http://hdl.handle.net/2122/87 Ricerca nel canale cerca http://www.earth-prints.org/simple-search http://hdl.handle.net/2122/5979 Titolo: Effects of increased CO2 levels on monsoons<br/><br/>Autori: Cherchi, A; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Alessandri, A; Centro Euromediterraneo per i Cambiamenti Climatici, Bologna, Italy; Masina, S; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: Increased atmospheric carbon dioxide concentration provided warmer atmospheric temperature and higher atmospheric water vapor content, but not necessarily more precipitation. A set of experiments performed with a state-of-the-art coupled general circulation model forced with increased atmospheric CO2 concentration (2, 4 and 16 times the present-day mean value) were analyzed and compared with a control experiment to evaluate the effect of increased CO2 levels on monsoons. Generally, the monsoon precipitation responses to CO2 forcing are largest if extreme concentrations of carbon dioxide are used, but they are not necessarly proportional to the forcing applied. In fact, despite a common response in terms of an atmosphericwater vapor increase to the atmospheric warming, two out of the six monsoons studied simulate less or equal summer mean precipitation in the 16xCO2 experiment compared to the intermediate sensitivity experiments. The precipitation differences between CO2 sensitivity experiments and CTRL have been investigated specifying the contribution of thermodynamic and purely dynamic processes. As a general rule, the differences depending on the atmospheric moisture content changes (thermodynamiccomponent) are large and positive, and they tend to be damped by the dynamic component associated with the changes in the vertical velocity. However, differences are observed among monsoons in terms of the role played byother terms (like moisture advection and evaporation) in shaping the precipitation changes in warmer climates. The precipitation increase, even if weak, occurs despite a weakening of the mean circulation in the monsoon regions(‘‘precipitation-wind paradox’’). In particular, the tropical east-west Walker circulation is reduced, as found from velocity potential analysis. The meridional component of the monsoon circulation is changed as well, with larger (smaller) meridional (vertical) scales. http://hdl.handle.net/2122/5978 Titolo: Trend termopluviometrici, siccità e disponibilità di acque sotterranee<br/><br/>Autori: Polemio, M.; CNR-IRPI; Casarano, D.; CNR-IRPI; Dragone, V.; CNR-IRPI<br/><br/>Curatori: Piccolo, D.; Università di Napoli; Ubertini, L.; Università La Sapienza<br/><br/>Abstract: Lo studio caratterizza le modfIcazioni tendenziali delle principali vat-lab iii che determinano la disponibilità di risorse idriche. Verficata la recente ed anomala incidenza di pet-lodE siccitosi, Si valutano gil effetti tendenziali sulla disponibilità di acque sotrerranee. Si utilizzano datE mensili inerenri le precipitazioni meteoriche e le temperature atmosferiche di 126 stazioni collocate in Italia meridionale, tra il 1821 e ii 2001. Si osservano cali tendenziali della piovosità effettiva in 114 stazioni con trend negativi fino a —9 mm/anno. La tendenza negativa riguarda piI1 del 95% dell ‘area; ii test di Mann-Kendall ne con fermo la sign,fIcativitâ su scala locale e regionale. hi particolare, emerge un consistente deficit di precipitazioni a partire dal 1980. La tendenza è negativa doll ‘autunno alla primavera ed è molto accentuata in inverno. Se le variazioni tendenziali di temperatura non sono risult ate evidenti ed omogenee, ii calcolo delia piovosità efficace ha segnalato una tendenza al calo ancora più grave di quanto osservato per la piovsità effettiva, stante la maggiore incidenza del calo pluviometrico nei mesi umidi. Gil effetti suile acque sotterranee sono valutati mediante serie storiche mensili, dal 1965 al 2003, relative a 63 stazioni piezometriche ubicate nei principali acquferi della Puglia. Mediante metodi di statistica delle serie storiche si caratterizzano I rapporti intercorrenti tra piovosità, temperatura e variazioni piezornetriche. I trend piezometrici risuitano negativi: equivalgono a cali piezomefrici considerevoli in tutte le unità idrogeologiche. http://hdl.handle.net/2122/5895 Titolo: The CLIVAR C20C Project: Which components of the Asian-Australian monsoon circulation variations are forced and reproducible?<br/><br/>Autori: Zhou, T.; Wu, B.; Scaife, A.; Bronnimann, S.; Cherchi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Feredey, D.; Folland, C. K.; Jin, K. E.; Kinter, J.; Knight, J. R.; Kucharski, F.; Kusunoki, S.; Lau, N. C.; Li, L.; Nath, M. J.; Nakaegawa, T.; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Pegion, P.; Rozanov, E.; Schubert, S.; Spryshev, P.; Voldoire, A..; Wen, X.; Yoon, J. H.; Zeng, N.<br/><br/>Abstract: A multi-model set of atmospheric simulations forced by historical sea surface temperature (SST) or SSTs plus Greenhouse gases and aerosol forcing agents for the period of 1950–1999 is studied to identify and understand which components of the Asian–Australian monsoon (A–AM) variability are forced and reproducible. The analysis focuses on the summertime monsoon circulations, comparing model results against the observations. The priority of different components of the A–AM circulations in terms of reproducibility is evaluated. Among the subsystems of the wide A–AM, the South Asian monsoon and the Australian monsoon circulations are better reproduced than the others, indicating they are forced and well modeled. The primary driving mechanism comes from the tropical Pacific. The western North Pacific monsoon circulation is also forced and well modeled except with a slightly lower reproducibility due to its delayed response to the eastern tropical Pacific forcing. The simultaneous driving comes from the western Pacific surrounding the maritime continent region. The Indian monsoon circulation has a moderate reproducibility, partly due to its weakened connection to June–July–August SSTs in the equatorial eastern Pacific in recent decades. Among the A–AM subsystems, the East Asian summer monsoon has the lowest reproducibility and is poorly modeled. This is mainly due to the failure of specifying historical SST in capturing the zonal land-sea thermal contrast change across the East Asia. The prescribed tropical Indian Ocean SST changes partly reproduce the meridional wind change over East Asia in several models. For all the A–AM subsystem circulation indices, generally the MME is always the best except for the Indian monsoon and East Asian monsoon circulation indices. http://hdl.handle.net/2122/5885 Titolo: Nella spirale del clima. Culture e società mediterranee di fronte ai mutamenti climatici<br/><br/>Autori: Guidoboni, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: Il clima è sempre cambiato e i mutamenti hanno causato danni e rischi non previsti, che hanno richiesto nuovi adattamenti e risposte adeguate sul piano sociale, culturale ed economico. Gli autori, coadiuvati da un gruppo di ricercatori, hanno esplorato la storia degli ultimi tre millenni delle civiltà mediterranee, presentando un excursus divulgativo, basato su autorevoli studi scientifici e storici. Lo scopo è di delineare in modo complessivo non solo l’andamento dei mutamenti climatici e le loro ripercussioni sociali, ma anche le idee e le teorie sul clima, dai filosofi dell’antica Grecia, agli scrittori latini, agli enciclopedisti medievali, cristiani e arabi, fino al pensiero di età moderna, all’illuminismo e al positivismo ottocentesco. Le previsioni del tempo, il clima e la salute, il rapporto fra clima e ambiente sono temi presenti in tutte le civiltà mediterranee antiche e recenti: su questi temi le culture hanno sempre elaborato interpretazioni e risposte. Questo “viaggio” nel passato, che mette in luce una storia inedita e in gran parte da esplorare, giunge fino all’attuale riscaldamento globale. Questa nuova sfida è meglio valutabile in una prospettiva di “mutamento climatico storico”, a cui l’azione antropica sta aggiungendo un formidabile acceleratore. http://hdl.handle.net/2122/5805 Titolo: The double-ITCZ syndrome in coupled general circulation models: the role of large-scale vertical circulation regimes<br/><br/>Autori: Bellucci, A.; Centro Euro-Mediterraneo per i Cambiamenti Climatici; Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Abstract: The double-intertropical convergence zone (DI) systematic error, affecting state-of-the-art coupled general circulation models (CGCM) is examined in the multi-model Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) ensemble of simulations of the twentieth-century climate. Aim of this study is to quantify the DI error on precipitation in the tropical Pacific, with a specific focus on the relationship between the DI error and the representation of large-scale vertical circulation regimes in climate models. The DI rainfall signal is analysed using a regime sorting approach for the vertical circulation regimes. Through the use of this compositing technique, precipitation events are regime-sorted based on the large scale vertical motions, as represented by the mid-tropospheric lagrangian pressure tendency omega500 dynamical proxy. This methodology allows the partition of the precipitation signal into deep and shallow convective components. Following the regime-sorting diagnosis, the total DI bias is split into an error affecting the magnitude of precipitation associated with individual convective events and an error affecting the frequency of occurrence of single convective regimes. It is shown that, despite the existing large intra-model differences, CGCMs canbe ultimately grouped into a few homegenous clusters, each featuring a well defined rainfall-vertical circulation relationship in the DI region. Three major behavioural clusters are identified within the AR4 models ensemble:two unimodal distributions, featuring maximum precipitation under subsidence and deep convection regimes, respectively, and one bimodal distribution, displaying both components. Extending this analysis to both coupled and uncoupled (atmosphere-only) AR4 simulations reveals that the DI bias in CGCMs is mainly due to the overly frequent occurrence of deep convection regimes, whereas the error on rainfall magnitude associated with individual convective events is overall consistent with errors already present in the corresponding atmosphere stand-alone simulations.A critical parameter controlling the strength of the DI systematic error is identified in the model-dependent sea surface temperature (SST) threshold leading to the onset of deep convection (THR), combined with the average SST in the south-eastern Pacific. http://hdl.handle.net/2122/5694 Titolo: Evidence for Obliquity Forcing of Glacial Termination II<br/><br/>Autori: Drysdale, R. N.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; Hellstrom, J. C.; School of Earth Sciences, University of Melbourne, Parkville, Victoria 2010, Australia; Zanchetta, G.; Department of Earth Sciences, University of Pisa, Pisa 56100, Italy; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, Pisa, Italy; IGG-CNR, Pisa, Italy; Fallick, A. E.; Scottish Universities Environmental Research Centre, East Kilbride G75 0GF, UK.; Sanchez-Goni, M. F.; EPHE, UMR CNRS 5805 EPOC, Université Bordeaux 1, 33405 Talence, France.; Couchoud, I.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; McDonald, J.; Environmental and Climate Change Group, University of Newcastle, Callaghan, New South Wales 2308, Australia; Maas, R.; School of Earth Sciences, University of Melbourne, Parkville, Victoria 2010, Australia; Lohmann, G.; Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.; Isola, I; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia<br/><br/>Abstract: Variations in the intensity of high-latitude Northern Hemisphere summer insolation, driven largely by precession of the equinoxes, are widely thought to control the timing of Late Pleistocene glacial terminations. However, recently it has been suggested that changes in Earth’s obliquity may be a more important mechanism. We present a new speleothem-based North Atlantic marine chronology that shows that the penultimate glacial termination (Termination II) commenced 141,000 ± 2500 years before the present, too early to be explained by Northern Hemisphere summer insolation but consistent with changes in Earth’s obliquity. Our record reveals that Terminations I and II are separated by three obliquity cycles and that they started at near-identical obliquity phases. http://hdl.handle.net/2122/5439 Titolo: Changes in Tropical Cyclone Activity due to Global Warming in a General Circulation Model<br/><br/>Autori: Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Curatori: Elsner, J. B.; Department of Geography, Florida State University, Tallahassee; Jagger, T.H.; Department of Geography, Florida State University, Tallahassee<br/><br/>Abstract: This study investigates the possible changes that the greenhouse global warming might generate in the characteristics of the tropical cyclones (TCs). The analysis has been performed using scenario climate simulations carried out with a fully coupled high-resolution global general circulation model. The capability of the model to reproduce a reasonably realistic TC climatology has been assessed by comparing the model results from a simulation of the 20th Century with observations. The model appears to be able to simulate tropical cyclone-like vortices with many features similar to the observed TCs. The simulated TC activity exhibits realistic geographical distribution, seasonal modulation and interannual variability, suggesting that the model is able to reproduce the major basic mechanisms that link the TC occurrence with the large scale circulation. The results from the climate scenarios reveal a substantial general reduction of the TC frequency when the atmospheric CO2 concentration is doubled and quadrupled. The reduction appears particularly evident for the tropical North West Pacific (NWP) and North Atlantic (ATL). In the NWP the weaker TC activity seems to be associated with a reduced amount of convective instabilities. In the ATL region the weaker TC activity seems to be due to both the increased stability of the atmosphere and a stronger vertical wind shear. Despite the generally reduced TC activity, there is evidence of increased rainfall associated with the simulated cyclones. Despite the overall warming of the tropical upper ocean and the expansion of warm SSTs to the subtropics and mid-latitudes, the action of the TCs remains well confined to the tropical region and the peak of TC number remains equatorward of 20° latitude in both Hemispheres. An extended version of this work is in available on Journal of Climate (Gualdi et al.,2008 - DOI:10.1175/2008JCLI1921.1) http://hdl.handle.net/2122/5315 Titolo: An Intercomparison of Precipitable Water Vapor Measurements Obtained During the ECOWAR Field Campaign<br/><br/>Autori: Fiorucci, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Muscari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Di Girolamo, P.; Dipartimento di Ingegneria e Fisica dell'Ambiente, Università della Basilicata, Potenza, Italy; Esposito, F.; Dipartimento di Ingegneria e Fisica dell'Ambiente, Università della Basilicata, Potenza, Italy; Grieco, G.; Dipartimento di Ingegneria e Fisica dell'Ambiente, Università della Basilicata, Potenza, Italy; Summa, D.; Dipartimento di Ingegneria e Fisica dell'Ambiente, Università della Basilicata, Potenza, Italy; Bianchini, G.; Istituto di Fisica Applicata "Nello Carrara", IFAC-CNR, Sesto Fiorentino, Firenze, Italy; Palchetti, L.; Istituto di Fisica Applicata "Nello Carrara", IFAC-CNR, Sesto Fiorentino, Firenze, Italy; Cacciani, M.; Dipartimento di Fisica, Università di Roma "La Sapienza", Roma, Italy; Di Iorio, T.; Dipartimento di Fisica, Università di Roma "La Sapienza", Roma, Italy; Pavese, G.; Istituto di Metodologie per l’Analisi Ambientale, IMAA-CNR, Tito Scalo, Potenza, Italy; Cimini, D.; CETEMPS, Dipartimento di Fisica, Università di L’Aquila, L’Aquila, Italy; de Zafrah, R. L.; Department of Physics and Astronomy, and Institute for Terrestrial and Planetary Atmospheres, State University of New York, Stony Brook, U.S.A.<br/><br/>Abstract: In this study we present an intercomparison of measurements of very low water vapor column content obtained with a Ground-Based Millimeter-wave Spectrometer (GBMS), Vaisala RS92k radiosondes, a Raman Lidar, and an IR Fourier Transform Spectrometer. These sets of measurements were carried out during the primary field campaign of the ECOWAR (Earth COoling by WAter vapor Radiation) project which took place on the Western Italian Alps from 3 to 16 March, 2007. http://hdl.handle.net/2122/4711 Titolo: Mineralogy and geochemical trapping of CO2 in an Italian carbonatic deep saline aquifer: preliminary results<br/><br/>Autori: Cantucci, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Procesi, M.; Univeristà Roma TRE; Buttinelli, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Montegrossi, G.; CNR-IGG Firenze; Vaselli, O.; Dip. Sci. Terra Firenze; Quattrocchi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia<br/><br/>Abstract: CO2 Capture & Storage (CCS) is presently one of the most promising technologiesfor reducing anthropogenic emissions of CO2 . Among the several potential geologi-cal CO2 storage sites, e.g. depleted oil and gas field, unexploitable coal beds, salineaquifers, the latter are estimated to have the highest potential capacity (350-1000 GtCO2 ) and, being relatively common worldwide, a higher probability to be locatedclose to major CO2 anthropogenic sources. In these sites CO2 can safely be retainedat depth for long times, as follows: a) physical trapping into geologic structures; b) hy-drodynamic trapping where CO2(aq) slowly migrates in an aquifer, c) solubility trap-ping after the dissolution of CO2(aq) and d) mineral trapping as secondary carbon-ates precipitate. Despite the potential advantages of CO2 geo-sequestration, risks ofCO2 leakage from the reservoir have to be carefully evaluated by both monitoringtechniques and numerical modeling used in “CO2 analogues”, although seepage fromsaline aquifers is unlikely to be occurring. The fate of CO2 once injected into a salineaquifer can be predicted by means of numerical modelling procedures of geochemicalprocesses, these theoretical calculations being one of the few approaches for inves-tigating the short-long-term consequences of CO2 storage. This study is focused onsome Italian deep-seated (>800 m) saline aquifers by assessing solubility and min-eral trapping potentiality as strategic need for some feasibility studies that are aboutto be started in Italy. Preliminary results obtained by numerical simulations of a geo-chemical modeling applied to an off-shore Italian carbonatic saline aquifer potentialsuitable to geological CO2 storage are here presented and discussed. Deep well data,still covered by industrial confidentiality, show that the saline aquifer, includes sixLate Triassic-Early Jurassic carbonatic formations at the depth of 2500-3700 m b.s.l.These formations, belonging to Tuscan Nappe, consist of porous limestones (mainlycalcite) and marly limestones sealed, on the top, by an effective and thick cap-rock(around 2500 m) of clay flysch belonging to the Liguride Units. The evaluation of thepotential geochemical impact of CO2 storage and the quantification of water-gas-rockreactions (solubility and mineral trapping) of injection reservoir have been performedby the PRHEEQC (V2.11) Software Package via corrections to the code default ther-modynamic database to obtain a more realistic modelling. The main modifications tothe Software Package are, as follows: i) addition of new solid phases, ii) variationof the CO2 supercritical fugacity and solubility under reservoir conditions, iii) addi-tion of kinetic rate equations of several minerals and iv) calculation of reaction sur-face area. Available site-specific data include only basic physical parameters such astemperature, pressure, and salinity of the formation waters. Rocks sampling of eachconsidered formation in the contiguous in-shore zones was carried out. Mineralogywas determined by X-Ray diffraction analysis and Scanning Electronic Microscopyon thin sections. As chemical composition of the aquifer pore water is unknown, thishas been inferred by batch modeling assuming thermodynamic equilibrium betweenminerals and a NaCl equivalent brine at reservoir conditions (up to 135 ̊C and 251atm). Kinetic modelling was carried out for isothermal conditions (135 ̊C), under aCO2 injection constant pressure of 251 atm, between: a) bulk mineralogy of the sixformations constituting the aquifer, and b) pre-CO2 injection water. The kinetic evolu-tion of the CO2 -rich brines interacting with the host-rock minerals performed over 100years after injection suggests that solubility trapping is prevailing in this early stageof CO2 injection. Further and detailed multidisciplinary studies on rock properties,geochemical and micro seismic monitoring and 3D reservoir simulation are necessaryto better characterize the potential storage site and asses the CO2 storage capacity. http://hdl.handle.net/2122/4684 Titolo: ANALYSIS OF TROPICAL CYCLONE ACTIVITY IN A WARMER CLIMATE: RESULTS FROM A HIGH-RESOLUTION COUPLED GENERAL CIRCULATION MODEL<br/><br/>Autori: Scoccimarro, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Gualdi, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia<br/><br/>Curatori: AOGS<br/><br/>Abstract: This study investigates the possible changes that the greenhouse global warming might generate in the characteristics of the tropical cyclones (TCs). The analysis has been performed using climate scenario simulations carried out with a fully coupled high–resolution global general circulation model. The capability of the model to reproduce a reasonably realistic TC climatology has been assessed by comparing the model results from a simulation of the XX Century with observations. The model appears to be able to simulate tropical cyclone-like vortices with many features similar to the observed TCs. The simulated TC activity exhibits realistic geographical distribution, seasonal modulation and interannual variability, suggesting that the model is able to reproduce the major basic mechanisms that link the TC occurrence with the large scale circulation. The results from the climate scenarios reveal a substantial general reduction of the TC frequency when the atmospheric CO2 concentration is doubled and quadrupled. The reduction appears particularly evident for the tropical north west Pacific (NWP) and north Atlantic (ATL). In the NWP the weaker TC activity seems to be associated with a reduced amount of convective instabilities. In the ATL region the weaker TC activity seems to be due to both the increased stability of the atmosphere and a stronger vertical wind shear. Despite the generally reduced TC activity, there is evidence of increased rainfall associated with the simulated cyclones. The tropical cyclone-ocean interaction is captured by the model and the impact of the ocean response to the storm forcing is analyzed under different radiative forcing conditions.