South African Land Degradation Monitor (SALDI) – A German – South African SPACES collaboration to advance land degradation assessments

&amp;lt;p&amp;gt;South Africa is greatly affected by land degradation, partly due to the high variability of its climatic conditions, the strong population growth and resulting economic demands. Thus reaching a number of SDGs, like achieving food security (#2), access to clean water (#6), and the sustainable use of terrestrial (#15) and marine (#14) resources represents a clear challenge under the present global change pressures. Land degradation has been linked in South Africa to the terms veld degradation and soil degradation and has been addressed by numerous measures. But there is still uncertainty on the extent of human induced land degradation as compared to periodic climate induced land surface property changes.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;In cooperation with South African institutions and stakeholders (ARC-ISCW, SAEON, SANParks, SANSA, Stellenbosch University and University of the Free State, Equispectives Research and Consulting Services, Nuwejaars Wetlands SMA), the overarching goal of SALDi is to implement novel, adaptive, and sustainable tools for assessing land degradation in multi-use landscapes in South Africa. Building upon the state of the art in land degradation assessments, the project aims to advance current methodologies for multi-use landscapes by innovatively incorporating inter-annual and seasonal variability in a spatially explicit approach. SALDi takes advantage of the emerging availability of high spatio-temporal resolution Earth observation data (e.g. Copernicus Sentinels, DLR TanDEM-X, NASA/USGS Landsat program), growing sources of in-situ data and advancements in modelling approaches. Particularly, SALDi aims to:&amp;lt;/p&amp;gt;&amp;lt;ol&amp;gt;&amp;lt;li&amp;gt;i) develop an automated system for high temporal frequency (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics,&amp;lt;/li&amp;gt; &amp;lt;li&amp;gt;ii) develop, adapt and apply a Regional Earth System Model (RESM) to South Africa and investigate the feedbacks between land surface properties and the regional climate,&amp;lt;/li&amp;gt; &amp;lt;/ol&amp;gt;&amp;lt;p&amp;gt;iii)&amp;amp;#160;&amp;amp;#160;&amp;amp;#160; advance current soil degradation process assessment tools for soil erosion, as this process represents an intrinsic limiting factor for biomass production and other regulating, supporting and provisioning ecosystem services, like providing clean water.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;The aim of this presentation is to introduce this new cooperative research project to the EGU Community and to seek new opportunities for collaboration.&amp;lt;/p&amp;gt; </jats:p

25. Commission de Photométrie Stellaire

Much material extending our knowledge of stellar magnitudes has accumulated during the last four years. In the appendix to this report will be found a list of recent catalogues, a summary of the discussion made at Mt Wilson by Seares and the formulae that he finds for the reduction of these catalogues to a fundamental system, until such time as a more extended discussion shall have furnished definitive corrections.</jats:p

28. Commission des Nébuleuses et des Amas Stellaires

1. Since the field covered by Commission No. 28 extends over the problems of three very different types of objects—external galaxies, galactic nebulae, and star clusters—it has been proposed occasionally that the Commission might well be subdivided, or possibly eventually split into three separate Commissions. As Trumpler points out, these three fields “have often been grouped together...more on a historical basis than on an actual similarity of the researches... which are more and more drifting apart.” But some members of the Commission have noted that a distinct difference also separates globular clusters and galactic clusters; and that planetary nebulae and dark absorbing clouds involve at times widely different types of investigations. The chairman of the Commission has made a canvass of the opinions of the members and finds that a large majority believe that no division or subdivision is advisable at this time. It is suggested that the organization or reorganization of a Commission should be left to the Union as a whole or to the Executive Committee.</jats:p

25. Commission de Photométrie Stellaire

The following summarizes the activities of various members of the Commission in matters pertaining to stellar photometry during the interval 1932-35: La partie photométrique des trois derniers volumes du Catalogue Astrographique (zone de Catane entre +46° et +55°) est soigneusement dressée sur le système de Miss Leavitt (Harv. Annals, 81). L’erreur moyenne des grandeurs, d’après la réduction de 100 plaques (zones +51° à + 54°, entre 6h et I2h), n’est que de ± om.o8. Nos réductions photométriques ont été effectuées par la formuleD = a-bg+cg2-dg3,où D dénote le diamètre de l’image photographique et G=8m+g dénote la grandeur de l’étoile.</jats:p

25. Commission de Photométrie Stellaire

The committee of the Carte du Ciel in 1910 adopted the following convention : That for Ao stars between magnitudes 5·5 and 6·5 the mean photographic magnitude should equal the mean Harvard visual magnitude. As a corollary, the colour index of Ao stars would then be zero.The zero point of the photographic magnitudes of the International Polar Sequence was fixed as nearly as possible in accordance with this definition; but it was by no means certain that the magnitudes thus adopted for the few stars of the Sequence represented the zero point defined by all the Ao stars specified.</jats:p

28. Commission des Nébuleuses et des Amas Stellaires

During the past three years observational and theoretical work has been uncommonly extensive and fruitful in two of the fields within the interests of Commission 28—namely, the distribution of external galaxies and the analysis of diffuse nebulosity, the latter including interstellar absorbing material. Important work is also under way at a number of observatories in the interpretation of planetary nebulae. Studies of clusters, however, have been limited to a few active workers, and progress has not been rapid in the analysis of individual galaxies.</jats:p

UVMag:stellar formation, evolution, structure and environment with space UV and visible spectropolarimetry

Important insights into the formation, structure, evolution and environment of all types of stars can be obtained through the measurement of their winds and possible magnetospheres. However, this has hardly been done up to now mainly because of the lack of UV instrumentation available for long periods of time. To reach this aim, we have designed UVMag, an M-size space mission equipped with a high-resolution spectropolarimeter working in the UV and visible spectral range. The UV domain is crucial in stellar physics as it is very rich in atomic and molecular lines and contains most of the flux of hot stars. Moreover, covering the UV and visible spectral domains at the same time will allow us to study the star and its environment simultaneously. Adding polarimetric power to the spectrograph will multiply tenfold the capabilities of extracting information on stellar magnetospheres, winds, disks, and magnetic fields. Examples of science objectives that can be reached with UVMag are presented for pre-main sequence, main sequence and evolved stars. They will cast new light onto stellar physics by addressing many exciting and important questions. UVMag is currently undergoing a Research &amp; Technology study and will be proposed at the forthcoming ESA call for M-size missions. This spectropolarimeter could also be installed on a large UV and visible observatory (e.g. NASA’s LUVOIR project) within a suite of instruments