1,721,093 research outputs found
Monitoring and modeling for investigating driver/pressure-state/impact relationships in coastal ecosystems: Examples from the Lagoon of Venice
No full textIn this paper, we show how the integration of monitoring data and mathematical model can generate valuable information by using a few examples taken from a well studied but complex ecosystem, namely the Lagoon of Venice. We will focus on three key issues, which are of concern also for many other coastal ecosystems, namely: (1) Nitrogen and Phosphorus annual budgets; (2) estimation of Net Ecosystem Metabolism and early warnings for anoxic events; (3) assessment of ecosystem status. The results highlight the importance of framing monitoring activities within the "DPSIR" conceptual model, thus going far beyond the monitoring of major biogeochemical variables and including: (1) the estimation of the fluxes of the main constituents at the boundaries; (2) the use of appropriate mathematical models. These tools can provide quantitative links among Pressures and State/Impacts, thus enabling decision makers and stakeholders to evaluate the effects of alternative management scenarios
2005-2099 High resolution bioclimatic variables for the surface and bottom of the Mediterranean Sea.
No full textThis dataset provides annual statistical descriptors (mean, minimum, maximum, range and standard deviation) of key biogeochemical and physical variables for the Mediterranean Sea. It covers the period 2005-2099 under the RCP8.5 scenario, with a spatial resolution of 1/24 degree (~4km2). Variables include temperature, salinity, pH, water velocity, nutrients (NO3, PO4, NH4), dissolved inorganic carbon, oxygen, and net primary production. Data are available for both surface and at bathymetry level. The original projections were generated using OGSTM-BFM and MFS16 models at daily time and 1/16 degree grid resolution. We downscaled these to 1/24 degree and applied Quantile Delta Mapping bias correction using CMEMS reanalysis products for 2005-2020. The dataset is provided in a user-friendly format, making it accessible for various ecological and environmental modelling applications
THERMAL EXCHANGES AT AIR WATER INTERFACES AND REPRODUCTION OF TEMPERATURE VERTICAL PROFILES IN WATER COLUMNS
No full textFor a 3-D eutrophication-diffusion macromodel of the central part of the Venice Lagoon, air-water heat fluxes are computed interpolating, through Fourier series expansion, meteoclimatic variables averaged over a thirty years survey. Also reproduced with the same interpolation methods, is the daily fluctuation of incident light as well as the annual variation of the photoperiod. With an iterative procedure temperature values, to be assigned at each grid's point and corresponding to each hour of a reference year, are computed also accounting for the thermal inertia of water columns of varying depths. By statistical examination of temperature vertical profiles, depth varying diffusivities are also estimated, which enables, without assumption of an instantaneous mixing, the reproduction of heat diffusion from the surface to the bottom water cells. Procedures. preliminarly refined and verified for a one-dimensional vertical system input, are next implemented on a three-dimensional submodel of reduced size provided of ''open boundaries'': this last submodel, under a continuous input of energy and of matter is seen to attain a steady states as well as to be capable of simulating regime conditions. A further validation is performed. on a submodel of 43 x 47 x 20 cells. encompassing a limited portion of the macromodel and presenting the actual lagoon bathymetry. Macromodel's seasonalisation so achieved, enables for a more correct simulation of the periodical behaviour of light and of temperature, forcing functions governing the eutrophication phenomena
AN INFORMATIONAL APPROACH TO MODEL TIME-SERIES OF ENVIRONMENTAL DATA THROUGH NEGENTROPY ESTIMATION
No full textA methodology based on the minimum negentropy criterion (minimum cross-entropy) is proposed, which enables one to determine the optimal order of a model candidate to reproduce the behaviour of time series of environmental data. The procedure, which involves the computation of the prediction error, represents a unifying approach of conventional and inferential statistics and permits at the same time to account for all informational content embodied in the data and it avoids both underfitting and overfitting of experimental observations, thus guaranteeing the principle of model's parameter parsimony and balanced accuracy. Following the theoretical derivation of the approach, the method is verified through harmonic analysis of data sets collected in the lagoon of Venice and exhibiting high variability: surface data temperature, exceptional tidal observations, chlorophyll a and ammonia concentrations. Extensions of the procedure to other type of data and of class of model, are also prospected
Global sensitivity analysis of a shallow-water 3D eutrophication model
No full textThe dynamic of a shallow water system has been studied using a 3D transport-water-quality model. This model was originally designed to study the eutrophication in the central part of the Venice lagoon. Four model outputs and six input factors are considered in this paper. Sensitivity analysis is performed using the Sobol' method:and linear regression based methods. Results of this study suggest that nitrogen load, the main controllable factor, plays a major role in governing the primary production of the whole system. However, the "history" of the system, represented by the initial density of benthic algae, is even more important in determining the occurrence of dramatic events, such as anoxic crisis, which may happen in particular areas
Impact of different forcing factors on N:P balance in a semi-enclosed bay: the Gulf of Trieste (North Adriatic Sea).
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