http://hdl.handle.net/2122/180 Sat, 25 May 2013 00:16:29 GMT 2013-05-25T00:16:29Z http://hdl.handle.net/2122/8581 Title: Strengthening of the hydrological cycle in future scenarios: atmospheric energy and water balance perspective Authors: Alessandri, A.; ENEA; Fogli, P. G.; CMCC; Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Zeng, N.; University of Mariland Abstract: Future climate scenarios experiencing global warming are expected to strengthen the hydrological cycle during the 21st century (21C). We analyze the strengthening of the global-scale increase in precipitation from the perspective of changes in whole atmospheric water and energy balances. By combining energy and water equations for the whole atmosphere, we obtain constraints for the changes in surface fluxes and partitioning at the surface between sensible and latent components. We investigate the differences in the strengthening of the hydrological cycle in two centennial simulations performed with an Earth system model forced with specified atmospheric concentration pathways. Alongside the Special Report on Emissions Scenario (SRES) A1B, which is a medium-high non-mitigation scenario, we consider a new aggressive-mitigation scenario (E1) with reduced fossil fuel use for energy production aimed at stabilizing global warming below 2 K. Our results show that the mitigation scenario effectively constrains the global warming with a stabilization below 2 K with respect to the 1950–2000 historical period. On the other hand, the E1 precipitation does not follow the temperature field toward a stabilization path but continues to increase over the mitigation period. Quite unexpectedly, the mitigation scenario is shown to strengthen the hydrological cycle even more than SRES A1B till around 2070. We show that this is mostly a consequence of the larger increase in the negative radiative imbalance of atmosphere in E1 compared to A1B. This appears to be primarily related to decreased sulfate aerosol concentration in E1, which considerably reduces atmospheric absorption of solar radiation compared to A1B. The last decades of the 21C show a marked increase in global precipitation in A1B compared to E1, despite the fact that the two scenarios display almost the same overall increase of radiative imbalance with respect to the 20th century. Our results show that radiative cooling is weakly effective in A1B throughout the 21C. Two distinct mechanisms characterize the diverse strengthening of the hydrological cycle in the middle and end- 21C. It is only through a very large perturbation of surface fluxes that A1B achieves a larger increase in global precipitation in the last decades of the 21C. Our energy/water budget analysis shows that this behavior is ultimately due to a bifurcation in the Bowen ratio change between the two scenarios. This work warns that mitigation policies that promote aerosol abatement, may lead to an unexpected stronger intensification of the hydrological cycle and associated changes that may last for decades after global warming is effectively mitigated. On the other hand, it is also suggested that predictable components of the radiative forcing by aerosols may have the potential to effectively contribute to the decadal-scale predictability of changes in the hydrological strength. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8581 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8195 Title: Impacts of natural and anthropogenic climate variations on North Pacific plankton in an Earth System Model Authors: Patara, L.; CMCC; Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Abstract: The impacts of natural atmospheric variability and anthropogenic climate change on the spatial distribution, seasonality, structure, and productivity of North Pacific plankton groups are investigated by means of an Earth System Model (ESM) that contains a plankton model with variable stoichiometry. The ESM is forced with observed greenhouse gases for the 20th century and with the Intergovernmental Panel on Climate Change A1B Emission Scenario for the 21st century. The impacts of the two main modes of variability – connected with the Aleutian Low (AL) strength and with the North Pacific Oscillation (NPO) – are considered. When the AL is strong, primary productivity and chlorophyll concentrations are higher in the central Pacific, the seasonality of plankton is enhanced, and the classical grazing chain is stimulated, whereas in the Alaskan Gyre the model simulates a chlorophyll decrease and a shift toward smaller phytoplankton species. A stronger NPO increases productivity and chlorophyll concentration at ∼45°N. In the anthropogenic climate change scenario, simulated sea surface temperature is 4 °C higher with respect to contemporary conditions, leading to reduced mixing and nutrient supply at middle-subpolar latitudes. The seasonal phytoplankton bloom is reduced and occurs one month earlier, the flow of carbon to the microbial loop is enhanced, and phytoplanktonic stoichiometry is nutrient-depleted. Primary productivity is enhanced at subpolar latitudes, due to increased ice-free regions and possibly to temperature-related photosynthesis stimulation. This study highlights that natural climate variability may act alternatively to strengthen or to weaken the human-induced impacts, and that in the next decades it will be difficult to distinguish between internal and external climate forcing on North Pacific plankton groups. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8195 2011-12-31T23:00:00Z http://hdl.handle.net/2122/8193 Title: Global response to solar radiation absorbed by phytoplankton in a coupled climate model Authors: Patara, L.; CMCC; Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Fogli, P. G.; CMCC; Manzini, E.; MPI Abstract: The global climate response to solar radiation absorbed by phytoplankton is investigated by performing multi-century simulations with a coupled ocean–atmosphere-biogeochemistry model. The absorption of solar radiation by phytoplankton increases radiative heating in the near-surface ocean and raises sea surface temperature (SST) by overall ~0.5°C. The resulting increase in evaporation enhances specific atmospheric humidity by 2–5%, thereby increasing the Earth’s greenhouse effect and the atmospheric temperatures. The Hadley Cell exhibits a weakening and poleward expansion, therefore reducing cloudiness at subtropical-middle latitudes and increasing it at tropical latitudes except near the Equator. Higher SST at polar latitudes reduces sea ice cover and albedo, thereby increasing the high-latitude ocean absorption of solar radiation. Changes in the atmospheric baroclinicity cause a poleward intensification of mid-latitude westerly winds in both hemispheres. As a result, the North Atlantic Ocean meridional overturning circulation extends more northward, and the equatorward Ekman transport is enhanced in the Southern Ocean. The combination of local and dynamical processes decreases upper-ocean heat content in the Tropics and in the subpolar Southern Ocean, and increases it at middle latitudes. This study highlights the relevance of coupled ocean–atmosphere processes in the global climate response to phytoplankton solar absorption. Given that simulated impacts of phytoplankton on physical climate are within the range of natural climate variability, this study suggests the importance of phytoplankton as an internal constituent of the Earth’s climate and its potential role in participating in its long-term climate adjustments. Sat, 31 Dec 2011 23:00:00 GMT http://hdl.handle.net/2122/8193 2011-12-31T23:00:00Z http://hdl.handle.net/2122/7629 Title: Marine biogeochemical responses to the North Atlantic Oscillation in a coupled climate model Authors: Patara, L.; CMCC; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Visbeck, M.; IFM-Kiel; Krahmann, G.; IFM-Kiel; Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia Abstract: In this study a coupled ocean‐atmosphere model containing interactive marine biogeochemistry is used to analyze interannual, lagged, and decadal marine biogeochemical responses to the North Atlantic Oscillation (NAO), the dominant mode of North Atlantic atmospheric variability. The coupled model adequately reproduces present‐day climatologies and NAO atmospheric variability. It is shown that marine biogeochemical responses to the NAO are governed by different mechanisms according to the time scale considered. On interannual time scales, local changes in vertical mixing, caused by modifications in air‐sea heat, freshwater, and momentum fluxes, are most relevant in influencing phytoplankton growth through light and nutrient limitation mechanisms. At subpolar latitudes, deeper mixing occurring during positive NAO winters causes a slight decrease in late winter chlorophyll concentration due to light limitation and a 10%–20% increase in spring chlorophyll concentration due to higher nutrient availability. The lagged response of physical and biogeochemical properties to a high NAO winter shows some memory in the following 2 years. In particular, subsurface nutrient anomalies generated by local changes in mixing near the American coast are advected along the North Atlantic Current, where they are suggested to affect downstream chlorophyll concentration with 1 year lag. On decadal time scales, local and remote mechanisms act contemporaneously in shaping the decadal biogeochemical response to the NAO. The slow circulation adjustment, in response to NAO wind stress curl anomalies, causes a basin redistribution of heat, freshwater, and biogeochemical properties which, in turn, modifies the spatial structure of the subpolar chlorophyll bloom. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7629 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7628 Title: The emergence of ocean biogeochemical provinces: a quantitative assessment and a diagnostic for model evaluation. Authors: Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Allen, J. I.; PML; Masina, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Hardman-Mountford, N.; PML Abstract: The concept of ocean biogeochemical provinces is based on the observation that large ocean regions are characterized by coherent physical forcing and environmental conditions, which are eventually representative of macroscale ocean ecosystems. Biogeochemical models of the global ocean focus on simulating the coupling between prevalent physical conditions and the biogeochemical processes with the assumption that biological properties respond coherently to physics and therefore should produce such provinces as an emergent property. In this paper, we quantitatively assess the emergence of a reference set of predefined biogeochemical provinces in the available global data sets and propose a province‐based approach to the evaluation of one of the most comprehensive models of ocean biogeochemistry. Multivariate statistical tools were applied to model and observation data, verifying the existence, distinctiveness and reliability of the predefined provinces and quantifying the correlation of model results with observations at the global scale. The analysis of similarity between provinces shows that they are statistically separable in data and model output and therefore can be used as reliable metrics. The analyses indicate that provinces can be more easily distinguished in terms of their environmental features rather than using chlorophyll concentration. The characterization of provinces by means of chlorophyll values shows a significant overlap in both the Sea‐viewing Wide Field‐of‐view Sensor (SeaWiFS) data and the model. It is likely this is related to the choice of province boundaries based on coarse‐resolution mapped data, which are not necessarily the same as those derivable from high‐resolution satellite data. We also demonstrated through cluster analysis that the long‐term time series data collected at Joint Global Ocean Flux Study (JGOFS) stations are representative of environmental conditions of the respective province and can thus be used to evaluate model results extracted from that province. The method shows promise for helping to overcome problems with model verification due to under sampling of most ocean biogeochemical variables but also gives indications that unsupervised clustering may be required when more spatially resolved data and models are available. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7628 2010-12-31T23:00:00Z http://hdl.handle.net/2122/7104 Title: Societal need for improved understanding of climate change, anthropogenic impacts, and geo-hazard warning drive development of ocean observatories in European Seas Authors: Ruhl, H. A.; NOCS; Andrè, M.; UPC; Beranzoli, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Çagatay, M. N.; ITU; Colaço, A.; Univ. Azores; Cannat, M.; IPGP; Dañobeitia, J. J.; CSIC-UTM; Favali, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Géli, L.; IFREMER; Gillooly, M.; IMI; Greinert, J.; NIOZ; Hall, P. O. J.; Univ. Goteborg; Huber, R.; MARUM; Karstensen, J.; Univ. Kiel; Lampitt, R. S.; NOCS; Larkin, K. E.; NOCS; Lykousis, V.; HCMR; Mienert, J.; Univ. Tromsø; Miranda, J. M.; Univ. Lisboa; Person, R.; IFREMER; Priede, I. G.; Univ. Aberdeen; Puillat, I.; IFREMER; Thomsen, L.; Jacobs Univ. Bremen; Waldmann, C.; MARUM Abstract: Society’s needs for a network of in situ ocean observing systems cross many areas of earth and marine science. Here we review the science themes that benefit from data supplied from ocean observatories. Understanding from existing studies is fragmented to the extent that it lacks the coherent long-term monitoring needed to address questions at the scales essential to understand climate change and improve geo-hazard early warning. Data sets from the deep sea are particularly rare with long-term data available from only a few locations worldwide. These science areas have impacts on societal health and well-being and our awareness of ocean function in a shifting climate. Substantial efforts are underway to realise a network of open-ocean observatories around European Seas that will operate over multiple decades. Some systems are already collecting high-resolution data from surface, water column, seafloor, and sub-seafloor sensors linked to shore by satellite or cable connection in real or near-real time, along with samples and other data collected in a delayed mode. We expect that such observatories will contribute to answering major ocean science questions including: How can monitoring of factors such as seismic activity, pore fluid chemistry and pressure, and gas hydrate stability improve seismic, slope failure, and tsunami warning? What aspects of physical oceanography, biogeochemical cycling, and ecosystems will be most sensitive to climatic and anthropogenic change? What are natural versus anthropogenic changes? Most fundamentally, how are marine processes that occur at differing scales related? The development of ocean observatories provides a substantial opportunity for ocean science to evolve in Europe. Here we also describe some basic attributes of network design. Observatory networks provide the means to coordinate and integrate the collection of standardised data capable of bridging measurement scales across a dispersed area in European Seas adding needed certainty to estimates of future oceanic conditions. Observatory data can be analysed along with other data such as those from satellites, drifting floats, autonomous underwater vehicles, model analysis, and the known distribution and abundances of marine fauna in order to address some of the questions posed above. Standardised methods for information management are also becoming established to ensure better accessibility and traceability of these data sets and ultimately to increase their use for societal benefit. The connection of ocean observatory effort into larger frameworks including the Global Earth Observation System of Systems (GEOSS) and the Global Monitoring of Environment and Security (GMES) is integral to its success. It is in a greater integrated framework that the full potential of the component systems will be realised. Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2122/7104 2010-12-31T23:00:00Z http://hdl.handle.net/2122/6042 Title: EMEP/EEA air pollutant emission inventory guidebook 2009 Authors: Etiope, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Studies performed since 2000 have demonstrated that geologic emissions of methane are an important global greenhouse-gas source (Etiope, 2004; Kvenvolden and Rogers, 2005; Etiope al, 2008). It is recognised that significant amounts of methane, produced within the Earth crust, released naturally into the atmosphere through faults and fractured rocks. Major emissions are related to hydrocarbon production in sedimentary basins (microbial and thermogenic methane), through continuous exhalation and eruptions from more than 1 200 onshore and offshore mud volcanoes, more than 10 000 onshore and shallow marine seeps and through diffuse soil microseepage. Specifically, six source categories must be considered: mud volcanoes, gas seeps (independent of mud volcanism), microseepage (diffuse exhalation from soil in petroleum basins), submarine seepage, geothermal (non-volcanic) manifestations and volcanoes. Global emission estimates range from 42 to 64 Tg y-1 (mean of 53 Tg y-1), almost 10 % of the total CH4 emission, representing the second most important natural methane source after wetlands. Geo-CH4 sources would also represent the missing source of fossil methane recognised in the recent re-evaluation the fossil methane budget in the atmosphere (about 30 %; Lassey et al,, 2007; Etiope et al, 2008), which implies a total fossil methane emission much higher than that due to fossil fuel industry. The global geo-CH4 emission estimates are of the same level as or higher than other sources or sinks considered in the Intergovernmental Panel on Climate Change (IPCC) tables, such as biomass burning, termites and soil uptake. Recent studies indicate that Earth’s degassing also accounts for at least 17 % and 10 % of total ethane and propane emissions (Etiope and Ciccioli, 2009). Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2122/6042 2008-12-31T23:00:00Z http://hdl.handle.net/2122/6041 Title: GLOGOS, A New Global Onshore Gas-Oil Seeps Dataset Authors: Etiope, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Petroleum seeps have historically been important drivers of global petroleum exploration. Still today they can serve as direct indicators of gas and/or oil subsurface accumulations. In particular the assessment of the origin of seeping gas is a key task for understanding, without drilling, the subsurface hydrocarbon potential, genesis and quality; e.g., the presence of shallow microbial gas, deeper thermogenic accumulations, the presence of oil and non-hydrocarbon undesirable gases (CO2, N2, H2S). Seeps are then indicators of tectonic discontinuities (faults) and fractured rocks; they can also represent geo-hazards and sources of greenhouse gas (methane) and photochemical pollutants (ethane and propane). A new global dataset of onshore gas and oil seeps (GLOGOS) is here presented. GLOGOS includes more than 1150 seeps from 84 countries (version August 2009), and it is continuously updated and expanded. The dataset includes geographical and gas-geochemical data (molecular and isotopic composition of the main gases). Many seeps are recently discovered or never reported in other databases. Seeps are catalogued by country and classified in three types: gas seeps, oil seeps and mud volcanoes. All seeps have a bibliographic or www reference. GLOGOS is a unique tool for hydrocarbon exploration, assessment of Total Petroleum Systems and geo- structural studies. Sun, 27 Sep 2009 22:00:00 GMT http://hdl.handle.net/2122/6041 2009-09-27T22:00:00Z http://hdl.handle.net/2122/6040 Title: A GLOBAL DATASET OF ONSHORE GAS AND OIL SEEPS: A NEW TOOL FOR HYDROCARBON EXPLORATION Authors: Etiope, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia Abstract: Petroleum seeps have historically been important drivers of global petroleum exploration. Still today they can serve as direct indicators of gas and/or oil subsurface accumulations. In particular the assessment of the origin of seeping gas is a key task for understanding, without drilling, the subsurface hydrocarbon potential, genesis and quality, e.g. the presence of shallow microbial gas, deeper thermogenic accumulations, the presence of oil and non-hydrocarbon undesirable gases (CO2, N2, H2S). Low quality, biodegraded petroleum can also be recognised, before drilling, through specific geochemical features of the seeping gas. Seeps are then indicators of tectonic discontinuities (faults) and fractured rocks; they can also represent geo-hazards and sources of greenhouse gas (methane) and photochemical pollutants (ethane and propane). A new global dataset of onshore gas and oil seeps (GLOGOS) is here presented. GLOGOS includes more than 1150 seeps from 84 countries (version August 2009) and it is continuously updated and expanded. The data-set includes geographical and gas-geochemical data (molecular and isotopic composition of the main gases). Many seeps are recently discovered or never reported in other data-bases. Seeps are catalogued by country and classified in three types: gas seeps, oil seeps and mud volcanoes. All seeps have a bibliographic or www reference. GLOGOS is a unique tool for hydrocarbon exploration, assessment of Total Petroleum Systems and geo-structural studies. Wed, 30 Sep 2009 22:00:00 GMT http://hdl.handle.net/2122/6040 2009-09-30T22:00:00Z http://hdl.handle.net/2122/5744 Title: Modelling approach to the assessment of biogenic fluxes at a selected Ross Sea site, Antarctica Authors: Vichi, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Coluccelli, A.; UniPoliMa; Ravaioli, F.; CNR-ISMAR; Giglio, F.; CNR-ISMAR; Langone, L.; CNR-ISMAR; Azzaro, M.; CNR-IAMC; Azzaro, F.; CNR-IAMC; La Ferla, R.; CNR-IAMC; Catalano, G.; CNR-ISMAR; Cozzi, S.; CNR-ISMAR Abstract: Several biogeochemical data have been collected in the last 10 years of Italian activity in Antarctica (ABIOCLEAR, ROSSMIZE, BIOSESO-I/II). A comprehensive 1-D biogeochemical model was implemented as a tool to link observations with processes and to investigate the mechanisms that regulate the flux of biogenic material through the water column. The model is ideally located at station B (175° E–74° S) and was set up to reproduce the seasonal cycle of phytoplankton and organic matter fluxes as forced by the dominant water column physics over the period 1990–2001. Austral spring-summer bloom conditions are assessed by comparing simulated nutrient drawdown, primary production rates, bacterial respiration and biomass with the available observations. The simulated biogenic fluxes of carbon, nitrogen and silica have been compared with the fluxes derived from sediment traps data. The model reproduces the observed magnitude of the biogenic fluxes, especially those found in the bottom sediment trap, but the peaks are markedly delayed in time. Sensitivity experiments have shown that the characterization of detritus, the choice of the sinking velocity and the degradation rates are crucial for the timing and magnitude of the vertical fluxes. An increase of velocity leads to a shift towards observation but also to an overestimation of the deposition flux which can be counteracted by higher bacterial remineralization rates. Model results suggest that the timing of the observed fluxes depends first and foremost on the timing of surface production and on a combination of size-distribution and quality of the autochtonous biogenic material. It is hypothesized that the bottom sediment trap collects material originated from the rapid sinking of freshly-produced particles and also from the previous year's production period. Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2122/5744 2008-12-31T23:00:00Z