Thongchai Thailand

THE GREAT SALINITY ANOMALY OF AGW

Posted on: February 11, 2020

bandicam 2020-02-11 09-45-16-567NASA-1

 

[LINK TO THE HOME PAGE OF THIS SITE]

 

RELATED POSTS ON ARCTIC SEA ICE: 

[LINK] [LINK] [LINK] [LINK] [LINK] 

 

THIS POST IS A CRITICAL REVIEW OF A DOCUMENT POSTED ONLINE BY NASA [LINK] CLAIMING THAT: 

(1) HUMANS CAUSE AGW CLIMATE CHANGE, (2) AGW CLIMATE CHANGE CAUSES ARCTIC SEA ICE TO MELT, (3) MELTING ARCTIC SEA ICE CAUSES THE BEAUFORT GYRE TO BECOME FASTER AND MORE TURBULENT, (4) THIS CAUSES THE BEAUFORT GYRE TO TRANSFER COLD FRESHWATER FROM ARCTIC SEA ICE MELT INTO THE ATLANTIC, (5) THIS IS HOW AGW CREATES A GREAT SALINITY ANOMALY, AND (6) THE AGW GREAT SALINITY ANOMALY SLOWS DOWN THE ATLANTIC MERIODONAL OVERTURNING CIRCULATION: {NOTE: THE BEAUFORT GYRE IS AN OCEAN AND ICE CIRCULATION PATTERN OBSERVED IN THE BEAUFORT SEA NORTH OF ALASKA [LINK] }

 

 

THE NASA STATEMENT 

  1. The 2011 NASA ICESCAPE mission was a study of “Impacts of Climate on Ecosystems and Chemistry of the Arctic Pacific Environment”. It was a shipborne investigation to study how changing conditions in the Arctic affect the ocean’s chemistry and ecosystems. The bulk of the research took place in the Beaufort and Chukchi seas in summer 2010 and 2011. 
  2. A major ocean current in the Arctic (a reference to the Beaufort Gyre) is faster and more turbulent as a result of rapid sea ice melt, a new study from NASA shows. The current is part of a delicate Arctic environment that is now flooded with fresh water, an effect of human-caused climate change.
  3. Using 12 years of satellite data, scientists have measured how this circular current, called the Beaufort Gyre, has precariously balanced an influx of unprecedented amounts of cold, fresh water – a change that could alter the currents in the Atlantic Ocean and cool the climate of Western Europe. 
  4. The Beaufort Gyre keeps the polar environment in equilibrium by storing fresh water near the surface of the ocean. Wind blows the gyre in a clockwise direction around the western Arctic Ocean, north of Canada and Alaska, where it naturally collects fresh water from glacial melt, river runoff and precipitation. This fresh water is important in the Arctic in part because it floats above the warmer, salty water and helps to protect the sea ice from melting, which in turn helps regulate Earth’s climate. The gyre then slowly releases this fresh water into the Atlantic Ocean over a period of decades, allowing the Atlantic Ocean currents to carry it away in small amounts. 
  5. But the since the 1990s, the gyre has accumulated a large amount of fresh water — 1,920 cubic miles (8,000 cubic kilometers) — or almost twice the volume of Lake Michigan. The new study, published in Nature Communications, found that the cause of this gain in freshwater concentration is the loss of sea ice in summer and autumn. This decades-long decline of the Arctic’s summertime sea ice cover has left the Beaufort Gyre more exposed to the wind, which spins the gyre faster and traps the fresh water in its current.
  6. Persistent westerly winds have also dragged the current in one direction for over 20 years, increasing the speed and size of the clockwise current and preventing the fresh water from leaving the Arctic Ocean. This decades-long western wind is unusual for the region, where previously, the winds changed direction every five to seven years.
  7. Scientists have been keeping an eye on the Beaufort Gyre in case the wind changes direction again. If the direction were to change, the wind would reverse the current, pulling it counterclockwise and releasing the water it has accumulated all at once.
  8. If the Beaufort Gyre were to release the excess fresh water into the Atlantic Ocean, it could potentially slow down its circulation. And that would have hemisphere-wide implications for the climate, especially in Western Europe.
  9. Fresh water released from the Arctic Ocean to the North Atlantic can change the density of surface waters. Normally, water from the Arctic loses heat and moisture to the atmosphere and sinks to the bottom of the ocean, where it drives water from the North Atlantic Ocean down to the tropics like a conveyor belt.
  10. This important current is called the Atlantic Meridional Overturning Circulation and helps regulate the planet’s climate by carrying heat from the tropically-warmed water to northern latitudes like Europe and North America. If slowed enough, it could negatively impact marine life and the communities that depend it. We don’t expect a shutting down of the Gulf Stream, but we do expect impacts. That’s why we’re monitoring the Beaufort Gyre so closely.
  11. The study also found that, although the Beaufort Gyre is out of balance because of the added energy from the wind, the current expels that excess energy by forming small, circular eddies of water. While the increased turbulence has helped keep the system balanced, it has the potential to lead to further ice melt because it mixes layers of cold, fresh water with relatively warm, salt water below. The melting ice could, in turn, lead to changes in how nutrients and organic material in the ocean are mixed, significantly affecting the food chain and wildlife in the Arctic.
  12. The results reveal a delicate balance between wind and ocean as the sea ice pack recedes under climate change. What this study is showing is that the loss of sea ice has really important impacts on our climate system that we’re only just discovering. 

RESPONSE TO THE NASA STATEMENT

  1. The essential AGW/human cause case is that a causal link exists from AGW climate change to the great salinity anomaly of the 1990s. The causation sequence claimed  is as follows:  (1) AGW climate change caused Arctic sea ice to melt in summer and autumn. (2) The decline in Arctic sea ice cover rendered the Beaufort Gyre unstable and more susceptible to wind.
  2. The wind was then able to spin the Gyre around faster and faster creating turbulence and trapping more and more fresh water that had been made more abundant from the AGW driven sea ice melt.
  3. Unusually and unnaturally persistent westerly winds increased the speed and size of the Beaufort Gyre and also kept it moving in directions that would prevent all that fresh water from leaving the Arctic. The unusual persistence of the westerly winds for a decade may also be a creation of AGW climate change. (See also the assessment of the great salinity anomaly of the 1990s by Belkin (2004) in the “Great Salinity Anomalies” bibliography below.)
  4. Some conditional statements follow. IF the wind direction changes, the wind COULD reverse the Gyre’s flow to counterclockwise and that COULD release all that fresh water it had trapped and IF the fresh water were to be released into the Atlantic Ocean it COULD slow down the Atlantic Meridional Overturning Circulation and that COULD render the AMOC dysfunctional in the sense that it would be unable to regulate the planet’s climate by carrying heat from the Tropics to the Northern Latitudes. And that would surely create some CLIMATE IMPACTS. We don’t know what those impacts will be yet but it’s pretty  certain that there will be impacts.
  5. Postscript on the AMOC: As a footnote consider also the claim by Carl Wunsch that complex ocean circulation systems have been simplified to the point where the resulting analysis delivers more misinformation than information [LINK]
  6. Postscript on the “Great Salinity Anomalies” of the past:  A bibliography of salinity anomalies is provided below. An interesting note is the observation by many authors that Arctic salinity anomalies are controlled more by fresh water discharge than by ice melt.

 

 

AGW CLIMATE CHANGE & ARCTIC SEA ICE MELT IN SUMMER AND AUTUMN

  1. It is claimed in the NASA statement presented above that the salinity anomaly is a creation of AGW climate change because the process begins with sea ice melt in summer and autumn and because these melt events that create the fresh water causing the salinity anomaly are the creation of AGW climate change.
  2. That at a time of global warming subsequent years will be warmer than prior years and that warmer air temperatures would cause more sea ice melt appears to be logical. For example, this causation is seen in the seasonal cycle. A strong relationship between surface air temperature and sea ice volume in the seasonal cycle causes Arctic air temperature cycles of 40C or so from winter to summer to create the significant sea ice melt cycles in sea ice volume seen in the data.
  3. However, there is a significant difference between the seasonal cycle and long term AGW warming in terms of the range of temperatures seen in these two phenomena. The seasonal cycle range of approximately 40C from winter to summer is significantly larger than the range of deseasonalized temperatures ascribed to global warming.  For example, in the 41-year period 1979-2019, a period during which significant sea ice loss due to AGW climate change was claimed by climate science, the temperature range is closer to 4C. Therefore, seasonal cycle sea ice dynamics do not serve as a model for understanding the effect of global warming on sea ice volume. These are entirely different phenomena. A graphical display of the difference between the seasonal cycle and year to year changes in temperature  is provided below in Figure 3.
  4. Here, we use detrended correlation analysis to assess whether changes in year to year sea ice volume are related to the observed temperature rise over the Arctic that has been ascribed to AGW climate change. The results of this analysis is summarized in the correlation table presented below in Figure 6 below. If year to year temperature increases cause decreasing sea ice volume, we would expect to find a negative correlation between these two variables in the calendar months where AGW driven sea ice melt is claimed. And in fact, the second row of the correlation table labeled “CORR” does show strong statistically significant negative correlations for all calendar months.
  5. However, as described in related posts on this site, [LINK] , correlation between two time series derives not only from the responsiveness of one to the other but also from shared trends. For example if both time series are rising the shared trend will impose a positive correlation even when there is no responsiveness at the time scale of the proposed causation hypothesis. Therefore to test for responsiveness at a given time scale, the two time series must be detrended so that the trend effect is removed.
  6. Detrended correlations in the correlation table in Figure 6 are listed in the row labeled DETCOR. There we find that even at the high value of α=0.05, no detrended correlation at an annual time scale is found in the summer and fall months when AGW climate change is hypothesized to be melting sea ice and thereby creating a great salinity anomaly. The results summarized in the correlation table do not provide evidence that AGW climate change causes sea ice melt in summer and autumn. A GIF video image is provided in Figure 5 so that these correlations can be visualized.
  7. A further argument against the proposition that sea ice melt had caused a great salinity anomaly is found in many of the papers listed in the bibliography below where precipitation and fresh water runoff from rivers are proposed as the primary fresh water sources in such anomalies in the Arctic. We also find in these papers that “Great Salinity Anomalies” are not unique to AGW driven changes to the ocean described by NASA but that The Great Salinity Anomaly of the 1990s mentioned in the NASA article was just the latest such event that followed in the sequence that is traced to the Great Salinity Anomaly of the 1960s, The Great Salinity Anomaly of the 1970s,  and The Great Salinity Anomaly of the 1980s – non of which had an AGW climate change interpretation. The novelty of the current salinity anomaly as a peculiar climate change impact is less credible in this context.
  8. In summary, we find no evidence to support the claim that AGW climate change had caused a great salinity anomaly in the Arctic as described in the NASA article cited above.

 

Related post on the Ice Free Arctic Obsession of Climate Science [LINK]

 

 

FIGURE 1: Arctic Temperature Anomalies & Sea Ice Volume 1979-2019

 

FIGURE 2: The Seasonal Cycle in Arctic Sea Ice Volume 1979-2019

 

FIGURE 3: THE SEASONAL CYCLE AND LONG TERM MELT COMPARED

COMPARE-LOSSES

FIGURE 4: THE SEASONAL CYCLE IN TEMPERATURE AND ICE MELT: 1979-2019

 

FIGURE 5: VISUAL CORRELATION BETWEEN TEMPERATURE AND SEA ICE VOLUME

 

FIGURE 6: DETRENDED CORRELATION ANALYSIS: CORRELATION TABLE

CORRTABLE

 

 

 

 

 

 

 

 

 

BIBLIOGRAPHY

THE GREAT SALINITY ANOMALIES OF THE 1960S, 1970S, 1980S, & 1990S

  1. Dickson, Robert R., et al. “The “great salinity anomaly” in the northern North Atlantic 1968–1982.” Progress in Oceanography 20.2 (1988): 103-151The widespread freshening of the upper 500–800m layer of the northern North Atlantic, which this paper describes, represents one of the most persistent and extreme variations in global ocean climate yet observed in this century. Though a range of explanations have been advanced to explain this event, including in situ changes in the surface moisture flux, this paper describes the Great Salinity Anomaly as largely an advective event, traceable around the Atlantic subpolar gyre for over 14 years from its origins north of Iceland in the mid-to-late 1960s until its return to the Greenland Sea in 1981–1982. The overall propagation speed around this subpolar gyre is estimated at about 3cm s−1. Of the total salt deficit associated with the anomaly as it passed south along the Labrador Coast in 1971–1973 (about 72 × 109 tonnes), a deficit equivalent to about two thirds of this figure (47 × 109 tonnes) ultimately passed through the Faroe-Shetland Channel to the Barents Sea, Arctic Ocean and Greenland Sea during the mid-1970s.
  2. Häkkinen, Sirpa. “An Arctic source for the Great Salinity Anomaly: A simulation of the Arctic ice‐ocean system for 1955–1975.” Journal of Geophysical Research: Oceans 98.C9 (1993): 16397-16410.  A fully prognostic Arctic ice‐ocean model is used to study the interannual variability of the sea ice during the period 1955–1975 and to explain the large variability of the ice extent in the Greenland and Iceland seas during the late 1960’s. In particular, the model is used to test the conjecture of Aagaard and Carmack (1989) that the Great Salinity Anomaly (GSA) was a consequence of the anomalously large ice export in 1968. The objective here is to explore the high‐latitude ice‐ocean circulation changes due to wind field changes. In the simulations the ice extent in the Greenland Sea increased during the 1960’s, reaching a maximum in 1968, as observed, and maxima in ice extent were always preceded by large pulses of ice export through the Fram Strait. The ice export event of 1968 was the largest in the simulation, being about twice as large as the average and corresponding to 1600 km3 of excess fresh water. The simulated upper water column in the Greenland Sea has a salinity minimum in the fall of 1968, followed by very low winter salinities. The simulations suggest that, besides the above average ice export to the Greenland Sea, there was also fresh water export to support the larger than average ice cover. Three low‐salinity anomalies, which are created by the variability in ice production/melt, exited through the Fram Strait in 1963–1965, 1966, and 1967–1969, the later two events being associated with a net freshwater export of about 900 km3.The total simulated freshwater input of 2500 km3 to the Greenland Sea compares well with the estimated total freshwater excess of the GSA of about 2200 km3 as it passed through the Labrador Sea (Dickson et al., 1988). Considering the uncertainties in the model, it is possible that the ice export could account for even larger portion of the freshwater excess. However, the main conclusion is that these model results show the origin of the GSA to be in the Arctic, as suggested by Aagaard and Carmack (1989) and support the view that the Arctic may play an active role in climate change.
  3. Häkkinen, Sirpa. “A simulation of thermohaline effects of a great salinity anomaly.” Journal of Climate 12.6 (1999): 1781-1795.  Model simulations of an idealistic “Great Salinity Anomaly” (GSA) demonstrate that variability in the sea ice export from the Arctic when concentrated to short pulses can have a large influence on the meridional heat transport and can lead to an altered overturning state. One single freshwater disturbance resulting from excess ice export, as in 1968, can disrupt the deep mixing process. The critical condition for a large oceanic response is defined by the intensity, duration, and timing of the ice pulse, in particular, as it exits through the Denmark Strait. A recovery from this event takes several years for advection and diffusion to remove the salinity anomaly. Concurrently, the influence of the GSA propagates to the subtropics via the boundary currents and baroclinic adjustment. As a result of this adjustment, there are large (up to 20%) changes in the strength of the overturning cell and in the meridional heat transport in the subtropics and subpolar areas. Simulations show a temperature–salinity shift toward colder and fresher subpolar deep waters after the GSA, which is also found in hydrographic data.
  4. Belkin, Igor M. “Propagation of the “Great Salinity Anomaly” of the 1990s around the northern North Atlantic.” Geophysical Research Letters 31.8 (2004).   Time series of Temperature and Salinity extending through 2001 are used to describe propagation of the “Great Salinity Anomaly” of the 1990s (GSA’90s). Comparison of the distance‐time relations for the GSA’70s, ’80s, and ’90s reveals a substantial intensification of the large‐scale circulation in the northern North Atlantic, especially in the Subarctic Gyre between Newfoundland and the Faroes. The advection rate of the GSA’70s, ’80s, and ’90s between Newfoundland and the Faroe‐Shetland Channel is conservatively estimated to have been 3.5, 10, and 10 cm/s, respectively. The circulation intensification apparently occurred within a decade between the GSA’70s and ’80s. During the next decade the advection rate increased from 10 to 13 cm/s between Newfoundland and Iceland Basin. The GSA’90s was advected towards the Faroe‐Shetland Channel by the northern (Iceland Basin’s) branch of the North Atlantic Current, whereas the contribution of the southern branch via the Rockall Trough was minimal.

 

 

 

 

 

 

BIBLIOGRAPHY: ARCTIC SALINITY ANOMALIES

  1. Macdonald, R. W., et al. “Connections among ice, runoff and atmospheric forcing in the Beaufort Gyre.” Geophysical Research Letters 26.15 (1999): 2223-2226.  During the SHEBA, thin ice and freshening of the Arctic Ocean surface in the Beaufort Sea led to speculation that perennial sea ice was disappearing [McPhee et al., 1998]. Since 1987, we have collected salinity, δ18O and Ba profiles near the initial SHEBA site and, in 1997, we ran a section out to SHEBA. Resolving fresh water into runoff and ice melt, we found a large background of Mackenzie River water with exceptional amounts in 1997 explaining much of the freshening at SHEBA. Ice melt went through a dramatic 4–6 m jump in the early 1990s coinciding with the atmospheric pressure field and sea‐ice circulation becoming more cyclonic. The increase in sea‐ice melt appears to be a thermal and mechanical response to a circulation regime shift. Should atmospheric circulation revert to the more anticyclonic mode, ice conditions can also be expected to revert although not necessarily to previous conditions. Note: SHEBA refers to a sea surface salinity anomaly study 1987-2004 possibly motivated by “The Great Salinity Anomaly of the 1970s” when reductions in salinity of 0.1 to 0.5 psu was observed along with water temperature anomalies of -1C to -2C. SHEBA is an acronym for “Heat Budget of the Arctic Ocean”, More information on the SHEBA study may be found here:  [LINK]. PSU , or “Practical Salinity Unit, is a measure of sea water salinity based on its conductivity. 
  2. Steele, M., et al. “Adrift in the Beaufort Gyre: A model intercomparison.” Geophysical Research Letters 28.15 (2001): 2935-2938.  Output from six regional sea ice‐ocean climate model simulations of the arctic seas is compared to investigate the models’ ability to accurately reproduce the observed late winter mean sea surface salinity. The results indicate general agreement within the Nordic seas, strong differences on the arctic continental shelves, and the presence of a climate drift that leads to a high salinity bias in most models within the Beaufort Gyre. The latter is highly sensitive to the wind forcing and to the simulation of freshwater sources on the shelves and elsewhere.
  3. Proshutinsky, Andrey, R. H. Bourke, and F. A. McLaughlin. “The role of the Beaufort Gyre in Arctic climate variability: Seasonal to decadal climate scales.” Geophysical Research Letters 29.23 (2002): 15-1[FULL TEXT]. This paper presents a new hypothesis along with supporting evidence that the Beaufort Gyre (BG) plays a significant role in regulating the arctic climate variability. We propose and demonstrate that the BG accumulates a significant amount of fresh water (FW) during one climate regime (anticyclonic) and releases this water to the North Atlantic (NA) during another climate regime (cyclonic). This hypothesis can explain the origin of the salinity anomaly (SA) periodically found in the NA as well as its role in the decadal variability in the Arctic region.
  4. Carmack, Eddy, et al. “Freshwater storage in the Northern Ocean and the special role of the Beaufort Gyre.” Arctic–subArctic ocean fluxes. Springer, Dordrecht, 2008. 145-169.  As part of the global hydrological cycle, freshwater in the form of water vapour moves from warm regions of evaporation to cold regions of precipitation and freshwater in the form of sea ice and dilute seawater inexorably moves from cold regions of freezing and net precipitation to warm regions of melting and net evaporation. The global plumbing that supports the ocean’s freshwater loop is complicated, and involves land–sea exchanges, geographical and dynamical constraints on flow pathways as well as forcing variability over time (cf. Lagerloef and Schmitt 2006). The Arctic Ocean is a central player in the global hydrological cycle in that it receives, transforms, stores, and exports freshwater, and each of these processes and their rates both affect and are affected by climate variability. And within the Arctic Ocean, the Canada Basin (see Fig. 7.1) is of special interest for three reasons: (1) it processes freshwater from the Pacific, from North American and Eurasian rivers and from ice distillation; (2) it is the largest freshwater storage reservoir in the northern oceans; and (3) it has exhibited changes in halocline structure and freshwater storage in recent years.

    In this chapter we examine the distribution of freshwater anomalies (relative to a defined reference salinity) in northern oceans by reviewing criteria that have been used to construct freshwater budgets and then by comparing freshwater disposition in the subarctic Pacific, subarctic Atlantic and Arctic oceans. This comparison provides a useful basis for the interpretation of Arctic Ocean flux measurements and affirms that the Canada Basin is a significant freshwater reservoir (Section 7.2). We next examine various hydrographic data sources within the Canada Basin (a geographical feature) to define the role of the Beaufort Gyre (a wind-forced dynamical feature) in freshwater storage and release (Section 7.3). Due to this latter feature, the upper layer circulation in the Beaufort Gyre is anticyclonic whereas circulation elsewhere in the Arctic Ocean is cyclonic. Then we examine the Canada Basin’s role as a reservoir with respect to sources of its freshwater components (e.g. meteoritic (runoff and precipitation), sea-ice melt and Pacific throughflow), and also to its water mass structure, within which freshwater components are stored (Section 7.4). This distinction among source components and among water mass affiliations is a prerequisite to interpreting downstream freshwater fluxes and to predicting the response of the Arctic system to climate variability. Finally, we combine geochemical data and recent freshwater budget estimates to calculate the relative contributions of freshwater components from the Canada Basin to other Arctic basins

  5. McPhee, M. G., et al. “Rapid change in freshwater content of the Arctic Ocean.” Geophysical Research Letters 36.10 (2009)[FULL TEXT] The dramatic reduction in minimum Arctic sea ice extent in recent years has been accompanied by surprising changes in the thermohaline structure of the Arctic Ocean, with potentially important impact on convection in the North Atlantic and the meridional overturning circulation of the world ocean. Extensive aerial hydrographic surveys carried out in March–April, 2008, indicate major shifts in the amount and distribution of fresh‐water content (FWC) when compared with winter climatological values, including substantial freshening on the Pacific side of the Lomonosov Ridge. Measurements in the Canada and Makarov Basins suggest that total FWC there has increased by as much as 8,500 cubic kilometers in the area surveyed, effecting significant changes in the sea‐surface dynamic topography, with an increase of about 75% in steric level difference from the Canada to Eurasian Basins, and a major shift in both surface geostrophic currents and freshwater transport in the Beaufort Gyre. Fresh water exiting the Arctic in both the upper ocean and the sea ice cover plays a major role in controlling convection in the North Atlantic, and consequently the global thermohaline circulation [Aagaard and Carmack, 1989Walsh and Chapman, 1990Serreze et al., 2006Peterson et al., 2006]. Changes in the distribution and discharge of Arctic fresh water may thus figure prominently in the response of the world ocean to climate change: e.g., Aagaard and Carmack [1989] pointed out that a 25% increase in the freshwater discharge through Fram Strait maintained for two years (equivalent to freshwater excess of about 2,000 km3) would account for the salinity deficit observed in the North Atlantic during the “Great Salinity Anomaly” (GSA) of the 1970s, considered by Dickson et al. [1988] to be one of the major ocean climate events observed in the 20th century. The single largest feature in freshwater storage in the Arctic is the Beaufort Gyre (BG), an extensive anticyclonic ocean circulation in the Canada Basin north of Alaska [Carmack et al., 2008]. Here we report evidence from an International Polar Year (IPY) airborne hydrographic survey executed in March–April, 2008, of both significant redistribution and net increase in volume of Arctic FWC compared with climatological values. The freshening is concentrated mainly in the BG, and appears to have accelerated in concert with recent dramatic reduction in minimum sea ice extent [Maslanik et al., 2007]. Associated changes in sea‐surface dynamic topography have modified Arctic ocean circulation, with a large increase in northward transport of freshened water in the Canada Basin, toward the Fram Strait and Canadian Archipelago passages to the North Atlantic.
  6. Proshutinsky, Andrey, et al. “Beaufort Gyre freshwater reservoir: State and variability from observations.” Journal of Geophysical Research: Oceans 114.C1 (2009)[FULL TEXT]  We investigate basin‐scale mechanisms regulating anomalies in freshwater content (FWC) in the Beaufort Gyre (BG) of the Arctic Ocean using historical observations and data collected in 2003–2007. Specifically, the mean annual cycle and interannual and decadal FWC variability are explored. The major cause of the large FWC in the BG is the process of Ekman pumping (EP) due to the Arctic High anticyclonic circulation centered in the BG. The mean seasonal cycle of liquid FWC is a result of interplay between the mechanical (EP) and thermal (ice transformations) factors and has two peaks. One peak occurs around June–July when the sea ice thickness reaches its minimum (maximum ice melt). The second maximum is observed in November–January when wind curl is strongest (maximum EP) and the salt input from the growing ice has not yet reached its maximum. Interannual changes in FWC during 2003–2007 are characterized by a strong positive trend in the region varying by location with a maximum of approximately 170 cm a−1 in the center of EP influenced region. Decadal FWC variability in the period 1950–2000 is dominated by a significant change in the 1990s forced by an atmospheric circulation regime change. The center of maximum FWC shifted to the southeast and appeared to contract in area relative to the pre‐1990s climatology. In spite of the areal reduction, the spatially integrated FWC increased by over 1000 km3 relative to climatology.
  7. Giles, Katharine A., et al. “Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre.” Nature Geoscience 5.3 (2012): 194-197.  The Arctic Ocean’s freshwater budget comprises contributions from river runoff, precipitation, evaporation, sea-ice and exchanges with the North Pacific and Atlantic1. More than 70,000 km3 of freshwater2 are stored in the upper layer of the Arctic Ocean, leading to low salinities in upper-layer Arctic sea water, separated by a strong halocline from warm, saline water beneath. Spatially and temporally limited observations show that the Arctic Ocean’s freshwater content has increased over the past few decades, predominantly in the west3,4,5. Models suggest that wind-driven convergence drives freshwater accumulation6. Here we use continuous satellite measurements between 1995 and 2010 to show that the dome in sea surface height associated with the western Arctic Beaufort Gyre has been steepening, indicating spin-up of the gyre. We find that the trend in wind field curl—a measure of spatial gradients in the wind that lead to water convergence or divergence—exhibits a corresponding spatial pattern, suggesting that wind-driven convergence controls freshwater variability. We estimate an increase in freshwater storage of 8,000±2,000 km3 in the western Arctic Ocean, in line with hydrographic observations4,5, and conclude that a reversal in the wind field could lead to a spin-down of the Beaufort Gyre, and release of this freshwater to the Arctic Ocean.
  8. Morison, James, et al. “Changing arctic ocean freshwater pathways.” Nature 481.7379 (2012): 66-70Freshening in the Canada basin of the Arctic Ocean began in the 1990s1,2 and continued3 to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly4,5of the 1970s, raising the spectre of slowing global ocean circulation6. Freshening has been attributed to increased sea ice melting1 and contributions from runoff7, but a leading explanation has been a strengthening of the Beaufort High—a characteristic peak in sea level atmospheric pressure2,8—which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors2 must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation9 index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation. (Note: This is a bold and anti “consensus” view. The consensus view is that AGW melts sea ice and sea ice melt causes salinity anomalies)
  9. Krishfield, Richard A., et al. “Deterioration of perennial sea ice in the Beaufort Gyre from 2003 to 2012 and its impact on the oceanic freshwater cycle.” Journal of Geophysical Research: Oceans 119.2 (2014): 1271-1305[FULL TEXT]   Time series of ice draft from 2003 to 2012 from moored sonar data are used to investigate variability and describe the reduction of the perennial sea ice cover in the Beaufort Gyre (BG), culminating in the extreme minimum in 2012. Negative trends in median ice drafts and most ice fractions are observed, while open water and thinnest ice fractions (<0.3 m) have increased, attesting to the ablation or removal of the older sea ice from the BG over the 9 year period. Monthly anomalies indicate a shift occurred toward thinner ice after 2007, in which the thicker ice evident at the northern stations was reduced. Differences in the ice characteristics between all of the stations also diminished, so that the ice cover throughout the region became statistically homogenous. The moored data are used in a relationship with satellite radiometer data to estimate ice volume changes throughout the BG. Summer solid fresh water content decreased drastically in consecutive years from 730 km3 in 2006 to 570 km3 in 2007, and to 240 km3 in 2008. After a short rebound, solid fresh water fell below 220 km3 in 2012. Meanwhile, hydrographic data indicate that liquid fresh water in the BG in summer increased 5410 km3 from 2003 to 2010 and decreased at least 210 km3 by 2012. The reduction of both solid and liquid fresh water components indicates a net export of approximately 320 km3 of fresh water from the region occurred between 2010 and 2012, suggesting that the anticyclonic atmosphere‐ocean circulation has weakened.
  10. Manucharyan, Georgy E., and Michael A. Spall. “Wind‐driven freshwater buildup and release in the Beaufort Gyre constrained by mesoscale eddies.” Geophysical Research Letters 43.1 (2016): 273-282[FULL TEXT] Recently, the Beaufort Gyre has accumulated over 20,000 km3 of freshwater in response to strong anticyclonic atmospheric winds that have prevailed over the gyre for almost two decades. Here we explore key physical processes affecting the accumulation and release of freshwater within an idealized eddy‐resolving model of the Beaufort Gyre. We demonstrate that a realistic halocline can be achieved when its deepening tendency due to Ekman pumping is counteracted by the cumulative action of mesoscale eddies. Based on this balance, we derive analytical scalings for the depth of the halocline and its spin‐up time scale and emphasize their explicit dependence on eddy dynamics. Our study further suggests that the Beaufort Gyre is currently in a state of high sensitivity to atmospheric winds. However, an intensification of surface stress would inevitably lead to a saturation of the freshwater content—a constraint inherently set by the intricacies of the mesoscale eddy dynamics.

 

 

 

 

 

 

 

Leave a Reply to chaamjamal Cancel reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s


  • chaamjamal: Maybe you're right about that but there are some asian countries that aspire to nukedom but are prevented from inadequate access.
  • Mark Ulmer: And the third is cost (resulting from regulatory compliance). Cost and disposal are not unique to nuclear (renewables have the same issues) and are, i
  • chaamjamal: It seems like they are married to the renewable option. Note also the disadvantages of nuclear noted in the post. Weaponization and waste disposal are
%d bloggers like this: