Science learning via participation in online citizen science

We propose a theoretical framework of the dispersion in turbulent flows near non-smooth objects with agglomerations of bluff parts sitting on a relatively smooth surface. Examples can be flows through roughness in channels, near surfaces of planes or ships, where roughness is created by attached devices, or through urban canopies

An agenda for land-surface hydrology research and a call for the second international hydrological decade.

Hydrologic research at the interface between the atmosphere and land surface is undergoing a dramatic change in focus, driven by new societal priorities, emerging technologies, and better understanding of the earth system. In this paper an agenda for land surface hydrology research is proposed in order to open the debate for more comprehensive prioritization of science and application activities in the hydrologic sciences. Sets of priority science questions are posed and research strategies for achieving progress are identified. The proposed research agenda is also coupled with ongoing international data collection programs. The driving science questions and related research agenda lead to a call for the second International Hydrologic Decade. This activity will help to ensure that hydrology starts the new millennium as a coherent and vital discipline

Spatially-averaged flow statistics within a canopy of large bluff bodies: Results from direct numerical simulations.

The flow within a canopy of large bluff bodies is highly turbulent and spatially heterogeneous. Results from direct numerical simulations over groups of cubical obstacles are analysed using the double-averaging methodology. The obstacles occupy a significant fraction of the canopy space; this gives rise to substantial dispersive stresses within the canopy. The underlying bluff-body turbulent dynamics is different from typical canopy turbulence, and this is reflected in the double-averaged statistics. The spatially-averaged velocities, stresses and drag force depend significantly upon the layout of the obstacles. An ongoing challenge is to parameterise these spatially-averaged quantities in terms of the obstacle geometry and layout