| 1. |
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| 2. |
- Wang, Jianfeng, 1984-, et al.
(författare)
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A Hybrid Statistical-Dynamical Downscaling of Air Temperature over Scandinavia Using the WRF Model
- 2020
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Ingår i: Advances in Atmospheric Sciences. - : Springer. - 0256-1530 .- 1861-9533. ; 37:1, s. 57-74
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Tidskriftsartikel (refereegranskat)abstract
- An accurate simulation of air temperature at local scales is crucial for the vast majority of weather and climate applications. In this work, a hybrid statistical–dynamical downscaling method and a high-resolution dynamical-only downscaling method are applied to daily mean, minimum and maximum air temperatures to investigate the quality of localscale estimates produced by downscaling. These two downscaling approaches are evaluated using station observation data obtained from the Finnish Meteorological Institute over a near-coastal region of western Finland. The dynamical downscaling is performed with the Weather Research and Forecasting (WRF) model, and the statistical downscaling method implemented is the Cumulative Distribution Function-transform (CDF-t). The CDF-t is trained using 20 years of WRF-downscaled Climate Forecast System Reanalysis data over the region at a 3-km spatial resolution for the central month of each season. The performance of the two methods is assessed qualitatively, by inspection of quantile-quantile plots, and quantitatively, through the Cramer-von Mises, mean absolute error, and root-mean-square error diagnostics. The hybrid approach is found to provide significantly more skillful forecasts of the observed daily mean and maximum air temperatures than those of the dynamical-only downscaling (for all seasons). The hybrid method proves to be less computationally expensive, and also to give more skillful temperature forecasts (at least for the Finnish near-coastal region).
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| 3. |
- Fonseca, Ricardo, et al.
(författare)
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High-Resolution Dynamical Downscaling of Re-Analysis Data over the Kerguelen Islands using the WRF Model
- 2019
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Ingår i: Journal of Theoretical and Applied Climatology. - : Springer. - 0177-798X .- 1434-4483. ; 135:3-4, s. 1259-1277
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Tidskriftsartikel (refereegranskat)abstract
- We have used the Weather Research and Forecasting (WRF) model to simulate the climate of the Kerguelen Islands (49° S, 69° E) and investigate its inter-annual variability. Here, we have dynamically downscaled 30 years of the Climate Forecast System Reanalysis (CFSR) over these islands at 3-km horizontal resolution. The model output is found to agree well with the station and radiosonde data at the Port-aux-Français station, the only location in the islands for which observational data is available. An analysis of the seasonal mean WRF data showed a general increase in precipitation and decrease in temperature with elevation. The largest seasonal rainfall amounts occur at the highest elevations of the Cook Ice Cap in winter where the summer mean temperature is around 0 °C. Five modes of variability are considered: conventional and Modoki El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), Subtropical IOD (SIOD) and Southern Annular Mode (SAM). It is concluded that a key mechanism by which these modes impact the local climate is through interaction with the diurnal cycle in particular in the summer season when it has a larger magnitude. One of the most affected regions is the area just to the east of the Cook Ice Cap extending into the lower elevations between the Gallieni and Courbet Peninsulas. The WRF simulation shows that despite the small annual variability, the atmospheric flow in the Kerguelen Islands is rather complex which may also be the case for the other islands located in the Southern Hemisphere at similar latitudes.
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| 4. |
- Wang, Jianfeng, 1984-, et al.
(författare)
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Weather Simulation Uncertainty Estimation using Bayesian Hierarchical Model
- 2019
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Ingår i: Journal of Applied Meteorology and Climatology. - : American Meteorological Society. - 1558-8424 .- 1558-8432. ; 58:3, s. 585-603
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Tidskriftsartikel (refereegranskat)abstract
- Estimates of the uncertainty of model output fields (e.g. 2-meter temperature, surface radiation fluxes or wind speed) are of great value to the weather and climate communities. The traditional approach for the uncertainty estimation is to conduct an ensemble of simulations where the model configuration is perturbed, and/or different models are considered. This procedure is very computationally expensive and may not be feasible in particular for higher resolution experiments. In this paper a new method based on Bayesian Hierarchical Models (BHM) that requires just one model run is proposed. It is applied to the Weather Research and Forecasting (WRF) model’s 2-meter temperature in the Botnia-Atlantica region in Scandinavia for a 10-day period in the winter and summer seasons. For both seasons, the estimated uncertainty using the BHM is found to be comparable to that obtained from an ensemble of experiments in which different Planetary Boundary Layer (PBL) schemes are employed. While WRF-BHM is not capable of generating the full set of products obtained from an ensemble of simulations, it can be used to extract commonly used diagnostics including the uncertainty estimation which is the focus of this work. The methodology proposed here is fully general and can easily be extended to any other output variable and numerical model.
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| 5. |
- Cockell, Charles S., et al.
(författare)
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Subsurface scientific exploration of extraterrestrial environments (MINAR 5) : analogue science, technology and education in the Boulby Mine, UK
- 2019
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Ingår i: International Journal of Astrobiology. - : Cambridges Institutes Press. - 1473-5504 .- 1475-3006. ; 18:2, s. 157-182
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Tidskriftsartikel (refereegranskat)abstract
- The deep subsurface of other planetary bodies is of special interest for robotic and human exploration. The subsurface provides access to planetary interior processes, thus yielding insights into planetary formation and evolution. On Mars, the subsurface might harbour the most habitable conditions. In the context of human exploration, the subsurface can provide refugia for habitation from extreme surface conditions. We describe the fifth Mine Analogue Research (MINAR 5) programme at 1 km depth in the Boulby Mine, UK in collaboration with Spaceward Bound NASA and the Kalam Centre, India, to test instruments and methods for the robotic and human exploration of deep environments on the Moon and Mars. The geological context in Permian evaporites provides an analogue to evaporitic materials on other planetary bodies such as Mars. A wide range of sample acquisition instruments (NASA drills, Small Planetary Impulse Tool (SPLIT) robotic hammer, universal sampling bags), analytical instruments (Raman spectroscopy, Close-Up Imager, Minion DNA sequencing technology, methane stable isotope analysis, biomolecule and metabolic life detection instruments) and environmental monitoring equipment (passive air particle sampler, particle detectors and environmental monitoring equipment) was deployed in an integrated campaign. Investigations included studying the geochemical signatures of chloride and sulphate evaporitic minerals, testing methods for life detection and planetary protection around human-tended operations, and investigations on the radiation environment of the deep subsurface. The MINAR analogue activity occurs in an active mine, showing how the development of space exploration technology can be used to contribute to addressing immediate Earth-based challenges. During the campaign, in collaboration with European Space Agency (ESA), MINAR was used for astronaut familiarization with future exploration tools and techniques. The campaign was used to develop primary and secondary school and primary to secondary transition curriculum materials on-site during the campaign which was focused on a classroom extra vehicular activity simulation.
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| 6. |
- Martin-Torres, Javier, et al.
(författare)
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Brine-Induced Tribocorrosion Accelerates Wear on Stainless Steel: Implications for Mars Exploration
- 2021
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Ingår i: Advances in Astronomy. - : Hindawi Publishing Corporation. - 1687-7969 .- 1687-7977. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- Tribocorrosion is a degradation phenomenon of material surfaces subjected to the combined action of mechanical loading and corrosion attack caused by the environment. Although corrosive chemical species such as materials like chloride atoms, chlorides, and perchlorates have been detected on the Martian surface, there is a lack of studies of its impact on materials for landed spacecraft and structures that will support surface operations on Mars. Here, we present a series of experiments on the stainless-steel material of the ExoMars 2020 Rosalind Franklin rover wheels. We show how tribocorrosion induced by brines accelerates wear on the materials of the wheels. Our results do not compromise the nominal ExoMars mission but have implications for future long-term surface operations in support of future human exploration or extended robotic missions on Mars.
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| 7. |
- Singh, Shaktiman, et al.
(författare)
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Quantifying the Congruence between Air and Land Surface Temperatures for Various Climatic and Elevation Zones of Western Himalaya
- 2019
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Ingår i: Remote Sensing. - : MDPI. - 2072-4292. ; 11:24
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Tidskriftsartikel (refereegranskat)abstract
- The surface and near-surface air temperature observations are primary data for glacio-hydro-climatological studies. The in situ air temperature (Ta) observations require intense logistic and financial investments, making it sparse and fragmented particularly in remote and extreme environments. The temperatures in Himalaya are controlled by a complex system driven by topography, seasons, and cryosphere which further makes it difficult to record or predict its spatial heterogeneity. In this regard, finding a way to fill the observational spatiotemporal gaps in data becomes more crucial. Here, we show the comparison of Ta recorded at 11 high altitude stations in Western Himalaya with their respective land surface temperatures (Ts) recorded by Moderate Resolution Imagining Spectroradiometer (MODIS) Aqua and Terra satellites in cloud-free conditions. We found remarkable seasonal and spatial trends in the Ta vs. Ts relationship: (i) Ts are strongly correlated with Ta (R2 = 0.77, root mean square difference (RMSD) = 5.9 °C, n = 11,101 at daily scale and R2 = 0.80, RMSD = 5.7 °C, n = 3552 at 8-day scale); (ii) in general, the RMSD is lower for the winter months in comparison to summer months for all the stations, (iii) the RMSD is directly proportional to the elevations; (iv) the RMSD is inversely proportional to the annual precipitation. Our results demonstrate the statistically strong and previously unreported Ta vs. Ts relationship and spatial and seasonal variations in its intensity at daily resolution for the Western Himalaya. We anticipate that our results will provide the scientists in Himalaya or similar data-deficient extreme environments with an option to use freely available remotely observed Ts products in their models to fill-up the spatiotemporal data gaps related to in situ monitoring at daily resolution. Substituting Ta by Ts as input in various geophysical models can even improve the model accuracy as using spatially continuous satellite derived Ts in place of discrete in situ Ta extrapolated to different elevations using a constant lapse rate can provide more realistic estimates.
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| 8. |
- Durán, Pablo, et al.
(författare)
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Meso-microscale coupling for wind resource assessment using averaged atmospheric stability conditions
- 2019
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Ingår i: Meteorologische Zeitschrift. - : Schweizerbart science publishers. - 0941-2948 .- 1610-1227. ; 28:4, s. 273-291
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Tidskriftsartikel (refereegranskat)abstract
- A methodology to couple Numerical Weather Prediction (NWP) models with steady-state Computational Fluid Dynamic (CFD) models for wind resource assessment applications is proposed. NWP simulations are averaged according to their atmospheric stability and wind direction. The averaged NWP simulations are used to generate the initial and boundary conditions of the CFD model. The method is applied using one year of Weather Research and Forecasting (WRF) simulations at the Honkajoki wind farm in Finland and validated by Sonic Detection and Ranging (SODAR) measurements at the site. It is shown that coupled simulations reproduce a more realistic shear for heights above 150 m. In terms of estimated energy production, there is not a big difference between coupled and standalone models. Nevertheless, a considerable difference in the horizontal wind speed patterns can be seen between the coupled and non-coupled approaches. The WRF model resolution has only a small influence on the coupled CFD results.
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| 9. |
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| 10. |
- Mathanlal, Thasshwin, et al.
(författare)
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Self-Sustainable Monitoring Station for Extreme Environments (S3ME2): Design and validation
- 2019
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Ingår i: 2018 Second International Conference on Green Computing and Internet of Things (ICGCIoT). - : IEEE. - 9781538656570 ; , s. 240-245
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Konferensbidrag (refereegranskat)abstract
- We describe the development of a robust, self-sustainable, versatile environmental monitoring station, the S3ME2, with a multitude of sensors capable of operating in extreme environments (from cold arid sub-arctic regions to hot deserts and high-altitude mountain terrains), providing realtime quality data of critical climate and geophysical parameters for a wide field of research such as pressure, surface and subsurface temperature and humidity, magnetic field and seismic activity. The dedicated communication modem utilizes IoT technology and can deliver this data from remote regions. The S3ME2 has been designed as a low-cost instrument to facilitate the production of multiple units. During the pilot phase, it has demonstrated continuous operability for up to 6 months, including survival during extremely cold, snowy, and low insolation, and low wind periods in the Sub-Arctic region. With its robust design, S3ME2 exploits the use of renewable sources of energy such as solar and wind power to power the system. The S3ME2 has also been designed from a modular point of view with commercial off the shelf components (COTS) and open source hardware, considering long term operability of the station. The sensor modules can be easily added, replaced, or upgraded such that a stable functioning of the system is guaranteed.
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