scholarly journals Long-term accumulation and improvements in seismic event data for the polar regions by the International Seismological Centre

Polar Science ◽  
2015 ◽  
Vol 9 (1) ◽  
pp. 5-16 ◽  
Author(s):  
Dmitry A. Storchak ◽  
Masaki Kanao ◽  
Emily Delahaye ◽  
James Harris
Keyword(s):  
Seismic Event ◽  
Polar Regions ◽  
Event Data ◽  
International Seismological Centre

scholarly journals Ice processes and growth history on Arctic and sub-Arctic lakes using ERS-1 SAR data

Polar Record ◽  
1995 ◽  
Vol 31 (177) ◽  
pp. 115-128 ◽  
Author(s):  
K. Morris ◽  
M. O. Jeffries ◽  
W. F. Weeks
Keyword(s):  
Arctic Lakes ◽  
Polar Regions ◽  
Lake Ice ◽  
Sar Images ◽  
The North ◽  
Growth History ◽  
North Slope Of Alaska ◽  
Term Monitoring ◽  
Selection Of

AbstractA survey of ice growth and decay processes on a selection of shallow and deep sub-Arctic and Arctic lakes was conducted using radiometrically calibrated ERS-1 SAR images. Time series of radar backscatter data were compiled for selected sites on the lakes during the period of ice cover (September to June) for the years 1991–92 and 1992–93. A variety of lake-ice processes could be observed, and significant changes in backscatter occurred from the time of initial ice formation in autumn until the onset of the spring thaw. Backscatter also varied according to the location and depth of the lakes. The spatial and temporal changes in backscatter were most constant and predictable at the shallow lakes on the North Slope of Alaska. As a consequence, they represent the most promising sites for long-term monitoring and the detection of changes related to global warming and its effects on the polar regions.

scholarly journals Mysteriously high Δ<sup>14</sup>C of the glacial atmosphere: Influence of <sup>14</sup>C production and carbon cycle changes

2020 ◽  
Author(s):  
Ashley Dinauer ◽  
Florian Adolphi ◽  
Fortunat Joos
Keyword(s):  
Carbon Cycle ◽  
Production Rate ◽  
Polar Regions ◽  
Computationally Efficient ◽  
Drastic Reduction ◽  
Qualitative And Quantitative ◽  
Time Period ◽  
Climate Simulations ◽  
The Last Glacial

Abstract. Despite intense focus on the ~ 190 permil drop in atmospheric Δ14C across the deglacial “mystery interval”, the specific mechanisms responsible for the apparent Δ14C excess in the glacial atmosphere have received considerably less attention. The computationally efficient Bern3D earth system model of intermediate complexity, designed for long-term climate simulations, allows us to address a very fundamental but still elusive question concerning the atmospheric Δ14C record: How can we explain the persistence of relatively high Δ14C values during the millennia after the Laschamp event? Large uncertainties in the pre-Holocene 14C production rate, as well as in the older portion of the Δ14C record, complicate our qualitative and quantitative interpretation of the glacial Δ14C elevation. Here we begin with sensitivity experiments that investigate the controls on atmospheric Δ14C in more idealized settings. We show that the long-term process of sedimentation may be much more important to the simulation of Δ14C than had been previously thought. In order to provide a bounded estimate of glacial Δ14C change, the Bern3D model was integrated with five available estimates of the 14C production rate as well as reconstructed and hypothesized paleoclimate forcing. Model results demonstrate that none of the available reconstructions of past changes in 14C production can reproduce the elevated Δ14C levels during the last glacial. In order to increase atmospheric Δ14C to glacial levels, a drastic reduction of air-sea exchange efficiency in the polar regions must be assumed, though discrepancies remain for the portion of the record younger than ~ 33 kyr BP. We end with an illustration of how the 14C production rate would have had to evolve to be consistent with the Δ14C record, by combining an atmospheric radiocarbon budget with the Bern3D model. The overall conclusion is that the remaining discrepancies with respect to glacial Δ14C may be linked to an underestimation of 14C production and/or a biased-high reconstruction of Δ14C over the time period of interest. Alternatively, we appear to still be missing an important carbon cycle process for atmospheric Δ14C.

LONG TERM RESULTS OF PAEDIATRIC ROSS PROCEDURE: A NEW METHODOLOGY OF TIME-TO-EVENT DATA META-ANALYSIS

2016 ◽  
Vol 32 (10) ◽  
pp. S170-S171
Author(s):  
W. Ben Ali ◽  
T. Ducruet ◽  
I. El-Hamamsy ◽  
D. Bouchard ◽  
N.C. Poirier
Keyword(s):  
Meta Analysis ◽  
Long Term Results ◽  
Ross Procedure ◽  
Event Data ◽  
Time To Event ◽  
Time To Event Data

A global perspective on Bromine monoxide composition in volcanic plumes derived from three years of S5-P/TROPOMI data

2021 ◽  
Author(s):  
Simon Warnach ◽  
Holger Sihler ◽  
Christian Borger ◽  
Nicole Bobrowski ◽  
Stefan Schmitt ◽  
...  
Keyword(s):  
Global Perspective ◽  
Coefficient Of Determination ◽  
Optical Absorption Spectroscopy ◽  
Polar Regions ◽  
Volcanic Gas ◽  
Volcanic Plumes ◽  
Molar Ratios ◽  
Volcanic Events ◽  
Global Coverage

&lt;p&gt;Bromine monoxide (BrO) is a halogen radical capable of influencing atmospheric chemical processes, in particular the abundance of ozone, e. g. in the troposphere of polar regions, the stratosphere as well as in volcanic plumes. Furthermore, the molar bromine to sulphur ratio in volcanic gas emissions is a proxy for the magmatic composition of a volcano and potentially an eruption forecast parameter.&lt;/p&gt;&lt;p&gt;The high spatial resolution of the S5-P/TROPOMI instrument (up to 3.5x5.5km&lt;sup&gt;2&lt;/sup&gt;) and its daily global coverage offer the potential to detect BrO even during minor eruptions and also to determine BrO/SO&lt;sub&gt;2&lt;/sub&gt; ratios during continuous passive degassing.&lt;/p&gt;&lt;p&gt;Here, we present a global overview of BrO/SO&lt;sub&gt;2&lt;/sub&gt; molar ratios in volcanic plumes derived from a systematic long-term investigation of three years of TROPOMI data.&lt;/p&gt;&lt;p&gt;We retrieved column densities of BrO and SO&lt;sub&gt;2&lt;/sub&gt; using Differential Optical Absorption Spectroscopy (DOAS) and calculated mean BrOSO&lt;sub&gt;2&lt;/sub&gt; molar ratios for each volcano. As expected, the calculated BrO/SO&lt;sub&gt;2&lt;/sub&gt; molar ratios differ strongly between different volcanoes ranging from several 10&lt;sup&gt;-5&lt;/sup&gt; up to several 10&lt;sup&gt;-4&lt;/sup&gt;. In our study of three years of S5P/TROPOMI data we successfully recorded elevated BrO column densities for more than 100 volcanic events and were able to derive meaningful (coefficient of determination, R&lt;sup&gt;2&lt;/sup&gt; exceeding 0.5) BrO/SO&lt;sub&gt;2&lt;/sub&gt; ratios for multiple volcanoes.&lt;/p&gt;

scholarly journals The Global Radiative Energy Budget in MERRA and MERRA-2: Evaluation with Respect to CERES EBAF Data

2019 ◽  
Vol 32 (6) ◽  
pp. 1973-1994 ◽  
Author(s):  
Laura M. Hinkelman
Keyword(s):  
Radiative Energy ◽  
Energy Budgets ◽  
Polar Regions ◽  
Marine Stratocumulus ◽  
Radiative Fluxes ◽  
Clear Sky ◽  
Tropical Oceans ◽  
Net Flux ◽  
Errors Analysis

The representation of the long-term radiative energy budgets in NASA’s MERRA and MERRA-2 reanalyses has been evaluated, emphasizing changes associated with the reanalysis system update. Data from the CERES EBAF Edition 2.8 satellite product over 2001–15 were used as a reference. For both MERRA and MERRA-2, the climatological global means of most TOA radiative flux terms agree to within ~3 W m−2 of EBAF. However, MERRA-2’s all-sky reflected shortwave flux is ~7 W m−2 higher than either MERRA or EBAF’s, resulting in a net TOA flux imbalance of −4 W m−2. At the surface, all-sky downward longwave fluxes are problematic for both reanalyses, while high clear-sky downward shortwave fluxes indicate that their atmospheres are too transmissive. Although MERRA-2’s individual all-sky flux terms agree better with EBAF, its net flux agreement is worse (−8.3 vs −3.3 W m−2 for MERRA) because MERRA benefits from cancellation of errors. Analysis by region and surface type gives mixed outcomes. The results consistently indicate that clouds are overrepresented over the tropical oceans in both reanalyses, particularly MERRA-2, and somewhat underrepresented in marine stratocumulus areas. MERRA-2 also exhibits signs of excess cloudiness in the Southern Ocean. Notable discrepancies occur in the polar regions, where the effects of snow and ice cover are important. In most cases, MERRA-2 better represents variability and trends in the global mean radiative fluxes over the period of analysis. Overall, the performance of MERRA-2 relative to MERRA is mixed; there is still room for improvement in the radiative fluxes in this family of reanalysis products.

scholarly journals Snow and ice applications of AVHRR in polar regions: report of a workshop held in Boulder, Colorado, 20 May 1992

1993 ◽  
Vol 17 ◽  
pp. 1-16 ◽  
Author(s):  
K. Steffen ◽  
R. Bindschadler ◽  
G. Casassa ◽  
J. Comiso ◽  
D. Eppler ◽  
...  
Keyword(s):  
Sea Ice ◽  
Satellite Data ◽  
Quality Data ◽  
Polar Regions ◽  
Data Set ◽  
Ice Surface ◽  
The Status ◽  
Ice Surface Temperature ◽  
Snow And Ice

The third symposium on Remote Sensing of Snow and Ice, organized by the International Glaciological Society, took place in Boulder, Colorado, 17–22 May 1992. As part of this meeting a total of 21 papers was presented on snow and ice applications of Advanced Very High Resolution Radiometer (AVHRR) satellite data in polar regions. Also during this meeting a NASA sponsored Workshop was held to review the status of polar surface measurements from AVHRR. In the following we have summarized the ideas and recommendations from the workshop, and the conclusions of relevant papers given during the regular symposium sessions. The seven topics discussed include cloud masking, ice surface temperature, narrow-band albedo, ice concentration, lead statistics, sea-ice motion and ice-sheet studies with specifics on applications, algorithms and accuracy, following recommendations for future improvements. In general, we can affirm the strong potential of AVHRR for studying sea ice and snow covered surfaces, and we highly recommend this satellite data set for long-term monitoring of polar process studies. However, progress is needed to reduce the uncertainty of the retrieved parameters for all of the above mentioned topics to make this data set useful for direct climate applications such as heat balance studies and others. Further, the acquisition and processing of polar AVHRR data must become better coordinated between receiving stations, data centers and funding agencies to guarantee a long-term commitment to the collection and distribution of high quality data.

Long-term variability of Atlantic water temperature in the Svalbard fjords in conditions of past and recent global warming

2015 ◽  
Vol 5 (2) ◽  
pp. 134-142 ◽  
Author(s):  
Daniil I. Tislenko ◽  
Boris V. Ivanov
Keyword(s):  
Global Warming ◽  
Surface Air Temperature ◽  
Atlantic Water ◽  
The Arctic ◽  
Observation Data ◽  
Polar Regions ◽  
Arctic Amplification ◽  
The West ◽  
West Spitsbergen

Within last decades, the climate of our planet has underwent remarkable changes. The most notable are those called "Arctic amplification." is the changes comprise a decrease in the area of ​​multi-years ice in 2007 and 2012 in polar regions of the Northern hemisphere, accompanied by the temperature rise of intermediate Atlantic waters, increasing surface temperature. In this paper, an analysis of long-term variability of temperature transformed Atlantic waters (TAW) in the fjords of the West-Spitsbergen island (Isfjorden, Grnfjorden, Hornsund and Kongsfjorden) in the first period (1920–1940) and modern (1990–2009) warming in the Arctic is reported. It is shown that the instrumental observation data corresponds to the periods of rise in temperature in the layer of the TAW and surface air temperature (SAT) for the area of ​​the Svalbard.

Problems in the Law of the Sea Relating to Insular Formations in Ice-bound Seas and Polar Regions of the Arctic, with Particular Reference to Judicial Dicta in US v Alaska (1996) and to Recent Discoveries of New Arctic Islands (such as ‘Yaya’) due to Glacial Melt

2018 ◽  
Vol 9 (1) ◽  
pp. 283-311
Author(s):  
Clive R. Symmons
Keyword(s):  
Sea Water ◽  
The Arctic ◽  
Polar Regions ◽  
Surface Appearance ◽  
Sea Levels ◽  
Ice Melt ◽  
Continental Shelves ◽  
Regional Problem ◽  
Definition Of

It is generally accepted that UNCLOS applies to polar seas. However, particular problems can arise thereunder in such seas because of their ice-bound environment. One such regional problem is because global warming causes particular issues for insular formations there; not only in terms of the very definition of ‘islands’ (e.g., is frozen sea water equivalent to “land” in terms of above-surface appearance under Art. 121 [1] of UNCLOS?); but also in terms of their lawful use in generation of maritime zones therefrom. For example, in recent years new above-surface formations have been discovered in the Arctic (such as ‘Yaya Island’) because of glacial melting and sudden visibility. These formations may potentially generate new maritime zones for their owner State (albeit not EEZs/continental shelves because of Art. 121 [3] of UNCLOS); and may be opportunistically used in negotiation of maritime polar boundaries (as in the case of Tobias Island off Greenland). Where tips of glacial capes have been used as straight baseline points, any remaining terrestrial formations may be a useful ‘fall-back’ position on ice melt-down. Typically low-lying new terrestrial features (now uncovered by glaciers) may have no prospect of long-term existence above sea level; and some may have inherent mobility (as is a particular Arctic problem with ‘barrier islands’). The other side of the coin of polar ice melt-down is that existing low-lying and small islands will likely disappear with increasing sea levels; so causing problems of continued use as basepoints for generation of maritime zones; and a potential duty to retract maritime claims.

scholarly journals Worldwide atmospheric mercury measurements: a review and synthesis of spatial and temporal trends

2010 ◽  
Vol 10 (1) ◽  
pp. 1261-1307 ◽  
Author(s):  
F. Sprovieri ◽  
N. Pirrone ◽  
R. Ebinghaus ◽  
H. Kock ◽  
A. Dommergue
Keyword(s):  
Temporal Trends ◽  
Ambient Air ◽  
Atmospheric Mercury ◽  
Water Soluble ◽  
Polar Regions ◽  
Mercury Emissions ◽  
Gaseous Mercury ◽  
National Programs ◽  
Spatial And Temporal Trends

Abstract. A large number of activities have been carried out during the last decade in different regions of the world, including polar regions, aiming to assess the level of mercury (Hg) species in ambient air and in precipitation observing their variation over time and with changing meteorological conditions. Following the discovery of atmospheric Hg depletion events (AMDEs) in Polar Regions several studies have indeed been conducted in order to assess the chemical-physical mechanisms related to AMDEs occurred in polar atmospheres with special attention to the consequences of these phenomena in terms of contamination of polar environment due to the rapid conversion of atmospheric gaseous Hg (Hg0) into reactive and water-soluble forms that may potentially become bioavailable. The understanding of the way in which mercury released to the atmosphere is eventually incorporated into biota is of crucial importance not only for the polar regions but also for the marine environment in general. The world's oceans and seas are in fact both sources and sinks of Hg and although it appears that the atmosphere is the major transport/distribution medium for Hg, because most Hg emissions are to the atmosphere, oceans and seas also play an important role. Currently, however, a coordinated observational network for Hg does not exist. There are a number of state and national programs that are collecting atmospheric Hg data but the parameters monitored, the locations of the monitoring sites and the methods employed may prohibit their utility in assessing Hg long-trend variations. The large increase in mercury emissions in fast developing countries (i.e., China, India) over the last decade due primarily to a sharp increase in energy production from the combustion of coal are not currently reflected in the long-term measurements of total gaseous mercury in ambient air and in precipitation data at several continuous monitoring sites in North Europe and North America. The discrepancy between observed gaseous mercury concentrations (steady or decreasing) and global mercury emission inventories (increasing) is not yet clear however, could be at least in part accounted by the increasing in the potential oxidation of the atmosphere recently documented. Therefore, measurements of other key atmospheric constituents at the global monitoring sites are necessary for us to develop a better understanding of the global redistribution of Hg and to further refine model parameterizations of the key processes. The sharing of data from this network, allowing, in fact, access to comparable and long-term data from a wide array of locations for understanding temporal and spatial patterns of Hg transport, deposition and re-emission process producing thus data that will support the validation of regional and global atmospheric Hg models. This paper presents a detailed overview of atmospheric mercury measurements conducted in the Northern and Southern Hemispheres at several terrestrial sites (industrial, rural and remote) during the last decade as well as measurements performed over the world's ocean and seas and in Polar Regions with reference to the monitoring techniques and location of monitoring sites in most of the continents.

scholarly journals Recovery and validation of Odin/SMR long term measurements ofmesospheric carbon monoxide

2020 ◽  
Author(s):  
Francesco Grieco ◽  
Kristell Pérot ◽  
Donal Murtagh ◽  
Patrick Eriksson ◽  
Peter Forkman ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Middle Atmosphere ◽  
Phase Lock Loop ◽  
Polar Regions ◽  
Line Broadening ◽  
Mixing Ratios ◽  
Correct Location ◽  
Relative Differences ◽  
Co Observations

Abstract. The Sub-Millimetre Radiometer (SMR) on board the Odin satellite performs limb sounding measurements of the middle atmosphere to detect molecular emission from different species. Carbon monoxide (CO) is an important tracer of atmospheric dynamics at these altitudes, due to its long photochemical lifetime and high vertical concentration gradient. In this study, we have successfully recovered over 18 years of SMR observations, providing the only dataset to date being so extended in time and stretching out to the polar regions, with regards to satellite-measured mesospheric CO. This new dataset is part of the Odin/SMR version 3.0 level 2 data. The much of the level 1 dataset – except the October 2003 to October 2004 period – was affected by a malfunctioning of the Phase-Lock Loop (PLL) in the frontend used for CO observations. Because of this technical issue, the CO line could be shifted away from its normal frequency location causing the retrieval to fail or leading to an incorrect estimation of the CO concentration. An algorithm was developed to locate the CO line and shift it to its correct location. Nevertheless, another artifact causing an underestimation of the concentration, i.e. a line broadening, stemmed from the PLL malfunctioning. This was accounted for by using a broader response function. The application of these corrections resulted in the recovery of a large amount of data that was previously being flagged as problematic and therefore not processed. A validation study has been carried out, showing how SMR CO volume mixing ratios are in general in good accordance with the other instruments considered in the study. Overall, the agreement is very good between 60 and 80 km altitude, with relative differences close to zero. A positive bias at low altitudes (50–60 km) up to +20 % and a negative bias up to −20 % at high altitudes (80–100 km) were found with respect to the compared instruments.

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