1,720,981 research outputs found
2000-2019 MODIS Greenland ice sheet monthly 1km albedo grids (MOD10A1M_GR)
No full text1km monthly albedo grids over the Greenland ice sheet
Gapless semi-empirical daily snow and ice albedo from Sentinel-3 OLCI
No full textSnow and ice broadband albedo from Sentinel-3 OLCI measurements after Kokhanovsky et al 2020 (snow areas) and empirical regression (ice areas) (doi:10.22008/FK2/SNX8L6) where two post-processing steps have been applied:
- downward outlier detection and removal based on a relation as a function of elevation
- cumulative data filling (gapless product
Snow and ice broadband albedo from Sentinel-3 OLCI measurements and empirical regression
No full textThis dataset contains:
snow and ice broadband albedo mosaics over Greenland for years 2018 and 2019 computed from a simple empirical approach (Wehrlé et al, 2021).
This approach consists of a fit between 4729 hourly PROMICE albedo measurements and the nearest in time and space OLCI Top of Atmosphere (TOA) reflectances spanning 3 years (2017–2019). We then defined the broadband albedo from a fit to the average of four OLCI TOA reflectances:
A = α (R400 nm+ R560 nm+ R865 nm + R1020 nm) / 4+ β
where α corresponds to the slope of the linear regression between OLCI TOA and PROMICE albedo measurements (1.003), and β is its intercept (0.058).
Clouds were detected and thereafter masked in Sentinel-3 imagery using the Simple Cloud Detection Algorithm (SCDA) version 2.0 (Metsämäki et al. 2015; Wehrlé & Box 2021). This algorithm consists of up to six tests on Sea and Land Surface Temperature Radiometer (SLSTR) TOA reflectances (550 and 1600 nm) and brightness temperatures (3.7, 11 and 12 μm).
Processing scripts:
https://github.com/AdrienWehrle/SICE_tools
Related studies:
- Wehrlé A.; Box J.E.; Niwano M.; Anesio A.M.; Fausto R.S., Greenland bare ice
albedo from PROMICE automatic weather station measurements and
Sentinel-3 satellite observations, GEUS bulletin, in press 2021
- Wehrlé, A. & Box, J., SICE implementation of the Simple Cloud Detection Algorithm (SCDA) v2.0, GEUS Dataverse, 2021 https://doi.org/10.22008/FK2/N0XWSJ
- Metsämäki, S.; Pulliainen, J.; Salminen, M.; Luojus, K.; Wiesmann, A.; Solberg, R.; Böttcher, K.; Hiltunen, M.;Ripper E, Introduction to globSnow snow extent products with considerations for accuracy assessment. Remote Sensing of Environment, 2015
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SICEv2.3.2 Greenland snow and ice broadband albedo and surface optical properties from Sentinel-3’s OLCI at 1000 m resolution, 2017-2023
No full textProcessing scripts:
https://github.com/GEUS-SICE/SICE
https://github.com/GEUS-SICE/pySIC
Daily Near Real Time (NRT) Iceland snow and ice broadband albedo, SSA and cloud mask from Sentinel-3 (500m resolution)
No full textProcessing scripts:
https://github.com/GEUS-SICE/SIC
Snow broadband albedo, specific surface area and optical grain diameter from Sentinel-3's OLCI, daily 1 km mosaics, Greenland
No full textThis dataset contains:
albedo_bb_planar_sw.tif
Shortwave broadband planar albedo (300-2400 nm)
diagnostic_retrieval.tif
Per-pixel information about the retrieval.
al.tif
Effective absorption length (mm)
r0.tif
Reflectance of a semi-infinite non-absorbing snow layer
snow_specific_area.tif
Snow specific surface area (m^2 kg^-1)
grain_diameter.tif
Snow effective optical grain diameter (mm)
Can be used to flag surface melt above 0.64 mm.
For TOA reflectance, see:
Vandecrux, Baptiste; Box, Jason; Mankoff, Ken; Wehrlé, Adrien, 2021, "OLCI top-of-the-atmosphere reflectances with auxillary data, daily 1 km mosaics, Greenland",
https://doi.org/10.22008/FK2/B674AR
, GEUS Dataverse
In this version:
- Clouds have been removed
- SNAP7 was used with per-pixel geocoding
- pySICEv1.4 was used
Processing scripts:
https://github.com/GEUS-SICE/SICE
https://github.com/GEUS-SICE/pySICE
ATBD:
Kokhanovsky, A.; Box, J.; Vandecrux, B. Pre-operational Sentinel-3 Snow and Ice (SICE) Products: Algorithm Theoretical Basis Document. Preprints 2020,
https://doi.org/10.20944/preprints202009.0529.v1).
Related studies:
Kokhanovsky, A.; Lamare, M.; Danne, O.; Brockmann, C.; Dumont, M.; Picard, G.; Arnaud, L.; Favier, V.; Jourdain, B.; Le Meur, E.; Di Mauro, B.; Aoki, T.; Niwano, M.; Rozanov, V.; Korkin, S.; Kipfstuhl, S.; Freitag, J.; Hoerhold, M.; Zuhr, A.; Vladimirova, D.; Faber, A.-K.; Steen-Larsen, H.C.; Wahl, S.; Andersen, J.K.; Vandecrux, B.; van As, D.; Mankoff, K.D.; Kern, M.; Zege, E.; Box, J.E. Retrieval of Snow Properties from the Sentinel-3 Ocean and Land Colour Instrument. Remote Sens. 2019, 11, 2280.
https://doi.org/10.3390/rs11192280
Kokhanovsky, A.; Box, J.E.; Vandecrux, B.; Mankoff, K.D.; Lamare, M.; Smirnov, A.; Kern, M. The Determination of Snow Albedo from Satellite Measurements Using Fast Atmospheric Correction Technique. Remote Sens. 2020, 12, 234.
https://doi.org/10.3390/rs12020234
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SICE implementation of the Simple Cloud Detection Algorithm (SCDA) v2.0
No full textThe Programme for Monitoring of the Greenland Ice Sheet (PROMICE) provides surface meteorological and glaciological measurements from widespread on-ice automatic weather stations since mid-2007. In this study, we use 105 PROMICE ice-ablation time series to identify the timing of seasonal bare-ice onset preceded by snow cover conditions. From this collection, we find a bare-ice albedo at ice-ablation onset (here called bare-ice-onset albedo) of 0.565 ± 0.109 that has no apparent spatial dependence among 20 sites across Greenland. We then apply this snow-to-ice albedo transition value to measure the variations in daily Greenland bare-ice area in Sentinel-3 optical satellite imagery covering the extremely low and high respective melt years of 2018 and 2019. Daily Greenland bare-ice area peaked at 153 489 km² in 2019, 1.9 times larger than in 2018 (80 220 km²), equating to 9.0% (in 2019) and 4.7% (in 2018) of the ice sheet area
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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