ALBERT

Description: In 2017, the astronomical and geodetic communities will celebrate the 50-year anniversary of the first Very Long Baseline Interferometry (VLBI) experiments. The Journal of Geodesy Special Issue titled “VLBI contribution to reference frames and Earth’s rotation studies” is dedicated to this great jubilee. VLBI plays a key role in astronomy and geodesy. It provides unprecedented spatial resolution and position measurements on the sky with an accuracy superior to other techniques. VLBI is a key space geodetic technique since the 1970s, which fundamentally contributes to the maintenance of terrestrial (TRF) and celestial (CRF) reference frames, including the International Terrestrial (ITRF) and Celestial (ICRF) Reference Frames, and monitoring of the Earth’s rotation with respect to the ITRF and ICRF through determination of highly accurate Earth orientation parameters (EOP). Furthermore, the VLBI technique is unique in determining the Universal Time and the precession–nutation of the Earth’s rotation axis in space. Consequently, it is the only technique capable to provide a consistent TRF–EOP–CRF solution. VLBI also essentially contributes to Solar System dynamics and space and terrestrial navigation, atmospheric studies and refining geophysical models, crustal movements and plate tectonics, time and frequency transfer, and testing physical theories. The most accurate and valuable VLBI results are obtained from global VLBI station networks involving radio telescopes located in different countries on different continents. Therefore, a successful realization of the VLBI observing programs requires both inter-institutional and international cooperation. Since 1999, this cooperation is realized through the International VLBI Service for Geodesy and Astrometry (IVS). Moreover, the IVS provides the combined IVS products, such as EOP and VLBI TRF realization (VTRF). The latter essentially contributes to the multi-technique ITRF solution providing the longest station position time series and defining, together with Satellite Laser Ranging (SLR), the ITRF scale and scale rate. Including the radio source positions in the combination is under investigation. A dedicated paper in this issue describes the current state and perspectives of the IVS operations. The previous Special Issue of Journal of Geodesy devoted to VLBI and published in June 2007 (volume 81, issue 6–8) was highly successful. Since that time, many important changes and impressive improvements in the VLBI technique and analysis happened, such as VLBI2010 technical design, the start of the next-generation global VLBI network VLBI Global Observing System (VGOS), publishing ICRF2 and preparing ICRF3, and implementing new IVS combined EOP–TRF products based on combination of datum-free normal equations. All these researches and developments aim at achieving the 1 mm accuracy in TRF and EOP. To reach this goal, the development of technology should be accompanied by improvement in the geophysical and astronomical modelling as well as in the analysis strategy. This Special Issue of Journal of Geodesy is intended to put together papers describing the latest developments in geodetic and astrometric VLBI. Taking into account the scope of the Journal and the limited size of the volume, only the papers devoted to the geodetic and astrometric data analysis were called for. After the Call for papers was sent to the community, we received many responses from our colleagues expressing their interest to contribute to the volume. We believe that the papers published here comprise a representative collection reflecting the main topics of geodetic and astrometric data analysis, which will provide a good reference source for future research in the field. It is a pleasure to express our gratitude to all the authors presenting their results in this issue. All the papers submitted to this volume have passed a peer-review process following the standard procedure of the Journal of Geodesy. We are much indebted to many reviewers whose valuable comments and suggestions helped to prepare the final papers of high quality included in this volume. Finally, we would like to acknowledge the hard and continuous work of all the IVS components over many years—stations, correlators, technology development, operational and analysis centers that regularly deliver data and products of highest quality for scientific analysis and practical applications.

Description: Impacts of human civilization on ecosystems threaten global biodiversity. In a changing environment, traditional in situ approaches to biodiversity monitoring have made significant steps forward to quantify and evaluate BD at many scales but still, these methods are limited to comparatively small areas. Earth observation (EO) techniques may provide a solution to overcome this shortcoming by measuring entities of interest at different spatial and temporal scales. This paper provides a comprehensive overview of the role of EO to detect, describe, explain, predict and assess biodiversity. Here, we focus on three main aspects related to biodiversity − taxonomic diversity, functional diversity and structural diversity, which integrate different levels of organization − molecular, genetic, individual, species, populations, communities, biomes, ecosystems and landscapes. In particular, we discuss the recording of taxonomic elements of biodiversity through the identification of animal and plant species. We highlight the importance of the spectral traits (ST) and spectral trait variations (STV) concept for EO-based biodiversity research. Furthermore we provide examples of spectral traits/spectral trait variations used in EO applications for quantifying taxonomic diversity, functional diversity and structural diversity. We discuss the use of EO to monitor biodiversity and habitat quality using different remote-sensing techniques. Finally, we suggest specifically important steps for a better integration of EO in biodiversity research. EO methods represent an affordable, repeatable and comparable method for measuring, describing, explaining and modelling taxonomic, functional and structural diversity. Upcoming sensor developments will provide opportunities to quantify spectral traits, currently not detectable with EO, and will surely help to describe biodiversity in more detail. Therefore, new concepts are needed to tightly integrate EO sensor networks with the identification of biodiversity. This will mean taking completely new directions in the future to link complex, large data, different approaches and models.