Recent and future changes of the Arctic sea-ice cover

The present and future state of the Arctic sea ice cover is explored using new observations and a coupled one dimensional air–sea–ice model. Updated satellite observations of Fram Strait ice-area export show an increase over the last four years, with 37% increase in winter 07–08. Atmospheric poleward energy flux declined since 1990, but advection of oceanic heat has recently increased. Simulations show that the ice area export is a stronger driver of thinning than the estimated ocean heat fluxes of 40 TW. Increased ocean heat transport will raise primarily Atlantic layer temperature. The ‘present 2007’ state of the Arctic ice could be a stable state given the recent high ice area export, but if ocean heat advection and ice export decrease, the ice cover will recover. A 2*CO2 scenario with export and oceanic heat flux remaining strong, forecasts a summer Arctic open ocean area of 95% around 2050.publishedVersio

Recent wind driven high sea ice area export in the Fram Strait contributes to Arctic sea ice decline

Arctic sea ice area has been decreasing for the past two decades. Apart from melting, the southward drift through Fram Strait is the main ice loss mechanism. We present high resolution sea ice drift data across 79° N from 2004 to 2010. Ice drift has been derived from radar satellite data and corresponds well with variability in local geostrophic wind. The underlying East Greenland current contributes with a constant southward speed close to 5 cm s−1, and drives around a third of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25% larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice area export likely has a significant influence on the summer sea ice variability and we find low values in the 1960's, the late 1980's and 1990's, and particularly high values during 2005–2008. The study highlights the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice during the last decadespublishedVersio

Dispensations of benzodiazepines, zhypnotics, and gabapentinoids to patients receiving opioid agonist therapy; a prospective cohort study in Norway from 2013 to 2017

Background Dispensations of benzodiazepines, z-hypnotics, and gabapentinoids to patients on opioid agonist therapy (OAT) are common and have pros and cons. The objectives of the current study are to define the dispensation rates of these potentially addictive drugs, and whether the number and the mean daily doses of dispensed OAT opioids and discontinuing OAT, are associated with being dispensed benzodiazepines, z-hypnotics and gabapentinoids among patients on OAT in Norway in the period 2013 to 2017. Methods Information about all dispensed opioids, benzodiazepines, z-hypnotics and gabapentinoids were recorded from the Norwegian Prescription Database (NorPD). A total of 10,371 OAT patients were included in the study period. The dispensation rates were defined as the number of patients who were dispensed at least one of the potentially addictive drugs divided among the number of patients who have dispensed an OAT opioid per calendar year. Mean daily doses were calculated, and for benzodiazepines and z-hypnotics, stated in diazepam equivalents. The association between dispensed potentially addictive drugs, and the number and the type of dispensed OAT opioids were calculated by using logistic regression models. Results Half of the OAT patients received at least one dispensation of a benzodiazepine or z-hypnotic, and 11% were dispensed at least a gabapentinoid in 2017. For dispensed benzodiazepines or z-hypnotics, the mean daily dose was reduced from 21 mg (95% confidence interval (CI): 20–23) diazepam equivalents in 2013 to 17 mg (95% CI: 16–17) in 2017. The mean daily dose of pregabalin increased from 365 mg (95% CI: 309–421) in 2013 to 386 mg (95% CI: 349–423) in 2017. Being dispensed a gabapentinoid (adjusted odds ratio (aOR) = 2.5, 95% CI: 2.1–3.0) or a non-OAT opioid (aOR = 3.0, 95% CI: 2.6–3.5) was associated with being dispensed a benzodiazepine or z-hypnotic. Discontinuing OAT did not affect the number of dispensations and the doses of potentially addictive drugs. Conclusion The dispensation rates of potentially addictive drugs are high in the OAT population. Treatment indications, as well as requirements for prescription authority, need to be debated and made explicit. Randomized controlled trials evaluating the benefits and risks of such co-prescription are required.publishedVersio

Satellite data acquisition for iceberg monitoring in the Svalbard area

Observation and forecasting of icebergs is an important task for offshore oil and gas development in Arctic regions. For many decades the Russian conducted regular aircraft monitoring of icebergs in Arctic seas, but in the last 15 years only occasional expeditions with icebreakers and aircraft have collected iceberg data in the Barents Sea. Monitoring of icebergs from satellites has been studied in research projects since the early 1990s, but has not yet been implemented as an operational service. New satellite systems are under development that can improve iceberg detection in the coming years. This report presents a set of high-resolution satellite images collected in the Svalbard area for iceberg detection in April-May 2007. Several images were taken during the field expedition with Lance north of Svalbard. During the Lance expedition, ICEX buoys with ARGOS transmitters provided by CMR were deployed on four different icebergs. The ARGOS data were used during April and May to follow the four icebergs. Two of the icebergs continued to send ARGOS positions from June to August. Two types of high-resolution satellite images were used: optical images from SPOT, Landsat and Terra ASTER, and Synthetic Aperture Radar (SAR) images form ENVISAT and Radarsat. The optical satellite data are limited by cloud cover. This means that good-quality images can be produced only on days with little clouds. SAR data gives good quality radar images independent of clouds and daylight, but the SAR images have speckle noise which disturbs the detection of icebergs. For optimal observation of icebergs it is necessary to use both optical and SAR images of resolution 10 m or better. Most of the images are presented in quicklook format, which is useful for an overview and planning the analysis of full-resolution images. In this study, a few examples of full-resolution images are presented. One RADARSAT SAR and one SPOT image covering the positions of the tagged icebergs were analysed in detail. In some cases potential icebergs were found in the images, but in other cases there was no iceberg signal even if iceberg positions were documented by ARGOS data. The size of the tagged icebergs were around 50 m, which is rather small size for detection in the present images. The possibility to detect the known icebergs in the satellite images depends on several factors such as the ice conditions around the icebergs, the size and shape of the icebergs and resolution of the satellite images. This study has demonstrated how satellite data collection for iceberg monitoring can be done for the Svalbard area. More information about icebergs in this area can be obtained if the images are analysed in full-resolution. In particular several of the 35 SPOT images are expected to give more data on icebergs in the Hopen and Kong Karls Land area. This area was also covered by high-resolution SAR images in alternating polarization images. Also the area around Nordaustlandet have icebergs that potentially can be detected in the images. Future schemes for iceberg monitoring should include use of new high resolution SAR images with full polarization, optical images, airborne surveys with fixed-wing aircraft or helicopters, and deployment of Argos buoys on selected icebergsNERSC Technical Report no. 282. Funded by STATOIL, Contract 4501294663

Recent wind driven high sea ice area export in the Fram Strait contributes to Arctic sea ice decline

Arctic sea ice area has been decreasing for the past two decades. Apart from melting, the southward drift through Fram Strait is the main ice loss mechanism. We present high resolution sea ice drift data across 79° N from 2004 to 2010. Ice drift has been derived from radar satellite data and corresponds well with variability in local geostrophic wind. The underlying East Greenland current contributes with a constant southward speed close to 5 cm s−1, and drives around a third of the ice export. We use geostrophic winds derived from reanalysis data to calculate the Fram Strait ice area export back to 1957, finding that the sea ice area export recently is about 25% larger than during the 1960's. The increase in ice export occurred mostly during winter and is directly connected to higher southward ice drift velocities, due to stronger geostrophic winds. The increase in ice drift is large enough to counteract a decrease in ice concentration of the exported sea ice. Using storm tracking we link changes in geostrophic winds to more intense Nordic Sea low pressure systems. Annual sea ice area export likely has a significant influence on the summer sea ice variability and we find low values in the 1960's, the late 1980's and 1990's, and particularly high values during 2005–2008. The study highlights the possible role of variability in ice export as an explanatory factor for understanding the dramatic loss of Arctic sea ice during the last decade

Fram Strait sea ice export variability over the last 80 years

A new long-term data record of Fram Strait sea ice area export from 1935 to 2014 is developed using a combination of satellite radar images and station observations of surface pressure across Fram Strait. This data record shows that the long-term annual mean export is about 880?000 km**2, representing 10 % of the sea-ice-covered area inside the basin. The time series has large interannual and multi-decadal variability but no long-term trend. However, during the last decades, the amount of ice exported has increased, with several years having annual ice exports that exceeded 1 million km**2. This increase is a result of faster southward ice drift speeds due to stronger southward geostrophic winds, largely explained by increasing surface pressure over Greenland. Evaluating the trend onwards from 1979 reveals an increase in annual ice export of about +6 % per decade, with spring and summer showing larger changes in ice export (+11 % per decade) compared to autumn and winter (+2.6 % per decade). Increased ice export during winter will generally result in new ice growth and contributes to thinning inside the Arctic Basin. Increased ice export during summer or spring will, in contrast, contribute directly to open water further north and a reduced summer sea ice extent through the ice?albedo feedback. Relatively low spring and summer export from 1950 to 1970 is thus consistent with a higher mid-September sea ice extent for these years. Our results are not sensitive to long-term change in Fram Strait sea ice concentration. We find a general moderate influence between export anomalies and the following September sea ice extent, explaining 18?% of the variance between 1935 and 2014, but with higher values since 2004