Monitoring the Norwegian Atlantic slope current using a single moored current meter

Monitoring the Atlantic inflow (AI) of warm and saline water into the Nordic Seas (Norwegian, Greenland and Iceland Seas) is of great importance becauce of its impact on climate and ecology in Northern Europe and Arctic. In this study, an observation system for establishment of simple, robust and cost effective monitoring of the AI is validated in the Svinøy section, cutting through the AI just to the north of the Faroe-Shetland Channel. We concentrate on the eastern branch of the AI, the Norwegian Atlantic Slope Current (NwASC), an about 40km wide flow along the steep Norwegian slope. The database is an array of 15 current meters on 4 moorings covering the NwASC over a 2-year period 1998–2000. We test the hypothesis that long-term monitoring of the NwASC can be performed by using one single current meter suitable placed in the flow. The volume flux can then be estimated by construction of simple regression models using the single current meter record as the independent variable. For validation of statistical properties as stability, confidence and stationarity, the time series is split into two 1-year segments: a model period and a test period. Gridded correlation fields between currents and volume transport show correlation maxima in the core of the NwASC, ranging from 0.84 on a daily timescale to 0.97 on a monthly timescale. A more comprehensive correlation/ coherence analysis for each current meter record against volume transport on 7-day timescales, enable us to choose the optimal current meter for a linear regression model with (correlation, slope) coefficients of (0.87, 0.13) for the model period and (0.80, 0.13) for the test period. The similarity of the statistical properties for the model and test periods substantiates the stationarity, stability and robustness of the model. A linear regression model underestimates large fluxes and is thus extended to a second degree polynomia. This improves the curve fitting for strong currents with a minor increase in overall correlation, but is more sensistive and less stable. Overall, we find a linear regression model to be more robust and applicable for monitoring the NwASC. The applicability of a linear regression model as an estimator for volume flux of the NwASC is demonstrated using a 2-year time series, and validated against calculated transport. The calculated transport agrees with the statistical analysis and reveals a noisy fit on daily timescale, while the curves coincide well on both 7- and 30-day timescales with correlation coefficients of 0.84 and 0.86, respectively. On all timescales, the calculated and model transport give an overall mean flow of 4.4 Sv and show fluctuations on timescales of days to months, with the seasonal cycle being the most prominent

The Return of Lake Agassiz: The University of North Dakota and the Flood of 1997

On April 19, 1997, Grand Forks and East Grand Forks were overtaken by the largest flood seen in the cities in modern times. Tens of thousands abandoned their homes. Scattered throughout the region, they could do little more than wait for news reports and worry about what they would find when the waters subsided. At the University of North Dakota, the academic year had come to an abrupt end. Students, faculty and staff were among the evacuated. A small group of UND personnel now had to decide how to protect, as much as possible, an institution worth hundreds of millions of dollars.https://commons.und.edu/und-books/1036/thumbnail.jp

Perceived risk in online services and its effect on password strength

Passwords are the most used method for authentication in online platforms. At the same time, password management continues to be one of the biggest security risks for individual users. This is due to both inadequate password behavior of most users, especially related to password strength which depends on the parameters assigned by the user in most cases. Two of the most prevalent behaviors that can expose users to danger are password reuse and weak password strength. Our thesis focuses on the problem of weak password strength usage. Therefore, we seek to answer the following research problem: “Does the perception of risk associated with different online services influence password strength and is this universally applied?”. We conducted the research study on Norwegian students from the University of Agder. To answer our question, we followed a quantitative methodology in form of an online distributed survey. The study was based on findings from a literature review which helped us get an understanding of different factors affecting users’ password behavior, risk perception, knowledge, and the state of password strength. The survey received 99 respondents of which 70 were eligible for further analysis. The analyses of the data were conducted using Excel. We present our findings in figures, tables, and descriptive analysis. Our results show that using different password strengths for different online services is common among users. In addition, there are no significant changes in password strength between the services when analyzing behaviors of individual users. Moreover, the perceived risk of user accounts being attempted compromised, and the consequences of compromise in services have low correlation with password strength, with a few exceptions for some services. Two of these exceptions being porn, and news. Furthermore, we discuss our findings in detail by looking at outliers and trends in the data, and some commonalities between the services that follow a similar pattern in our findings. We concluded that password strength differs among online services, and that certain online services are more likely to have weaker passwords than others

On the role of eddies and surface forcing in the heat transport and overturning circulation in marginal seas

Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 24 (2011): 4844–4858, doi:10.1175/2011JCLI4130.1.The factors that determine the heat transport and overturning circulation in marginal seas subject to wind forcing and heat loss to the atmosphere are explored using a combination of a high-resolution ocean circulation model and a simple conceptual model. The study is motivated by the exchange between the subpolar North Atlantic Ocean and the Nordic Seas, a region that is of central importance to the oceanic thermohaline circulation. It is shown that mesoscale eddies formed in the marginal sea play a major role in determining the mean meridional heat transport and meridional overturning circulation across the sill. The balance between the oceanic eddy heat flux and atmospheric cooling, as characterized by a nondimensional number, is shown to be the primary factor in determining the properties of the exchange. Results from a series of eddy-resolving primitive equation model calculations for the meridional heat transport, overturning circulation, density of convective waters, and density of exported waters compare well with predictions from the conceptual model over a wide range of parameter space. Scaling and model results indicate that wind effects are small and the mean exchange is primarily buoyancy forced. These results imply that one must accurately resolve or parameterize eddy fluxes in order to properly represent the mean exchange between the North Atlantic and the Nordic Seas, and thus between the Nordic Seas and the atmosphere, in climate models.This study was supported by the National Science Foundation under Grants OCE-0726339 and OCE-0850416

Perceived risk in online services and its effect on password strength

Passwords are the most used method for authentication in online platforms. At the same time, password management continues to be one of the biggest security risks for individual users. This is due to both inadequate password behavior of most users, especially related to password strength which depends on the parameters assigned by the user in most cases. Two of the most prevalent behaviors that can expose users to danger are password reuse and weak password strength. Our thesis focuses on the problem of weak password strength usage. Therefore, we seek to answer the following research problem: “Does the perception of risk associated with different online services influence password strength and is this universally applied?”. We conducted the research study on Norwegian students from the University of Agder. To answer our question, we followed a quantitative methodology in form of an online distributed survey. The study was based on findings from a literature review which helped us get an understanding of different factors affecting users’ password behavior, risk perception, knowledge, and the state of password strength. The survey received 99 respondents of which 70 were eligible for further analysis. The analyses of the data were conducted using Excel. We present our findings in figures, tables, and descriptive analysis. Our results show that using different password strengths for different online services is common among users. In addition, there are no significant changes in password strength between the services when analyzing behaviors of individual users. Moreover, the perceived risk of user accounts being attempted compromised, and the consequences of compromise in services have low correlation with password strength, with a few exceptions for some services. Two of these exceptions being porn, and news. Furthermore, we discuss our findings in detail by looking at outliers and trends in the data, and some commonalities between the services that follow a similar pattern in our findings. We concluded that password strength differs among online services, and that certain online services are more likely to have weaker passwords than others