Mauro Boccolari

The contributions of the MAGIC project to the COST 716 objectives of assessing the operational potential of ground-based GPS meteorology on an international scale

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.

Trends and variability of cloud fraction cover in the Arctic, 1982–2009

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.

Classification of Microseismic Activity in an Unstable Rock Cliff

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.

Sea-ice area variability and trends in Arctic sectors of different morphology, 1996–2015

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 ) while it is even greater in the Beaufort Sea.

On the measure of sea ice area from sea ice concentration data sets

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.

Sea-ice distribution and variability in the East Greenland Sea, 2003-13

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.

Statistics of some Synthetic Parameters of Vertical Profiles of Pressure and Temperature obtained by One Year of ECMWF’s Analysis over Europe

SummaryIn this paper monthly distributions of synthetic parameters of vertical profiles of temperature 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, distributions 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 a layered troposphere and lower stratosphere has been obtained.