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The historic house of Sheikh Mohammed Bin Khalifa, Al Ain (Abu Dhabi, UAE) belongs to the World Heritage Cultural Sites. The courtyard and two rooms include mudbrick archaeological remains that are preserved in showcases for public display. The building lies in a hot desert climate and needs air conditioning to be comfortable. This paper is concerned with indoor showcases and their compatibility with the indoor climate. Sometimes, misting for condensation is generated on the glass panes for the temperature and humidity contrast between the room climate and the showcases that are embedded in the floor. When misting occurs, the remains cannot be viewed. This paper investigates indoor glass misting, the exchanges of heat and moisture between archaeological remains, showcases and rooms, and the results after a year of environmental monitoring. An aim is to assess the potential risks for the preservation of the remains, recognizing the frequency and severity of the conditions for condensation. Another aim is to discuss mitigation methodologies to avoid glass misting, e.g., (i) reducing the room cooling; (ii) raising the glass pane temperature with electrical devices; (iii) increasing air exchanges between showcases and rooms; (iv) adopting a combination of these methodologies. [ABSTRACT FROM AUTHOR]

The European Standard EN 15757: 2010 'Conservation of Cultural Property—Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials' is a guide specifying the allowed limits of variability of the indoor climate, in particular relative humidity (RH) to preserve cultural heritage objects and collections composed of climate-vulnerable materials. This paper is finalized to provide useful elements to improve the Standard at its next revision, based on focused research. The methodologies and the mathematical tools used are performed on 18 case studies representing different buildings, climates, and use, including heated and unheated buildings, museums, churches, concert halls, archives, and storage rooms. The first aim is to compare the method based on the centred moving average suggested by Annex A of EN15757 with an alternative method based on percentile interpolation to calculate the reference RH values, and in particular the safe band of RH variability, as well as the upper and lower risky bands. It has been found that the two methods provided the same results, but the latter is easier to manage. The second aim is to verify if the duration of the record necessary for the determination of the safe band is really 13 months of measurements as required by the Standard to account for the specific request of the centred moving average with a 30-day time window. This paper demonstrates that the same goal may be reached with a 12-month record, but extracting from the record itself the two periods required by the time window, i.e., the last 15 days of the year will be copied before the start of the record, and the same with the first 15 days after the end. The third aim is to test if the particular choice of the width of the time window is influential on the width of the safe band, and to assess the relationship between the width of the safe band and the width of the time window. The results show that the safe band logarithmically depends on the length of the time window, so it is crucial to respect the 30-day window established by the Standard. [ABSTRACT FROM AUTHOR]

For general climatic purposes, rain is measured in terms of amount, intensity and frequency. In this paper, the problem of wind-driven rain impinging on monuments and mountain slopes is considered because the normal meteorological stations measure the precipitation falling on the horizontal plane, but miss the vector dimension (i.e. the vertical and horizontal components). The rain impinging on vertical surfaces remains unknown. The convenience of representing rainfall as a vector is discussed, especially when it is necessary to know the impact of rain in urban environments, on stone monuments (e.g. stone erosion) or mountain slopes (landslide risk assessment). An analysis is made of: wind driven rain; its trajectory; the effective catch areas that funnels with horizontal and vertical openings have when the drop trajectory is inclined; and the precipitation amounts that can be collected using a combination of a horizontal and a vertical funnel. Fixed and wind-orientated vectopluviometers with vertical funnels are commented. From these inputs, it is possible to calculate the precipitation falling at any inclination angle, or impinging on any slant surface. As wind-driven rain is a vector, the two components collected by the combination of a horizontal and a vertical gauge should be added between them in vector form. Useful formulae are presented and commented. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the relationship between selected percentiles, return periods and the concepts of rare and extreme events in climate and hydrological series, considering both regular and irregular datasets, and discusses the IPCC and WMO indications. IPCC (Annex II: Glossary. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, 2014) establishes that an extreme event should be rare and exceed selected upper and lower thresholds (10th and 90th percentiles); WMO (Guidelines on the definition and monitoring of extreme weather and climate events—TT-DEWCE WMO 4/14/2016. World Meteorological Organization, Geneva, 2016) suggests thresholds near the ends of the range, but leaves them undetermined. The concept of "rare" relates the extreme events to the time domain and is typically expressed in terms of return period (RP). The key is to find the combination between "rare", percentile and return period. In particular, two crucial items are analysed: (1) how the return period may vary in response to the choice of the threshold, in particular when it is expressed in terms of percentiles; (2) how the choice of producing a regular or irregular dataset may affect the yearly frequency and the related return periods. Some weather variables (e.g. temperature) are regular and recorded at fixed time intervals, while other phenomena (e.g. tornadoes) occur at times. Precipitation may be considered either regular, all-days being characterized by a precipitation amount from 0 (no precipitation) to the top of the range, or irregular (rainy-days only) considering a precipitation day over a selected instrumental or percentile threshold. These two modes of interpreting precipitation include a different number of events per year (365 or less) and generate different return periods. Every climatic information may be affected by this definition. The 90th percentile applied to observations with daily frequency produces 10-day return period and the percentiles necessary to get 1 year, 10 years or other return periods are calculated. The general case of events with selected or variable frequencies, and selected percentiles, is also considered with an example of a precipitation series, two-century long. [ABSTRACT FROM AUTHOR]

Extreme weather and climate events, although rare at any particular location, can lead to different amount of loss to exposed human and natural systems, even to disasters. In this paper, the most authoritative definitions of "extreme events" given by the World Meteorological Organization and Intergovernmental Panel on Climate Change have been considered, as well as the underlying basic concepts, i.e., selected intensity levels, selected percentiles, multiples of the standard deviation, return period, distribution tails, imprint left, cause-effect relationships, natural disasters. Definitions and criteria have been tested with real world case studies using long instrumental records (300 years of daily temperature and 200 years of daily precipitation in Bologna, Italy) and proxy series (1000 years of Venice lagoon frozen over and 300 years of Po River outflow). The analysis reveals that each definition leads to particular consequences, e.g., in the peak over threshold theory, if the threshold is expressed in absolute terms, the number of extreme events may change with the climate period as tested with the Venice case study; as opposed, the relative definition based on percentiles or standard deviation will keep unchanged this frequency. Again, considering extreme events those external to the 10th or 90th percentile of the distribution may lead to a return period too short, e.g., 10 days for daily records, while a 10 years return period would require 1st or 99th percentiles, as tested with the daily temperature and precipitation in Bologna. In addition, the distribution of a series may substantially change shape passing from daily to monthly and yearly averages as tested with the series taken as examples. The specific case of proxies is also considered analysing their uncertainties and categorization. The lagoon frozen over as a consequence of exceptionally severe winters constitutes an example of extremes based on an absolute threshold, as well as cause-effect relationship, and the return period was highly affected by the change of climate periods. The example of the overflow of the Po River suggests that the occurrence of extremes, and their intensity, may be altered by other factors that concur to the final result. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Efficiency of electro-osmosis pumping is better in warm than in cold climate. • Comparison of electro-osmotic intervention can only be made for building under the same climate conditions. • How temperature affects the electro-osmosis efficiency. • Suggestions to make better use of electro-osmosis to dry walls or soil. Abstract Electro-osmosis is popularly used as a pump to dry soils or to reduce rising damp in buildings, but the literature results are contradictory. The basic formula of electro-osmosis has been analysed to point out its dependence on temperature, which is masked behind two coefficients, i.e. the dielectric 'constant' of water (that is not constant), and the coefficient of dynamic viscosity. These two physical quantities have been calculated with the accurate formulae by Malmberg and Maryott (the dielectric constant) and Voegel (the dynamic viscosity). The electro-osmosis formula includes the ratio between these two coefficients. Although the two formulae that represent them are formulated with equations having a formally different mathematical apparatus, their ratio strictly follows a straight line with values increasing with temperature. Dividing this equation by its initial value (i.e. considered at 0.1 °C) one obtains the Temperature Magnification Factor (TMF) that indicates how much the effectiveness of the system may vary with temperature. TMF is linearly increasing and has been calculated for the whole range of liquid water, i.e. from 0.1 to 99.9 °C. In the interval of the most common wall temperatures, from 0 to 50 °C, TMF increases from 1 to 2.5, showing that in summer, or in warm climate, the efficiency of this method is much higher (e.g. 2.5 times) than in winter or in cold regions. A comparison of the effectiveness of electro-osmotic interventions against rising damp can only be made for buildings under the same climate conditions. This explains the contradictory results found in the literature when case studies from different geographic areas, and different climates, are compared. [ABSTRACT FROM AUTHOR]

The paper introduces a novel method for risk assessment and preventive conservation of organic hygroscopic cultural heritage objects. The method is based on the analysis of the historic climate that is established in the European Standard EN 15757:2010. This new approach enables interpreting visible damage and assessing cause–effect relationships and it finds practical application in improving conservation strategies for real life buildings and objects. The paper investigates how it may be advantageous to reconstruct the historic climate back in time to obtain sound information about the target relative humidity (RH) level and the domain of RH fluctuations that can be considered safe for conservation. The method was applied to an inlaid wooden choir in the basilica of S. Giustina, Padua, Italy. The past indoor climate has been reconstructed over the whole life of the object, built in 1477, with documentary proxy data, instrumental readings and building simulation. Winter has been found to be the most critical season for the mechanical stress and wood yield. For the future, the indoor climate has been simulated until 2100 to timely devise preventive conservation measures to reduce the risk induced by climate change. Finally an evaluation of uncertainties has been considered. [ABSTRACT FROM AUTHOR]

Abstract: This article illustrates a preventive conservation methodology for wooden collections and objects based on the respect of the historic climate, as established by the European standard EN 15757:2010. This requires the knowledge of the past indoor climate that should be kept unchanged in the present and the future, because discontinuities would be noxious for conservation. To this aim, a very vulnerable object, i.e. a wooden inlay bookcase cabinet built by G.M. Platina in 1477 AD has been considered. The paper illustrates the methodology used to reconstruct the historic climate, i.e. with proxy data from 1500 to 1715 and from 1716 to 2009 with instrumental observations. For the present, the indoor climate of the exhibition room and the cabinet response have been investigated to remove the perturbing factors that are damaging the cabinet. For the future, the ENSEMBLES model has been used for a probabilistic forecast of the temperature and humidity over the next century, the sustainability and the potential risk for conservation connected with the expected climate change. This research constitutes an example of a novel methodology based on the relevance of the Historic climate, and includes a synergistic effort of climatologists, material scientists and conservators, to be applied for preventive conservation and to evaluate and face the negative impact of the expected climate change. [Copyright &y& Elsevier]

Abstract: The longest series of instrumental observations have a number of problems in the early period. This paper is focused on the recovery of early indoor and outdoor observations in Padua and their transformation in terms of a modern series. The Padua series was started by Giovanni Poleni with outdoor observations in 1716–1718, but soon, the readings passed indoors (1725–1764) to join the directives of the Royal Society, London. The indoor readings were recovered within the EU project IMPROVE, but it was necessary to transform indoor observations into outdoor ones, and this was possible thanks to the presence of simultaneous indoor and outdoor observations by Morgagni in Padua and Beccari in Bologna. These parallel series were also useful to fill a short gap. Another problem was to reconstruct the calibration of the Amontons thermometer, which changed when Poleni moved to a new house. Also the problem of the use of variable and/or different sampling times was solved making reference to the trend of the daily cycles in the different seasons and under diverse weather conditions. The data analysis has shown a trend that appears similar to the well-known results (IPCC 2007) for the last 160yr but a less marked recent warming for winter and autumn. The 18th century was characterized by cold winters (culminated 1709 and 1740) and springs, and warm summers and autumns. A well-marked Bruckner cycle (35.8yr), continually repeated and attenuated, is visible for the period 1716–1930. The wide time scale and the repetition of warmer and colder periods over two-thirds of the series noted in Padua and other Mediterranean stations may induce us to suppose that such cycles could continue in the future, at least on the local scale. [Copyright &y& Elsevier]

The earliest daily barometric pressure readings were taken during the Maunder Minimum of Solar activity (1645-1715). In Italy, observations were made at Pisa over the years 1657-1658 by V. Viviani and A. Borelli, and at Modena during the year 1694 by B. Ramazzini. These readings have been recovered, corrected and adjusted to modern units. The early instruments used and their problems have been thoroughly discussed. Barometer observations recorded by John Locke in Essex (UK) during the year 1694 have also been recovered and corrected. Daily observations were recorded during the same period in Paris by L. Morin; these have previously been published by Legrand and Le Goff (1992: Les observations météorologiques de Louis Morin. Monographie No. 6, Direction de la Météorologie Nationale, Ministère de l'Equipement, de Logement et des Transports, 41 pp.). However, cross-comparisons with the Locke and Ramazzini data have shown that the Paris series needed a further correction to take into account instrumental error. Using these three corrected series, it has been possible to reconstruct the atmospheric circulation over Europe for the year 1694. An indication of the state of the atmospheric circulation can also be made by using the earlier observations recorded in Italy. A common feature of the two periods studied (1657-1658 and 1694) is that winters were characterized by higher pressure compared with the reference period 1961-1990, while the summers generally experienced lower pressure. This latter conclusion indicates that the Azores High was late or not well developed, favouring low temperature and frequent rain in the late spring and early summer. [ABSTRACT FROM AUTHOR]

Abstract: The European project Friendly-Heating (FH): comfortable to people and compatible with conservation of artworks preserved in churches addressed the problems caused by the continuous or intermittent heating of historic churches, which disturbs the microclimatic conditions to which the building and the artworks preserved inside have acclimatised. As thermal comfort and the preservation of artworks often conflict with each other, a balance between the two needs is necessary. The proposed heating strategy is to provide a small amount of heat directly to people in the pew area while leaving the conditions in the church, as a whole, undisturbed. This novel heating system is based on some low-temperature radiant emitters mounted in a pew to provide a desirable distribution of heat to the feet, legs and hands of people occupying it. Due to little heat dispersion, this novel system not only significantly reduces the risk of mechanical stress in wooden artworks and panel or canvas paintings, fresco soiling and cyclic dissolution-recrystallization of soluble salts in the masonry, but is energy-efficient. The detailed environmental monitoring was conducted in the church of Santa Maria Maddalena in Rocca Pietore, Italy over a 3-year period to verify the performance of the novel heating system in comparison to the warm-air system that was active earlier in the church. The methodology and results of this comprehensive and multidisciplinary study were included in three draft standards of the European Committee for Standardisation intended for use in the study and control of environments of cultural heritage objects. [Copyright &y& Elsevier]

Abstract: The impact of lighting, heating and people in re-using historical buildings are discussed for the case study concerning the ceremony room (i.e. the Giant Hall) of a mediaeval palace in Padova. The Hall has substantially four major problems for conservation: (i) the impact of heating, lighting and people when the room is used; (ii) many cracks on the oak panels of the coffered ceiling; (iii) the soiling by dust and soot particles deposited on the frescoes; (iv) the stained glass windows. A microclimate study was performed to know the impact of the environmental variables, and the use of the room, on the artworks preserved inside. The study has proved the impact of the lamps (both incandescence and compact fluorescent lamps) on the ceiling, the penetration of external air in the room, the heat and the moisture released by people, the impact of sunshine through windows and the scatter diagram of the daily cycles in temperature (T) and relative humidity (RH). During winter concerts, the strips of lead which are wrapped round the edge of the cut glass pieces in stained glass windows easily drop below the dew point and form condensation, starting corrosion. A discussion concerns the allowed variability, which should not exceed risk thresholds. A safe interval can be established within the area determined by the most frequent T and RH natural cycles. In fact, both of the cycles were compatible with the artefacts, or the artefacts were already damaged to allow the exceeding dimensional changes. Attention should be paid in the variability external to this area, especially approaching or exceeding a limit equal to twice the mode of the natural variability. [Copyright &y& Elsevier]

Due to its geographical position, and because it was built at sea level, Venice is extremely sensitive to climate changes and, in the future, risks being submerged as a consequence of the expansion of oceanic water in response to global warming. A key problem is the increasing frequency of storm surges with the sea flooding the city (locally named acqua alta) that has reached an unsustainable level. After careful examination of both proxy documentary and instrumental data, it has been possible to reconstruct the extreme weather conditions and natural hazards, which have taken place in the last two millennia, with particular reference to surges. A key problem with proxy data from written sources is that periods with missing data may be misinterpreted as ‘normal’, or that inaccurate reporting may lead to duplication or even multiplication of events. For this reason, the accuracy of the proxy data has been checked by comparing it with other known events. An accurate series of the flood surges has been obtained combining instrumental observations (1872–2000) with documentary data for the previous period. The period of minimum solar activity of Spo¨rer (1416–1534) was anomalous for surges. Not only have meteorologically perturbed periods been identified, but also the effects of the accelerated subsidence of the city and of certain works undertaken in the lagoon that varied the exchanges between the sea and the lagoon. The impact of subsidence and of the modified dynamical exchanges of the lagoon on the change in flooding frequency has been established. During the instrumental period, the tide gauge measured a 31-cm rise. The frequency of surges has dramatically increased since the 1960s, reaching about two flooding events per year, the greatest value since 792 AD. [Copyright &y& Elsevier]

Samples of White and Green Carrara marble, and three types of limestone and brick exposed in the field vertically and horizontally were used to evaluate condensation on monuments during clear sky nights. Experiments in a simulation chamber under controlled conditions led to a general equation for the actual amount of water deposited on a surface by dew. This is determined by: How much and for how long the surface temperature falls below the dew point, the moisture content in the air and the ventilation. On clear nights, the condensation on building structures facing the sky may reach some 0.2 kg m-2 (or 0.2 mm), whereas condensation on vertical surfaces is very small. Computation of the seasonal trend of night-time condensation showed that the maximum amount of water condensed per night occurs in the autumn, with the more abundant concentration of moisture in the air. The total amount of water condensed per month is found to be a maximum in the summer-autumn period. Morning condensation for the thermal inertia of monuments is also relevant, and has been calculated to reach the same order of magnitude as the nocturnal dew. A detailed analysis of the temperature and mixing ratio profiles near a condensing surface has shown two different situations. In still air, the two profiles follow an exponential law and the thermal and the concentration layers lie within a few tens of millimetres. In the presence of turbulence, the thickness of these two layers is dramatically reduced. In still air, in front of a vertical, chilly surface, the deposition rate of air pollutants by thermophoresis and/or Stefan flow is increased by 3 or 4 times in comparison with a horizontal surface. In the presence of turbulence, the thickness of the thermal and concentration layers was dramatically reduced, making these two kinds of deposition much faster. [ABSTRACT FROM AUTHOR]

Two multidisciplinary field surveys, one in winter and the other in summer, have monitored the indoor microclimate, the air pollution, the deposition and origin of the suspended particulate matter and the microorganisms of the Kunsthistorisches Museum, Vienna. These surveys were part of a European project aimed at identifying potential environmental risks for conservation in museums. Experimental methodologies were refined within this study. The project underscores pros and cons of the heating ventilating and air conditioning system, proposing a more effective filtration, since the system seemed to worsen indoor pollution. The impact of mass tourism during a special exhibition was investigated, showing that even a good ventilation is unable to deal with the heat and moisture released by huge crowds. The sources of gaseous and particulate pollution were discussed. Microbiological investigations identified a considerable load of bacteria. The cleaning of paintings by brush is shown to resuspend a considerable amount of particles, which are free to deposit again on the paintings. [ABSTRACT FROM AUTHOR]

Most artworks require a stable microclimate and a field study has been undertaken to understand the environmental risks in a mountain church that is heated once a week. The church was selected on the basis of the artworks present and the existing heating system: a hot-air system which is popular due to its low cost and rapid response. The heating system is switched on only during the liturgieal services and generates rapid temperature and humidity changes which, in the long run, are very damaging. The temperature stratification leaves people with their feet in cold air, whereas the air in the upper levels is too hot and dry. Moisture condenses on the cold walls. Deliquescent salta in masonry and frescoes undergo dangerous crystallization cycles. Wooden artifacts contract and expand in line with humidity cycles. Deposition of candle and incense smoke is increased, darkening the artworks. The paper discusses these problems, some common errors, and possible methods to mitigate the risk factors. [ABSTRACT FROM AUTHOR]

The Basilica of Santa Maria Maggiore, Rome, is an example of how ancient buildings with thick walls lessen the impact of the external temperature and humidity variations. The external influence on the internal microclimate is studied in order to gather information on how the building exchanges heat and moisture. Correlations between outdoor and indoor values are found. The results are applied to the calculation of the condensation-evaporation cycles inside micropores due to the Kelvin effect, to assess their impact on works of arts placed inside and outside the Basilica. It was found that the building attenuation is not sufficient to avoid damage due to condensation-evaporation cycles on stones and plasters. Some suggestions are made in order to mitigate the temperature variations during the liturgical offices. [ABSTRACT FROM AUTHOR]

The Hall of the Giants (Sala dei Giganti) in the former Carrara Palace, now part of the University of Padua, Italy, contains sixteenth-century frescoes which are subject to soiling by airborne pollutants and to mechanical stress due to heating/cooling cycles. Field surveys were undertaken in the Hall to measure the microclimate and the distribution of suspended particulate matter at different times of year: winter, summer and autumn. By analyzing maps of thermohygrometric cross-sections of the Hall, several factors which disturb the indoor microclimate were identified: solar radiation, which causes seasonal and daily warming cycles; radiators which are controlled by a thermostat and a timer, thus generating discontinuities in the heat supply; the use of the room for lectures and concerts; human activity in adjoining rooms; old windows with leaded glass panes which are very large so that thermal conductivity is high and insulation is poor; external air which enters between the roof and the ceiling through ventilation apertures and then penetrates through fissures in the coffered ceiling; and the daily use of a vacuum cleaner, which dramatically increases the concentration of suspended particulate matter. Actions to be taken in order to mitigate the adverse factors are discussed. [ABSTRACT FROM AUTHOR]

The body of the Great Sphinx has suffered severe weathering, exfoliation and wind erosion; the face is not reached by coarse granules and is well preserved, The body lies below the level of the desert, and the excavated area that surrounds the Sphinx constitutes a low-pass filter for the size of the sand grains. In past millennia, when the Sphinx was immersed in the floating sand dunes, severe wind erosion was caused by the coarse quartz granules that advance by saltation in the first metre above the variable sand level. Clearing out the excavated area has proved to be an effective preservation technique. [ABSTRACT FROM AUTHOR]

The study of long precipitation series constitutes an important issue in climate research and risk assessment. However, long datasets are affected by inhomogeneities that can lead to biased results. A frequent but sometimes underestimated problem is the definition of the climatological day. The choice of different starting times may lead to inhomogeneity within the same station and misalignment with other stations. In this work, the problem of temporal misalignment between precipitation datasets characterized by different starting times of the observation day is analyzed. The most widely used adjustment methods (1 day and uniform shift) and two new methods based on reanalysis (NOAA and ERA5) are evaluated in terms of temporal alignment, precipitation statistics, and percentile distributions. As test series, the hourly precipitation series of Padua and nearby stations in the period of 1993–2022 are selected. The results show that the reanalysis-based methods, in particular ERA5, outperform the others in temporal alignment, regardless of the station. But, for the periods in which reanalysis data are not available, 1-day and uniform shift methods can be considered viable alternatives. On the other hand, the reanalysis-based methods are not always the best option in terms of precipitation statistics, as they increase the precipitation frequency and reduce the mean value over wet days, NOAA much more than ERA5. The use of the series of a station near the target one, which is mandatory in case of missing data, can sometimes give comparable or even better results than any adjustment method. For the Padua series, the analysis is repeated at monthly and seasonal resolutions. In the tested series, the adjustment methods do not provide good results in summer and autumn, the two seasons mainly affected by heavy rains in Padua. Finally, the percentile distribution indicates that any adjustment method underestimates the percentile values, except ERA5, and that only the nearby station most correlated with Padua gives results comparable to ERA5. [ABSTRACT FROM AUTHOR]

This review paper comments the international standards to measure the moisture content in building materials, i.e. EN 772-10:1999; EN 13183-1:2002; EN 13183-2:2002; EN 13183-3:2005; EN 1428:2012; EN-ISO 11461: 2014; EN-ISO 15512:2014; ISO 11465:1993; ISO 12570: 2013; ISO 16979:2003 and ISO 760:1978. The above standards do apply to new building materials, with standardized composition and shape, in satisfactory state of conservation, without sampling restrictions. If they are applied to aged and deteriorated materials, as in the field of cultural heritage, the results may be misleading. The paper discusses the difference between ‘moisture content’ and ‘water content’ and the various problems met with cultural heritage materials, e.g. ethical problem when test specimens are needed; the biased response when wood was attacked by moulds or insect tunnelling, or was impregnated with oil, wax or preservatives; or when masonry contains soluble salts or subsurface discontinuities. The most recent, comprehensive standard is presented, i.e. EN16682 (2017) ‘ Conservation of cultural heritage – Methods of measurement of moisture content, or water content, in materials constituting immovable cultural heritage ’ that considers all existing methods and discusses pros and cons of each of them in relation with the real world of aged and deteriorated materials. [ABSTRACT FROM AUTHOR]

This paper considers the bias of the Newton linseed oil thermometer with respect to the non-linearity of thermometric liquid expansion. The bias is larger than for mercury thermometers but much smaller (5 times less) than for alcohol thermometers. The bias of linseed oil thermometers increases with temperature, and the maximum is achieved in summer; in the UK it may underestimate the temperature by as much as −0.5 degC relative to mercury thermometers. The evaluation of the bias has been possible thanks to some calibration experiments performed in the eighteenth and nineteenth century. [ABSTRACT FROM AUTHOR]

The article presents a study that investigates the wooden altarpiece in the Church of Santa Maria Maddalena in Rocca Pietore, Italy. In this study, triangulation laser displacement sensors were used to the continuous in-situ monitoring of the dimensional response of the altarpiece between December 2002 and March 2005. Moreover, a small inductive sensor was applied to monitor the width of a crack in one of the elements. The measurements revealed that only the external layer of wood, several millimeters thick, continually absorbs and releases water vapor following external variations in relative humidity.

Abstract: Foreland basins are flat elongated areas occurring along subduction and collision zones worldwide. We show that, in such basins, subsidence can be induced by earthquakes generated along bordering thrust faults due to coseismic displacement, postseismic displacement and liquefaction-induced compaction. As an example, the potential effects of earthquakes on the subsidence of Venice, which is located in the Po Plain foreland basin, are discussed. It is generally assumed that natural subsidence of Venice is continuous and that subsidence rates are rather constant through time. However, catastrophic pulses of subsidence cannot be ruled out as taught by the sudden disappearance of the island of Malamocco at the beginning of the XII century. The results of numerical models specifically run suggest that the risk of subsidence accelerations in Venice due to coseismic displacements is negligible. Modelling results from literature suggest that postseismic subsidence could be of the order of 1 cm. Although the effects of a single event should be improbably detectable, such a subsidence is not a priori negligible considering the number of seismogenic sources located within 100 km from the town. Historical sources are utilized to discuss the feasibility of liquefaction-induced subsidence in Venice. It is shown that the destruction and sinking of ancient Malamocco is roughly coincident with a strong earthquake cycle that was associated to phenomena that can be explained with liquefaction of sandy layers. Although the historical documents do not permit to establish a clear causal link between the earthquake and land subsidence, it is concluded that liquefaction-induced subsidence cannot be ruled out as a potential source for local subsidence acceleration. [Copyright &y& Elsevier]

Venice Lagoon (Italy), the largest wetland in the Mediterranean basin, is extremely vulnerable to variations in relative sea level (RSL) which is locally defined by an average rising rate of about 2.5 mm per year, resulting from both sea-level change and vertical land movements. The environmental pressures stemming from projected higher RSL rising rates will have a profound impact on Venetian coastal ecosystems with a significant loss of wetlands partly due to a drastic reduction of salt marsh habitats. To understand how changes in marine influence could create such ecological upheaval in the near future, and fully remodel these coastal salt marshes, we reconstructed 5650 years of RSL rise history and land subsidence impacts on ecosystem dynamics during the Holocene transgression of Venice Lagoon. We show that the evolution of ecosystems mainly mirrors the gradual intrusion of salt water that progressively reshaped the coastal vegetation by turning the area into salt lagoon habitats. Before marine influence became dominant, the area was mainly fed by substantial freshwater supplies allowing the development of a diversified alluvial vegetation. Environmental pressures increased markedly about 6800–6600 years ago when seawater began to significantly influence the area, affecting marsh-swamp ecosystems. These marine inputs promoted the spread of halophytic and salt-tolerant vegetation types which laid the foundations for what would become the current salt marsh habitats. Venice Lagoon serves as a stark reminder of how rising sea levels, accompanied by increased saltwater intrusion into freshwater habitats and adjacent lands, can drastically alter and reshape pre-existing ecosystems. The lagoon's long-term ecological record indicates that contemporary fluctuations in RSL pose a substantial ecological threat, potentially culminating in a major upheaval of aquatic habitats in the near future. • New curve for the Holocene RSL history of Venice Lagoon. • Freshwater wetlands transitioned into salt marshes around 6655 ± 70 BP. • A first ecological upheaval resulted from marine intrusions. • Projected sea-level rise will generate a second ecological upheaval. [ABSTRACT FROM AUTHOR]

We analysed long‐term variability and trends in meteorological droughts across Western Europe using the Standardized Precipitation Index (SPI). Precipitation data from 199 stations spanning the period 1851–2018 were employed, following homogenisation, to derive SPI‐3 and SPI‐12 series for each station, together with indices on drought duration and severity. Results reveal a general absence of statistically significant long‐term trends in the study domain, with the exception of significant trends at some stations, generally covering short periods. The largest decreasing trends in SPI‐3 (i.e., increasing drought conditions) were found for summer in the British and Irish Isles. In general, drought episodes experienced in the last two or three decades have precedents during the last 170·years, emphasizing the importance of long records for assessing change. The main characteristic of drought variability in Western Europe is its strong spatial diversity, with regions exhibiting a homogeneous temporal evolution. Notably, the temporal variability of drought in Western Europe is more dominant than long‐term trends. This suggests that long‐term drought trends cannot be confirmed in Western Europe using precipitation records alone. This study provides a long‐term regional assessment of drought variability in Western Europe, which can contribute to better understanding of regional climate change during the past two centuries. [ABSTRACT FROM AUTHOR]

Historical reanalyses that span more than a century are needed for a wide range of studies, from understanding large‐scale climate trends to diagnosing the impacts of individual historical extreme weather events. The Twentieth Century Reanalysis (20CR) Project is an effort to fill this need. It is supported by the National Oceanic and Atmospheric Administration (NOAA), the Cooperative Institute for Research in Environmental Sciences (CIRES), and the U.S. Department of Energy (DOE), and is facilitated by collaboration with the international Atmospheric Circulation Reconstructions over the Earth initiative. 20CR is the first ensemble of sub‐daily global atmospheric conditions spanning over 100 years. This provides a best estimate of the weather at any given place and time as well as an estimate of its confidence and uncertainty. While extremely useful, version 2c of this dataset (20CRv2c) has several significant issues, including inaccurate estimates of confidence and a global sea level pressure bias in the mid‐19th century. These and other issues can reduce its effectiveness for studies at many spatial and temporal scales. Therefore, the 20CR system underwent a series of developments to generate a significant new version of the reanalysis. The version 3 system (NOAA‐CIRES‐DOE 20CRv3) uses upgraded data assimilation methods including an adaptive inflation algorithm; has a newer, higher‐resolution forecast model that specifies dry air mass; and assimilates a larger set of pressure observations. These changes have improved the ensemble‐based estimates of confidence, removed spin‐up effects in the precipitation fields, and diminished the sea‐level pressure bias. Other improvements include more accurate representations of storm intensity, smaller errors, and large‐scale reductions in model bias. The 20CRv3 system is comprehensively reviewed, focusing on the aspects that have ameliorated issues in 20CRv2c. Despite the many improvements, some challenges remain, including a systematic bias in tropical precipitation and time‐varying biases in southern high‐latitude pressure fields. [ABSTRACT FROM AUTHOR]

Background: The present study reports results from the large-scale integrated EU project "Climate for Culture". The full name, or title, of the project is Climate for Culture: damage risk assessment, economic impact and mitigation strategies for sustainable preservation of cultural heritage in times of climate change. This paper focusses on implementing high resolution regional climate models together with new building simulation tools in order to predict future outdoor and indoor climate conditions. The potential impact of gradual climate change on historic buildings and on the vast collections they contain has been assessed. Two moderate IPCC emission scenarios A1B and RCP 4.5 were used to predict indoor climates in historic buildings from the recent past until the year 2100. Risks to the building and to the interiors with valuable artifacts were assessed using damage functions. A set of generic building types based on data from existing buildings were used to transfer outdoor climate conditions to indoor conditions using high resolution climate projections for Europe and the Mediterranean. Results: The high resolution climate change simulations have been performed with the regional climate model REMO over the whole of Europe including the Mediterranean region. Whole building simulation tools and a simplified building model were developed for historic buildings; they were forced with high resolution climate simulations. This has allowed maps of future climate-induced risks for historic buildings and their interiors to be produced. With this procedure future energy demands for building control can also be calculated. Conclusion: With the newly developed method described here not only can outdoor risks for cultural heritage assets resulting from climate change be assessed, but also risks for indoor collections. This can be done for individual buildings as well as on a larger scale in the form of European risk maps. By using different standardized and exemplary artificial buildings in modelling climate change impact, a comparison between different regions in Europe has become possible for the first time. The methodology will serve heritage owners and managers as a decision tool, helping them to plan more effectively mitigation and adaption measures at various levels. [ABSTRACT FROM AUTHOR]

This paper reports the results of three innovative laboratory tests implemented during winter 2013 in the framework of the Climate for Culture European Project (2009–2014). Thermal analysis was used to assess the heating efficiency of some heaters with different power consumption, geometric shape and dimensions. Experimental laboratory results were obtained under natural indoor environmental conditions and the outcomes were applied to a real case study of two churches on the Italian Alps during the Friendly Heating project. Results provide useful information to help final users and/or conservators to exploit at the best the heating efficiency of some heaters on the basis of the geometric characteristics of the elements and represent helpful advices for their installation, considering both the optimal position for the maximum comfort performance and the need for not exceeding specific risk thresholds for artwork preservation. [ABSTRACT FROM AUTHOR]

A calibration of reconstructed winter, spring and autumn precipitation series in Portugal from 1600 onwards is undertaken in the present study using new instrumental sources for the period of 1815–2012. As summer precipitation in Portugal is scarce and irregular, it is not considered. A consistency analysis of the calibrated time series is then undertaken using: (1) precipitation indices for Portugal in 1675–1799; (2) teleconnections between seasonal precipitation and large-scale atmospheric flow; (3) two paleoclimatic experiments (ERIK1 and ERIK2), generated from a global/regional climate model chain (ECHO-G/MM5); and (4) tree-ring records from oak trees in Portugal (Serra do Buçaco). These are the first multi-centennial records of tree-ring growth in Portugal (the earliest series begin in 1675). General agreement is found between indices and calibrated precipitation for their common period on an annual basis. Overall, the atmospheric teleconnection patterns are dynamically coherent between the instrumental and pre-instrumental periods. The inter-annual to inter-decadal variability in the calibrated series reveals similar distributions as in the paleoclimatic simulations. Low-frequency variability in spring precipitation is validated by 12 tree-ring series. This study provides calibrated seasonal precipitation series in Portugal from 1600 onwards, revealing high consistency with several independent sources for winter and spring, enabling future applications to climate research. [ABSTRACT FROM PUBLISHER]

This work presents the reconstruction of a time series of annual winter air temperatures across Central and Southern Italy for the period 1500-2010 that largely overlaps the Little Ice Age (LIA) period (1300-1850). A detailed analysis was undertaken on winter mean temperature data using both observations (1871-2010) and proxy-based reconstructions (1500-1870). Based on this homogeneized reconstructed series, a time-dependency in low-frequency time-pattern of temperatures (70- and 130-year cycles) was suggested although the temporal oscillation was not merely periodic. The LIA was characterized by marked climatic variability over this part of Southern Europe, with particular emphasis during the so-called 'Maunder Minimum' (MM), between 1645 and 1715. The interannual variability of low temperatures, in particular, makes the MM an outstanding climatic period. There is some consistency that patterns of warming conditions observed in recent times also occurred in the past. Quasiperiodic cycles appear as a consequence of stochastic resonance emerging in long time scales but the variability inherent to the series of winter temperatures, although likely generated by processes internal to the climate system, is difficult to forecast because the system is chaotic and affected by unpredictable noise. [ABSTRACT FROM AUTHOR]

This paper has exploited, for Central and Southern Italy (Mediterranean Sub-regional Area), an unprecedented historical dataset as an attempt to model seasonal (winter and summer) air temperatures in pre-instrumental time (back to 1500). Combining information derived from proxy-documentary data and large-scale simulation, a statistical downscaling approach in the form of mixed regression model was developed to adapt larger-scale estimations (regional component) to the sub-regional temperature pattern (local component). It interprets local temperature anomalies by means of monthly based Temperature Anomaly Scaled Index in the range −5 (very cold conditions in June) to 2 (very warm conditions). The modelled response agrees well with the independent data from the validation sample (Nash-Sutcliffe efficiency coefficient, >0.60). The advantage of the approach is not merely increased accuracy in estimation. Rather, it relies on the ability to extract (and exploit) the right information to replicate coherent temperature series in historical times. [ABSTRACT FROM AUTHOR]

Abstract: A multidisciplinary approach was used to study the reason behind the deterioration of four stucco panels that decorate the vault of Room VI in the Galleria Borghese in Rome. During the last nine years the panels were subjected twice to restoration because some cracks, which appeared over the surface of the reliefs jeopardizing the integrity of the gladiators. Since the deterioration continued diagnostic investigations of the components of the stucco panels were performed to analyze both the elements and compounds, and the mineralogical structure. A microclimate study was conducted to assess the impact of the indoor environment on the panels. Measurements and statistical analysis of the data were performed in accordance with the European Standards EN 15757:2010, EN 15758:2010, and EN 16242:2012. It was concluded that the deterioration is related to high temperatures in a dry environment exacerbated by artificial lighting with incandescent lamps, located in the proximity of the panels and continuously on for 12h daily. The body heat released by numerous visitors on a daily basis is an additional problem which should not be overlooked. [Copyright &y& Elsevier]

Indoor and outdoor atmospheres of the ‘Koninklijk Museum voor Schone Kunsten’ (KMSK, Royal Museum of Fine Arts) in Antwerp, Belgium, were thoroughly characterised to determine the air quality inside the museum and the factors controlling it. During a winter and a summer campaign aerosol particles, pollutant gases, bacteria and fungi were sampled and different indoors microclimatic parameters were measured. The chemical composition of particulates suspended in indoor and outdoor air was analysed, both with reference to bulk aerosol matter and to individual particles. Outdoor sources largely determined the composition of indoor aerosol. The main particle types identified in winter were Ca-rich, Ca–Si and sea salt particles. In summer, S-rich particles were most abundant. Dry deposition was sampled in order to determine the amount of particulate matter that could potentially deposit onto the works of art. The concentrations of NO2 and SO2 amounted to 12 and 5–6 ppb, respectively, both in winter and in the summer. The microclimates inside the exhibition rooms were affected by poorly balanced heating and air-conditioning, free-standing humidifiers, ventilating and lighting systems and the daily flux of visitors, which produced rapid changes and marked thermo-hygrometric gradients. Based on these results, suggestions for the improvement of the heating and air-conditioning system could be made. Microbial loads were higher in summer than in winter. However, the proportion of microorganisms capable of degrading proteins or hydrolysing fats, and thus pernicious to works of art, was not significantly increased inside the museum. [Copyright &y& Elsevier]

The peculiar microclimate inside cultural hypogeal sites needs to be carefully investigated. This study presents a methodology that aimed at providing a user-friendly assessment of the frequently occurring hazards in such sites. A Risk Index was specifically defined as the percentage of time for which the hygrothermal values lie in ranges that are considered to be hazardous for conservation. An environmental monitoring campaign that was conducted over the past ten years inside the Mithraeum of the Baths of Caracalla (Rome) allowed for us to study the deterioration before and after a maintenance intervention. The general microclimate assessment and the specific conservation risk assessment were both carried out. The former made it possible to investigate the influence of the outdoor weather conditions on the indoor climate and estimate condensation and evaporation responsible for salts crystallisation/dissolution and bio-colonisation. The latter took hygrothermal conditions that were close to wall surfaces to analyse the data distribution on diagrams with critical curves of deliquescence salts, mould germination, and growth. The intervention mitigated the risk of efflorescence thanks to reduced evaporation, while promoting the risk of bioproliferation due to increased condensation. The Risk Index provided a quantitative measure of the individual risks and their synergism towards a more comprehensive understanding of the microclimate-induced risks. [ABSTRACT FROM AUTHOR]