Claudio Cassardo

Localization of source and sink regions of carbon dioxide through the method of the synoptic air trajectory statistics

Abstract The main purpose of this paper is to contribute to the improvement of the present knowledge concerning the transient components of the global carbon cycle, superimposed to the periodic seasonal oscillation and to the yearly trend. This purpose has been achieved through the comparison among the calculated concentration fields of atmospheric CO2 and its comparison with the sea-surface temperature patterns, forestation maps, forest fires, and the anthropogenic emissions extracted from Edgar V.2.0 database. In order to identify with high spatial resolution the most relevant areas of CO2 sources and sinks, we have applied a methodology based on a statistical analysis of simulated back-trajectories related to atmospheric concentration values measured at some receptor sites where the back-trajectories originate. In particular, we have used a 2-year time series (1996 and 1997) of CO2 concentration data observed in three receptor sites located in high mountain areas, in order to reduce significantly the effects due to local influences (such as emissions from industries and urban areas or the absorption processes due to the vegetation). The back-trajectories were computed by means of the wind fields provided by the ECMWF analysis (T213/L31 model) on a regular grid. The area investigated was from 11°W to 36°E in longitude and from 30°N to 57°N in latitude. The final concentration field was computed by means of a statistical source–receptor model, based on a methodology developed by Stohl (Atmos. Environ. 30 (1996) 579) and adapted here with some modifications in the pre- and post-processing phases. Before applying the model, a careful evaluation of its sensitivity to the input data has been performed, followed by an analysis to identify the optimal configuration of the model. The results have shown a satisfactory accuracy in the identification of the major sources and sinks considered.

A study of the assessment of air temperature, and sensible-and latent-heat fluxes from sonic-anemometer observations

SummaryIn the past ten years, use of sonic anemometers to provide fast-response wind sensing in the atmospheric surface layer became more and more intensive, due to their increasing availability, decreasing cost and increasing number of publications regarding their data treatment. In this paper, we present an algorithm we have developed in order to analyse the data of one of the most diffused types of sonic anemometer,i.e. the Gill sonic anemometer. Our software allows to evaluate the air temperature and the sensible- and latent-heat fluxes if also low-response measurements of air humidity at the same level of sonic anemometer, and of net radiation and ground surface flux are available. We let our software the option of evaluating the fluxes along the mean local streamline (thus the turbulent fluxes are associated with transport across mean streamline surfaces). By using the data gathered in two field experiments, we discuss the applications of the proposed formulations and check the accuracy of our method by comparing the evaluated fluxes with those measured by fluxmeter.

A study of the performance of a land surface process model (LSPM)

In this paper, a reliable Land-Surface Process Model (LSPM), which is a new version of the LPM of Ji and Hu (1989), is described. The LSPM has been validated with experimental data measured at two stations in the Po Valley (Northern Italy).

Soil Surface Energy and Water Budgets during a Monsoon Season in Korea

Abstract In this study, attention has been focused on the climatology of some variables linked to the turbulent exchanges of heat and water vapor in the surface layer during a summer monsoon in Korea. In particular, the turbulent fluxes of sensible and latent heat, the hydrologic budget, and the soil temperatures and moistures have been analyzed. At large scale, because the measurements of those data are not only fragmentary and exiguously available but also infeasible for the execution of climatologic analyses, the outputs of a land surface scheme have been used as surrogate of observations to analyze surface layer processes [this idea is based on the methodology Climatology of Parameters at the Surface (CLIPS)] in the Korean monsoonal climate. Analyses have been made for the summer of 2005. As a land surface scheme, the land surface process model (LSPM) developed at the University of Torino, Italy, has been employed, along with the data collected from 635 Korean meteorological stations. The LSPM predict...

The Hydrological Balance of the October 2000 Flood in Piedmont, Italy: Quantitative Analysis and Simulation

This paper aims to analyze in detail the flood event that occurred in October 2000 over the northwestern Italian regions and to test the capability of mesoscale model RAMS-LSPM in reproducing the main characteristics of the hydrological budget components during the event. On 13-16 October 2000, a deep, quasi-stationary trough hung over the western Mediterranean, causing extreme precipitation over northwestern Italy. Values exceeded 600 mm in four days, causing huge flooding and landslides with significant damage to houses and infrastructures. Also several lives were reported lost in the Italian regions of Piedmont and Aosta Valley. This disastrous flood was associated with heavy rainfall episodes over a relatively small area during the course of a four-day period. The intense rainfall over the Alps was enhanced by the confluence of the surface southeasterly flow and of the upper-level southerly current. This confluence was strongest over the zones where the maxima of rainfall and vertical wind velocity were observed. This event was analyzed in detail, using the observational network of the Piedmont Region, the GTS network, and model analyses. The interest was focused on the detailed distribution of precipitation in time and space, in order to understand the dominant role of complex orography in enhancing and modifying the precipitation distribution, and on the hydrological budget. The mesoscale Regional Atmospheric Modelling System (RAMS), driven by the European Centre for Medium-Range Weather Forecasts analyses, was used to simulate this event. The interest was focused on the hydrologic budget during the flood; thus the original soil water balance scheme of RAMS (a simplified version of BATS, the Biosphere Atmosphere Transfer Scheme) was replaced by the Land Surface Process Model (LSPM). This method, already applied in the analysis of a previous flood that occurred on the same region in 1994, allowed all components of the hydrologic budget to be inferred during the flood episode, particularly the surface runoff and soil moisture content. The results of the simulation demonstrated that the coupled model RAMS-LSPM was able to give a quite realistic representation of the flood. The coupling with LSPM improved RAMS not only because the coupled model could represent the upper- and surface-level fields (geopotential, potential temperature, and specific humidity), but also because it provided quantitative estimates of the hydrologic budget and other surface parameters.

Analysis of spontaneous pneumothorax in the city of Cuneo: environmental correlations with meteorological and air pollutant variables

Background and PurposePrimary spontaneous pneumothorax (PSP) tends to cluster. Previous studies have found a correlation between PSP and atmospheric pressure variations or thunderstorms. We conducted this study to analyze the PSP correlations with meteorological variables and the concentrations of air pollutants in the city of Cuneo in Italy (IT).MethodsWe evaluated prospectively 451 consecutive PSP patients treated between 2004 and 2010. For each day within the period analyzed, the meteorological parameters and pollutants data were recorded. Statistical analyses on PSP were done for distribution characteristics, spectral autocorrelation, and spectral analysis. Multivariate regression analyses were performed using artificial neural networks.ResultsAnalysis of annual, seasonal, and monthly distributions showed no significant correlation between PSP and the time series. The spectral analysis showed that PSP events were not random. Correlations between meteorological and environmental variables confirmed that PSP was significantly more likely to occur on warm windy days with high atmospheric pressure and high mean nitrogen dioxide concentration.ConclusionsMeteorological parameters and atmospheric pollutants might explain the cluster onset of PSP.

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.

A study of greenhouse gases and air trajectories at Plateau Rosa

SummaryThe attention paid to changes in atmospheric concentrations of greenhouse gases has recently increased, with particular regard to the relationships between variations of their annual trends and of their shorter-period fluctuations on the one hand, and some geophysical and biological natural processes (like atmospheric transport, volcanic eruptions, ENSO events, seasonal vegetation cycles, and so on) on the other hand. Careful analysis and interpretation of the above relationships, in fact, can often disclose unknown mechanisms acting on modulations of these gases and make it possible for us to better understand the contributions made to them by natural causes, contrasted with anthropogenic ones. This paper presents and discusses the results of a series of CO2 air concentration data, measured at Plateau Rosa (3480 m a.s.l.—Italian Western Alps) over a period of about four years, and correlated with atmospheric transport processes on synoptic scale. These results have shown the leading role played by some kinds of atmospheric circulation patterns in creating situations of not fully mixed air streams (and, as such, not representative of background conditions) and have also suggested a «meteorological» selection scheme for CO2 data to be used in evaluating more reliable annual trends.

Climatological study of air trajectories arriving at three alpine sites

SummaryWithin the frame of the EUROTRAC project and in collaboration with ENEL/C.R.T.N. of Milan, a research activity aiming at a meteorological interpretation of smaples of trace chemical compounds collected in alpine glaciers started. With reference to that, availing ourselves of a wind data set coming from the ECMWF analysis, backward air trajectories arriving at three alpine sites six hours for five years (1981–1985) have been computed. The origin of the trajectories at various distances has been evidentiated through their partition in sectors and in altitude.

Statistical study of the trajectories of the air masses flow in the Alpine area

SummaryAs a part of our activity in the transboundary transport, this study examines a five years’ trajectory climatology interesting Northern Italy. Our analysis is twofold: firstly we examine the statistics of air masses arriving at an Alpine location (Brenner Pass) separating between rainy only trajectories and all trajectories, and, secondly, we study the climatology of trajectories, going out from the Po Valley. Trajectories are computed by means of a simple three-dimensional trajectory method using the wind data obtained by the analysis of the ECMWF. The distribution of the arrival (or departure) directions of the trajectories is presented and commented. The differences in the travel times for the different directions are presented as well. The vertical distribution of the trajectories is finally computed. The main results are discussed.