Suchergebnisse

scritte dagli ambasciadori veneti Molini, Bellegno e Foscarini. Con note ed illustr. del N. U. Luigi Cibrario ; Volltext // Exemplar mit der Signatur: München, Bayerische Staatsbibliothek -- Don.Lud. 173

Abstract. Forecast verification is a long-standing issue of the whole meteorologists' community. A common definition of a truly satisfying prediction skill has not been achieved so far. Even the definition of "event", due to its spatio-temporal discontinuity, is highly affected by uncertainty. Moreover, decision-making demands numerical weather prediction modellers to provide information about the "inner" uncertainty, i.e. the degree of uncertainty related to the choice of a specific setting of the model (microphysics, turbulence scheme, convective closure, etc.). Most European Mediterranean countries, due to dense development, steep coastal orography and short hydrological response time of the drainage basins, have to deal very frequently with flash floods and sudden shallow land sliding impacting on urban areas. Civil protection organizations are in place to issue early warnings in order to allow local authorities and population to take precautionary measures. To do so in Mediterranean catchments, hydrologists are required to use numerical rainfall predictions in place of rainfall observations on large European catchments. Estimating the measure of uncertainty is for this reason crucial. The goal of this work is to propose an objective evaluation of the performance of the currently operational weather prediction model COSMO-I7 over quite a long time period and to check forecast verification at different space-time scales by the comparison of predictions with observations. Due to large investments in the last years, in fact, Italy has built up one of the most dense hourly-reporting network of rain gauges. The network has a mean space density of about 1/100 km2, very similar to the horizontal resolution of currently operating limited area models. An objective procedure to identify and compare the extreme events of precipitation has been applied to the full set of rainfall observations and over the severe events forecast by COSMO-I7 and announced in official warnings by Italian Civil Protection Department. The procedure allows to classify rainfall events as long-lived and spatially distributed or as having a shorter duration and a minor spatial extent. We show that long-lived events are less affected by overall uncertainty than short-lived ones, yet the inner uncertainty of the event affects both.

Modifying the national poverty line to the context of observed consumption patterns of the poor is becoming popular. A context-specific poverty line would be more consistent with preferences. This paper provides theoretical and empirical evidence that the contrary holds and that the national poverty line is more appropriate for comparing living standards among the poor, at least under prevailing conditions in Mozambique and Ghana. The problem lies in the risk of downscaling the burden associated with cheap-calorie diets and the low nonfood component of the rural poor. The paper illustrates how observed behavior may neither reveal preferences nor detect heterogeneous preferences among the poor. Rather, the consumption pattern is the upshot of the poverty condition itself. Poverty is confused with preferences if observed cheap-calorie diets are seen as a matter of taste, whereas in fact they reflect a lack of means to consume a preferred diet of higher quality, as food Engel curve estimates indicate. Likewise, a smaller nonfood component is not a matter of a particular distaste, but an adaptation to the fact that various nonfood items (such as transport) and basic services (such as electricity and health) are simply absent in rural areas.