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Mauro BOCCOLARI

Ricercatore Universitario
Dipartimento di Scienze Chimiche e Geologiche - Sede Dipartimento di Scienze Chimiche e Geologiche

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Pubblicazioni

2020 - Contribution of water geochemistry and isotopes (δ18O, δ2H, 3H, 87Sr/86Sr and δ11B) to the study of groundwater flow properties and underlying bedrock structures of a deep landslide [Articolo su rivista]
Deiana, M.; Mussi, M.; Pennisi, M.; Boccolari, M.; Corsini, A.; Ronchetti, F.
abstract

A comprehensive understanding of bedrock lithology and groundwater circulation is necessary to identify areas prone to landslide initiation and reactivation. This necessity is particularly required in the case of outcroppings of weak rocks such as gypsum that, due to their high solubility and low mechanical strength, can promote slope deformation with the development of caves and collapses. In the Upper Secchia River Valley, where gypsum outcrops extensively and is covered by landslide deposits, an accurate identification of the gypsum outcrops and their distribution is needed to reduce the damage to urbanized slopes. In this paper, a hydrologic and geochemical approach is used in the Montecagno landslide to identify the origin, flow paths and transit time of groundwater circulating inside the landslide body and to identify gypsum deposits and their distribution in the bedrock. The results of groundwater-level monitoring, δ18O-δ2H and 3H isotope analyses and FLOWPC modelling suggest a local and recent origin of the groundwater hosted in shallow flow paths inside the landslide. Chemical and isotope (87Sr/86Sr, δ11B) analyses offer evidence of the presence inside the landslide of small blocks of gypsum that, due to their dimensions, probably have a minor influence on landslide stability. This research demonstrates that the methodology used can provide satisfactory information about bedrock structures and their hydrological aspects.

2019 - On the statistical contribution of cloud fraction cover to the summer sea-ice extent of 15 Arctic sub-regions, 1982-2015 [Poster]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

Sea ice is one of the most important components of the polar climate system. The decline of the Arctic sea-ice extent (SIE), particularly during the melting season (Aug.-Oct.), is widely observed. Important roles in the melting process are played by the changes in thermodynamics and radiation forcing, in particular in relation to surface temperature and cloud cover, and also by the ocean and atmospheric circulation. Even if several studies already analysed the behaviour of SIE in the Arctic using standard linear and non-linear regression methods, this work aims to investigate the correlation between cloud fraction cover (CFC) and summer SIE in 15 Arctic sub-regions. CFC, together with surface temperature and u- and v- wind components, are also used as predictor variables in multiple regression equations for a statistical forecast of SIE for each one of the 15 sub-regions. The data used are: i) monthly SIE, obtained from the sea ice concentration (SIC) dataset over the Arctic as provided by the National Snow and Ice Data Center (NSIDC) and computed using the Nasa Team (NT) algorithm; ii) monthly CFC (for all, high, middle and low clouds) available from the CLARA-A2 dataset produced by the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF), the data being on a 25km x 25km regular grid; iii) monthly air temperatures and u- and v- wind components at sigma 0.995 collected from NCEP/NCAR R1. All data are given on a global regular lat-lon grid with resolution 2.5x2.5 and refer to the period 1982-2015; they were also seasonally and spatially averaged over each sub-region. As expected, the contribution of cloud fraction cover to the SIE variability is lower of that due to thermodynamic forcing through the ‘surface’ temperature and the ‘surface’ wind. However, for some sub-regions (e. g. Greenland Sea, Beaufort Sea) the cloud cover contribution to SIE became relevant. For most sub-regions, the largest contribution seems to come from the middle clouds (440hPa - 680 hPa).

2018 - Analysis of microseismic signals collected on an unstable rock face in the Italian Prealps [Articolo su rivista]
Arosio, Diego; Longoni, Laura; Papini, Monica; Boccolari, Mauro; Zanzi, Luigi
abstract

In this work we present the analysis of more than 9000 signals collected from February 2013 to January 2016 by a microseismic monitoring network installed on a 300 m high limestone cliff in the Italian Prealps. The investigated area was affected by a major rockfall in 1969 and several other minor events up to nowadays. The network features five three-component geophones and a weather station and can be remotely accessed thanks to a dedicated radio link. We first manually classified all the recorded signals and found out that 95 per cent of them are impulsive broad-band disturbances, while about 2 per cent may be related to rockfalls or fracture propagation. Signal parameters in the time and frequency domains were computed during the classification procedure with the aim of developing an automatic classification routine based on linear discriminant analysis. The algorithm proved to have a hit rate higher than 95 per cent and a tolerable false alarm rate and it is now running on the field PC of the acquisition board to autonomously discard useless events. Analysis of lightning data sets provided by the Italian Lightning Detection Network revealed that the large majority of broad-band signals are caused by electromagnetic activity during thunderstorms. Cross-correlation between microseismic signals and meteorological parameters suggests that rainfalls influence the hydrodynamic conditions of the rock mass and can trigger rockfalls and fracture propagation very quickly since the start of a rainfall event. On the other hand, temperature seems to have no influence on the stability conditions of the monitored cliff. The only sensor deployed on the rock pillar next to the 1969 rockfall scarp typically recorded events with higher amplitude as well as energy. We deem that this is due to seismic amplification phenomena and we performed ambient noise recording sessions to validate this hypothesis. Results confirm that seismic amplification occurs, although we were not able to identify any spectral peak with confidence because the sensors used are not suitable for this task. In addition, we found out that there is a preferential polarization of the wave field along the EW direction and this is in agreement with the geological analysis according to which the pillar is overhanging towards the 1969 rockfall scarp and may preferentially evolve in a wedge failure. Event location was not possible because of the lack of a velocity model of the rock mass. We tried to distinguish between near and far events by analysing the covariance matrix of the three-component recordings. Although the parameters and the outcomes of this analysis should be evaluated very carefully, it seems that about 90 per cent of the considered microseismic signals are related to the stability conditions of the monitored area.

2018 - Sea ice extent annual extremes analysis in the Arctic regions [Poster]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

This work analyses the minimum and maximum annual values of Sea Ice Extent (SIE) in the entire Arctic region and in some of its sub-regions. The SIE was computed from the daily sea ice concentration (SIC) data provided by the National Snow and Ice Data Center (NSIDC). The analysis, which covers the 1979-2016 period, aims to answer the following questions: (1) Do annual SIE maxima and minima trends of the various Arctic sub-regions present substantial differences among them? (2) Is the time span between SIE maxima and minima changing over the 38 years of the analysed period? (3) Which maxima and minima extremes can be detected, according to some objective criteria? (4) How much effective are the cross-correlations between the annual SIE maxima and minima time series and between these and some important climatic oscillations indices (Southern Oscillation and Arctic Oscillation)? and (5) are there any relationships of these cross-correlations with the extremes eventually identified in point (3)? With regard to the first point, SIE minima show a substantial decreasing trend, more or less statistically significant; for some sub-regions it can be observed that, after 2007 – year of a strong summer melting– previous sea ice levels have never resumed, suggesting that, around 2007, a substantial reduction of multi-year ice occurred. On the contrary, SIE maxima, show a decreasing trend in some sub-regions and an increasing one in others, a result which may be explained by the relative geographic location. For the different sub-regions: i) the time span between maxima and minima does not change significantly; ii) extremes of SIE maxima and/or minima have been detected for several years; and iii) significant cross-correlations of SIE maxima and/or minima with SOI have been found.

2018 - Trends and variability of cloud fraction cover in the Arctic, 1982–2009 [Articolo su rivista]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

Climatology, trends and variability of cloud fraction cover (CFC) data over the Arctic (north of 70°N), were analysed over the 1982–2009 period. Data, available from the Climate Monitoring Satellite Application Facility (CM SAF), are derived from satellite measurements by AVHRR. Climatological means confirm permanent high CFC values over the Atlantic sector during all the year and during summer over the eastern Arctic Ocean. Lower values are found in the rest of the analysed area especially over Greenland and the Canadian Archipelago, nearly continuously during all the months. These results are confirmed by CFC trends and variability. Statistically significant trends were found during all the months over the Greenland Sea, particularly during the winter season (negative, less than −5 % dec−1) and over the Beaufort Sea in spring (positive, more than +5 % dec−1). CFC variability, investigated by the Empirical Orthogonal Functions, shows a substantial “non-variability” in the Northern Atlantic Ocean. Statistically significant correlations between CFC principal components elements and both the Pacific Decadal Oscillation index and Pacific North America patterns are found.

2017 - Classification of Microseismic Activity in an Unstable Rock Cliff [Relazione in Atti di Convegno]
Arosio, Diego; Boccolari, Mauro; Longoni, Laura; Papini, Monica; Zanzi, Luigi
abstract

We installed a microseismic monitoring network on a 300 m high unstable rock face threatening the city of Lecco, in Northern Italy. The network is active since February 2013 and consists of 5 electromagnetic velocimeters, two of which are deployed in boreholes, two temperature sensors in air and in a shallow fracture, and a rain gauge. Regarding the detection of microseismic events, we decided to set the triggering algorithm in order to tolerate false alarms, and, as a consequence, the network has collected several thousands of events so far. Hence, it is necessary to develop an automatic processing scheme able to discard all the recorded events that are not related to the instability of the rock slope. According to the outcomes of previous studies presented in the scientific literature and to careful analysis of the collected data, we first focused on manual classification of recorded signals according to two main classes: a first one grouping events related to the stability conditions of the slope (referred to as MS and local events), and a second one clustering all disturbances (referred to as spikes, mixed event and unclassified noise). Then, we attempted to develop a classification routine in order to cluster possibly all the signals manually classified as MS events, and at the same time having few false positives. The development of classification algorithm involved analysis of parameters in both time and frequency domains, also supported by spectrograms and Radon transform computations, correlation with meteorological datasets, polarization assessment of the 3-component recordings along with principal component analysis. The algorithm we developed has proved to have a satisfactory success rate. We are now focusing on the last step of the microseismic monitoring activity that involves the localization of events related to the instability of the slope.

2017 - Liquid water path over Arctic and Antarctica between 1982 and 2015 during the summer season [Poster]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

This study investigates trend and variability of cloud liquid water path (LWP) over both the North Pole (NP) and the South Pole (SP). The period of analysis covers 34 years, from 1982 to 2015. Because of some main limitations of the LWP retrieval (availability of daylight and the problems with LWP retrieval over ice and snow) the study is focused on the summer seasons of the respective region that is June- July-August for the NP, and December-January-February for the SP). These summer seasons are those of sea ice melting whose trends have a signi cant importance in the study of climate change. Seasonal data were computed from monthly LWP, which is part of the cloud products of the CLARA-A2 archive, available from the EUMETSAT SAF on Climate Monitoring (CM SAF), derived from AVHRR observations of NOAA and EUMETSAT MetOp satellites. Observations for the Arctic and Antarctic regions are available on two equal-area polar grids at 25 km resolution and covers an area of 1000km 1000km. Linear trend in liquid water path during the analysed period sum- mer seasons are positive for both (about 1:0 kgm2=dec and 0:5 kgm2=dec for SP and NP, respectively), but the trend is statistical signi cant (at = 0:05) only for SP. At a ner spatial resolution, substantial differences are observed: i) in the Arctic, a signi cant increase over Greenland and a decrease over the Arctic Ocean; ii) in Antarctica, a signi cant increase over all the continent, apart a modest decrease around the pole, over the Ross Sea and near the western Antarctic coast. Spatial variability was tested by means of EOF technique. For both the Arctic and Antarctica, only the rst main eigenvector seems signi cant, in both cases explaining about the 20% of the variance. For the Arctic, the higher variability is noted near the pole and in the south-east of Greenland, while, for Antarctica, over the Ross Sea and its surrounding areas and near the opposite coastlines.

2017 - Sea-ice area variability and trends in Arctic sectors of different morphology, 1996–2015 [Articolo su rivista]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

This study presents a comparison of the sea-ice cover of the whole Arctic Ocean with two arctic sectors of different morphology: the Greenland Sea, as a typical “open sea”, and the Beaufort Sea, as a typical “closed sea”. The study refers to the period January 1996–December 2015 and makes use of the Arctic sea-ice concentration data set produced, on a daily basis, by the Institute of Environmental Physics of the University of Bremen. From the whole Arctic data set, two subsets, covering the Greenland Sea and the Beaufort Sea, were extracted. The extent of sea-ice cover was obtained by the sea-ice area (SIA) parameter, which was computed according to the conventional NASA method. Our analysis shows that the strong summer decline of the Arctic SIA in the last 20 years is not observed in the Greenland Sea (the trend of SIA minimum values is 0.7± 2:0 103 km^2 year^-1) while it is even greater in the Beaufort Sea.

2017 - Seasonal co-variability of surface downwelling longwave radiation for the 1982–2009 period in the Arctic [Relazione in Atti di Convegno]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

Trends and variability of the Arctic sea ice extent depend on various physical processes, including those related to changes in radiative fluxes, which are associated with cloudiness and water vapour and, in turn, with the atmospheric moisture transport over the Arctic. Aim of this work was: (i) to extract seasonal spatial patterns of the co-variability between the sea ice concentration (SIC) and the surface downwelling longwave radiation (SDL) in the Arctic Ocean during the 1982–2009 period; and (ii) to estimate the correlation coefficients between these patterns and the indices associated to some climate oscillation modes (AO, NAO, PNA, PDO and AMO). Maximum Covariance Analysis (MCA) was the main technique used in this study. Among our results, we highlight two areas of maximum co-variability SIC/SDL centered over the Barents Sea in winter and over the Chukchi Sea in summer. In addition, some statistically significant correlations (at 95 %) between the spatial patterns of co-variability and climate oscillation indices were assessed, e.g. with PDO and AMO in November– January, with NAO and AMO in May–July, and with PNA in August–October.

2017 - Understanding slope behavior through microseismic monitoring [Abstract in Atti di Convegno]
Arosio, Diego; Boccolari, Mauro; Longoni, Laura; Papini, Monica; Zanzi, Luigi
abstract

It is well known that microseismic activity originates as an elastic stress wave at locations where the material is mechanically unstable. Monitoring techniques focusing on this phenomenon have been studied for over seventy years and are now employed in a wide range of applications. As far as the study of unstable slope is concerned, microseismic monitoring can provide real-time information about fracture formation, propagation and coalescence and may be an appropriate solution to reduce the risk for human settlements when structural mitigation interventions (e.g., rock fall nets and ditches) cannot cope with large rock volumes and high kinetic energies. In this work we present the datasets collected in a 4-year period with a microseismic monitoring network deployed on an unstable rock face in Northern Italy. We mainly focus on the classification and the interpretation of collected signals with the final aim of identifying microseismic events related to the kinematic and dynamic behavior of the slope. We have analyzed signal parameters both in time and frequency domains, spectrograms, polarization of 3-component recordings supported by principal component analysis. Clustering methodologies have been tested in order to develop an automatic classification routine capable to isolate a cluster with most of the events related to slope behavior and to discard all disturbances. The network features both geophones and meteorological sensors so that we could also explore the correlation between microseismic events and meteorological datasets, although no significant relationships emerged. On the contrary, it was found that the majority of the events collected by the network are short-time high-frequency signals generated by electromagnetic activity caused by near and far thunderstorms. Finally, we attempted a preliminary localization of the most promising events according to an oversimplified homogeneous velocity model to get a rough indication about the regions of the monitored area that could be prone to collapse.

2016 - Seasonal co-variability of surface downwelling longwave radiation for the 1982-2009 period in the Arctic [Abstract in Atti di Convegno]
Boccolari, Mauro; Flavio, Parmiggiani
abstract

The decreasing of the sea ice cover observed in the Arctic represent a strong indicator of the ongoing climate change. Several physical processes are contributing to this one. The study of the co-variability of sea ice concentration (SIC) with other physical parameters may be useful to a better understanding of the strength and nature of the Arctic sea ice decline. This work concerns the investigation of the mutual variability between the seasonal fields of SIC and the downwelling surface shortwave radiation (SIS) in clear sky conditions, for the 1982-2009 period. SIC and SIS monthly data were collected from the National Snow and Ice Data Center (NSDIC) and from the Satellite Application Facility on Climate Monitoring (SAFCM), respectively. Then mainly analyzed through the method of maximum covariance analysis (MCA). Interesting results were found during the summer season, which is the relevant season since the sea ice melting: regions of maximum co-variability are located close to the Barents Sea and the Kara Sea. In addition, in these areas, expansion coefficients time series (of principal modes), show statistically significant (at 95%) correlations with climate oscillations such as the Northern Annular Mode (NAM), the North Atlantic Oscillation (NAO) and the Pacific North America (PNA) pattern.

2016 - Singular value decomposition analysis of cloud fraction cover and sea ice concentration over the Arctic region, 1982-2009 [Relazione in Atti di Convegno]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

In this study, the coupled spatial and temporal variability between seasonal data of Cloud Fraction Cover (CFC) and Sea Ice Concentration (SIC) in the Arctic Ocean for the 1982-2009 period were investigated by using the Singular Value Decomposition (SVD) method. The spatial patterns of CFCs related to the first mode of co-variability, identify the maximum covariance, for all seasons, in the Barents Sea and in the Arctic Ocean Canada, while the SIC and 'found in the Chukchi Sea in autumn (in according to the maximum sea ice melting) and the Barents sea during both the winter and spring. CFC spatial patterns related to the first mode of co-variability, locate maximum covariance, for all seasons, in the Barents Sea and in the Canadian side of the Arctic Ocean, while for SIC is found in the Chukchi Sea during autumn (corresponding to the maximum sea ice melting) and in the Barents Sea during both the winter and spring. Finally, the correlation between the seasonal time series of expansion coefficients derived from the SVD analysis, for both CFC and SIC fields, with the seasonal time series of some relevant climate indices for the Arctic (NAO, AO, PDO and PNA). Statistically significant values for both fields were found during summer with the AO, and during autumn with the PNA.

2015 - On the measure of sea ice area from sea ice concentration data sets [Relazione in Atti di Convegno]
Boccolari, Mauro; Parmiggiani, Flavio
abstract

The measure of sea ice surface variability provides a fundamental information on the climatology of the Arctic region. Sea ice extension is conventionally measured by two parameters, i.e. Sea Ice Extent (SIE) and Sea Ice Area (SIA), both parameters being derived from Sea Ice Concentration (SIC) data sets. In this work a new parameter (CSIA) is introduced, which takes into account only the compact sea-ice, which is defined as the sea-ice having concentration at least equal the 70%. Aim of this study is to compare the performances of the two parameters, SIA and CSIA, in analyzing the trends of three monthly time-series of the whole Arctic region. The SIC data set used in this study was produced by the Institute of Environmental Physics of the University of Bremen and covers the period January 2003 - December 2014, i.e. the period in which the data set is built using the new AMSR passive microwave sensor.

2014 - Sea Ice Area Investigation over the East Greenland Sea during 2003-13 [Abstract in Atti di Convegno]
Boccolari, Mauro; Guerrieri, Lorenzo; Parmiggiani, Flavio
abstract

Climate datasets derived from satellite images represent the most useful sources for monitoring and investigating present and (short) past climate, in order to understand the climate change evolution. In this work, a subset of AMSR-E and AMSR-2 Sea Ice Concentration (SIC) data set retrieved from the archive of the Institute of Environmental Physics (IEP) of the University of Bremen, is investigated in order to assess the variability and a possible significant trend of sea ice area over the East Greenland Sea during the period 2003 – 2013. The target area goes, approximately, from 60 to 85N and from 45W to 20E. The analysis sho ws that the strong decline of Arctic sea-ice extent in the last 10 years is not observed in the Greenland Sea, suggesting that large reductions have occurred in the Canadian and Russian Arctic. Similar preliminary investigations over West Greenland Sea and Bering Sea are being carried out. Besides, for approximately the same period and target area, ATOVS tropospheric humidity and temperature fields and AVHRR fractional clouds cover (CFC) datasets have been collected from the Satellite Application Facility on Climate Monitoring (CM-SAF), to perform and analyze the correlation with sea ice area. As expected, results show a high anti-correlation between air temperature (and also tropospheric humidity) with observed sea ice area.

2014 - Sea-ice distribution and variability in the East Greenland Sea, 2003-13 [Relazione in Atti di Convegno]
Boccolari, Mauro; Guerrieri, Lorenzo; Parmiggiani, Flavio
abstract

This study presents an analysis of the sea-ice area time series for the East Greenland Sea for the period January 2003 – December 2013. The data used are a subset of the Arctic Sea Ice Concentration data set derived from the observations of the passive microwave sensors AMSR-E and AMSR-2 and produced, on a daily basis, by the Inst. of Environ. Physics of the University of Bremen. The area of interest goes, approximately, from 57◦N to 84◦N and from 53◦W to 15◦E. On the basis of previous studies, the parameter Sea Ice Area as the sum of all pixels whose sea ice concentration is above 70%, was introduced for measuring sea-ice extent. A first survey of the Greenland Sea data set showed a large anomaly in year 2012; this anomaly, clearly linked with the transition period from AMSR-E to AMSR-2 when re-sampled SSM/I data were used, was partially corrected with a linear regression procedure. The correlation between monthly mean Sea Ice Area and other geophysical parameters, like air temperature, surface wind and cloud cover, was further investigated. High anti-correlation coefficients between air temperature, at sea level and in five different tropospheric layers, and observed ice cover is confirmed. Our analysis shows that the strong decline of Arctic sea-ice area in the last 10 years is not observed in the East Greenland Sea; this implies that large reductions have occurred in the Canadian and Russian Arctic. This result confirms a hypothesis recently postulated to explain the different sea-ice decline in the Arctic and Antarctic regions.

2013 - Changes in temperature and precipitation extremes observed in Modena, Italy [Articolo su rivista]
Boccolari, Mauro; Malmusi, Simona
abstract

Climate changes has become one of the most analysed subjects from researchers community, mainly because of the numerous extreme events that hit the globe. To have a better view of climate changes and trends, long observations time series are needed. During last decade a lot of Italian time series, concerning several surface meteorological variables, have been analysed and published. No one of them includes one of the longest record in Italy, the time series of the Geophysical Observatory of the University of Modena and Reggio Emilia. Measurements, collected since early 19th century, always in the same position, except for some months during the second world war, embrace daily temperature, precipitation amount, relative humidity, pressure, cloudiness and other variables. In this work we concentrated on the analysis of yearly and seasonal trends and climate extremes of temperature, both minimum and maximum, and precipitation time series, for the periods 1861–2010 and 1831–2010 respectively, in which continuous measurements are available. In general, our results confirm quite well those reported by IPCC and in many other studies over Mediterranean area. In particular, we found that minimum temperature has a non significant positive trend of +0.1 °C per decade considering all the period, the value increases to 0.9 °C per decade for 1981–2010. For maximum temperature we observed a non significant +0.1 °C trend for all the period, while +0.8 °C for the last thirty years. On the other hand precipitation is decreasing, -6.3 mm per decade, considering all the analysed period, while the last thirty years are characterised by a great increment of 74.8 mm per decade. For both variables several climate indices have been analysed and they confirm what has been found for minimum and maximum temperatures and precipitation. In particular, during last 30 years frost days and ice days are decreasing, whereas summer days are increasing. During the last 30-year tropical nights and warm spell duration indices are characterised by a particular strong increment, if compared to the ones of the entire period. Finally, a cursory comparison between winter precipitation and NAO index was done, showing a high anti-correlation, especially since the second half of 20th century.

2011 - Correlations between atmospheric water vapour content and outgoing longwave radiation from satellite observations [Abstract in Rivista]
Malmusi, Simona; Boccolari, Mauro
abstract

Datasets of radiative fluxes at TOA and water vapour content observations, both obtained from space measurementsand for a period of several years (since 2004 till now), are available from CM-SAF. Despite being a fairlyshort time period to draw conclusions about climate changes, it is possible to perform a correlation analysis ontrends and on space-time variability between the radiation budget at TOA and water vapour content, based onexclusively polar and geostationary satellite datasets.In this work monthly data of thermal radiative fluxes at TOA and water vapour content from CM-SAF, coveringan area that comprises Europe, Africa and the Atlantic Ocean, are simultaneously analysed.A previous analysis of water vapour content, derived from CM-SAF dataset, have shown positive trends, withdifferent values for land and sea areas, with a good consistency with literature (e.g. IPCC reports). Because of thestrong effect of water vapour on the thermal emitted radiative flow, the correlation between them is confirmed.Moreover, by using some multivariate statistical techniques, the space variability between water vapour and OLRfields has been analysed. Results have confirmed their reciprocal coupling.

2010 - Observed tropical and extratropical modes of variability in moisture fields from climate satellite dataset [Abstract in Rivista]
Malmusi, Simona; Boccolari, Mauro
abstract

Global and high resolution climate dataset taken from satellite images represents one of the most interestingsources for the monitoring and the investigation of present climate and, for short time periods (decadal), analternative to NWP reanalysis datasets. The Satellite Application Facility on Climate Monitoring (CM-SAF)archive represents a complete global dataset since January 2004 of several daily and monthly averaged atmosphericvariables such as radiative flows at surface and TOA, clouds parameters, precipitable water, surface albedo and soon.In this study CM-SAF daily data of layered precipitable water and relative humidity for a period of six years,all over the globe (with the exception of polar regions), have been analyzed. Applying teleconnectivity mapsboth in horizontal and in vertical, and multivariate statistics methods (EOF) to moisture fields, the appearanceof principal modes of general circulation variability patterns over the tropical band (Indian peninsula, southernAfrica, Australia and West Pacific Ocean) seems to have been revealed. Moreover, comparisons of precipitablewater fields with surface albedo and clouds data, yet collected from CM-SAF archive, have been evaluated.

2010 - Upper and middle precipitable water calculated from METEOSAT-8/-9 tropospheric humidity and NCEP/NCAR temperatures [Articolo su rivista]
Malmusi, Simona; Boccolari, Mauro
abstract

The aim of this work is the estimation and the analysis of precipitable water in the middle-upper troposphere (850 hPa–300 hPa), obtained through Meteosat-8/-9 tropospheric humidity products, together with air temperature data, from NCEP/NCAR daily global reanalysis 1. The period of observation goes from 1st February 2004 to 30th November 2008, on a regular grid of 2.5° × 2.5° resolution, over Meteosat-8/-9 area, included between about 63°N–63°S of latitude and between about 63°W–63°E of longitude.Daily averages of tropospheric humidity products have been checked with two data sets: the first one was vertically averaged relative humidity from 97 Integrated Global Radiosonde Archive (IGRA) stations, the second one was relative humidity averaged from NCEP/NCAR daily global reanalysis 1. These comparisons have shown an underestimation of Meteosat relative humidity data respect the radiosounding data, in particular in the middle layer (850–600 hPa).Estimated middle-upper tropospheric precipitable water has shown a general coherence with typical climatological values representing about 30–45% of whole precipitable water in the same area. Linear trends for middle-upper troposphere shows values comprised between − 1.0 kg m− 2 yr− 1 and 0.2 kg m− 2 yr− 1, with bigger values (up to − 1.6 kg m− 2 yr− 1) mainly in the equatorial area, over South America. Hovmöller analysis underline mainly the middle-upper precipitable water seasonality with maximum values oscillating around the equator, following ITCZ migration, more marked over land than over the Ocean, from North to South.

2010 - Variability of middle-upper tropospheric precipitable water from satellite images [Abstract in Rivista]
Malmusi, Simona; Boccolari, Mauro
abstract

Aim of this work is the investigation of middle-upper tropospheric (above 850 hPa) precipitable water space-time distribution obtained from satellite images, in order to look for typical patterns related to tropical and extra-tropical teleconnections.Precipitable water data are calculated from daily tropospheric humidity product derived from two water vapour channels of meteorological geostationary satellites Meteosat-8/-9. Tropospheric humidity provides a layer-mean relative humidity for two tropospheric layers (between 600 and 850 hPa and between 850 and 600 hPa).Monthly analysis of precipitable water has been realized for the period February 2004 - January 2009, over a circular area covered by satellites Meteosat-8/-9 (the satellite radiometer has a resolution of 3 km), included between 63 degree north and south of latitude and between 63 degree west and east of longitude. This area comprises all African continent and Middle East, Atlantic Ocean, the east part of Brazil and the major part of Europe.The time-space analysis of monthly middle-upper tropospheric precipitable water fields has been obtained by using different explorative and statistical analysis methods (e.g. extended EOF). It has revealed a weak and a moderate El Niño phenomena (between JJA 2004 and JFM 2005 and between JAS 2006 and DJF 2007) and a moderate La Niña event (between ASO 2007 and AMJ 2008).

2008 - Middle-upper water vapour estimation from MSG/UTH products combined with NCEP/NCAR analysis [Relazione in Atti di Convegno]
Malmusi, Simona; Boccolari, Mauro
abstract

Atmospheric water vapour is extremely variable on almostall scales, mainly in the troposphere Its distribution and variation knowledge is still incomplete and long term changes, mainly in the upper troposphere, are difficult to evaluateLong time satellite observations, collected since severalyears, could be useful for a better comprehension ofmoisture climatology.Objectives of our work is: • integrate tropospheric humidity satellite observations withanalysis dataset in order to estimate daily middle/upperprecipitable water (MUPW)• check its consistence with known moisture climatic fields

2007 - Confronto di Acqua Precipitabile ottenuta da osservazioni GPS al suolo con/senza misure meteorologiche in loco [Abstract in Atti di Convegno]
Boccolari, Mauro; Barbati, A.; Fazlagic, Slobodan; Malmusi, Simona
abstract

I sistemi di navigazione satellitare (GNSS) rappresentano, da diversi anni, un confermato e valido strumento per le osservazioni meteorologiche (diagnostica in tempo quasi reale e miglioramento dei modelli di previsione numerica) e per il monitoraggio del clima. In particolare, l’osservazione GPS al suolo permette, attraverso la combinazione dei ritardi zenitali troposferici totali dei segnali GPS con misure di pressione e temperatura alla superficie, la stima del contenuto colonnare totale del vapor acqueo (acqua precipitabile) in atmosfera. La maggior parte delle stazioni permanenti GPS non colleziona misure meteorologiche in corrispondenza effettiva alle rispettive antenne, per cui la valutazione dell’acqua precipitabile necessita l’utilizzo di altri dataset meteorologici. Obiettivo di questo lavoro è stato quello di confrontare, per ogni stazione presa in considerazione, i valori di acqua precipitabile ottenuti dai ritardi GPS, sia utilizzando misure meteorologiche in loco sia utilizzando analisi NCEP/NCAR (risoluzione 2.5° x 2.5°). Le stazioni GPS, da cui sono stati collezionati ritardi zenitali troposferici totali giornalieri prodotti dal Bundesamt für Kartographie und Geodäsie (BKG), appartengono alla rete permanente europea EUREF. Le stazioni analizzate sono state dieci per un periodo di sei anni (2001-2006). I confronti dei dati di acqua precipitabile ottenuti con i due metodi hanno mostrato, per il periodo complessivo e per tutte le stazioni, bias ed RMSE inferiori a 2 kg/m2. Questi risultati suggeriscono un impiego estensivo delle osservazioni GPS (inclusione delle stazioni permanenti prive di misure meteorologiche in loco) per un monitoraggio globale del vapor acqueo in atmosfera.

2006 - Comparison between Precipitable Water Vapor data, obtained from METEOSAT products and NCEP Data [Abstract in Rivista]
Malmusi, Simona; Barbati, A; Boccolari, Mauro; Fazlagic, Slobodan; Pinelli, F; Santangelo, Renato
abstract

Water vapor in atmosphere plays an important role in the mechanisms to the base of meteorology and climatology. Precipitable water vapor trends study is an usefulmethod in order to analyse and observe climate and its changes, both on a regional and global scale.The aim of this work is to study precipitable water vapor spatial and temporal distribution obtained from satellite observations.Precipitable water vapor values are calculated from tropospheric humidity data, a product derived from two water vapor channels of meteorological satellite Meteosat-8. The tropospheric humidity product provides a layer-mean relative humidity for twotropospheric layers (between 600 and 850 hPa and between 850 and 600 hPa). In this work the integrated precipitable water vapor between 300 and 850 hPa isobaric layers is analyzed, for the period from February to December 2004. The geographicalarea studied in this work coincides with the one that satellite Meteosat - 8 analyses (the satellite instrument has a resolution of 3 km), a circular area included between 63 degree north and south of latitude and between 63 degree west and east of longitude.Analyzing precipitable water vapor trends, a connection between its temporal variation and the North Atlantic Oscillation (NAO) is noted. Seen the lack of phenomena of El Nino or La Nina in year 2004, eventually connections between precipitable watervapor temporal trends and the Southern Oscillation (SO) couldn’t be observed and therefore analysed.In order to evaluate the results consistence, daily global analysis of precipitable water vapor data from National Centers for Environmental Prediction (NCEP), with a 2.5 degree resolution, is done.

2006 - GPS coordinate estimates by a priori tropospheric delays from NWP using ultra-rapid orbits [Articolo su rivista]
Boccolari, Mauro; S., Fazlagic; Santangelo, Renato
abstract

High accuracy GPS positioning estimates using scientific GPS software through three different processing strategies were compared. The two Italian baselines in a time period of 5 months during 2004 made a calculus data set. For high accuracy GPS differential positioning the use of global tropospheric delay models can be replaced by the implementation of other techniques. The GPS coordinate can be repeated when the tropospheric delay is calculated in Near-Real Time (NRT) from a Numerical Weather Prediction (NWP) model. For the NRT approach IGS ultra-rapid orbits instead of precise orbits were used. Concerning coordinate repeatability, the NWP-based strategy with tropospheric error adjustment appeared more accurate (at the submillimetric level) than a standard GPS strategy. Furthermore, several hundreds km long baselines demonstrated the standard deviation at the level of millimeters (from 4.2 to 7.6 mm). Practically, the NWP-based strategy offers the advantage of tropospheric delay estimations closer to realistic meteorological values. The application of a more accurate meteorology leads to satisfactory coordinate estimations, and vice versa well-defined GPS estimations of coordinates may serve as the additional meteorological parameters source.

2006 - GPS, NCEP Data and METEOSAT Precipitable Water Comparison for Balkan Area [Relazione in Atti di Convegno]
Boccolari, Mauro; Fazlagic, Slobodan; A., Barbati; Malmusi, Simona; Santangelo, Renato
abstract

Integrated Precipitable Water Vapor (IPWV) studies are an important mode for the hydrological regime evaluation with respect to the vertical structure of the atmosphere. The aim of this work is to integrate different observation systems (for instance Global Positioning System and METEOSAT-8) and data sources in order to study IPWV spatial and temporal distribution for Balkans region, sparsely covered with atmospheric vertical observations, as the helpful aid in the analysis of weather and synoptic processes.Global Positioning System (GPS) represents an enormous ongoing three-dimensional atmospheric observation system since the wet component of the tropospheric delay in GPS signals is nearly proportional to the quantity of integrated precipitable water vapor (IPWV). Tropospheric solutions for Balkans GPS sites of Sarajevo, Osjek, Dubrovnik and Ohrid are studied and presented in comparison to METEOSAT-8 and NCEP data.Tropospheric humidity product derived from the two water vapor channels of meteorological satellite METEOSAT-8 provides a layer-mean relative humidity for two tropospheric layers (between about 500 and 200hPa and between 850 and 300 hPa) with the resolution of 3 km, subsequently a biased estimation of IPWV can be obtained.Daily global analysis precipitable water data since 1980 available at 2.5 degrees resolution from the National Centres for Environmental Prediction (NCEP) is a helpful climate data source to evaluate humidity observations.

2006 - Refilling of aquifers (seasonal and special periods of heavy rains) [Abstract in Atti di Convegno]
Balestri, Lorenzo; Boccolari, Mauro; DE LEVA, Maria; Fazlagic, Slobodan; Santangelo, Renato; Vincenzi, S.
abstract

Measurements in wells down to aquifers in territory around Modena. TV inspections inside wells will be presented in particular from screen windows in well toward aquifer. Flow measurements close to windos and piezometric measurements around well will be also presented. Aim is to reconstruct piezometry and flow fields.a simple model under cylindrical approximation will be presented capable to represent fields immediately ouside screen window.Time series of observed fields will be studied to show an eventual correlation with external observations of heavy rains, during appropriate season or during exceptional events of heavy rains.

2006 - SAF-CM water vapor products and their relationship to large and intense precipitation over Europe during 2005 [Abstract in Rivista]
Pinelli, F; Barbati, A; Boccolari, Mauro; Fazlagic, Slobodan; Malmusi, Simona; Santangelo, Renato
abstract

Climate data available by Satellite Application Facility (SAF) on Climate Monitoring (CM) represent a new important data source to investigate on climate changes, hydrology, and environmental sciences.The behavior of some atmospheric parameters like Cloud water liquid path (CWLP) and Humidity Composite Products (HCP) can be essential to understand the generation of intense and large events of precipitation.In this work temporal and spatial evolution of CWLP and HCP fields patterns over the CM-SAF baseline area during the year 2005 are analysed in connection to flooding episodes and extreme rainfall events.Furthermore, CLWP connections to North Atlantic Oscillation and Mediterranean Oscillation are shown.The area of analysis includes the European continent, the Mediterranean sea, and parts of North Atlantic and Middle East, ranging from 30° N up to 80° N and from 60° W to 60° E.CLWP product is derived from data obtained by instruments on-board of polar orbiting NOAA satellites (AVHRR) and the Meteosat Second Generation (SEVIRI) geostationary satellite. The products have a spatial resolution of 15 Km2

2006 - SNOWFALL TIME SERIES COMPARISON BETWEEN APENNINES AND BALKANS PENINSULAS - A CLIMATE CHANGE CHALLENGE [Abstract in Atti di Convegno]
Fazlagic, Slobodan; Boccolari, Mauro; Lombroso, Luca; Majstorović, Z.; Quattrocchi, Salvatore; Tais, M.
abstract

Precipitation long-term time series are important source for the climate variability evaluation. In this work snowfall records for Apennines Peninsula sites of Modena (34 m asl, since 1830 till 2005) and Abetone (1390 m asl, since 1969 till 2005) together to Balkans Peninsula sites of Sarajevo (630 m asl, since 1888 till 2005) and Mount Bjelasnica (2067 m asl, since 1950 till 2005) are examined. Total annually (seasonally) snowfall amounts are discussed using a moving average over 30 years. From the moving averages it can be noted a quasi-linear downward trend for the recent period (from 1960 till 2000), but seemingly interrupted in the last several years. Moreover, in order to obtain smooth signal and more clear indications of possible climate oscillations, the snow precipitation signal has been filtered with one of the known wavelet transforms (the discrete Meyer wavelet is applied). Apparently, from the 3-level and especially from the 4-level approximations of the wavelet transform, oscillatory thirty/forty year’s snowfalls periods can be distinguished also in the past 150 years. The coincidence of snowfalls series either at Apennines or at Balkans Peninsula with the North Atlantic Oscillation (NAO) is found.

2003 - Detection of meteorological inconsistencies by GPS [Articolo su rivista]
Balestri, Lorenzo; Boccolari, Mauro; Fazlagic, Slobodan; Pugnaghi, Sergio; Santangelo, Renato
abstract

GPS observations, distances from satellites to receivers and meteorological conditions in neutral atmosphere are known to obey a constraint, which provides a residual or in other words a quality index. A method is discussed which provides a residual epoch by epoch in near real time. In general, distribution of residuals during several consecutive epochs belonging to the same satellites, allows estimates of a mean and a standard deviation of mean. Under normal meteorological conditions distribution of residuals appears to be consistent with zero mean as expected. However. consecutive residuals sometimes appear to have a mean different from zero by more than three standard deviations of mean. Such significant consecutive epochs provide a warning of existing inconsistencies among GPS observations, distances from satellites to receivers as obtained by orbital information, meteorological conditions above receivers (as obtained by ground measurements or by extrapolation of meteorological analysis). A procedure has been set up which warns about these inconsistencies in near real time.

2002 - Comparison of independent integrated water vapour estimates from GPS and sun photometer measurements and a meteorological model [Articolo su rivista]
Pugnaghi, Sergio; Boccolari, Mauro; S., Fazlagic; R., Pacione; Santangelo, Renato; H., Vedel; F., Vespe
abstract

Measurements using the Global Positioning System (GPS) are affected by the so-called tropospheric delay. Of this, the so-called wet delay is related mainly to the amount of water vapour along the path of the GPS signal through the troposphere. Precise knowledge of the abundance of water vapour, in space and time, is important for meteorology, both in forecasting and now-casting as well as in climate studies. Both because water vapour is the predecessor of precipitation, which is a forecast product, and because a very significant fraction of the energy released to the atmosphere comes from latent heat via water vapour. Despite the high variability of water vapour compared to other meteorological fields, like pressure and wind, water vapour observations are scarce; wherefore additional measurements of water vapour are expected to benefit meteorology. Water vapour is crucial for the development of the small scale, but sometimes very severe,precipitation events which are often seen at mid latitudes, and which are very hard to predict. In this work a comparison between radiometric (sun photometer) and GPS integrated water vapour (IWV) is presented. A sun photometer has been installed at the ENEA (Ente per le Nuove tecnologie, l'Energia e l'Ambiente) base of Lampedusa Island. The sun photometer is quite close (less then 4 km) to an ASI (Agenzia Spaziale Italiana) GPS permanent receiver. In Venezia an ASI GPS permanent receiver is collocated with another sun photometer. Both sun photometers are installed as part of the AERONET (AErosol and Robotic NETwork) program. A long record of sun photometric measurements, GPS data, and meteorological data is available for the Venezia site. A shorter record (summer period of the year 2000) is available for the station at Lampedusa. The comparison among the three different methods for water vapour delay estimation is presented. We find that the GPS and sun photometric data are better correlated (S.D. about 10 mm for the wet delay) than are the measurements with the NWP model predictions. This is an indication that GPS delay data may contain information useful for weather prediction. (C) 2002 Elsevier Science Ltd. All rights reserved.

2002 - GPS Zenith Total Delays and precipitable water in comparison with special meteorological observations in Verona (Italy) during MAP-SOP [Articolo su rivista]
Boccolari, Mauro; S., Fazlagic; L., Lombroso; P., Frontero; Pugnaghi, Sergio; Santangelo, Renato; S., Corradini; Teggi, Sergio
abstract

Continuous meteorological examination of the Pre-Alpine zones in Northern Italy (Po Valley) is important for determination of atmospheric water cycles connected kith floods and rainfalls. During a special meteorological observing period (MAP-SOP). radiosounding and other measurements were made in the site of Verona (Italy), This paper deals with Zenith Total Delay (ZTD) and Precipitable Water (PW) comparisons obtained by GPS, radiosounding and other meteorological measurements. PW and ZTD from ground-based GPS data in comparison with classical techniques (e.g.. WVR, radiosounding,) from recent literature present an accurate tool for use in meteorology applications (e.g., assimilation in Numerical Weather Prediction (NWP) models oil short-range precipitation forecasts). Comparison of such ZTD for MAP-SOP showed a standard deviation of 16.1 mm and PW comparison showed a standard deviation of 2.7 mm, confirming the accuracy of GPS measurements for meteorology applications. In addition, PW data and its time variation are also matched with time series of meteorological situations. Those results indicate that changes in PW values could be connected to changes in air masses, i.e. to passages of both cold and warm fronts. There is also a correlation between precipitation. forthcoming increase and the following decrease of PW. A good agreement between oscillation of PW and precipitation and strong cyclonic activities is found.

2001 - A REVIEW OF MAP-SOP EVENTS IN THE NORTH-EASTERN ITALY LOOKING AT VERONA SOUNDINGS [Articolo su rivista]
Boccolari, Mauro; Fazlagic, Slobodan; Lombroso, Luca; Frontero, Paolo; Pugnaghi, Sergio; Santangelo, Renato; Corradini, Stefano; Teggi, Sergio
abstract

http://www.map.ethz.ch/NL15

2001 - The contributions of the MAGIC project to the COST 716 objectives of assessing the operational potential of ground-basedGPS meteorology on an international scale [Articolo su rivista]
J., Haase; E., Calais; J., Talaya; A., Rius; F., Vespe; Santangelo, Renato; X. Y., Huang; J. M., Davila; M., Ge; L., Cucurul; A., Flores; C., Sciarretta; R., Pacione; Boccolari, Mauro; Pugnaghi, Sergio; H., Vedel; K., Mogensen; X., Yang; J., Garate
abstract

MAGIC (Meteorological Applications of GPS Integrated Column Water Vapor Measurements in the Western Mediterranean) is a 3 year project financed in part by the European Commission for research on deriving and validating robust GPS integrated water vapor (IWV) and zenith tropospheric delay (ZTD) data sets and developing methods to assimilate the data into numerical weather prediction models (NWP) and test their impact. It was conceived independently from the COST 716 action, which seeks to coordinate research in the domain at an international scale, but addresses some of the same objectives. This has led to a productive cooperation between the two initiatives and their participants, and motivated the decision of MAGIC participants to provide research results as part of the COST demonstration system. Currently a database of 1.5 years of ZTD data are available on the MAGIC web site which has been validated through comparisons with radiosondes which gives differences with a standard deviation of 10 mm ZTD or the equivalent error in IWV of 1.6 kg/m2. NWP assimilation tests will be carried out in the final year of the project.

1994 - Statistics of some Synthetic Parameters of Vertical Profiles of Pressure and Temperature obtained by One Year of ECMWF’s Analysis over Europe [Articolo su rivista]
Boccolari, Mauro; Morelli, Sandra; Santangelo, Renato
abstract

In this paper monthly distributions of synthetic parameters of vertical profiles of temperture and pressure over Europe are shown. the data have been obtained by fits of one-year data analysis of the ECMWF model. In particular, distributions of lapse rates, distribution of heights of the layers and distributions of temperature and dry-air pressure of the lower level are reported. Within the precision of the input data and by disregarding the boundary layer, a finer subdivision of layered troposphere and lower stratosphere has been obtained.

1991 - Strutture dell'Osservatorio Geofisico di Modena a supporto di campagne di misura sul clima mediterraneo [Relazione in Atti di Convegno]
Boccolari, Mauro; Frontero, Paolo; Lombroso, Luca; Morelli, Sandra; Pugnaghi, Sergio; Santangelo, Renato
abstract

L'Osservatorio Geofisico vanta una secolare tradizione nella raccolta di dati meteorologici, la serie storica delle osservazioni inizia infatti nel 1827. Già da alcuni anni la maggior parte dei dati è stata trasferita su supporto magnetico direttamente utilizzabile da calcolatore ed è continuamente aggiornata.

1991 - Un metodo per la determinazione automatica della quota in un qualsiasi punto del territorio italiano [Articolo su rivista]
Boccolari, Mauro; Morelli, Sandra; Santangelo, Renato
abstract

In alcune applicazioni scientifiche è richiesta la conoscenza della quota in punti generici di un vasto territorio. In questa nota viene descritta una nuova metodologia per la stima automatica della altezza, utilizzante come banca dati la cartografia digitalizzata 1:500000 dell'Istituto Geografico Militare. Tali carte digitalizzate hanno il vantaggio di ricoprire l'intero territorio italiano, anche se esse sono un insieme di dati di altimetria spazialmente meno denso di campioni già utilizzati in altri lavori.