- 标题
- 摘要
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- 实验方案
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Terrestrial Remote Sensing of Snowmelt in a Diverse High-Arctic Tundra Environment Using Time-Lapse Imagery
摘要： Snow cover is one of the crucial factors influencing the plant distribution in harsh Arctic regions. In tundra environments, wind redistribution of snow leads to a very heterogeneous spatial distribution which influences growth conditions for plants. Therefore, relationships between snow cover and vegetation should be analyzed spatially. In this study, we correlate spatial data sets on tundra vegetation types with snow cover information obtained from orthorectification and classification of images collected from a time-lapse camera installed on a mountain summit. The spatial analysis was performed over an area of 0.72 km2, representing a coastal tundra environment in southern Svalbard. The three-year monitoring is supplemented by manual measurements of snow depth, which show a statistically significant relationship between snow abundance and the occurrence of some of the analyzed land cover types. The longest snow cover duration was found on 'rock debris' type and the shortest on 'lichen-herb-heath tundra', resulting in melt-out time-lag of almost two weeks between this two land cover types. The snow distribution proved to be consistent over the different years with a similar melt-out pattern occurring in every analyzed season, despite changing melt-out dates related to different weather conditions. The data set of 203 high resolution processed images used in this work is available for download in the supplementary materials.
关键词： tundra vegetation,arctic,snow cover dynamics,snowmelt,orthorectification,time-lapse photography,ground based camera,Svalbard,tundra environment
更新于2025-09-23 15:23:52
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Remote sensing quantifies widespread abundance of permafrost region disturbances across the Arctic and Subarctic
摘要： Local observations indicate that climate change and shifting disturbance regimes are causing permafrost degradation. However, the occurrence and distribution of permafrost region disturbances (PRDs) remain poorly resolved across the Arctic and Subarctic. Here we quantify the abundance and distribution of three primary PRDs using time-series analysis of 30-m resolution Landsat imagery from 1999 to 2014. Our dataset spans four continental-scale transects in North America and Eurasia, covering ~10% of the permafrost region. Lake area loss (?1.45%) dominated the study domain with enhanced losses occurring at the boundary between discontinuous and continuous permafrost regions. Fires were the most extensive PRD across boreal regions (6.59%), but in tundra regions (0.63%) limited to Alaska. Retrogressive thaw slumps were abundant but highly localized (<10?5%). Our analysis synergizes the global-scale importance of PRDs. The findings highlight the need to include PRDs in next-generation land surface models to project the permafrost carbon feedback.
关键词： permafrost,disturbances,Subarctic,fires,remote sensing,lakes,retrogressive thaw slumps,Arctic
更新于2025-09-23 15:23:52
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Simulated and observed horizontal inhomogeneities of optical thickness of Arctic stratus
摘要： Two-dimensional (2D) horizontal fields of cloud optical thickness derived from airborne measurements of solar spectral radiance during the Vertical Distribution of Ice in Arctic Clouds (VERDI) campaign (carried out in Inuvik, Canada in April/May 2012) are compared with semi-idealized Large Eddy Simulations (LES) of Arctic stratus performed with the COnsortium for Small-Scale MOdeling (COSMO) atmospheric model. The input for the LES is obtained from collocated airborne dropsonde observations. Four consecutive days of a persistent Arctic stratus observed above the sea-ice free Beaufort Sea are selected for the comparison. Macrophysical cloud properties such as cloud top altitude and vertical extent are well captured by COSMO. Cloud horizontal inhomogeneity quantified by the standard deviation and one-dimensional (1D) inhomogeneity parameters show that COSMO produces only half of the measured horizontal cloud inhomogeneities, while the directional structure of the cloud inhomogeneity is well represented by the model. Differences between the individual cases are mainly associated with the wind shear near cloud top and the vertical structure of the atmospheric boundary layer. A sensitivity study changing the wind velocity in COSMO by a vertically constant scaling factor shows that the directional cloud inhomogeneity structures strongly depend on the mean wind speed. A threshold wind velocity is identified, which determines when the cloud inhomogeneity stops increasing with increasing wind velocity.
关键词： airborne measurements,COSMO model,horizontal inhomogeneity,wind speed sensitivity,Large Eddy Simulation,Arctic stratus,cloud optical thickness
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - Multiband Polarimetric SAR in Arctic Scenarios
摘要： In relation to a working group on future capabilities for applications in the Arctic region, the Danish Defence Acquisition and Logistics Organization (DALO) has conducted test campaigns with the multi-band, fully polarimetric F-SAR system owned by the German Aerospace Center (DLR) in order to explore the possibilities that advanced synthetic aperture radar (SAR) systems provide for surveillance, change detection, moving target identification and high resolution imaging. Examples of results and some preliminary conclusions are presented in this paper.
关键词： detection,SAR,polarimetry,surveillance,Arctic,recognition
更新于2025-09-23 15:23:52
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The influence of a protective environment during direct laser deposition on the formation of structure and properties of steel F690W (09CrNi2MoCu)
摘要： The article presents the study of the direct laser deposition (DLD) process of cold-resistant steel 09CrNi2MoCu (F690W). As a result, many bainite transformation products are produced. The formation of a bainitic structure in the process of deposition is still little studied; in the process of the growth of the deposited wall, the microstructure undergoes a phase transformation. The work details the equipment for direct laser deposition, describes the main technological parameters of the regime, and studies the surface of the steel powder. Mechanical tests for impact toughness were carried out at a temperature of (cid:1)40 (cid:1)C, with different laser emission powers. The results are given using the initial powder, as well as used powder with a different mixing ratio, and the results are analyzed. As a result of the study, it was established that the fractional composition of the F620W alloy powder has a signi?cant effect on the mechanical characteristics of samples obtained by direct laser deposition. The effect of recycled powder on the mechanical properties of the samples obtained is given.
关键词： Direct laser deposition,Arctic,Bainite structures,Additive technology,Cold resistant steel,Direct metal deposition
更新于2025-09-23 15:19:57
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Assessment with Controlled In-Situ Data of the Dependence of L-Band Radiometry on Sea-Ice Thickness
摘要： The European Space Agency (ESA) Soil Moisture and Ocean Salinity (SMOS) and the National Aeronautics and Space Administration (NASA) Soil Moisture Active Passive (SMAP) missions are providing brightness temperature measurements at 1.4 GHz (L-band) for about 10 and 4 years respectively. One of the new areas of geophysical exploitation of L-band radiometry is on thin (i.e., less than 1 m) Sea Ice Thickness (SIT), for which theoretical and empirical retrieval methods have been proposed. However, a comprehensive validation of SIT products has been hindered by the lack of suitable ground truth. The in-situ SIT datasets most commonly used for validation are affected by one important limitation: They are available mainly during late winter and spring months, when sea ice is fully developed and the thickness probability density function is wider than for autumn ice and less representative at the satellite spatial resolution. Using Upward Looking Sonar (ULS) data from the Woods Hole Oceanographic Institution (WHOI), acquired all year round, permits overcoming the mentioned limitation, thus improving the characterization of the L-band brightness temperature response to changes in thin SIT. State-of-the-art satellite SIT products and the Cumulative Freezing Degree Days (CFDD) model are veri?ed against the ULS ground truth. The results show that the L-band SIT can be meaningfully retrieved up to 0.6 m, although the signal starts to saturate at 0.3 m. In contrast, despite the simplicity of the CFDD model, its predicted SIT values correlate very well with the ULS in-situ data during the sea ice growth season. The comparison between the CFDD SIT and the current L-band SIT products shows that both the sea ice concentration and the season are fundamental factors in?uencing the quality of the thickness retrieval from L-band satellites.
关键词： sea ice thickness,retrieval model validation,upward looking sonar,Arctic,Soil Moisture Active Passive (SMAP),Soil Moisture and Ocean Salinity (SMOS) mission,L-band radiometry
更新于2025-09-23 15:19:57
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Bathymetric Photogrammetry to Update CHS Charts: Comparing Conventional 3D Manual and Automatic Approaches
摘要： The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through approximately 1000 navigational charts as well as hundreds of publications. One of the greatest challenges faced by the CHS is removing gaps in bathymetric survey data, particularly in the Canadian Arctic where only 6% of navigational water is surveyed to modern standards. Therefore, the CHS has initiated a research project to explore remote sensing methods to improve Canadian navigational charts. The major components of this project explore satellite derived bathymetry (SDB), coastline change detection and coastline extraction. This paper focuses on the potential of two stereo satellite techniques for deriving SDB: (i) automatic digital elevation model (DEM) extraction using a semi-global matching method, and (ii) 3D manual delineation of depth contours using visual stereoscopic interpretation. Analysis focused on quantitative assessment which compared estimated depths from both automatic and 3D manual photogrammetric approaches against available in situ survey depths. The results indicate that the 3D manual approach provides an accuracy of <2 m up to a depth of 15 m. Comparable results were obtained from the automatic approach to a depth of 12 m. For almost all investigated depth ranges for both techniques, uncertainties were found to be within the required vertical accuracies for the International Hydrographic Organization category zone of confidence (CATZOC) level C classification for hydrographic surveys. This indicates that both techniques can be used to derive navigational quality bathymetric information within the investigated study site. While encouraging, neither technique was found to offer a single solution for the complete estimation of depth within the study area. As a result of these findings, the CHS envisions a hybrid approach where stereo- and reflectance-based bathymetry estimation techniques are implemented to provide the greatest understanding of depth possible from satellite imagery. Overall, stereo photogrammetry techniques will likely allow for new potential for supporting the improvement of CHS charts in areas where modern surveys have not yet been obtained.
关键词： navigational charts,satellite derived bathymetry (SDB),stereo photogrammetry,Canadian Arctic,Canadian Hydrographic Service
更新于2025-09-19 17:15:36
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[IEEE 2019 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Vladivostok, Russia (2019.10.1-2019.10.4)] 2019 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) - Study of Solar Cells at Low Temperatures in the Arctic
摘要： Currently, the Arctic is of interest to many countries of the world. The challenge for exploring the Arctic is harsh weather. Researchers have big problems due to global climate change. In the Arctic, it is very difficult for researchers to produce electricity. Most often, they use gas generators that pollute the environment. We propose using solar modules to generate electricity in the Arctic from March to November. Most studies focus on the operation of solar cells at high temperatures and overheating. In the Arctic, most often the temperature is quite low. Even in summer, the temperature does not exceed low 12°C. The topic of the operation of solar cells at temperatures has not been studied well enough. This study focuses on the operation of solar cells at low temperatures. We investigated single-crystal, polycrystalline and amorphous solar cells and found that with decreasing temperature the efficiency of solar cells increases. Polycrystalline and amorphous solar cells have shown the best results.
关键词： solar cell energy production,conversion efficiency,Arctic.,solar cell,low temperatures,power generation,alternative energy sources
更新于2025-09-16 10:30:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Monitoring the Cryosphere for Commerce and Transportation
摘要： Changes in the Arctic sea ice present opportunities and challenges for commerce and transportation. Monitoring and forecasting the conditions and changes in the sea ice to increase the environmental intelligence in the Arctic is a critical component of the infrastructure required to exploit these opportunities. The Joint Polar Satellite System (JPSS) provides global coverage from five sensors of a variety of environmental parameters including observations of cryosphere. JPSS provides these observations on an operational basis 24x7 and will continue these observations through the 2030’s. The JPSS Proving Ground and Risk Reduction (PGRR) program is facilitating an initiative to increase or improve the use and value of cryosphere data products in user products, services, and application or service areas [1]. JPSS aims to evaluate and demonstrate the use of sea ice products for monitoring and forecast applications and work with the user communities to understand how these applications support commerce and transportation in the Arctic.
关键词： Arctic,U.S. Government Agencies,Monitoring,Satellites,Sea Ice
更新于2025-09-10 09:29:36
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Horizontal and vertical structure of reactive bromine events probed by bromine monoxide MAX-DOAS spectroscopy
摘要： Heterogeneous photochemistry converts bromide (Br-) to reactive bromine species (Br atoms and bromine monoxide, BrO) that dominate Arctic springtime chemistry. This phenomenon has many impacts such as boundary-layer ozone depletion, mercury oxidation and deposition, and modification of the fate of hydrocarbon species. To study environmental controls on reactive bromine events, the BRomine, Ozone, and Mercury EXperiment (BROMEX) was carried out from early March to mid April 2012 near Barrow (Utqia?vik), Alaska. We measured horizontal and vertical gradients in BrO with Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrumentation at three sites, two mobile and one fixed. During the campaign, a large crack in the sea ice (an open lead) formed pushing one instrument package ~250km downwind from Barrow (Utqia?vik). Convection associated with the open lead converted the BrO vertical structure from a surface-based event to a lofted event downwind of the lead influence. The column abundance of BrO downwind of the re-freezing lead was comparable to upwind amounts indicating direct reactions on frost flowers or open seawater was not a major reactive bromine source. When these three sites were separated by ~30km length scales of unbroken sea ice, the BrO amount and vertical distributions were highly correlated for most of the time, indicating the horizontal length scales of BrO events were typically larger than ~30 km in the absence of sea-ice features. Although correlation dominated most of the time, rapid changes in BrO with edges significantly sharper than this ~30km length scale episodically transported between the sites, indicating BrO events were large but with sharp edge contrasts. BrO was often found in shallow layers that recycled reactive bromine via heterogeneous reactions on snowpack. Episodically, these surface-based events propagated aloft, which required enhanced aerosol extinction aloft; however, the presence of aerosol particles aloft was not sufficient to produce BrO aloft. Highly depleted ozone (<1 nmol mol-1) repartitioned reactive bromine away from BrO and drove BrO events aloft in cases. This work demonstrates the interplay between atmospheric mixing and heterogeneous chemistry that affects the vertical structure and horizontal extent of reactive bromine events.
关键词： ozone depletion,reactive bromine,mercury oxidation,Arctic,MAX-DOAS
更新于2025-09-09 09:28:46