Small-scale mixing processes enhancing troposphere-to-stratosphere transport by pyro-cumulonimbus storms

Deep convection induced by large forest fires is an efficient mechanism for transport of aerosol particles and trace gases into the upper troposphere and lower stratosphere (UT/LS). For many pyro-cumulonimbus clouds (pyroCbs) as well as other cases of severe convection without fire forcing, radiometric observations of cloud tops in the thermal infrared (IR) reveal characteristic structures, featuring a region of relatively high brightness temperatures (warm center) surrounded by a U-shaped region of low brightness temperatures. We performed a numerical simulation of a specific case study of pyroCb using a non-hydrostatic cloud resolving model with a two-moment cloud microphysics parameterization and a prognostic turbulence scheme. The model is able to reproduce the thermal IR structure as observed from satellite radiometry. Our findings establish a close link between the observed temperature pattern and small-scale mixing processes atop and downwind of the overshooting dome of the pyroCb. Such small-scale mixing processes are strongly enhanced by the formation and breaking of a stationary gravity wave induced by the overshoot. They are found to increase the stratospheric penetration of the smoke by up to almost 30 K and thus are of major significance for irreversible transport of forest fire smoke into the lower stratosphere

Recent Advances in Graph Partitioning

We survey recent trends in practical algorithms for balanced graph partitioning together with applications and future research directions

Small-scale mixing processes enhancing troposphere-to-stratosphere transport by pyro-cumulonimbus storms

International audienceDeep convection induced by large forest fires is an efficient mechanism for transport of aerosol particles and trace gases into the upper troposphere and lower stratosphere (UT/LS). For many pyro-cumulonimbus clouds (pyroCbs) as well as other cases of severe convection without fire forcing, radiometric observations of cloud tops in the thermal infrared (IR) reveal characteristic structures, featuring a region of relatively high brightness temperatures (warm center) surrounded by a U-shaped region of low brightness temperatures. We performed a numerical simulation of a specific case study of pyroCb using a non-hydrostatic cloud resolving model with a two-moment cloud microphysics parameterization and a prognostic turbulence scheme. The model is able to reproduce the thermal IR structure as observed from satellite radiometry. Our findings establish a close link between the observed temperature pattern and small-scale mixing processes atop and downwind of the overshooting dome of the pyroCb. Such small-scale mixing processes are strongly enhanced by the formation and breaking of a stationary gravity wave induced by the overshoot. They are found to increase the stratospheric penetration of the smoke by up to almost 30 K and thus are of major significance for irreversible transport of forest fire smoke into the lower stratosphere

Aerosol modeling over Europe: 2. Interannual variability of aerosol shortwave direct radiative forcing

Aerosol distribution over Europe and its direct radiative forcing have been simulated with a regional atmosphere-chemistry model and an off-line radiation transfer model. Primary and secondary organic and inorganic aerosols have been considered. The simulation was conducted for meteorologically different years 2002 and 2003 to analyze the spatial and temporal variability of the aerosol distribution and the direct forcing. The accompanying paper focuses on the aerosol distribution, while radiative forcing is discussed in this paper. The mixing state of aerosols, externally or internally, is shown to influence the strength, regional distribution and sign of radiative forcing, thereby regulating the forcing efficiency. Positive top-of-the-atmosphere forcing was simulated over eastern and southeastern Europe in spring and winter because of contribution of black carbon. Its strength varies from +0.2 to +1 Wm-2, depending on aerosol mixing assumptions. Sensitivity studies show a mean European direct forcing of –0.3 Wm-2 in winter and –2.5 Wm-2 in summer, regionally ranging from –5 to + 4 Wm-2

Scheduling in HPC Resource Management Systems: Queuing vs. Planning

Abstract. Nearly all existing HPC systems are operated by resource management systems based on the queuing approach. With the increasing acceptance of grid middleware like Globus, new requirements for the underlying local resource management systems arise. Features like advanced reservation or quality of service are needed to implement high level functions like co-allocation. However it is difficult to realize these features with a resource management system based on the queuing concept since it considers only the present resource usage. In this paper we present an approach which closes this gap. By assigning start times to each resource request, a complete schedule is planned. Advanced reservations are now easily possible. Based on this planning approach functions like diffuse requests, automatic duration extension, or service level agreements are described. We think they are useful to increase the usability, acceptance and performance of HPC machines. In the second part of this paper we present a planning based resource management system which already covers some of the mentioned features.

Impact of vegetation fires on composition and circulation of the atmosphere (EFEU)

The project addresses the contribution of vegetation fires to the local trace gas and particle budgets of the troposphere and the lower stratosphere, their direct and indirect radiative impact, their impact on cloud formation and chemical and microphysical processes in cloud