HYDROMETEORS PRODUCTION AND ADVECTION IN A GRAVITY WAVE ENVIRONMENT

Production and advection of precipitating water in a prescribed, time dependent flow is investigated by means of a simple 2D model in order to predict the periodical behaviour of rain rate and pressure which was observed in the Po valley during IOP8 of MAP. The (x,z,t)-dependent wave perturbations on wind and temperature fields were derived from a linear stability analysis and are superimposed on z-dependent background fields. The wave influence on the hydrometeors production and advection is discussed

Evolutionary spectral analysis of European climatic series

Five long historical time series of temperature and atmospheric pressure, with lengths from 149 to 279 years, three measured in Northern Italy and two in Sweden, were analyzed from the stationary and evolutionary spectral point of view, by means of the the Wavelet Transform and of the classical Fourier method. The main cyclicities revealed in the series of temperature showed interesting differences between the behaviors of Italian and Scandinavian stations. The time intervals in which each series exhibited in its wavelet spectrum a particularly important contribution by a given scale, or range of scales, were also studied. Opposite behaviors were found in Milan (Italy) and in Scandinavian stations, in the second half of the XXth century, as far as the coupling between temperature and pressure around a scale of 30 years is concerned

Međudjelovanje atmosfere s morem u Jadranu: simulacije bure i juga

Two simulations of the response of Adriatic Sea to severe wind performed by an atmosphere-ocean coupled model and the comparisons with observed data and modelled fields published in literature are presented. The model RAMS-DieCAST was applied to simulate the variations of sea currents and temperature profiles, from surface to bottom, induced by two episodes of intense wind over the Adriatic sea: a Bora wind event that occurred in January 1995 and a Sirocco wind event in November 2002. The results of the simulations are compared with observed data at the sea surface. In the Bora episode, the computed surface temperatures are compared with satellite SSTs and in situ observed temperatures; in the Sirocco event the simulated surface currents and temperatures are compared with experimental data collected by surface drifters released in different regions of the Adriatic Sea during the same Sirocco event. In both episodes the simulated temperature trends agree with the observed values and during the Sirocco episode the current fields are in quite good agreement with the drifter data. The modelled sea temperature and velocity fields show also a good concordance with other simulation results in literature.Dvije simulacije jakog vjetra nad Jadranom simuliraju se združenim atmosfersko-oceanografskim modelom te se analiziraju i uspoređuju s mjerenjima i drugim objavljenim modeliranim poljima. U tu svrhu se koristi model RAMS-DieCAST za simulaciju promjena morskih struja i temperaturnih profila po vertikali, uzrokovanih dvjema epizodama intenzivnog vjetra nad Jadranom: burom u siječnju 1995. godine i jugom u studenom 2002. godine. Rezultati simulacija se uspoređuju s opažanjima na morskoj površini. Tijekom bure, modelirana površinska temperatura uspoređuje se s površinskom temperaturom mora dobivene satelitskim mjerenjima i mjerenjima temperature u određenim točkama prostora. Tijekom juga, simulirane površinske struje i temperature se uspoređuju s eksperimentalnim mjerenjima dobivenih na temelju površinskih driftera koji su pušteni u različitim dijelovima Jadrana za istu epizodu. U obje epizode trendovi simulirane temperature dobro se podudaraju s opažanjima. Također se tijekom juga, površinske struje dobro podudaraju s mjerenjima driftera. Modelirana temperatura mora kao i vektorsko polje brzina pokazuju dobro slaganje s rezultatima sličnih simulacija u literaturi

Temperature variations in the low stratosphere (50–200 hPa) monitored by means of the atmospheric muon flux

The dependence of the muon flux on the atmospheric parameters (pressure and temperature) is a well-known effect since long time ago. We have correlated the muon flux recorded by the electromagnetic detector of EAS-TOP with the atmospheric temperature (up to few hPa level) monitored by the radio-soundings of the ITAV—Aeronautica Militare at Pratica di Mare (Rome). A significant effect has been observed when the muon flux is correlated with the atmospheric temperature in the region 50–200 hPa, as expected, since this is the region where the mesons of first generation are produced. The technique has been applied to two short periods of strong temperature variations in the low stratosphere, showing that the temporal pattern of the temperature is fairly well reproduced by the variations of the muon flux. The main results of this analysis are presented

Sensitivity Analysis and Investigation of the Behaviour of the UTOPIA Land-Surface Process Model : A Case Study for Vineyards in Northern Italy

We used sensitivity-analysis techniques to investigate the behaviour of the land-surface model UTOPIA while simulating the micrometeorology of a typical northern Italy vineyard (Vitis vinifera L.) under average climatic conditions. Sensitivity-analysis experiments were performed by sampling the vegetation parameter hyperspace using the Morris method and quantifying the parameter relevance across a wide range of soil conditions. This method was used since it proved its suitability for models with high computational time or with a large number of parameters, in a variety of studies performed on different types of biophysical models. The impact of input variability was estimated on reference model variables selected among energy (e. g. net radiation, sensible and latent heat fluxes) and hydrological (e. g. soil moisture, surface runoff, drainage) budget components. Maximum vegetation cover and maximum leaf area index were ranked as the most relevant parameters, with sensitivity indices exceeding the remaining parameters by about one order of magnitude. Soil variability had a high impact on the relevance of most of the vegetation parameters: coefficients of variation calculated on the sensitivity indices estimated for the different soils often exceeded 100 %. The only exceptions were represented by maximum vegetation cover and maximum leaf area index, which showed a low variability in sensitivity indices while changing soil type, and confirmed their key role in affecting model results