Validation and sensitivity tests on improved paramerizations of a land surface process model (LSPM) in the Po Valley

The Land Surface Process Model (LSPM) has been improved with respect to the 1st version of 1994. The modifications have involved the parametrizations of the radiation terms and of turbulent heat fluxes. A parametrization of runoff has also been developed, in order to close the hydrologic balance. This 2nd version of LSPM has been validated against experimental data gathered at Mottarone (Verbania, Northern Italy) during a field experiment. The results of this validation show that this new version is able to apportionate the energy into sensible and latent heat fluxes. LSPM has also been submitted to a series of sensitivity tests in order to investigate the hydrological part of the model. The physical quantities selected in these sensitivity experiments have been the initial soil moisture content and the rainfall intensity. In each experiment, the model has been forced by using the observations carried out at the synoptic stations of San Pietro Capofiume (Po Valley, Italy). The observed characteristics of soil and vegetation (not involved in the sensitivity tests) have been used as initial and boundary conditions. The results of the simulation show that LSPM can reproduce well the energy, heat and water budgets and their behaviours with varying the selected parameters. A careful analysis of the LSPM output shows also the importance to identify the effective soil type

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

Sensitivity tests on the criterion of potential vorticity index for discriminating the location of ozone sources and sinks over large continental areas

This paper presents the results of a sensitivity analysis of a statistical-dynamic model (ISOGASP, standing for Identification of SOurces of greenhouse GAS Plus), developed by our research group to reconstruct 3D concentration patterns of greenhouse gases in large and deep atmospheric regions over continental or oceanic areas and extending vertically from the lower troposphere to the lower stratosphere. The results of this analysis have shown the ability of the ISOGASP model to discriminate the locations of ozonesource s, according to the geographical distribution patterns of atmospheric O3 concentration inside a limited number of atmospheric layers at different heights above sea level, reconstructed through the method of backward trajectories simulating the travel of air parcels from each different layer to the receptor points at their own height. The potential vorticity index has been used to discriminate the sub-sets of trajectories belonging to stratosphere or troposphere

A reanalysis of the atmospheric boundary layer field experiment(SPCFLUX93) at San Pietro Capofiume (Italy)

A fortnight field experiment was carried out at San Pietro Capofiume(Po Valley, Italy)during the month of June, 1993, and was named SPCFLUX93. This location was chosen as representative of the Po Valley. The SPCFLUX93 experiment was devised according to the results of some previous measurements carried out in mountainous areas of South Europe (i.e. ALPEX—ALPine EXperiment, PYREX—PYRenean Experiment), and aimed to represent a prototype for further field observations. The dataset of the SPCFLUX93 experiment consisted of: i)meteorological and chemical data collected continuously with slow-response sensors in the atmospheric surface layer and into the soil; ii)data coming from fastresponse instrumentation (sonic anemometers and fluxmeter); iii) radiosoundings carried out with free and tethered balloons; iv)con tinuous vertical wind soundings with a Mini-Sodar. The aim of the SPCFLUX93 field experiment was to investigate the following topics: atmospheric turbulence, dry and wet atmospheric total deposition, energy balance, thermal wave propagation in the soil. Few years later, the atmospheric and hydrological scientific community conduced an extensive programme, the Mesoscale Alpine Programme (MAP), on weather and climate in mountainous regions. This programme considered many aspects of alpine meteorology, ranging from high-resolution numerical modelling to experimental campaigns performed on both sides of the Alps, with the aim to better understand the interaction processes of atmospheric fluxes with the orography. Many puzzling problems were posed by the complexity of these interactions; among them, the perturbations on the boundary layer structure caused by the airflows that cross the Alps and reach the Po Valley would still require more experimental observations and theoretical studies. These considerations prompted us to reanalyze the SPCFLUX93 dataset. In this paper, a layout of the field experiment (including the instrumentation details, the experimental relevant dataset and database composed by meteorological standard data, vertical profile data, ultrasonic anemometer data, and chemical data)is presented; the collected data are described; the details of the mesoscale meteorological situation over San Pietro Capofiume during the experiment are presented; finally, some analyses on the data are shown, and the main results coming from the several applications carried out using the dataset are illustrated or summarized. In particular, the most interesting results are related to the following topics: the characteristics of the turbulence in the surface layer (using the fast-response data), the validation of land surface schemes (using the surface observations), the evaluation of mixed layer depth (using radon flux data)and the estimate of deposition velocity

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

Validation and Physical Parametrization of a Gaussian Climatological Model Applied to a Complex Site

Seasonal sulphur-dioxide concentrations have been simulated in a topographically complex-coastal site, by means of a Gaussian type model. The model diffusion equation has been parametrized on the basis of the results from a series of field experiments conducted in the area to characterize the dynamic and thermodynamic properties of the local atmosphere. The validity of the adopted model formulation and physical parametrization has been discussed by comparing simulated and measured concentration values separately for unstable, neutral and stable situations, and by testing the model sensitivity with respect to changes in the parameters used. The analysis has shown that definition of the model physical parameters as indicated by the field experiments leads to a very satisfactory agreement between the calculated and measured concentrations. Therefore the model can be considered a suitable tool to implement air quality strategies in the area on a climatological basis. The study has been applied to the complex coastal sites of La Spezia, Italy, for the period March 1975 - February 1977

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

Obstacle-induced perturbations on turbulent quantities measured in airflows over the sea

An experimental campaign, aiming to investigate the perturbation effects induced by fixed obstacles on turbulence measurements in airflows at the air-sea interface, was carried out at the marine platform of the Italian Navy, located in the harbour of La Spezia (North Ligurian Sea, Italy), near Lerici, on 28th, 29th, and 30th June 1994. This study was prompted by the ever-growing interest in more reliable estimates of energy, mass, and momentum exchanges between water surfaces and atmosphere, whose measurements are severely limited by the geometrical constraints of floating or fixed platforms where they are installed. Two types of meteorological instruments have been used: fast response (20 and 21 Hz) ultrasonic anemometers and fluxmeters to measure turbulent momentum, sensible, and latent heat fluxes and slow-response sensors (less than 4 Hz and sampled at a rate of 1022 Hz) to measure average wind and temperature vertical profiles in the perturbed boundary layer. Both fast- and slow-response instruments have been located a few meters apart from each other, along horizontal and vertical directions, so as to establish also an upper limit to the reliability of horizontal and vertical divergences and gradients of average and turbulent quantities in the obstacle wake. It has been observed that, in the airflow perturbed by the marine platform and its fixed structures, the fast-response instruments of the same type and made by the same manufacturers gave results that compared well with each other, even if they were located at different positions and heights (except for the vertical component of turbulent wind speed), while the comparison among different types of fast instruments gave more uncertain results. On the contrary, as far as mean values of the physical quantities were concerned, the measurements of slow-response instruments in the perturbed airflow were always in good agreement with the averaged data of fast instruments, irrespective of their factory or construction features

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