Interchange reconnection: remote sensing of solar signature and role in heliospheric magnetic flux budget

Interchange reconnection at the Sun, that is, reconnection between a doubly-connected field loop and singly-connected or open field line that extends to infinity, has important implications for the heliospheric magnetic flux budget. Recent work on the topic is reviewed, with emphasis on two aspects. The first is a possible heliospheric signature of interchange reconnection at the coronal hole boundary, where open fields meet closed loops. The second aspect concerns the means by which the heliospheric magnetic field strength reached record-lows during the recent solar minimum period. A new implication of this work is that interchange reconnection may be responsible for the puzzling, occasional coincidence of the heliospheric current sheet and the interface between fast and slow flow in the solar wind.

Cloud-base vertical velocity statistics: a comparison between an atmospheric mesoscale model and remote sensing observations

The statistics of cloud-base vertical velocity simulated by the non-hydrostatic mesoscale model AROME are compared with Cloudnet remote sensing observations at two locations: the ARM SGP site in Central Oklahoma, and the DWD observatory at Lindenberg, Germany. The results show that, as expected, AROME significantly underestimates the variability of vertical velocity at cloud-base compared to observations at their nominal resolution; the standard deviation of vertical velocity in the model is typically 4-6 times smaller than observed, and even more during the winter at Lindenberg. Averaging the observations to the horizontal scale corresponding to the physical grid spacing of AROME (2.5 km) explains 70-80% of the underestimation by the model. Further averaging of the observations in the horizontal is required to match the model values for the standard deviation in vertical velocity. This indicates an effective horizontal resolution for the AROME model of at least 4 times the physically-defined grid spacing. The results illustrate the need for special treatment of sub-grid scale variability of vertical velocities in kilometer-scale atmospheric models, if processes such as aerosol-cloud interactions are to be included in the future.

The precipitation climate of Central Asia: intercomparison of observational and numerical data sources in a remote semiarid region

In this study, we systematically compare a wide range of observational and numerical precipitation datasets for Central Asia. Data considered include two re-analyses, three datasets based on direct observations, and the output of a regional climate model simulation driven by a global re-analysis. These are validated and intercompared with respect to their ability to represent the Central Asian precipitation climate. In each of the datasets, we consider the mean spatial distribution and the seasonal cycle of precipitation, the amplitude of interannual variability, the representation of individual yearly anomalies, the precipitation sensitivity (i.e. the response to wet and dry conditions), and the temporal homogeneity of precipitation. Additionally, we carried out part of these analyses for datasets available in real time. The mutual agreement between the observations is used as an indication of how far these data can be used for validating precipitation data from other sources. In particular, we show that the observations usually agree qualitatively on anomalies in individual years while it is not always possible to use them for the quantitative validation of the amplitude of interannual variability. The regional climate model is capable of improving the spatial distribution of precipitation. At the same time, it strongly underestimates summer precipitation and its variability, while interannual variations are well represented during the other seasons, in particular in the Central Asian mountains during winter and spring

Characterization of a highly biodiverse floodplain meadow using hyperspectral remote sensing within a plant functional trait framework

We assessed the potential for using optical functional types as effective markers to monitor changes in vegetation in floodplain meadows associated with changes in their local environment. Floodplain meadows are challenging ecosystems for monitoring and conservation because of their highly biodiverse nature. Our aim was to understand and explain spectral differences among key members of floodplain meadows and also characterize differences with respect to functional traits. The study was conducted on a typical floodplain meadow in UK (MG4-type, mesotrophic grassland type 4, according to British National Vegetation Classification). We compared two approaches to characterize floodplain communities using field spectroscopy. The first approach was sub-community based, in which we collected spectral signatures for species groupings indicating two distinct eco-hydrological conditions (dry and wet soil indicator species). The other approach was “species-specific”, in which we focused on the spectral reflectance of three key species found on the meadow. One herb species is a typical member of the MG4 floodplain meadow community, while the other two species, sedge and rush, represent wetland vegetation. We also monitored vegetation biophysical and functional properties as well as soil nutrients and ground water levels. We found that the vegetation classes representing meadow sub-communities could not be spectrally distinguished from each other, whereas the individual herb species was found to have a distinctly different spectral signature from the sedge and rush species. The spectral differences between these three species could be explained by their observed differences in plant biophysical parameters, as corroborated through radiative transfer model simulations. These parameters, such as leaf area index, leaf dry matter content, leaf water content, and specific leaf area, along with other functional parameters, such as maximum carboxylation capacity and leaf nitrogen content, also helped explain the species’ differences in functional dynamics. Groundwater level and soil nitrogen availability, which are important factors governing plant nutrient status, were also found to be significantly different for the herb/wetland species’ locations. The study concludes that spectrally distinguishable species, typical for a highly biodiverse site such as a floodplain meadow, could potentially be used as target species to monitor vegetation dynamics under changing environmental conditions.

Assisted remote viewing of a teleoperation work cell

Intelligent viewing systems are required if efficient and productive teleoperation is to be applied to dynamic manufacturing environments. These systems must automatically provide remote views to an operator which assist in the completion of the task. This assistance increases the productivity of the teleoperation task if the robot controller is responsive to the unpredictable dynamic evolution of the workcell. Behavioral controllers can be utilized to give reactive 'intelligence.' The inherent complex structure of current systems, however, places considerable time overheads on any redesign of the emergent behavior. In industry, where the remote environment and task frequently change, this continual redesign process becomes inefficient. We introduce a novel behavioral controller, based on an 'ego-behavior' architecture, to command an active camera (a camera mounted on a robot) within a remote workcell. Using this ego-behavioral architecture the responses from individual behaviors are rapidly combined to produce an 'intelligent' responsive viewing system. The architecture is single-layered, each behavior being autonomous with no explicit knowledge of the number, description or activity of other behaviors present (if any). This lack of imposed structure decreases the development time as it allows each behavior to be designed and tested independently before insertion into the architecture. The fusion mechanism for the behaviors provides the ability for each behavior to compete and/or co-operate with other behaviors for full or partial control of the viewing active camera. Each behavior continually reassesses this degree of competition or co-operation by measuring its own success in controlling the active camera against pre-defined constraints. The ego-behavioral architecture is demonstrated through simulation and experimentation.

Tarabotti fra omissioni e femminismo: il mistero della sua formazione

This paper given at the conference "Donne a Venezia" in May 2008 discloses the complexity of Arcangela Tarabotti (1604-1652), a proto-feminist polemist and writer who lived all her life in a remoted convent, Sant'Anna in Castello, in a remoted part of Venice. Despite having been cloistered at the age of 11, according to her account, she managed to publish her books and become a recognised member of the République des Lettres. How did she manage to develop her incredibly modern ideas, suggesting women should study and work and avoid getting married with astronomical dowries? The article deals with entirely new documents, uncovered in archives and tries to provide an answer to such dearing questions.

Interpreting at Vindolanda: commercial and linguistic mediation in the Roman army.

A fragmentary tablet from Vindolanda (Tab. Vindol. II, 213) contains an occurrence of the verb interpretari (‘interpret’, ‘explain’, ‘mediate’) in an apparently commercial context, relating to the grain supply for the Roman fort. This usage is paralleled in a text on a wooden stilus tablet from Frisia in the Netherlands. ‘Interpreters’ and their activities make rather infrequent appearances in the Latin epigraphic and documentary records. In the Danubian provinces, interpreters (interpretes) are attested as army officers and officials in the office of the provincial governor. ‘Interpreters’, in both Latin and Greek inscriptions and papyri, often, however, play more ambiguous roles, not always connected with language-mediation, but also, or instead, with mediation in commercial transactions

Mutamenti politico-istituzionali nella Venezia Giulia e a Trieste tra Tito e gli americani alla luce delle nuove testimonianze documentarie da Washington, 1944-1954

“La questione di Trieste”, ovvero la questione del confine italo-yugoslavo all’indomani della seconda guerra mondiale costituisce da lungo tempo oggetto di attenzione e di esame da parte della storiografia italiana e straniera. Con alcune importanti eccezioni, la ricostruzione complessiva di quelle vicende ha visto il più delle volte il prevalere di un approccio storico-diplomatico che ha reso difficile comprendere con chiarezza i rapporti e le interdipendenze fra contesto locale, contesto nazionale e contesto internazionale. Attraverso la lettura incrociata dell’ampia documentazione proveniente dai fondi dei National Archives Records Administration (NARA) questo studio tenta una rilettura delle varie fasi di sviluppo della questione nel periodo compreso tra il giugno del 1945 e l’ottobre del 1954 secondo una duplice prospettiva: nella prima parte si concentra sulla politica americana a Trieste, guardando nello specifico a due aspetti interni tra loro strettamente correlati, la gestione dell’ordine pubblico e la “strategia” del consenso da realizzarsi mediante il controllo dell’informazione da un lato e la promozione di una politica culturale dall’altro. Sono aspetti entrambi riconducibili al modello del direct rule, che conferiva al governo militare alleato (GMA) piena ed esclusiva autorità di governo sulla zona A della Venezia Giulia, e che ci appaiono centrali anche per cogliere l’interazione fra istituzioni e soggetti sociali. Nella seconda parte, invece, il modificarsi della fonte d’archivio indica un cambiamento di priorità nella politica estera americana relativa a Trieste: a margine dei negoziati internazionali, i documenti del fondo Clare Boothe Luce nelle carte dell’Ambasciata mostrano soprattutto come la questione di Trieste venne proiettata verso l’esterno, verso l’Italia in particolare, e sfruttata – principalmente dall’ambasciatrice – nell’ottica bipolare della guerra fredda per rinforzare il sostegno interno alla politica atlantica. Il saggio, dunque, si sviluppa lungo due linee: dentro e fuori Trieste, dentro 1945-1952, fuori 1953-1954, perché dalle fonti consultate sono queste ad emergere come aree di priorità nei due periodi. Abstract - English The “Trieste question”, or the question regarding the Italian - Yugoslav border after the Second World War, has been the object of careful examination in both Italian and foreign historiography for a long time. With a few important exceptions, the overall reconstruction of these events has been based for the most part on historic and diplomatic approaches, which have sometimes made it rather difficult to understand clearly the relationships and interdependences at play between local, national and international contexts. Through a comparative analysis of a large body of documents from the National Archives and Records Administration (NARA), College Park MD, this essay attempts a second reading of the various phases in which the question developed between June 1945 and October 1954, following a twofold perspective: the first part focuses on American policy for Trieste, specifically looking at two internal and closely linked aspects, on the one hand, the management of ‘law and order’, as well as a ‘strategy’ of consent, to be achieved through the control of all the means of information , and, on the other, the promotion of a cultural policy. Both aspects can be traced back to the ‘direct rule’ model, which gave the Allied Military Government (AMG) full and exclusive governing authority over Venezia Giulia’s Zone A. These issues are also fundamental to a better understanding of the relationships between institutions and social subjects. In the second part of the essay , the change in archival sources clearly indicates a new set of priorities in American foreign policy regarding Trieste: outside any international negotiations for the settlement of the question, the Clare Boothe Luce papers held in the Embassy’s archives, show how the Trieste question was focused on external concerns, Italy in particular, and exploited – above all by the ambassador – within the bi-polar optic of the Cold War, in order to strengthen internal support for Atlantic policies. The essay therefore follows two main lines of inquiry: within and outside Trieste, within in 1945-1952, and outside 1953-1954, since, from the archival sources used, these emerge as priority areas in the two periods.

Interpreting Differential Temperature Trends at the Surface and in the Lower Troposphere

Estimated global-scale temperature trends at Earth's surface (as recorded by thermometers) and in the lower troposphere (as monitored by satellites) diverge by up to 0.14°C per decade over the period 1979 to 1998. Accounting for differences in the spatial coverage of satellite and surface measurements reduces this differential, but still leaves a statistically significant residual of roughly 0.1°C per decade. Natural internal climate variability alone, as simulated in three state-of-the-art coupled atmosphere-ocean models, cannot completely explain this residual trend difference. A model forced by a combination of anthropogenic factors and volcanic aerosols yields surface-troposphere temperature trend differences closest to those observed.

Toward vicarious calibration of microwave remote-sensing satellites in arid environments

The Soil Moisture and Ocean Salinity (SMOS) satellite marks the commencement of dedicated global surface soil moisture missions, and the first mission to make passive microwave observations at L-band. On-orbit calibration is an essential part of the instrument calibration strategy, but on-board beam-filling targets are not practical for such large apertures. Therefore, areas to serve as vicarious calibration targets need to be identified. Such sites can only be identified through field experiments including both in situ and airborne measurements. For this purpose, two field experiments were performed in central Australia. Three areas are studied as follows: 1) Lake Eyre, a typically dry salt lake; 2) Wirrangula Hill, with sparse vegetation and a dense cover of surface rock; and 3) Simpson Desert, characterized by dry sand dunes. Of those sites, only Wirrangula Hill and the Simpson Desert are found to be potentially suitable targets, as they have a spatial variation in brightness temperatures of <4 K under normal conditions. However, some limitations are observed for the Simpson Desert, where a bias of 15 K in vertical and 20 K in horizontal polarization exists between model predictions and observations, suggesting a lack of understanding of the underlying physics in this environment. Subsequent comparison with model predictions indicates a SMOS bias of 5 K in vertical and 11 K in horizontal polarization, and an unbiased root mean square difference of 10 K in both polarizations for Wirrangula Hill. Most importantly, the SMOS observations show that the brightness temperature evolution is dominated by regular seasonal patterns and that precipitation events have only little impact.

A methodology for in-situ and remote sensing of microphysical and radiative properties of contrails as they evolve into cirrus

Contrails and especially their evolution into cirrus-like clouds are thought to have very important effects on local and global radiation budgets, though are generally not well represented in global climate models. Lack of contrail parameterisations is due to the limited availability of in situ contrail measurements which are difficult to obtain. Here we present a methodology for successful sampling and interpretation of contrail microphysical and radiative data using both in situ and remote sensing instrumentation on board the FAAM BAe146 UK research aircraft as part of the COntrails Spreading Into Cirrus (COSIC) study.

Sequential variations of phytoplankton growth and mortality in an NPZ model: a remote-sensing-based assessment

Radiometric data in the visible domain acquired by satellite remote sensing have proven to be powerful for monitoring the states of the ocean, both physical and biological. With the help of these data it is possible to understand certain variations in biological responses of marine phytoplankton on ecological time scales. Here, we implement a sequential data-assimilation technique to estimate from a conventional nutrient–phytoplankton–zooplankton (NPZ) model the time variations of observed and unobserved variables. In addition, we estimate the time evolution of two biological parameters, namely, the specific growth rate and specific mortality of phytoplankton. Our study demonstrates that: (i) the series of time-varying estimates of specific growth rate obtained by sequential data assimilation improves the fitting of the NPZ model to the satellite-derived time series: the model trajectories are closer to the observations than those obtained by implementing static values of the parameter; (ii) the estimates of unobserved variables, i.e., nutrient and zooplankton, obtained from an NPZ model by implementation of a pre-defined parameter evolution can be different from those obtained on applying the sequences of parameters estimated by assimilation; and (iii) the maximum estimated specific growth rate of phytoplankton in the study area is more sensitive to the sea-surface temperature than would be predicted by temperature-dependent functions reported previously. The overall results of the study are potentially useful for enhancing our understanding of the biological response of phytoplankton in a changing environment.

Modelling the time-evolution of phytoplankton size spectra from satellite remote sensing

A dynamic size-structured model is developed for phytoplankton and nutrients in the oceanic mixed layer and applied to extract phytoplankton biomass at discrete size fractions from remotely sensed, ocean-colour data. General relationships between cell size and biophysical processes (such as sinking, grazing, and primary production) of phytoplankton were included in the model through a bottom–up approach. Time-dependent, mixed-layer depth was used as a forcing variable, and a sequential data-assimilation scheme was implemented to derive model trajectories. From a given time-series, the method produces estimates of size-structured biomass at every observation, so estimates seasonal succession of individual phytoplankton size, derived here from remote sensing for the first time. From these estimates, normalized phytoplankton biomass size spectra over a period of 9 years were calculated for one location in the North Atlantic. Further analysis demonstrated that strong relationships exist between the seasonal trends of the estimated size spectra and the mixed-layer depth, nutrient biomass, and total chlorophyll. The results contain useful information on the time-dependent biomass flux in the pelagic ecosystem.