| 1. |
- Barabash, Victoria, Dr, et al.
(författare)
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Development of a Competence Ecosystem for the Future Space Workforce: Strategies, Practices and Recommendations from International Masterprograms in Northern Sweden
- 2021
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Ingår i: IAC 2021 Congress Proceedings, 72nd International Astronautical Congress (IAC), Dubai, United Arab Emirates. - : International Astronautical Federation (IAF).
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Konferensbidrag (refereegranskat)abstract
- Requirements from the global labor market have substantially changed in recent years. Graduate and postgraduate students with excellent subject knowledge, deep understanding of modern working methods, technical and higher-order thinking, engineering intuition and problem-solving skills are in great demand. They should also have professional skills such as well-developed abilities in communication and teamwork, usually in an international work environment. This review discusses the advantages of multidisciplinary study environment, educational strategies such as student-oriented teaching, project-based learning with its applicability to a "real-world" setting, active learning techniques, development of entrepreneurial skills, lessons learned and best practices from the international Master Program in Spacecraft Design and the Joint Master Program in Space Science and Technology – SpaceMaster at Luleå University of Technology in northern Sweden. The importance of complementarity between formal, informal and non-formal learning methods for science and engineering students has been specifically highlighted. Connections to the world of work, through active industry involvement in the education in a systematic way, e.g. External Advisory Board, shared services and facilities, joint projects and supervision of Master and PhD students, is recognised as a key success factor for professional training. A structural combination of modern pedagogical tools, strategic partnership with industry, business entities, academic partners and up-to-date multidisciplinary labs creates the conceptual framework for a Competence Ecosystem for fostering a new generation of space scientists and engineers.
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| 2. |
- Barabash, Victoria, Dr, et al.
(författare)
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Development of a competence ecosystem for the future space workforce: strategies, practices and recommendations from international master programs in northern Sweden
- 2022
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Ingår i: Acta Astronautica. - : Elsevier. - 0094-5765 .- 1879-2030. ; 197, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- Requirements from the global labor market have substantially changed in recent years. Graduate and post-graduate students with excellent subject knowledge, deep understanding of modern working methods, technicaland higher-order thinking, engineering intuition and problem-solving skills are in great demand. They should also have professional skills such as well-developed abilities in communication and teamwork, usually in an international work environment. This review discusses the advantages of multidisciplinary study environment, educational strategies such as student-oriented teaching, project-based learning with its applicability to a“real-world” setting, active learning techniques, development of entrepreneurial skills, lessons learned and best practices from the international Master Program in Spacecraft Design and the Joint Master Program in SpaceScience and Technology – SpaceMaster at Luleå University of Technology in northern Sweden. The importance of complementarity between formal, informal and non-formal learning methods for science and engineering studentshas been specifically highlighted. Connections to the world of work, through active industry involvementin the education in a systematic way, e.g. External Advisory Board, shared services and facilities, joint projectsand supervision of Master and PhD students, is recognised as a key success factor for professional training. A structural combination of modern pedagogical tools, strategic partnership with industry, business entities, academic partners and up-to-date multidisciplinary labs creates the conceptual framework for a CompetenceEcosystem for fostering a new generation of space scientists and engineers.
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| 3. |
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| 4. |
- Wolf, Veronika, et al.
(författare)
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Arctic ice clouds over northern Sweden: microphysical properties studied with the Balloon-borne Ice Cloud particle Imager B-ICI
- 2018
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus Publications. - 1680-7316 .- 1680-7324. ; 18:23, s. 17371-17386
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Tidskriftsartikel (refereegranskat)abstract
- Ice particle and cloud properties such as particle size, particle shape and number concentration influence the net radiation effect of cirrus clouds. Measurements of these features are of great interest for the improvement of weather and climate models, especially for the Arctic region. In this study, balloon-borne in situ measurements of Arctic cirrus clouds have been analysed for the first time with respect to their origin. Eight cirrus cloud measurements have been carried out in Kiruna (68∘ N), Sweden, using the Balloon-borne Ice Cloud particle Imager (B-ICI). Ice particle diameters between 10 and 1200 µm have been found and the shape could be recognized from 20 µm upwards. Great variability in particle size and shape is observed. This cannot simply be explained by local environmental conditions. However, if sorted by cirrus origin, wind and weather conditions, the observed differences can be assessed. Number concentrations between 3 and 400 L−1 have been measured, but the number concentration has reached values above 100 L−1 only for two cases. These two cirrus clouds are of in situ origin and have been associated with waves. For all other measurements, the maximum ice particle concentration is below 50 L−1 and for one in situ origin cirrus case only 3 L−1. In the case of in situ origin clouds, the particles are all smaller than 350 µm diameter. The PSDs for liquid origin clouds are much broader with particle sizes between 10 and 1200 µm. Furthermore, it is striking that in the case of in situ origin clouds almost all particles are compact (61 %) or irregular (25 %) when examining the particle shape. In liquid origin clouds, on the other hand, most particles are irregular (48 %), rosettes (25 %) or columnar (14 %). There are hardly any plates in cirrus regardless of their origin. It is also noticeable that in the case of liquid origin clouds the rosettes and columnar particles are almost all hollow.
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| 5. |
- Agües Paszkowsky, Núria, et al.
(författare)
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Vegetation and Drought Trends in Sweden’s Mälardalen Region – Year-on-Year Comparison by Gaussian Process Regression
- 2020
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Ingår i: 2020 Swedish Workshop on Data Science (SweDS). - : IEEE. - 9781728192048
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Konferensbidrag (refereegranskat)abstract
- This article describes analytical work carried out in a pilot project for the Swedish Space Data Lab (SSDL), which focused on monitoring drought in the Mälardalen region in central Sweden. Normalized Difference Vegetation Index (NDVI) and the Moisture Stress Index (MSI) – commonly used to analyse drought – are estimated from Sentinel 2 satellite data and averaged over a selection of seven grassland areas of interest. To derive a complete time-series over a season that interpolates over days with missing data, we use Gaussian Process Regression, a technique from multivariate Bayesian analysis. The analysis show significant differences at 95% confidence for five out of seven areas when comparing the peak drought period in the dry year 2018 compared to the corresponding period in 2019. A cross-validation analysis indicates that the model parameter estimates are robust for temporal covariance structure (while inconclusive for the spatial dimensions). There were no signs of over-fitting when comparing in-sample and out-of-sample RMSE.
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| 6. |
- Aires, Filipe, et al.
(författare)
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Towards more realistic hypotheses for the information content analysis of cloudy/precipitating situations - Application to a hyperspectral instrument in the microwave
- 2019
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Ingår i: Quarterly Journal of the Royal Meteorological Society. - : Wiley. - 0035-9009 .- 1477-870X. ; 145:718, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Information Content (IC) analysis can be used before an instrument is built to estimate its retrieval uncertainties and analyse their sensitivity to several factors. It is a very useful method to define/optimize satellite instruments. IC has shown its potential to compare instrument concepts in the infrared or the microwave. IC is based on some hypotheses such as the the Gaussian character of the radiative transfer (RT) and instrument errors, the first-guess errors (Gaussian character, std and correlation structure), or the linearization of the RT around a first guess. These hypotheses are easier to define for simple atmospheric situations. However, even in the clear-sky case, their complexity has never ceased to increase towards more realism, to optimize the assimilation of satellite measurements in numerical weather prediction (NWP) systems. In the cloudy/precipitating case, these hypotheses are even more difficult to define in a realistic way as many factors are still very difficult to quantify. In this study, several tools are introduced to specify more realistic IC hypotheses than the current practice. We focus on microwave observations as they are more pertinent for clouds and precipitation. Although not perfect, the proposed solutions are a new step towards more realistic IC assumptions of cloudy/precipitating scenes. A state-dependence of the RT errors is introduced, the first-guess errors have a more complex vertical structure, the IC is performed simultaneously on all the hydrometeors to take into account the contamination effect of the RT input uncertainties, and the IC is performed on a diversified set of cloudy/precipitating scenes with well-defined hydrometeor assumptions. The method presented in this study is illustrated using the HYperspectral Microwave Sensor (HYMS) instrument concept with channels between 6.9 and 874 GHz (millimetre and sub-millimetre regions). HYMS is considered as a potential next generation microwave sounder.
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| 7. |
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| 8. |
- Birman, Camille, et al.
(författare)
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Information content on hydrometeors from millimeter and sub-millimeter wavelengths
- 2017
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Ingår i: Tellus. Series A, Dynamic meteorology and oceanography. - : Taylor & Francis. - 0280-6495 .- 1600-0870. ; 69:1
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the information content on hydrometeors that could be provided by a future HYperspectralMicrowave Sensor (HYMS) with frequencies ranging from 6.9 to 874 GHz (millimeter and sub-millimeter regions). Through optimal estimation theory the information content is expressed quantitatively in terms of degrees of freedom for signal (DFS). For that purpose the Atmospheric Radiative Transfer Simulator (ARTS) and its Jacobians are used with a set of 25 cloudy and precipitating profiles and their associated errors from the European Centre for Medium-range Weather Forecasting (ECMWF) global numerical weather prediction model.In agreement with previous studies it is shown that frequencies between 10 and 40 GHz are the most informative ones for liquid and rain water contents. Similarly, the absorption band at 118 GHz contains significant information on liquid precipitation. A set of new window channels (15.37-, 40.25-, 101-GHz) could provide additional information on the liquid phase. The most informative channels on cloud icewater are the window channels at 664 and 874GHz and thewater vapour absorption bands at 325 and 448 GHz. Regarding snow water contents, the channels having the largest DFS values are located inwindow regions (150-, 251-, 157-, 101-GHz). However it is necessary to consider 90 channels in order to represent 90% of the DFS. The added value of HYMS has been assessed against current Special Sensor Microwave Imager/Sounder (SSMI/S) onboard the Defense Meteorological Satellite Program (DMSP) and future (Microwave Imager/Ice Cloud Imager (MWI/ICI) onboard European Polar orbiting Satellite – Second Generation (EPS-SG)) microwave sensors. It appears that with a set of 276 channels the information content on hydrometeors would be significantly enhanced: the DFS increases by 1.7 against MWI/ICI and by 3 against SSMI/S. A number of tests have been performed to examine the robustness of the above results. The most informative channels on solid hydrometeors remain the same over land and over ocean surfaces. On the other hand, the database is not large enough to produce robust results over land surfaces for liquid hydrometeors. The sensitivity of the results to the microphysical properties of frozen hydrometeors has been investigated. It appears that a change in size distribution and scattering properties can move the large information content of the channels at 664 and 874 GHz from cloud ice to solid precipitation.
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| 9. |
- Buehler, Stefan A., et al.
(författare)
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An upper tropospheric humidity data set from operational satellite microwave data
- 2008
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:14, s. D14110-
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Tidskriftsartikel (refereegranskat)abstract
- 183.31 GHz observations from the Advanced Microwave Sounding Unit B (AMSUB) instruments onboard the NOAA 15, 16, and 17 satellites were used to derive a new data set of Upper Tropospheric Humidity (UTH). The data set consist of monthly median and mean data on a 1.5 degrees latitude-longitude grid between 60 degrees S and 60 degrees N, and covers the time period of January 2000 to February 2007. The data from all three instruments are very consistent, with relative difference biases of less than 4% and relative difference standard deviations of 7%. Radiometric contributions by high ice clouds and by the Earth's surface affect the measurements in certain areas. The uncertainty due to clouds is estimated to be up to approximately 10%RH in areas with deep convection. The uncertainty associated with contamination from surface emission can exceed 10%RH in midlatitude winter, where the data therefore should be regarded with caution. Otherwise the surface influence appears negligible. The paper also discusses the UTH median climatology and seasonal cycle, which are found to be broadly consistent with UTH climatologies from other sensors. Finally, the paper presents an initial validation of the new data set against IR satellite data and radiosonde data. The observed biases of up to 9%RH (wet bias relative to HIRS) were found to be broadly consistent with expectations based on earlier studies. The observed standard deviations against all other data sets were below 6%RH. The UTH data are available to the scientific community on http://www.sat.ltu.se.
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| 10. |
- Kajtar, Rita Edit, 1988-
(författare)
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Improved data analysis methods for the millimetre-wave observation of strato-mesospheric ozone and winds over Northern Sweden
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis analyses and discusses the work done to improve an ozone retrieval method. The newly implemented method aims to invert emission spectra measured with the millimetre-wave radiometers KIMRA and MIRA2 at the Swedish Institute of Space Physics (IRF) in Kiruna. In addition, the thesis presents the testing of wind retrieval capabilities that were performed in connection to the ozone retrieval method. Ozone monitoring stations are unequally distributed across latitudes despite the growing demand for measurements in remote regions, such as the Arctic. According to the Global Atmospheric Watch program, there are no registered ozone monitoring stations in Northern Sweden. Furthermore, the need for inferring mid-stratosphere to mid-mesosphere wind profiles is a consequence of the relatively poor characterization of the complex atmospheric dynamics at these altitudes by the existing monitoring techniques. The ground-based monitoring station for trace gases at IRF is unique in Northern Scandinavia. It has the potential to investigate regional ozone distributions all-yearlong for altitudes between approximately 15 km and 55 km. KIMRA and MIRA2 are passive remote sensing instruments, and they operate in separate frequency ranges of the millimetre-wave spectral band. The radiometers were designed to continuously measure emission rates from trace gas molecules in different regions of the atmosphere. Being located in the Arctic gives the advantage of measuring ozone in the proximity of the polar vortex during the winter season. The retrieval version presented in this thesis was developed to correct for the deviations encountered in the previous method used at IRF to infer vertical ozone profiles from measurements done with the two radiometers. Moreover, in recent years, the former method’s purpose has been shifted more towards carbon monoxide retrievals (in the case of KIMRA), which left room for upgrading and stabilizing the ozone retrievals. The advanced versions of the Atmospheric Radiative Transfer Simulator (ARTS) used as a forward model, and the embedded Optimal Estimation Method (OEM) have allowed for a more robust data analysis setup. Recent developments in ARTS have led to a rather versatile simulator with a robust numerical setup and a more straightforward control file management. An analysis of prevailing conditions for middle atmospheric winds, together with preparations for retrievals of strato-mesospheric winds, are also discussed in this thesis. Among others, simulated retrievals and sensitivity studies based on synthetic spectrahave been conducted to prepare for possible retrievals using the radiometers in Kiruna.
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| 11. |
- Larsson, Richard, et al.
(författare)
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Martian magnetism with orbiting sub-millimeter sensor: simulated retrieval system
- 2017
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Ingår i: Geoscientific Instrumentation, Methods and Data Systems. - : Copernicus Publications. - 2193-0856 .- 2193-0864. ; 6:1, s. 27-37
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Tidskriftsartikel (refereegranskat)abstract
- A Mars-orbiting sub-millimeter sensor can be used to retrieve the magnetic field at low altitudes over large areas of significant planetary crustal magnetism of the sur- face of Mars from measurements of circularly polarized radi- ation emitted by the 368 GHz ground-state molecular oxygen absorption line. We design a full retrieval system for one ex- ample orbit to show the expected accuracies on the magnetic field components that one realization of such a Mars satellite mission could achieve. For one set of measurements around a tangent profile, we find that the two horizontal components of the magnetic field can be measured at about 200 nT error with a vertical resolution of around 4 km from 6 up to 70 km in tangent altitude. The error is similar regardless of the true strength of the magnetic field, and it can be reduced by re- peated measurements over the same area. The method and some of its potential pitfalls are described and discussed.
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| 12. |
- Nieto-Peroy, Cristóbal
(författare)
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Concurrent Engineering of Small Satellites using Hardware-in-the-loop Simulations
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The miniaturization of spacecraft has brough the possibility of conducting space missions to a vast portion of private enterprises and scientific institutions. The inaccessibility of modest developers to the resources that governmental agencies and primary contractors utilize to develop conventional satellites has not been an obstacle for them to apply different, more agile and risk-seeking approaches. However, the failure rate of Small Satellite missions has increased to a higher degree than the total number of missions, particularly if only CubeSats are considered.The research conducted in this thesis proposes an improvement to the development of space systems by focusing on the verification and validation processes. For that, the thesis revolves around two main areas. First, the thesis deals with the engineering methodology. The notions of concurrent engineering are generalized and combined with the test-driven development and behavior-driven development methodologies to perform the parallel, yet integrated, development of the various spacecraft subsystems that can be at different maturity levels. For example, these processes have been applied in-house to the development of onboard computers and telecommunication systems. The proposed methodology allows for the automation of the engineering workflow and the early detection and correction of defects in the system by frequently testing it along the process.Secondly, the research also deals with the development and utilization of a simulation environment that fits the proposed methodology. The thesis provides advancements on hardware-in-the-loop simulation techniques with a particular focus on frictionless platforms. Such a platform can perform, but is not limited to, dynamic simulations. Additionally, the thesis also provides the characterization of the platform to use it as a reference for comparison with other similar ones.All in all, the simulation environment has demonstrated to provide the versatility needed by the methodology. Such environment has served as a platform to develop different subsystems from the simulation of physical models to the testing of actual hardware prototypes. Two studies are provided as examples of such accomplishments, i.e., a study with the remote simulation of cooperative maneuvers and a different one with the development of flexible appendages for a spacecraft.
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| 13. |
- Nieto-Peroy, Cristóbal, et al.
(författare)
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Simulation of Spacecraft Formation Maneuvers by means of Floating Platforms
- 2021
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Ingår i: 2021 IEEE Aerospace Conference (50100). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- This article provides a proposal case for studying simulations of spacecraft formation maneuvers in a Hardware-in-the-Loop Simulation Testbed specifically devoted to nanosatellites. The design specifications of the setup to perform such simulations are given, as well as the methods and results of the preliminary characterization of the floating platform to be used. The intent is to create a corpus of tests to find the dynamic behavior in a frictionless simulation as part of a concurrent decentralized simulation between the NanoSat Lab in Luleå University of Technology and the Guidance and Navigation Lab at La Sapienza.
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| 14. |
- Vomero, Mariapina, et al.
(författare)
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Large-Scale Sea Ice Divergence and Convergence Monitoring in the Arctic Ocean during Spring 2018
- 2021
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Ingår i: Okhotsk Sea and Polar Oceans Research (OSPOR). - : Okhotsk Sea and Polar Oceans Research Association (OSPORA). ; , s. 31-35
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Konferensbidrag (refereegranskat)abstract
- This study investigates sea ice motion in the Arctic Ocean during the year 2018 to detect areas of ice deformation. We aim to improve the current understanding of large-scale sea ice circulation by examining ice convergence/divergence during the early melt-season. OSISAF sea ice drift data provided by EUMETSAT were used for the analysis during the months of March and April. Daily ice drifting speed and deformation parameters showed a strong correlation throughout the observed interval, while a local-scale analysis revealed different patterns for ice divergence and convergence in areas of enhanced ice drift.
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