COSMO model. The WCB flow is defined using off-line trajectory analysis. The two models represent the WCB split consistently. The split occurs early in the evolution of the WCB with WCB1 experiencing maximum ascent at lower latitudes and with higher moisture content than WCB2. WCB1 ascends abruptly along the cold front where the resolved ascent rates are greatest and there is also line convection. In contrast, WCB2 remains at lower levels for longer before undergoing saturated large-scale ascent over the system's warm front. The greater moisture in WCB1 inflow results in greater net potential temperature change from latent heat release, which determines the final isentropic level of each branch. WCB1 also exhibits lower outflow potential vorticity values than WCB2. Complementary diagnostics in the two models are utilised to study the influence of individual diabatic processes on the WCB. Total diabatic heating rates along the WCB branches are comparable in the two models, with microphysical processes in the large-scale cloud schemes being the major contributor to this heating. However, the different convective parametrization schemes used by the models cause significantly different contributions to the total heating. These results have implications for studies on the influence of the WCB outflow in Rossby wave evolution and breaking. Key aspects are the net potential temperature change and the isentropic level of the outflow, which together will influence the relative mass going into each WCB branch and the associated negative PV anomalies at the tropopause-level flow.

Quantification of climate-tourism potential for Athens, Greece – Recent and future climate simulations

<p>The aim of this paper is to present in a useful and understandable way how climatic change could be interpreted for tourism and recreation. Future climate change conditions are analyzed using the Climate Version of the Local Model (CLM) based on the COSMO model, which is currently used – among other weather services – by the DWD (Deutscher Wetterdienst) for operational weather forecast. The climate simulations concern the future periods 2021-2050 and 2071-2100 against the reference period 1961-1990, under A1B scenario. Based on regional climate simulations, the analysis for tourism can be performed using the Climate-Tourism-Information-Scheme (CTIS). The CTIS contains detailed climate information, which can be used by tourists to anticipate thermal comfort, aesthetical and physical conditions for planning their vacations. Furthermore, the Physiologically Equivalent Temperature (PET), which is one of the most popular physiological thermal indices derived from the human energy balance, is used in the analysis in order to describe the effect of climate. The future simulations concerning PET and CTIS for the area for Athens have been exemplary used, in order to consider them for tourism industry and local authorities for tourism planning.</p>

The effect of a sub-grid statistical cloud-cover scheme applied to the COSMO local numerical weather prediction model over the wider geographical domain of Greece

The COSMO model uses operationally two sub-grid schemes for the evaluation of stratus clouds. A semi-empirical scheme based on relative humidity is used in the radiation module while a statistical scheme is used in the turbulence module. The objective is to investigate the possibility of the implementation of the statistical scheme also in the radiation module. The relative impact is presented in reference to a spring test case with synoptic conditions that favor stratiform clouds. The domain considered is the wider Balkan region around the Hellenic geographical area and is characterized by comparable sea and land partitions. This particular domain choice gives rise to a strong coexistence of continental as well as marine clouds which is one of the most challenging features regarding the operational use of numerical weather prediction models by the Hellenic Meteorological Service. The results are evaluated through direct comparisons with satellite data as well as the observed 2-m temperatures for an approximate total of fifty Greek synoptic meteorological stations.The implementation of the statistical scheme led to an underestimation of low cloud-cover by the model in contrast to the implementation of the default relative-humidity scheme, while regarding medium cloud-cover the situation was reversed. Also, the daily 2-meter minimum and maximum temperatures were slightly better simulated, but not conclusively, when the statistical scheme was implemented in the radiation module. Although the statistical scheme cannot in its present form replace operationally the relative-humidity scheme in the radiation module, it is an important asset to COSMO model invoking valuable insight to the physics of the model and can be used as a basis to support the ongoing research in this crucial area of atmospheric sciences.

An online trajectory module (version 1.0) for the nonhydrostatic numerical weather prediction model COSMO

Abstract. A module to calculate online trajectories has been implemented into the nonhydrostatic limited-area weather prediction and climate model COSMO. Whereas offline trajectories are calculated with wind fields from model output, which is typically available every one to six hours, online trajectories use the simulated resolved wind field at every model time step (typically less than a minute) to solve the trajectory equation. As a consequence, online trajectories much better capture the short-term temporal fluctuations of the wind field, which is particularly important for mesoscale flows near topography and convective clouds, and they do not suffer from temporal interpolation errors between model output times. The numerical implementation of online trajectories in the COSMO-model is based upon an established offline trajectory tool and takes full account of the horizontal domain decomposition that is used for parallelization of the COSMO-model. Although a perfect workload balance cannot be achieved for the trajectory module (due to the fact that trajectory positions are not necessarily equally distributed over the model domain), the additional computational costs are found to be fairly small for the high-resolution simulations described in this paper. The computational costs may, however, vary strongly depending on the number of trajectories and trace variables. Various options have been implemented to initialize online trajectories at different locations and times during the model simulation. As a first application of the new COSMO-model module, an Alpine north foehn event in summer 1987 has been simulated with horizontal resolutions of 2.2, 7 and 14 km. It is shown that low-tropospheric trajectories calculated offline with one- to six-hourly wind fields can significantly deviate from trajectories calculated online. Deviations increase with decreasing model grid spacing and are particularly large in regions of deep convection and strong orographic flow distortion. On average, for this particular case study, horizontal and vertical positions between online and offline trajectories differed by 50–190 km and 150–750 m, respectively, after 24 h. This first application illustrates the potential for Lagrangian studies of mesoscale flows in high-resolution convection-resolving simulations using online trajectories.

A bulk parametrization of melting snowflakes with explicit liquid water fraction for the COSMO model

Abstract. A new snow melting parametrization is presented for the non-hydrostatic limited-area COSMO ("consortium for small-scale modelling") model. In contrast to the standard cloud microphysics of the COSMO model, which instantaneously transfers the meltwater from the snow to the rain category, the new scheme explicitly considers the liquid water fraction of the melting snowflakes. These semi-melted hydrometeors have characteristics (e.g., shape and fall speed) that differ from those of dry snow and rain droplets. Where possible, theoretical considerations and results from vertical wind tunnel laboratory experiments of melting snowflakes are used as the basis for characterising the melting snow as a function of its liquid water fraction. These characteristics include the capacitance, the ventilation coefficient, and the terminal fall speed. For the bulk parametrization, a critical diameter is introduced. It is assumed that particles smaller than this diameter, which increases during the melting process, have completely melted, i.e., they are converted to the rain category. The values of the bulk integrals are calculated with a finite difference method and approximately represented by polynomial functions, which allows an efficient implementation of the parametrization. Two case studies of (wet) snowfall in Germany are presented to illustrate the potential of the new snow melting parametrization. It is shown that the new scheme (i) produces wet snow instead of rain in some regions with surface temperatures slightly above the freezing point, (ii) simulates realistic atmospheric melting layers with a gradual transition from dry snow to melting snow to rain, and (iii) leads to a slower snow melting process. In the future, it will be important to thoroughly validate the scheme, also with radar data and to further explore its potential for improved surface precipitation forecasts for various meteorological conditions.

Verification of mesoscale forecasts in the 2014 Olympic Games region for the first test period. Part I: Verification techniques and polygonal quality assessments of the COSMO model forecasts

Described is a system of verification of mesoscale hydrodynamic forecasts for the territory of Sochi-2014 Winter Olympic Games worked out within the framework of FROST-2014 international project. A technological line comprises the observational and model output databases, the computing verification complex, and the optional program aids for aggregation and visualization of products. The METv4.0 verification complex developed in cooperation with forecasting and research centers of the USA is used as a core. The effectiveness of the verification system is demonstrated with the COSMO model products for the period of December 1, 2011–March 31, 2012. Preliminary assessments of the model potential in forecasting the surface air temperature, the velocity of the scalar wind, and the sea-level air pressure are made with the quality score aggregation over the selected polygons of verification.

Domain decomposition for implicit solvation models

This article is the first of a series of papers dealing with domain decomposition algorithms for implicit solvent models. We show that, in the framework of the COSMO model, with van der Waals molecular cavities and classical charge distributions, the electrostatic energy contribution to the solvation energy, usually computed by solving an integral equation on the whole surface of the molecular cavity, can be computed more efficiently by using an integral equation formulation of Schwarz's domain decomposition method for boundary value problems. In addition, the so-obtained potential energy surface is smooth, which is a critical property to perform geometry optimization and molecular dynamics simulations. The purpose of this first article is to detail the methodology, set up the theoretical foundations of the approach, and study the accuracies and convergence rates of the resulting algorithms. The full efficiency of the method and its applicability to large molecular systems of biological interest is demonstrated elsewhere.

Soil‐moisture memory in the regional climate model COSMO‐CLM during the Indian summer monsoon season

Soil moisture memory over the Indian subcontinent was investigated on the basis of a 101 year long simulation with the regional climate model (RCM) COSMO‐CLM (COSMO model in Climate Mode). The RCM was driven by lateral boundary conditions derived from a preindustrial control run of the coupled global ocean‐atmosphere model ECHAM5/MPIOM. To prevent an external atmospheric forcing, the simulation was done with constant greenhouse gas concentrations. This provides an estimate of the internal variability of the (modeled) climate system. The analysis, which was performed for the Indian summer monsoon season (ISM), shows that simulated memory lengths (a) increase with soil depth, and (b) are longer in the western region than in the eastern region (14 and 9 days, respectively, at 34 cm soil layer depth). Also, the meridionally averaged (20°N–30°N) variance of subsequent precipitation explained by soil‐moisture rises from east to west. This enhanced explained variance value in the western region reveals the potential usefulness of improved soil moisture initialization in subseasonal rainfall forecasting.

Projection of fire potential to future climate scenarios in the Alpine area: some methodological considerations

In Europe, wildfires are an issue not only for the Mediterranean area, but also in the Alpine regions in terms of increasing number of events and severity. In this study we evaluate the impact of climate change on the fire potential in the Alps in the past and in future scenarios. The Fine Fuel Moisture Code (FFMC) of the Canadian Forest Fire Danger Rating System, which successfully distinguishes among recorded fire/no fire events, is applied to projections of Regional Climate Models (RCMs) calculated on the SRES scenario A1B. We compare two different techniques: 1) a single model run of the COSMO-CLM RCM at 18 km resolution, and 2) a combination of 25-km resolution RCMs from the ENSEMBLES project, combined with the Multimodel SuperEnsemble technique and a new probabilistic Multimodel SuperEnsemble Dressing. The single-model RCM allows for a greater coherence among the input parameters, while the Multimodel techniques permit to reduce the model biases and to downscale to a higher resolution where long term records of observations are available. The projected changes with the Multimodel in the scenario give an estimation of increasing wildfire potential in the mid XXI century. In particular the frequency of severe wildfire potential days is shown to increase dramatically. The single (independent) COSMO model gives a weaker signal and in some regions of the study area the predicted changes are opposite to the ones by the Multimodel. This is mainly due to increasing precipitation amounts simulated especially in the northern parts of the Alps. However, there are also some individual models included in the Multimodel ensemble that show a similar signal. This confirms the ambiguity of any impact study based on a single climate model due to the uncertainty of the projections of the climate models.

Effects of temperature on flood forecasting: analysis of an operative case study in Alpine basins

Abstract. In recent years the interest in the forecast and prevention of natural hazards related to hydro-meteorological events has increased the challenge for numerical weather modelling, in particular for limited area models, to improve the quantitative precipitation forecasts (QPF) for hydrological purposes. After the encouraging results obtained in the MAP D-PHASE Project, we decided to devote further analyses to show recent improvements in the operational use of hydro-meteorological chains, and above all to better investigate the key role played by temperature during snowy precipitation. In this study we present a reanalysis simulation of one meteorological event, which occurred in November 2008 in the Piedmont Region. The attention is focused on the key role of air temperature, which is a crucial feature in determining the partitioning of precipitation in solid and liquid phase, influencing the quantitative discharge forecast (QDF) into the Alpine region. This is linked to the basin ipsographic curve and therefore by the total contributing area related to the snow line of the event. In order to assess hydrological predictions affected by meteorological forcing, a sensitivity analysis of the model output was carried out to evaluate different simulation scenarios, considering the forecast effects which can radically modify the discharge forecast. Results show how in real-time systems hydrological forecasters have to consider also the temperature uncertainty in forecasts in order to better understand the snow dynamics and its effect on runoff during a meteorological warning with a crucial snow line over the basin. The hydrological ensemble forecasts are based on the 16 members of the meteorological ensemble system COSMO-LEPS (developed by ARPA-SIMC) based on the non-hydrostatic model COSMO, while the hydrological model used to generate the runoff simulations is the rainfall–runoff distributed FEST-WB model, developed at Politecnico di Milano.

Solvent Effects in Calculated Vibrational Raman Optical Activity Spectra of α-Helices

We study the influence of solvation effects on vibrational Raman optical activity spectra of α-helices by means of quantum chemical calculations. Solvent effects are considered in the calculations via the conductor-like screening model COSMO and, in addition, via explicit water molecules. The so-called external type of hydration is employed. In this hydration pattern, the water molecules form hydrogen bonds to the carbonyl groups of the α-helical (Ala)20 model. It is found that the amide I bands are significantly shifted to lower wavenumbers if solvent effects are incorporated into the calculations. These computational results, obtained within the static picture employed in this work, suggest that the amide I bands may serve as a signature for the hydration of α-helices.

The impact of Typhoon Jangmi (2008) on the midlatitude flow. Part II: Downstream evolution

AbstractExtratropical transition (ET) of a tropical cyclone (TC) can modify the midlatitude flow and thus have implications for the weather and predictability in downstream regions such as North America or Europe. Albeit recurving and undergoing ET, the downstream impact of Typhoon Jangmi in September 2008 during the THORPEX Pacific Asian Regional Campaign (T‐PARC) was weak. In this study, we explore the physical processes inhibiting the reintensification of Jangmi and governing the forecast uncertainty during ET. The focus is on the relative contribution of the TC and the midlatitude flow. Quasi‐geostrophic diagnostics reveal that Jangmi is located south of and in phase with a midlatitude trough. Jangmi does not couple with the region favourable for reintensification ahead of the trough and subsequently decays. Instead, a weak frontal wave‐like cyclone develops. The role of the phasing of Typhoon Jangmi and the midlatitude Rossby wave pattern is tested in sensitivity experiments with the COSMO model in which Jangmi has been relocated. The simulations reveal two contrasting groups of scenarios. The first group reflects the weak actual ET and subsequent decay accompanied by a broad ridge over the Pacific. The second group is characterized by a strong ET with extratropical reintensification, the triggering of a pronounced Rossby wave train and downstream cyclogenesis. The displacement of Jangmi's initial position in the two contrasting groups is less than 1.25° (130 km). In the frame moving with the environmental background flow a critical bifurcation point for the track of Jangmi exists. The relative position to this bifurcation point determines whether Jangmi decays or reintensifies and triggers a Rossby wave train. A simple discrimination parameter is derived that allows for classifying the scenarios. The observed behaviour gives a simple explanation for the reduced predictability of the track and of the midlatitude flow in downstream regions during ET.

Evaluation of the QPF of convective flash flood rainfalls over the Czech territory in 2009

In this paper, quantitative precipitation forecasts (QPF) are evaluated using several verification techniques and analysis of the results from these techniques. The forecasts were produced by two limited-area numerical weather prediction models: the ALADIN-CZ model operated by the Czech Hydro-Meteorological Institute (CHMI) and the COSMO model operated by the German Weather Service (DWD). Each model was run using two horizontal resolutions over the domain covering the Czech Republic. The ALADIN-CZ model outputs were obtained using resolutions of approximately 9km and 4.7km, and the COSMO model outputs were obtained using resolutions of approximately 7km and 2.8km.The forecast quality is studied for the flash flood period that occurred in June and July of 2009, when convective rainfalls with durations of 1 to 3h and a return period of more than 100years caused devastating floods in many Czech localities. The radar-based rainfalls used to verify the forecasts were produced by the CHMI operational product MERGE, which merges radar-derived rainfalls with the rainfalls that are measured by ground rain gauges.A series of 56 consecutive forecasts of 3-h rainfalls were verified using traditional and spatial verification techniques, and the results from these analyses were compared. The verification was performed using traditional verification scores based on a contingency table, spatial verification by the fractions skill score (FSS) and the SAL (structure–amplitude–location) technique. The FSS represents a fuzzy verification technique and compares the fractional coverage of precipitation grids over a threshold in spatial windows around the observations and forecasts. The SAL is a spatial object-oriented verification technique used to evaluate the structure, amplitude, and location of a precipitation field.The quality of QPF depends strongly on the scale of convective precipitation, and all models provide good forecast quality for extended rainfall systems. The opposite is true for the local and more or less chaotic convection during the final part of the time period. The FSS indicates how the results depend on the threshold and scale of precipitation. The COSMO 2.8 model is able to determine the largest local rainfall values, but models with lower resolution, such as the ALADIN 9km and COSMO 7km, provide better results for lower thresholds and larger scales. The use of more verification techniques is suitable for a modeller-oriented evaluation of different aspects of forecast quality.

Comparison of PredictedpKaValues for Some Amino-Acids, Dipeptides and Tripeptides, Using COSMO-RS, ChemAxon and ACD/Labs Methods

Liquid-phase <i>pK<i/><sub><i>a<i/><sub/> values play a ke<sup><i>y<i/><sup/> role in food science. Chemical properties of molecules depend largely on whether they are ionized or not. Most organic molecules are capable of gaining and/or losing a proton in aqueous solutions. Proton transfer most. frequently occurs between water and any ionizable atom of the organic molecule. The molecule’s response to profanation or deprotonation depends significantly on the site that was disturbed by proton transfer. Partial charge distribution in the molecule also varies with protonation of the acidlbase active sites. Then it can he used to determine the <i>pK<i/><sub><i>a<i/><sub/> of a molecule. First, we use the COSMO-RS method, a combination of the quantum chemical dielectric continuum solvation model COSMO with a statistical thermodynamics treatment fin- more Realistic Solvation (RS) simulations, for the direct prediction of <i>pK<i/><sub><i>a<i/><sub/> constants of about 50 molecules (amino-acids, dipeptides and tripeptides). Then, we compare our results with experimental data and the <i>pK<i/><sub><i>a<i/><sub/> values predicted using two other methods. We used respectively the ChemAxon method using a program based on the calculation of partial charge of atoms in the molecule and the ACD/Labs method that enables to calculate single <i>pK<i/><sub><i>a<i/><sub/> values. for all possible dissociation centers when the rest of the molecule is considered neutral, using an internal database containing chemical structures and their experimental <i>pK<i/><sub>a<sub/> values. The averaged Root Mean Square Error (RMSE) of the predicted <i>pK<i/><sub><i>a<i/><sub/> values for each method compared to experimental results were respectively 0.596 for COSMO-RS, 0.445 for ChemAxon and 0.490 for ACD/Labs. While ACDILabs and ChemAxon are parameterized using a large set ofexperimental data (including several of the studied molecules), the COSMO- RS method was used in a fully predictive way. Regarding these results, COSMO-RS appears as a promising method to predict the <i>pK<i/><sub><i>a<i/><sub/> values of molecules of interest in food science with scarce available <i>pK<i/><sub><i>a<i/><sub/> values such as peptides. The final goal of this study is to use the <i>pK<i/><sub><i>a<i/><sub/> values in a predictive thermodynamics model for products of interest in food industry. For this purpose, the effects of several factors (like conformations set treatment in COSMO-RS calculations, ionic strength effect) that can affect the comparison between observed and predicted <i>pK<i/><sub><i>a<i/><sub/> data are discussed.

An advanced scheme for wet scavenging and liquid-phase chemistry in a regional online-coupled chemistry transport model

Abstract. Clouds are reaction chambers for atmospheric trace gases and aerosols, and the associated precipitation is a major sink for atmospheric constituents. The regional chemistry-climate model COSMO-ART has been lacking a description of wet scavenging of gases and aqueous-phase chemistry. In this work we present a coupling of COSMO-ART with a wet scavenging and aqueous-phase chemistry scheme. The coupling is made consistent with the cloud microphysics scheme of the underlying meteorological model COSMO. While the choice of the aqueous-chemistry mechanism is flexible, the effects of a simple sulfur oxidation scheme are shown in the application of the coupled system in this work. We give details explaining the coupling and extensions made, then present results from idealized flow-over-hill experiments in a 2-D model setup and finally results from a full 3-D simulation. Comparison against measurement data shows that the scheme efficiently reduces SO2 trace gas concentrations by 0.3 ppbv (−30%) on average, while leaving O3 and NOx unchanged. PM10 aerosol mass was increased by 10% on average. While total PM2.5 changes only little, chemical composition is improved notably. Overestimations of nitrate aerosols are reduced by typically 0.5–1 μg m−3 (up to −2 μg m−3 in the Po Valley) while sulfate mass is increased by 1–1.5 μg m−3 on average (up to 2.5 μg m−3 in Eastern Europe). The effect of cloud processing of aerosols on its size distribution, i.e. a shift towards larger diameters, is observed. Compared against wet deposition measurements the system tends to underestimate the total wet deposited mass for the simulated case study.

Strong interannual variation of the Indian summer monsoon in the Late Miocene

The modern Asian monsoon system exhibits strong interannual variation, which has profound environmental and economical impacts. It has been well-documented that the mean Asian monsoon state underwent significant changes in the Late Miocene (11–5 Ma ago). But how the interannual variability of the monsoon climate evolved during this period is still largely unknown. In this study, a long-term simulation of the Late Miocene with a fully coupled atmosphere–ocean general circulation model (ECHAM5/MPI-OM) at T31L19 resolution is used to explore the interannual variation of the Indian summer monsoon (ISM) in the Late Miocene. The regional climate model COSMO–CLM with a higher spatial resolution (~1° × 1°) is further employed to better characterize the spatial patterns of these variations. Our results show that although the mean ISM circulation is weaker in the Late Miocene runs, its interannual variation is as strong as or even stronger than at present and the dominant periods (~2.6–2.7 years) are shorter than at present (~3.4–8.4 years). It is noticed that while the extratropical influence on the ISM variability is weaker-than-present, a persistent El Nino-Southern Oscillation with stronger-than-present interannual variability is observed in our Late Miocene run. This may have maintained a strong interannual variation of the ISM with a shorter period in the Late Miocene. Our findings do not only improve our understanding of the Asian monsoon evolution in the Late Miocene, but also shed light on the future changes in the interannual variability of the ISM.

Prearrangement of the COSMO-CLM Model on the Chinese Region and Sensitivity Analysis

This report represents the description of the first activity performed within the work package 7.1.6 of the B action in the Gemina project. The B action of the Gemina project concerns the consolidation and development of international scientific network. In particular the cooperation between China and Italy is focused on the development of regional climate scenarios and the analysis of impacts on coastal areas on the Chinese region. The main goal of the WP 7.1.6. is to provide high climate simulation on the China region for the XXI century. In order to perform this activity, some preliminary simulations are requested, to find an optimal configuration for the high resolution climate model COSMO CLM. This report contains the description of the sensitivity analysis developed on a limited part of the Chinese region.

Hydrological simulation of extreme flood scenarios for operational flood management at the Middle Elbe river

Abstract. Operational flood management at the Middle Elbe river requires comprehensive knowledge about the magnitude and characteristics of possible extreme flood events. Since these events are not sufficiently included in available historical records, an extended sample of extreme flood events was generated by hydrological scenario simulation. Present paper emphasises simulations in the German part of the catchment of the Middle Elbe river and introduces the stochastic-conceptual precipitation-runoff model which was developed for this task. After validation of this model and its coupling with the weather forecast model COSMO and hydraulic-numerical models, a set of 25 flood scenarios could be simulated and provided for a planning of flood protection measures. Analysis of simulated scenarios reveal that extreme flood events at the Mulde and Middle Elbe rivers may have a wide spectrum of characteristics and may considerably exceed the magnitude of past flood events (e.g., those of August 2002).