A B S T R A C TThe atmospheric transport of moisture leading to extreme summer precipitation events in southern Sweden was investigated using a Lagrangian trajectory model. Surprisingly, we found that the trajectories crossed continental Europe and the Baltic Sea before arriving over Sweden; they did not arrive directly from the North Sea. Such transport pathways were not seen for a control sample of non-extreme rainfall events. We then used a new source region identification technique to investigate the hypothesis that Europe and the Baltic are important sources of the moisture that is rained out in the extreme events. Although the results varied between events, we found that this is indeed the case. Our results establish the atmospheric transport patterns that are apparently a pre-requisite for extreme rainfall events to occur in southern Sweden, and further suggest regional moisture availability may also play a key role.

Abstract. Since the mid 1990s, Australia's Commonwealth Science Industry and Research Organisation (CSIRO) has developed a biogeochemical (BGC) model for coupling with a hydrodynamic and sediment model for application in estuaries, coastal waters and shelf seas. The suite of coupled models is referred to as the CSIRO Environmental Modelling Suite (EMS) and has been applied at tens of locations around the Australian continent. At a mature point in the BGC model's development, this paper presents a full mathematical description, as well as links to the freely available code and User Guide. The mathematical description is structured into processes so that the details of new parameterisations can be easily identified, along with their derivation. The EMS BGC model cycles carbon, nitrogen, phosphorous and oxygen through multiple phytoplankton, zooplankton, detritus and dissolved organic and inorganic forms in multiple water column and sediment layers. The underwater light field is simulated by a spectrally-resolved optical model that includes the calculation of water-leaving reflectance for validation with remote sensing. The water column is dynamically coupled to the sediment to resolve deposition, resuspension and benthic-pelagic biogeochemical fluxes. With a focus on shallow waters, the model also includes particularly-detailed representations of benthic plants such as seagrass, macroalgae and coral polyps. A second focus has been on, where possible, the use of geometric derivations of physical limits to constrain ecological rates, which generally requires population-based rates to be derived from initially considering the size and shape of individuals. For example, zooplankton grazing considers encounter rates of one predator on a prey field based on summing relative motion of the predator with the prey individuals and the search area, chlorophyll synthesis includes a geometrically-derived self-shading term, and the bottom coverage of benthic plants is generically-related to their biomass using an exponential form derived from geometric arguments. This geometric approach has led to a more algebraically-complicated set of equations when compared to more empirical biogeochemical model formulations. But while being algebraically-complicated, the model has fewer unconstrained parameters and is therefore simpler to move between applications than it would otherwise be. The version of the biogeochemistry described here is implemented in the eReefs project that is delivering a near real time coupled hydrodynamic, sediment and biogeochemical simulation of the Great Barrier Reef, northeast Australia, and its formulation provides an example of the application of geometric reasoning in the formulation of aquatic ecological processes.

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Landscape-wide approaches integrating agriculture, forestry, energy, and water are considered key to address complex environmental problems and to avoid trade-offs. The objective of this paper is to analyse how knowledge production through multi-stakeholder dialogues on water, landscapes, forests, and agriculture can inform governance and the management of landscapes. Multi-stakeholder learning dialogues and platforms (MSPs) were established related to water and natural resources management, complemented by targeted reviews, to establish a shared understanding of the drivers of change and impacts on the hydrology of landscapes and ecosystem services. The MSP dialogues illustrate the need to address water as an integral part of landscape management and governance to achieve the wide range of the Sustainable Development Goals related to water and food security, climate action, life on land, as well as sustainable production and consumption, equality, and strong institutions. The co-production of knowledge through MSPs contributes to continuous learning that informs adaptive management of water flows in landscapes, above and below ground, as well as in the atmosphere. It helps to build a shared understanding of system dynamics and integrate knowledge about hydrology and water flows into policy recommendations. Co-production of knowledge also contributes to stakeholder participation at different levels, inclusiveness, and transparency, and to water stewardship.