Response of Convective Boundary Layer and Shallow Cumulus to Soil Moisture Heterogeneity: A Large‐Eddy Simulation Study

In this study, the impact of varying soil moisture heterogeneity (spatial variance and structure) on the development of the convective boundary layer and shallow cumulus clouds was investigated. Applying soil moisture heterogeneity generated via spatially correlated Gaussian random fields based on a power law model and idealized atmospheric vertical profiles as initial conditions, three sets of large‐eddy simulations provide insight in the influence of soil moisture heterogeneity on the ensuing growth of the convective boundary layer and development of shallow cumulus clouds. A sensitivity on the strong, weak, and unstructured soil moisture heterogeneity is investigated. The simulation results show that domain‐averaged land surface sensible heat and latent heat flux change strongly with changing soil moisture variance because of the interactions between surface heterogeneity and induced circulations, while domain means of soil moisture are identical. Vertical profiles of boundary layer characteristics are strongly influenced by the surface energy partitioning and induced circulations, especially the profiles of liquid water and liquid water flux. The amount of liquid water and liquid water flux increases with increasing structure. In addition, the liquid water path is higher in case of strongly‐structured heterogeneity because more available energy is partitioned into latent heat and more intensive updrafts exist. Interestingly, the increase of liquid water path with increasing soil moisture variance only occurs in the strongly structured cases, which suggests that soil moisture variance and structure work conjunctively in the surface energy partitioning and the cloud formation

On discontinuous Galerkin approach for atmospheric flow in the mesoscale with and without moisture

We present and discuss discontinuous Galerkin (DG) schemes for dry and moist atmospheric flows in the mesoscale. We derive terrain-following coordinates on the sphere in strong-conservation form, which makes it possible to perform the computation on a Cartesian grid and yet conserves the momentum density on an f -plane. A new DG model, i.e. DG-COSMO, is compared to the operational model COSMO of the Deutscher Wetterdienst (DWD). A simplified version of the suggested terrain-following coordinates is implemented in DG-COSMO and is compared against the DG dynamical core implemented within the DUNE framework, which uses unstructured grids to capture orography. Finally, a few idealised test cases, including 3d and moisture, are used for validation. In addition an estimate of efficiency for locally adaptive grids is derived for locally and non-locally occurring phenomena.publishedVersio

Large eddy simulation using the general circulation model ICON

ICON (ICOsahedral Nonhydrostatic) is a unified modeling system for global numerical weather prediction (NWP) and climate studies. Validation of its dynamical core against a test suite for numerical weather forecasting has been recently published by Zängl et al. (2014). In the present work, an extension of ICON is presented that enables it to perform as a large eddy simulation (LES) model. The details of the implementation of the LES turbulence scheme in ICON are explained and test cases are performed to validate it against two standard LES models. Despite the limitations that ICON inherits from being a unified modeling system, it performs well in capturing the mean flow characteristics and the turbulent statistics of two simulated flow configurations - one being a dry convective boundary layer and the other a cumulus-topped planetary boundary layer.BMBF/01LK1202

Asymmetric Digital Subscriber Line (ADSL)

ADSL (Asymmetric Digital Subscriber Line) is a technologythat allows transmission at 8.488 Mbps over the existingtelephone copper line (speed range depending on the distance).ADSL circuit connects the ADSL modems by twisted-pairtelephone lines creating three infonnation channels: high speedsimplex (maximum 9 Mbps), medium speed duplex channel(maximum 2 Mbps) and plain old telephone service channel.ADSL technology supports up to seven synchronous channelsthat can be configured to meet the needs of the end user.One could simultaneously view four movies stored in MPEG 1fonnat on separate television sets (MPEG 1 transmitted at 1.5Mbps), hold a video-conference (transmitted at 348 kbps),download data files from a server at 128 kbps via ISDN andeven receive a telephone call

Large‐eddy simulation of catchment‐scale circulation

The impact of soil moisture heterogeneity on the convective boundary layer (CBL) development was studied. Based on results from large‐eddy simulation (LES) applying soil moisture patterns along a river corridor and idealized atmospheric vertical profiles as initial conditions, this study provides insight in the influence of spatial scale of soil moisture heterogeneity on catchment‐scale circulations (CCs) and the ensuing growth of the CBL. The simulation results show that the intensity of organized circulations resulting from soil moisture heterogeneity is nonlinearly dependent upon soil moisture heterogeneity scale λ (SMHS) and horizontal gradient. Because of the large SMHS and strong soil moisture contrast, none of the simulations has reached a true steady state even after 24 h of simulation time. The intensity of organized circulations shows a sigmoidal dependence on SMHS. The optimal SMHS for horizontal transport is on the order of 19.2 km, while optimal SMHS for vertical motions occurs at 2.4 km. In these cases, the CCs also exert a strong influence on the boundary‐layer structure and the entrainment layer. The potential temperature is not constant with height due to a weak mixing in the boundary layer for large SMHS cases. Differences in sensible heat flux profiles between the heterogeneous cases increase with increasing height and reach a maximum at the top of the CBL. Interestingly, boundary‐layer height changes strongly with changing horizontal soil moisture gradient and SMHS while domain means, variances, and amplitudes of land surface energy fluxes are all almost identical. The entrainment flux and subsidence at the top of the CBL are jointly responsible for the CBL height variation

Comparison of dynamical cores for NWP models : comparison of COSMO and Dune

We present a range of numerical tests comparing the dynamical cores of the operationally used numerical weather prediction (NWP) model COSMO and the university code Dune, focusing on their efficiency and accuracy for solving benchmark test cases for NWP. The dynamical core of COSMO is based on a finite difference method whereas the Dune core is based on a Discontinuous Galerkin method. Both dynamical cores are briefly introduced stating possible advantages and pitfalls of the different approaches. Their efficiency and effectiveness is investigated, based on three numerical test cases, which require solving the compressible viscous and non-viscous Euler equations. The test cases include the density current (Straka et al. in Int J Numer Methods Fluids 17:1–22, 1993), the inertia gravity (Skamarock and Klemp in Mon Weather Rev 122:2623–2630, 1994), and the linear hydrostatic mountain waves of (Bonaventura in J Comput Phys 158:186–213, 2000)

Simulation of geophysical problems with DUNE-FEM

In this work we present simulations of different types of geophysical problems using the Dune and Dune-Fem software framework. We consider two-phase flow in porous media, a Stokes-Darcy coupled problem, and atmospheric flow problems. The basis of our schemes is the Discontinuous Galerkin discretizations

Towards big data-enabled terrestrial systems modelling at HPSC TerrSys

This manuscript to the proceedings of the ExtremeData – Demands, Technologies, and Services – Workshop1,gives an overview on the characteristics, components, steps andmethods of a complex data flow path around a fully coupledregional Earth system model and highlights the challenges weface working with very large data, as well as the concepts andstrategies towards a big data-enabled modeling chain