The primary goal of this paper is to demonstrate the dependence of Arctic Ocean sea-ice transport... more The primary goal of this paper is to demonstrate the dependence of Arctic Ocean sea-ice transport pathways on climate variations. We build our analysis on the results of Proshutinsky and Johnson (1997), Johnson and others (1999), Polyakov and others (1999) and Proshutinsky and others (1999), where we have shown that wind-driven ice motion and upper ocean circulation alternate between anticyclonic and cyclonic states. Shifts between regimes occur at 5−7 year intervals, resulting in a 10−15 year period. The anticyclonic circulation regime has been observed in our model results for 1946−52,1958−62,1972−79,1984−88 and 1998−present. The cyclonic circulation regime prevailed during 1953−57,1963−71,1980−83 and 1989−97. The regime shifts are fundamentally important to understanding the Arctic’s general circulation and particularly useful for estimating pollution transport by sea ice and surface waters. It is important to pollution studies to understand which circulation regime prevails. Ini...
Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean... more Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 deployments were performed over a period of 5 years in both the Arctic and Antarctic, involving 72 instruments. These provide both GPS drift tracks, and measurements of waves in ice. The data can, in turn, be used for tuning sea ice drift models, investigating waves damping by sea ice, and helping calibrate other sea ice measurement techniques, such as satellite based observations.
Journal of the Acoustical Society of America, May 1, 1995
Travel times of acoustic signals were measured between the bottom-mounted Kaneohe source near Oah... more Travel times of acoustic signals were measured between the bottom-mounted Kaneohe source near Oahu and seven SOSUS stations at 3000–4000-km distance during 1983–1989. The Naval Research Laboratory hydrodynamic eddy resolving model yields changes in travel time whose standard deviations are consistent with the data. The model predicts that between 1981–1993, Rossby waves modify travel times by one second. Mesoscale eddies modify travel times little compared to Rossby waves. The largest Rossby waves are descendants of El Nino. Travel times changes are sensitive indicators of predictable features in the Naval Research Laboratory model. [Work supported by the Strategic Environmental Research and Development Program, managed by the Advanced Research Projects Agency.]
The Journal of the Acoustical Society of America, 1999
The difficulties in detecting anthropogenic changes in ocean temperature due to the industrial re... more The difficulties in detecting anthropogenic changes in ocean temperature due to the industrial revolution are discussed using acoustic thermometry data taken between Oahu and seven SOSUS receivers at distances of 3000–4000 km. Measurements were made in late 1983, and over two 5-month intervals between 1987 and 1989. The travel times are dominated by interannual fluctuations. Two hydrodynamic ocean models are used to identify plausible oceanic features that could cause these variations. Modeled El Niños and La Niñas exhibit oceanic teleconnections between the Equator and mid-latitudes that lead to Rossby waves that propagate westward at mid−latitudes. Rossby waves are the dominant model features which affect the modeled acoustic travel times, and hence section-averaged temperatures in the eastern North Pacific. Modeled predictions of the travel times are significantly different than some of the data. The magnitude and rates of changes of the data are the same as those which result fr...
The International Journal of Supercomputing Applications, 1990
Two numerical models utilizing primitive equations (two momentum equations and a mass continuity ... more Two numerical models utilizing primitive equations (two momentum equations and a mass continuity equation) simulate the oceanography of the Pacific Ocean from 20°S to 50°N. Results show Kelvin waves thousands of kilometers long propagating from the equator to the northeast Pacific Ocean. Kelvin waves are very long waves that propagate along the equator and along solid boundaries with the boundary to their right. They are important to simulations of ocean circulation along the North American coast because they carry information at seasonal and longer periods from the equator poleward. Modeling an extensive region such as the Pacific Ocean with adequate two-dimensional resolution places heavy demands on computer memory and storage. We have found that the best way to examine the abundant model data is through visualization, by animating the appro priate model fields and viewing the time history of each model simulation as a color movie. The animations are used as research products to a...
There is a wide consensus within the polar science, meteorology, and oceanography communities tha... more There is a wide consensus within the polar science, meteorology, and oceanography communities that more in situ observations of the ocean, atmosphere, and sea ice are required to further improve operational forecasting model skills. Traditionally, the volume of such measurements has been limited by the high cost of commercially available instruments. An increasingly attractive solution to this cost issue is to use instruments produced in-house from open-source hardware, firmware, and postprocessing building blocks. In the present work, we release the next iteration of the open-source drifter and wave-monitoring instrument of Rabault et al. (see “An open source, versatile, affordable waves in ice instrument for scientific measurements in the Polar Regions”, Cold Regions Science and Technology, 2020), which follows these solution aspects. The new design is significantly less expensive (typically by a factor of 5 compared with our previous, already cost-effective instrument), much easi...
1. The recognized importance of the annual cycle of sea ice in the Arctic to heat budgets, human ... more 1. The recognized importance of the annual cycle of sea ice in the Arctic to heat budgets, human behavior, and ecosystem functions, requires consistent definitions of such key events in the ice cycle as break-up and freeze-up. An internally consistent and reproducible approach to characterize the timing of these events in the annual sea-ice cycle is described. An algorithm was developed to calculate the start and end dates of freeze-up and break-up and applied to time series of satellite-derived sea-ice concentration from 1979 to 2013. Our approach builds from discussions with sea-ice experts having experience observing and working on the sea ice in the Bering, Chukchi and Beaufort Seas. Applying the algorithm to the 1979–2013 satellite data reveals that freeze-up is delayed by two weeks per decade for the Chukchi coast and one week per decade for the Beaufort coast. For both regions, break-up start is arriving earlier by 5–7 days per decade and break-up end is arriving earlier by 1...
The primary goal of this paper is to demonstrate the dependence of Arctic Ocean sea-ice transport... more The primary goal of this paper is to demonstrate the dependence of Arctic Ocean sea-ice transport pathways on climate variations. We build our analysis on the results of Proshutinsky and Johnson (1997), Johnson and others (1999), Polyakov and others (1999) and Proshutinsky and others (1999), where we have shown that wind-driven ice motion and upper ocean circulation alternate between anticyclonic and cyclonic states. Shifts between regimes occur at 5−7 year intervals, resulting in a 10−15 year period. The anticyclonic circulation regime has been observed in our model results for 1946−52,1958−62,1972−79,1984−88 and 1998−present. The cyclonic circulation regime prevailed during 1953−57,1963−71,1980−83 and 1989−97. The regime shifts are fundamentally important to understanding the Arctic’s general circulation and particularly useful for estimating pollution transport by sea ice and surface waters. It is important to pollution studies to understand which circulation regime prevails. Ini...
Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean... more Variability in sea ice conditions, combined with strong couplings to the atmosphere and the ocean, lead to a broad range of complex sea ice dynamics. More in-situ measurements are needed to better identify the phenomena and mechanisms that govern sea ice growth, drift, and breakup. To this end, we have gathered a dataset of in-situ observations of sea ice drift and waves in ice. A total of 15 deployments were performed over a period of 5 years in both the Arctic and Antarctic, involving 72 instruments. These provide both GPS drift tracks, and measurements of waves in ice. The data can, in turn, be used for tuning sea ice drift models, investigating waves damping by sea ice, and helping calibrate other sea ice measurement techniques, such as satellite based observations.
Journal of the Acoustical Society of America, May 1, 1995
Travel times of acoustic signals were measured between the bottom-mounted Kaneohe source near Oah... more Travel times of acoustic signals were measured between the bottom-mounted Kaneohe source near Oahu and seven SOSUS stations at 3000–4000-km distance during 1983–1989. The Naval Research Laboratory hydrodynamic eddy resolving model yields changes in travel time whose standard deviations are consistent with the data. The model predicts that between 1981–1993, Rossby waves modify travel times by one second. Mesoscale eddies modify travel times little compared to Rossby waves. The largest Rossby waves are descendants of El Nino. Travel times changes are sensitive indicators of predictable features in the Naval Research Laboratory model. [Work supported by the Strategic Environmental Research and Development Program, managed by the Advanced Research Projects Agency.]
The Journal of the Acoustical Society of America, 1999
The difficulties in detecting anthropogenic changes in ocean temperature due to the industrial re... more The difficulties in detecting anthropogenic changes in ocean temperature due to the industrial revolution are discussed using acoustic thermometry data taken between Oahu and seven SOSUS receivers at distances of 3000–4000 km. Measurements were made in late 1983, and over two 5-month intervals between 1987 and 1989. The travel times are dominated by interannual fluctuations. Two hydrodynamic ocean models are used to identify plausible oceanic features that could cause these variations. Modeled El Niños and La Niñas exhibit oceanic teleconnections between the Equator and mid-latitudes that lead to Rossby waves that propagate westward at mid−latitudes. Rossby waves are the dominant model features which affect the modeled acoustic travel times, and hence section-averaged temperatures in the eastern North Pacific. Modeled predictions of the travel times are significantly different than some of the data. The magnitude and rates of changes of the data are the same as those which result fr...
The International Journal of Supercomputing Applications, 1990
Two numerical models utilizing primitive equations (two momentum equations and a mass continuity ... more Two numerical models utilizing primitive equations (two momentum equations and a mass continuity equation) simulate the oceanography of the Pacific Ocean from 20°S to 50°N. Results show Kelvin waves thousands of kilometers long propagating from the equator to the northeast Pacific Ocean. Kelvin waves are very long waves that propagate along the equator and along solid boundaries with the boundary to their right. They are important to simulations of ocean circulation along the North American coast because they carry information at seasonal and longer periods from the equator poleward. Modeling an extensive region such as the Pacific Ocean with adequate two-dimensional resolution places heavy demands on computer memory and storage. We have found that the best way to examine the abundant model data is through visualization, by animating the appro priate model fields and viewing the time history of each model simulation as a color movie. The animations are used as research products to a...
There is a wide consensus within the polar science, meteorology, and oceanography communities tha... more There is a wide consensus within the polar science, meteorology, and oceanography communities that more in situ observations of the ocean, atmosphere, and sea ice are required to further improve operational forecasting model skills. Traditionally, the volume of such measurements has been limited by the high cost of commercially available instruments. An increasingly attractive solution to this cost issue is to use instruments produced in-house from open-source hardware, firmware, and postprocessing building blocks. In the present work, we release the next iteration of the open-source drifter and wave-monitoring instrument of Rabault et al. (see “An open source, versatile, affordable waves in ice instrument for scientific measurements in the Polar Regions”, Cold Regions Science and Technology, 2020), which follows these solution aspects. The new design is significantly less expensive (typically by a factor of 5 compared with our previous, already cost-effective instrument), much easi...
1. The recognized importance of the annual cycle of sea ice in the Arctic to heat budgets, human ... more 1. The recognized importance of the annual cycle of sea ice in the Arctic to heat budgets, human behavior, and ecosystem functions, requires consistent definitions of such key events in the ice cycle as break-up and freeze-up. An internally consistent and reproducible approach to characterize the timing of these events in the annual sea-ice cycle is described. An algorithm was developed to calculate the start and end dates of freeze-up and break-up and applied to time series of satellite-derived sea-ice concentration from 1979 to 2013. Our approach builds from discussions with sea-ice experts having experience observing and working on the sea ice in the Bering, Chukchi and Beaufort Seas. Applying the algorithm to the 1979–2013 satellite data reveals that freeze-up is delayed by two weeks per decade for the Chukchi coast and one week per decade for the Beaufort coast. For both regions, break-up start is arriving earlier by 5–7 days per decade and break-up end is arriving earlier by 1...
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Papers by Mark Johnson