scholarly journals Remote Sensing of Ice Conditions in the Southeastern Baltic Sea and in the Curonian Lagoon and Validation of SAR-Based Ice Thickness Products

2020 ◽  
Vol 12 (22) ◽  
pp. 3754
Author(s):  
Igor E. Kozlov ◽  
Elena V. Krek ◽  
Andrey G. Kostianoy ◽  
Inga Dailidienė
Keyword(s):  
Sea Water ◽  
Temporal Analysis ◽  
In Situ Measurements ◽  
Curonian Lagoon ◽  
Ice Thickness ◽  
Finnish Meteorological Institute ◽  
Ice Conditions ◽  
Ice Regime ◽  
Sar Data

Here we analyze ice conditions in the Southeastern Baltic (SEB) Sea and in the Curonian Lagoon (CL) using spaceborne synthetic aperture radar (SAR) data combined with in-situ measurements from coastal stations during four winter seasons between 2009–2013. As shown, the ice conditions in the SEB and in the CL are strongly varying from year to year and do not always correlate with each other. In the SEB, ice cover may form only within 5–15 km band along the coast or spread up to 100 km offshore covering almost the entire region. The mean ice season duration here is 45 days. The CL is almost fully ice-covered every year apart of its northern part subjected to sea water inflow and active shipping. The ice regime is also more stable here, however, it also possesses multiple periods of partial melting and re-freezing. In this study we also perform a validation of three SAR-based ice thickness products (Envisat ASAR 0.5-km and 1-km, and RADARSAT-2 0.5-km) produced by the Finnish Meteorological Institute versus in-situ measurements in the CL. As shown, all satellite products perform rather well for the periods of gradual ice thickness growth. When the ice thickness grows rapidly, all products underestimate the observed values by 10–20 cm (20–50%). The best results were obtained for the RADARSAT-2 ice thickness product with the highest R2 value (0.68) and the root mean square error around 8 cm. The results of the study clearly show that multi-mission SAR data are very useful for spatial and temporal analysis of the ice regime in coastal waters and semi-enclosed shallow water bodies where the number of field observations is insufficient or lacking.

scholarly journals In situ measurements of the direct-current conductivity of Antarctic Sea ice: implications for airborne electromagnetic Sounding of Sea-ice thickness

2006 ◽  
Vol 44 ◽  
pp. 217-223 ◽  
Author(s):  
J.E. Reid ◽  
A. Pfaffling ◽  
A.P. Worby ◽  
J.R. Bishop
Keyword(s):  
Sea Ice ◽  
Direct Current ◽  
Sea Water ◽  
Vertical Direction ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice ◽  
Direct Current Conductivity

AbstractAirborne, Ship-borne and Surface low-frequency electromagnetic (EM) methods have become widely applied to measure Sea-ice thickness. EM responses measured over Sea ice depend mainly on the Sea-water conductivity and on the height of the Sensor above the Sea-ice–sea-water interface, but may be Sensitive to the Sea-ice conductivity at high excitation frequencies. We have conducted in Situ measurements of direct-current conductivity of Sea ice using Standard geophysical geoelectrical methods. Sea-ice thickness estimated from the geoelectrical Sounding data was found to be consistently underestimated due to the pronounced vertical-to-horizontal conductivity anisotropy present in level Sea ice. At five Sites, it was possible to determine the approximate horizontal and vertical conductivities from the Sounding data. The average horizontal conductivity was found to be 0.017 Sm–1, and that in the vertical direction to be 9–12 times higher. EM measurements over level Sea ice are Sensitive only to the horizontal conductivity. Numerical modelling has Shown that the assumption of zero Sea-ice conductivity in interpretation of airborne EM data results in a negligible error in interpreted thickness for typical level Antarctic Sea ice.

scholarly journals Aerosol measurements at the Gual Pahari EUCAARI station: preliminary results from in-situ measurements

2010 ◽  
Vol 10 (15) ◽  
pp. 7241-7252 ◽  
Author(s):  
A.-P. Hyvärinen ◽  
H. Lihavainen ◽  
M. Komppula ◽  
T. S. Panwar ◽  
V. P. Sharma ◽  
...  
Keyword(s):  
Rainy Season ◽  
In Situ Measurements ◽  
Aerosol Size Distribution ◽  
Finnish Meteorological Institute ◽  
Convective Mixing ◽  
Average Fraction ◽  
Mode Size ◽  
First Time ◽  
Pm10 Mass

Abstract. The Finnish Meteorological Institute (FMI), together with The Energy and Resources Institute of India (TERI), contributed to the European Integrated project on Aerosol Cloud Climate and Air Quality Interactions, EUCAARI, by conducting aerosol measurements in Gual Pahari, India, from December 2007 to January 2010. This paper describes the station setup in detail for the first time and provides results from the aerosol in-situ measurements, which include PM and BCe masses, aerosol size distribution from 4 nm to 10 μm, and the scattering and absorption coefficients. The seasonal variation of the aerosol characteristics was very distinct in Gual Pahari. The highest concentrations were observed during the winter and the lowest during the rainy season. The average PM10 concentration (at STP conditions) was 216 μgm−3 and the average PM2.5 concentration was 126 μgm−3. A high percentage (4–9%) of the PM10 mass consisted of BCe which indicates anthropogenic influence. The percentage of BCe was higher during the winter; and according to the diurnal pattern of the BCe fraction, the peak occurred during active traffic hours. Another important source of aerosol particles in the area was new particle formation. The nucleated particles grew rapidly reaching the Aitken and accumulation mode size, thus contributing considerably to the aerosol load. The rainy season decreased the average fraction of particle mass in the PM2.5 size range, i.e. of secondary origin. The other mechanism decreasing the surface concentrations was based on convective mixing and boundary layer evolution. This diluted the aerosol when sun radiation and the temperature was high, i.e. especially during the pre-monsoon day time. The lighter and smaller particles were more effectively diluted.

scholarly journals Snow depth uncertainty and its implications on satellite derived Antarctic sea ice thickness

2018 ◽  
Author(s):  
Daniel Price ◽  
Iman Soltanzadeh ◽  
Wolfgang Rack
Keyword(s):  
Sea Ice ◽  
Snow Depth ◽  
Snow Accumulation ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Growth Season ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice ◽  
Fast Ice

Abstract. Knowledge of the snow depth distribution on Antarctic sea ice is poor but is critical to obtaining sea ice thickness from satellite altimetry measurements of freeboard. We examine the usefulness of various snow products to provide snow depth information over Antarctic fast ice with a focus on a novel approach using a high-resolution numerical snow accumulation model (SnowModel). We compare this model to results from ECMWF ERA-Interim precipitation, EOS Aqua AMSR-E passive microwave snow depths and in situ measurements at the end of the sea ice growth season. The fast ice was segmented into three areas by fastening date and the onset of snow accumulation was calibrated to these dates. SnowModel falls within 0.02 m snow water equivalent (swe) of in situ measurements across the entire study area, but exhibits deviations of 0.05 m swe from these measurements in the east where large topographic features appear to have caused a positive bias in snow depth. AMSR-E provides swe values half that of SnowModel for the majority of the sea ice growth season. The coarser resolution ERA-Interim, not segmented for sea ice freeze up area reveals a mean swe value 0.01 m higher than in situ measurements. These various snow datasets and in situ information are used to infer sea ice thickness in combination with CryoSat-2 (CS-2) freeboard data. CS-2 is capable of capturing the seasonal trend of sea ice freeboard growth but thickness results are highly dependent on the assumptions involved in separating snow and ice freeboard. With various assumptions about the radar penetration into the snow cover, the sea ice thickness estimates vary by up to 2 m. However, we find the best agreement between CS-2 derived and in situ thickness when a radar penetration of 0.05-0.10 m into the snow cover is assumed.

Environmental influences on historical monuments: a multi-analytical characterization of degradation materials

2020 ◽  
Author(s):  
Joao Pedro Veiga ◽  
Fernanda Carvalho ◽  
Hugo Aguas ◽  
Giampiero Montesperelli ◽  
Elissavet Kavoulaki ◽  
...  
Keyword(s):  
Sea Water ◽  
Science And Technology ◽  
In Situ Measurements ◽  
Ex Situ ◽  
The European Union ◽  
Horizon 2020 ◽  
Surrounding Environment ◽  
Supporting Material ◽  
Salt Efflorescence

<div> <p>The Minoan Palace of Knossos and the Venetian coastal fortress “Rocca a mare” (Koules), located in Heraklion, Crete, Greece, are two important monuments for the history of mankind particularly vulnerable to environmental conditions, since they are located in an island subjected to strong variations in humidity and, as in the case of the Venetian fortress, in direct contact with sea water. In this type of surrounding environment, the formation of salt efflorescence as well as various other soluble salts crusts is a common situation. They occur according to the existing solubilization and crystallization conditions and can happen either in exterior or interior areas of the monuments. Their presence may stimulate further degradation, either due to the chemical dissolution of the substrate materials or due to the mechanical actions created by the formation of crystals, which may result in the decay of the substrate.</p> <p>A set of samples from both monuments were analysed using various laboratory (ex-situ) analytical methods such as optical microscopy (OM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy and Laser-Induced Breakdown Spectroscopy (LIBS). In-situ measurements using portable Raman and LIBS instruments were also performed. The comparative results from ex-situ analysis and in-situ measurements will be presented with emphasis to the chemical composition of the crusts and their origin. Results indicate that observed stalactites and salt efflorescence are directly related to the type of supporting material and the conditions of the surrounding environment. In general, the formation of crusts and salts are due to processes of alteration of the supporting material while the high impact of sea salt on the formation of the efflorescence at the Venetian coastal fortress was also confirmed.</p> <p> </p> <p>[1] This work was supported by the European Union’s Framework Programme for Research and Innovation HORIZON 2020 under Grant Agreement 700395 project HERACLES.</p> <p>Acknowledgment to the Portuguese Foundation for Science and Technology (FCT) UID/EAT/00729/2013 and EAT/00729-3 by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT—Portuguese Foundation for Science and Technology under the project number POCI-01-0145-FEDER-007688, Reference UID/CTM/50025/2013 NOVA.ID.FCT, and the PhD Scholarship SFRH/BD/145308/2019.</p> </div>

scholarly journals Can we extend local sea-ice measurements to satellite scale? An example from the N-ICE2015 expedition

2017 ◽  
Vol 59 (76pt2) ◽  
pp. 163-172 ◽  
Author(s):  
Anja Rösel ◽  
Jennifer King ◽  
Anthony P. Doulgeris ◽  
Penelope M. Wagner ◽  
A. Malin Johansson ◽  
...  
Keyword(s):  
Sea Ice ◽  
Satellite Data ◽  
Arctic Sea Ice ◽  
Ice Thickness ◽  
Remotely Sensed Data ◽  
Sea Ice Thickness ◽  
In Situ Data ◽  
Ice Conditions ◽  
Area North

ABSTRACTKnowledge of Arctic sea-ice conditions is of great interest for Arctic residents, as well as for commercial usage, and to study the effects of climate change. Information gained from analysis of satellite data contributes to this understanding. In the course of using in situ data in combination with remotely sensed data, the question of how representative local scale measurements are of a wider region may arise. We compare in situ total sea-ice thickness measurements from the Norwegian young sea ICE expedition in the area north of Svalbard with airborne-derived total sea-ice thickness from electromagnetic soundings. A segmented and classified synthetic aperture radar (SAR) quad-pol ALOS-2 Palsar-2 satellite scene was grouped into three simplified ice classes. The area fractions of the three classes are: 11.2% ‘thin’, 74.4% ‘level’, and 14.4% ‘deformed’. The area fractions of the simplified classes from ground- and helicopter-based measurements are comparable with those achieved from the SAR data. Thus, this study shows that there is potential for a stepwise upscaling from in situ, to airborne, to satellite data, which allow us to assess whether in situ data collected are representative of a wider region as observed by satellites.

scholarly journals Snow-driven uncertainty in CryoSat-2-derived Antarctic sea ice thickness – insights from McMurdo Sound

2019 ◽  
Vol 13 (4) ◽  
pp. 1409-1422
Author(s):  
Daniel Price ◽  
Iman Soltanzadeh ◽  
Wolfgang Rack ◽  
Ethan Dale
Keyword(s):  
Sea Ice ◽  
Snow Depth ◽  
Snow Accumulation ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Growth Season ◽  
Mcmurdo Sound ◽  
Sea Ice Thickness ◽  
Antarctic Sea Ice

Abstract. Knowledge of the snow depth distribution on Antarctic sea ice is poor but is critical to obtaining sea ice thickness from satellite altimetry measurements of the freeboard. We examine the usefulness of various snow products to provide snow depth information over Antarctic fast ice in McMurdo Sound with a focus on a novel approach using a high-resolution numerical snow accumulation model (SnowModel). We compare this model to results from ECMWF ERA-Interim precipitation, EOS Aqua AMSR-E passive microwave snow depths and in situ measurements at the end of the sea ice growth season in 2011. The fast ice was segmented into three areas by fastening date and the onset of snow accumulation was calibrated to these dates. SnowModel captures the spatial snow distribution gradient in McMurdo Sound and falls within 2 cm snow water equivalent (s.w.e) of in situ measurements across the entire study area. However, it exhibits deviations of 5 cm s.w.e. from these measurements in the east where the effect of local topographic features has caused an overestimate of snow depth in the model. AMSR-E provides s.w.e. values half that of SnowModel for the majority of the sea ice growth season. The coarser-resolution ERA-Interim produces a very high mean s.w.e. value 20 cm higher than the in situ measurements. These various snow datasets and in situ information are used to infer sea ice thickness in combination with CryoSat-2 (CS-2) freeboard data. CS-2 is capable of capturing the seasonal trend of sea ice freeboard growth but thickness results are highly dependent on what interface the retracked CS-2 height is assumed to represent. Because of this ambiguity we vary the proportion of ice and snow that represents the freeboard – a mathematical alteration of the radar penetration into the snow cover – and assess this uncertainty in McMurdo Sound. The ranges in sea ice thickness uncertainty within these bounds, as means of the entire growth season, are 1.08, 4.94 and 1.03 m for SnowModel, ERA-Interim and AMSR-E respectively. Using an interpolated in situ snow dataset we find the best agreement between CS-2-derived and in situ thickness when this interface is assumed to be 0.07 m below the snow surface.

scholarly journals Spring sea-ice evolution in Rijpfjorden (80° N), Svalbard, from in situ measurements and ice mass-balance buoy (IMB) data

2013 ◽  
Vol 54 (62) ◽  
pp. 253-260 ◽  
Author(s):  
Caixin Wang ◽  
Liqiong Shi ◽  
Sebastian Gerland ◽  
Mats A. Granskog ◽  
Angelika H.H. Renner ◽  
...  
Keyword(s):  
Sea Ice ◽  
Mass Balance ◽  
Ice Core ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Core Analysis ◽  
Svalbard Archipelago ◽  
Ice Mass Balance ◽  
Snow And Ice

AbstractRijpfjorden (808 N, 22° E) is a high-Arctic fjord on Nordaustlandet in the Svalbard archipelago. To monitor the thermodynamic change of sea ice in spring, an ice mass-balance buoy (IMB) was deployed for 2.5 months (10 April–26 June 2011), with accompanying in situ measurements, sea-ice sampling on three occasions and ice-core analysis. Uncertainties and sources of error in in situ measurements and IMB data are discussed. The in situ measurements, ice-core analysis and IMB data together depict the development of snow and ice in spring. Snow and ice thickness exhibited large spatial and temporal variability. After relatively stable conditions with only little change in ice thickness and accumulation of snow, a layer of superimposed ice ∼0.06 m thick formed at the snow-ice interface due to refreezing of snow meltwater in late spring. Ice thickness (except for growth of superimposed ice) did not change significantly based on in situ observations. In contrast, the under-ice sonar data from the IMB show reflections from a layer deeper than the underside of the ice during the melting phase. This can be explained as a reflection of the sonar pulses from an interface between a freshwater layer under the ice and more saline water below, or as a false-bottom formation.

scholarly journals Uncertainty Assessment of Ice Discharge Using GPR-Derived Ice Thickness from Gourdon Glacier, Antarctic Peninsula

Geosciences ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 12 ◽  
Author(s):  
Stefan Lippl ◽  
Norbert Blindow ◽  
Johannes J. Fürst ◽  
Sebastián Marinsek ◽  
Thorsten C. Seehaus ◽  
...  
Keyword(s):  
Uncertainty Assessment ◽  
In Situ Measurements ◽  
Ice Thickness ◽  
Outlet Glacier ◽  
In Situ Data ◽  
Continuity Equations ◽  
Reconstruction Methods ◽  
A Minor ◽  
Ground Penetrating

Ice cliffs within a glacier represent a challenge for the continuity equations used in many glacier models by interrupting the validity of input parameters. In the case of Gourdon Glacier on James Ross Island, Antarctica, a ∼300–500 m high, almost vertical cliff, separates the outlet glacier from its main accumulation area on the plateau of the island. In 2017 and 2018 we conducted ice thickness measurements during two airborne ground penetrating radar campaigns in order to evaluate differences to older measurements from the 1990s. The observed differences are mostly smaller than the estimated error bars. In comparison to the in situ data, the published “consensus ice thickness estimate” strongly overestimates the ice thickness at the outlet. We analyse three different interpolation and ice thickness reconstruction methods. One approach additionally includes the mass input from the plateau. Differences between the interpolation methods have a minor impact on the ice discharge estimation if the used flux gates are in areas with a good coverage of in situ measurements. A much stronger influence was observed by uncertainties in the glacier velocities derived from remote sensing, especially in the direction of the velocity vector in proximity to the ice cliff. We conclude that the amount of in situ measurements should be increased for specific glacier types in order to detect biases in modeled ice thickness and ice discharge estimations.

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