Chaos and weather prediction - A review of recent advances in Numerical Weather Prediction: Ensemble forecasting and adaptive observation targeting

The weather is a chaotic system. Small errors in the initial conditions of a forecast grow rapidly and predictability is limited by model errors due to the approximate simulation of atmospheric processes of the state-of-the-art numerical models. These two sources of uncertainties limit the skill of single, deterministic forecasts in an unpredictable way, with days of high/poor quality forecasts randomly followed by days of high/poor quality forecasts. Two recent advances in numerical weather prediction, the operational implementation of ensemble prediction systems and the development of objective procedures to target adaptive observations are discussed. These advances have been thought and designed to reduce forecast errors and to provide forecasters with more complete weather predictions. Ensemble prediction is a feasible method to estimate the probability distribution function of forecast states. Ensemble systems can provide forecasters with an objective way to predict the skill of single deterministic forecasts. Adaptive observations targeted in sensitive regions can reduce the initial conditions’ uncertainties, and thus decrease forecast errors. Singular vectors that identify unstable regions of the atmospheric flow can be used to identify optimal ways to adapt the atmospheric observing system. The European Centre for Medium-Range Weather Forecasts Ensemble Prediction System is described, and targeting experiments are discussed

The Hydrologic Ensemble Prediction EXperiment (HEPEX)

International audienceUsers of hydrologic predictions need reliable, quantitative forecast information, including estimates of uncertainty, for lead times ranging from less than an hour during flash flooding events to more than a year for long-term water management. To meet this need, operational agencies are developing hydrological ensemble forecast techniques to account for sources of uncertainty such as future precipitation, initial hydrological conditions, and hydrological model limitations including uncertain model parameters. Research advances in areas such as hydrologic modeling, data assimilation, ensemble prediction, and forecast verification need to be incorporated into operational forecasting systems to assure that the state-of-the-art products are reaching the forecast user community. The Hydrologic Ensemble Prediction EXperiment (HEPEX) has been formed to develop and demonstrate new hydrologic forecasting technologies, and to facilitate the implementation of beneficial technologies into the operational environment

Performance of the ARPA-SMR limited-area ensemble prediction system: two flood cases

The performance of the ARPA-SMR Limited-area Ensemble Prediction System (LEPS), generated by nesting a limited-area model on selected members of the ECMWF targeted ensemble, is evaluated for two flood events that occurred during September 1992. The predictability of the events is studied for forecast times ranging from 2 to 4 days. The extent to which floods localised in time and space can be forecast at high resolution in probabilistic terms was investigated. Rainfall probability maps generated by both LEPS and ECMWF targeted ensembles are compared for different precipitation thresholds in order to assess the impact of enhanced resolution. At all considered forecast ranges, LEPS performs better, providing a more accurate description of the event with respect to the spatio-temporal location, as well as its intensity. In both flood cases, LEPS probability maps turn out to be a very valuable tool to assist forecasters to issue flood alerts at different forecast ranges. It is also shown that at the shortest forecast range, the deterministic prediction provided by the limited area model, when run in a higher-resolution configuration, provides a very accurate rainfall pattern and a good quantitative estimate of the total rainfall deployed in the flooded regions

The transient atmospheric response to a reduction of sea-ice cover in the Barents and Kara seas

The observed reduction of Arctic sea-ice has drawn a lot of interest for its potential impact on mid-latitude weather variability. One of the outstanding challenges is to achieve a deeper understanding of the dynamical processes involved in this mechanism. To progress in this area, we have designed and performed an experiment with an intermediate complexity atmospheric model. The experiment shows a transient atmospheric response to a surface diabatic heating in the Barents and Kara seas leading to an anomalous circulation first locally, then over the polar region and finally over the Euro-Atlantic sector. A hypothesis that explains the mechanisms for the propagation of the signal is put forward. The discussion of this hypothesis provides an insight into the nature of the link between sea-ice forcing and the modes of internal variability of the atmosphere. We demonstrate that after removal of sea ice in the Barents and Kara seas, first the linear atmospheric response dominates and is confined in the proximity of the heating area, then a large-scale response, associated also to eddy-feedback, is found and finally anomalies reach the lower-stratosphere and show a hemispheric pattern in the troposphere. These results identify the drivers of the tropospheric connection between sea-ice variability and the North Atlantic Oscillation and highlight the role of the lower stratosphere

Il ruolo degli individui e delle istituzioni nell’affrontare il cambiamento climatico

If we want to reach net zero greenhouse gas emissions by 2050, we need to drastically change our life standards. Individuals can give a substantial contribution even without waiting for the fullest activation of regulatory frameworks : our example shows that reductions of the individual emissions of about 20% are achievable without a drastic change in their habits . But more sub- stantial reductions beyond 20% require political decisions and investments that would ‘enable’ them to achieve them. Single individuals constitute a sort of immense “climate innovation agent”, promoting the ever wider growth and consolidation of a global public sphere, which must be capable of directing politics towards such cha nges, or, above all, facilitating the acceptance of measures in this direction and giving voice to systemic and effective criticisms, where such measu- res which are now widely evident are not or are too weakly adopted. I nstitutions and politics must sup port them in adopt ing the change s required to achieve net zero emissions In this essay, it is first introduced the current state of the Earth's climate (§ 1). Then, the key facts lead ing to the conclusion that human activities are the main cause of climate change are summa- rized, and the role that individual choices can lead to a reduction in emissions is analysed (§ 2). There are several obstacles that must be overcome to reduce the emissions many of a politi cal nature above all and the essay examines various risks of ineffectiveness that could constellate a path that is complex and full of old and new difficulties (§ 3). The work carefully examine s some proposals on the actual advantages that could occur if institutions enable individuals to decide for a global change in emission behaviour s (§ 4). A multifaceted strategy, aimed at directing the individual's motivation towards a global change in consumption behaviour and energy saving, can lead to the require d change (§ 5). Such a strategy requires immediate and effective policy actions at institutional level, to enable the structural change we need and which the ongoing climate change, mainly caused by man, requires us to implement

The Soverato flood in Southern Italy: performance of global and limited-area ensemble forecasts

The predictability of the flood event affecting Soverato (Southern Italy) in September 2000 is investigated by considering three different configurations of ECMWF ensemble: the operational Ensemble Prediction System (EPS), the targeted EPS and a high-resolution version of EPS. For each configuration, three successive runs of ECMWF ensemble with the same verification time are grouped together so as to generate a highly-populated "super-ensemble". Then, five members are selected from the super-ensemble and used to provide initial and boundary conditions for the integrations with a limited-area model, whose runs generate a Limited-area Ensemble Prediction System (LEPS). The relative impact of targeting the initial perturbations against increasing the horizontal resolution is assessed for the global ensembles as well as for the properties transferred to LEPS integrations, the attention being focussed on the probabilistic prediction of rainfall over a localised area. At the 108, 84 and 60- hour forecast ranges, the overall performance of the global ensembles is not particularly accurate and the best results are obtained by the high-resolution version of EPS. The LEPS performance is very satisfactory in all configurations and the rainfall maps show probability peaks in the correct regions. LEPS products would have been of great assistance to issue flood risk alerts on the basis of limited-area ensemble forecasts. For the 60-hour forecast range, the sensitivity of the results to the LEPS ensemble size is discussed by comparing a 5-member against a 51-member LEPS, where the limited-area model is nested on all EPS members. Little sensitivity is found as concerns the detection of the regions most likely affected by heavy precipitation, the probability peaks being approximately the same in both configurations

Atmospheric predictability revisited

This article examines the potential to improve numerical weather prediction (NWP) by estimating upper and lower bounds on predictability by re-visiting the original study of Lorenz (1982) but applied to the most recent version of the European Centre for Medium Range Weather Forecasts (ECMWF) forecast system, for both the deterministic and ensemble prediction systems (EPS). These bounds are contrasted with an older version of the same NWP system to see how they have changed with improvements to the NWP system. The computations were performed for the earlier seasons of DJF 1985/1986 and JJA 1986 and the later seasons of DJF 2010/2011 and JJA 2011 using the 500-hPa geopotential height field. Results indicate that for this field, we may be approaching the limit of deterministic forecasting so that further improvements might only be obtained by improving the initial state. The results also show that predictability calculations with earlier versions of the model may overestimate potential forecast skill, which may be due to insufficient internal variability in the model and because recent versions of the model are more realistic in representing the true atmospheric evolution. The same methodology is applied to the EPS to calculate upper and lower bounds of predictability of the ensemble mean forecast in order to explore how ensemble forecasting could extend the limits of the deterministic forecast. The results show that there is a large potential to improve the ensemble predictions, but for the increased predictability of the ensemble mean, there will be a trade-off in information as the forecasts will become increasingly smoothed with time. From around the 10-d forecast time, the ensemble mean begins to converge towards climatology. Until this point, the ensemble mean is able to predict the main features of the large-scale flow accurately and with high consistency from one forecast cycle to the next. By the 15-d forecast time, the ensemble mean has lost information with the anomaly of the flow strongly smoothed out. In contrast, the control forecast is much less consistent from run to run, but provides more detailed (unsmoothed) but less useful information

Mental disorders and work integration: a retrospective study in a northern italian town.

OBJECTIVES: THE PRESENT STUDY WAS CONDUCTED IN A VOCATIONAL INTEGRATION SERVICE OF A NORTHERN ITALIAN TOWN WITH TWO MAJOR AIMS: to assess vocational integration programs undertaken from 1(st) January 2004 to 1(st) January 2007; and to identify job tenure-associated predictors. METHODS: This is a retrospective study; we collected data such as gender, age, duration, type and outcome of the vocational integration program, and number of interventions performed by the vocational integration service. Self-report questionnaires were also used to assess the satisfaction of users, caregivers, practitioners, and of the company contacts involved in the study. RESULTS: The service has enrolled 84 users during the observation period. Out of these users, 64.3% of them still had their jobs after three years. Users, caregivers and company contacts expressed high levels of satisfaction for the support received by the vocational integration service. The company expressed less satisfaction for the collaboration received by the Departments of Mental Health (DMHs) that coached the users. The only variable associated to the outcome was the number of interventions that the users received before their placement on the job. CONCLUSIONS: Despite all the limits of this study, its results show that the chance of taking advantage of a supported job placement service has likely proven itself effective in helping people with mental disorders to obtain and maintain a competitive employment. Our results, however, also point to the necessity of implementing newer strategies meant to develop a greater integration among all services dealing with mentally ill people

PARTECIPAZIONE E GRADIMENTO DI UN PERCORSO DI ACCOMPAGNAMENTO PSICOLOGICO RIVOLTO ALLE MATRICOLE DELLA FACOLTÀ DI MEDICINA

Obiettivi: valutare la partecipazione e il gradimento delle matricole che aderiscono al “Progetto Accoglienza”, un percorso di accoglienza e accompagnamento psicologico, attivo da quattro anni, presso il Corso di Laurea in Medicina e Chirurgia dell’Università degli Studi di Brescia. Metodo: il percorso si fonda sull’implementazione della figura di studenti senior (tutor), adeguatamente formati e supervisionati da docenti della Sezione di Psicologia Clinica, attraverso l’utilizzo di modalità gruppali, in accordo con specifiche metodologie utilizzate da tempo in psicologia clinica. I tutor fungono da riferimenti rassicuranti e identificatori per le matricole, che a loro volta aderiscono al progetto in modo volontario e ricevono crediti opzionali, al fine di riconoscere il valore formativo dello scambio fra studenti del primo anno e studenti senior. Per la valutazione del livello di gradimento è stato predisposto un questionario ad hoc, elaborato in parte sulla base di strumenti utilizzati nei corsi professionali in cui è previsto l’accreditamento e in parte sulla base di proposte e riflessioni fra i docenti di psicologia dell’Ateneo, che non hanno preso parte al progetto. Risultati: il numero di studenti che partecipa con regolarità al percorso di accoglienza è cresciuto nei quattro anni: da 125 a 164. Gli studenti hanno in media un’età di 19.3 anni (±1.7) e sono in prevalenza femmine. Il questionario di gradimento viene compilato in media dall’85% delle matricole coinvolte. Quasi la totalità di esse riferisce che ripeterebbe l’esperienza, anche senza crediti formativi; il 98% la consiglierebbe ad una nuova matricola. Per quanto riguarda rilevanza, efficacia e utilità del percorso rispetto alle proprie esigenze formative, anche in questo caso la maggior parte degli studenti riporta una valutazione positiva. Conclusioni: i dati raccolti mostrano un gradimento medio-alto, che si mantiene costante negli anni. Si ritiene che tale percorso possa fornire un aiuto concreto per fronteggiare le difficoltà associate all’ingresso nell’Università. Fra gli indicatori di efficacia di consimili interventi nel lungo periodo, riteniamo utile la ricaduta in termini di prevenzione del drop out e dell’ allungamento temporale del corso di studi