On the interaction of atmospheric dynamics Arctic and mid-latitudes under climate change (original) (raw)
Related papers
A dynamical link between the Arctic and the global climate system
Geophysical Research Letters, 2006
By means of simulations with a global coupled AOGCM it is shown that changes in the polar energy sink region can exert a strong influence on the mid- and high-latitude climate by modulating the strength of the mid-latitude westerlies and storm tracks. It is found, that a more realistic sea-ice and snow albedo treatment changes the ice-albedo feedback and the radiative exchange between the atmosphere and the ocean-sea-ice system. The planetary wave energy fluxes in the middle troposphere of mid-latitudes between 30 and 50°N are redistributed, which induces perturbations in the zonal and meridional planetary wave trains from the tropics over the mid-latitudes into the Arctic. It is shown, that the improved parameterization of Arctic sea-ice and snow albedo can trigger changes in the Arctic and North Atlantic Oscillation pattern with strong implications for the European climate.
Large-scale atmospheric circulation changes are associated with the recent loss of Arctic sea ice
Tellus Series A-dynamic Meteorology and Oceanography, 2010
Recent loss of summer sea ice in the Arctic is directly connected to shifts in northern wind patterns in the following autumn, which has the potential of altering the heat budget at the cold end of the global heat engine. With continuing loss of summer sea ice to less than 20% of its climatological mean over the next decades, we anticipate increased modification of atmospheric circulation patterns. While a shift to a more meridional atmospheric climate pattern, the Arctic Dipole (AD), over the last decade contributed to recent reductions in summer Arctic sea ice extent, the increase in late summer open water area is, in turn, directly contributing to a modification of large scale atmospheric circulation patterns through the additional heat stored in the Arctic Ocean and released to the atmosphere during the autumn season. Extensive regions in the Arctic during late autumn beginning in 2002 have surface air temperature anomalies of greater than 3 °C and temperature anomalies above 850 hPa of 1 °C. These temperatures contribute to an increase in the 1000–500 hPa thickness field in every recent year with reduced sea ice cover. While gradients in this thickness field can be considered a baroclinic contribution to the flow field from loss of sea ice, atmospheric circulation also has a more variable barotropic contribution. Thus, reduction in sea ice has a direct connection to increased thickness fields in every year, but not necessarily to the sea level pressure (SLP) fields. Compositing wind fields for late autumn 2002–2008 helps to highlight the baroclinic contribution; for the years with diminished sea ice cover there were composite anomalous tropospheric easterly winds of ∼1.4 m s–1, relative to climatological easterly winds near the surface and upper tropospheric westerlies of ∼3 m s–1. Loss of summer sea ice is supported by decadal shifts in atmospheric climate patterns. A persistent positive Arctic Oscillation pattern in late autumn (OND) during 1988–1994 and in winter (JFM) during 1989–1997 shifted to more interannual variability in the following years. An anomalous meridional wind pattern with high SLP on the North American side of the Arctic—the AD pattern, shifted from primarily small interannual variability to a persistent phase during spring (AMJ) beginning in 1997 (except for 2006) and extending to summer (JAS) beginning in 2005.
Atmospheric aspects of Arctic change
Three important features of recent Arctic change are the rather uniform pattern of Arctic temperature amplification in response to greenhouse gas forcing, the modification of atmospheric temperature and wind patterns over newly sea-ice-free regions, and the possible increased linkage between Arctic climate and sub-arctic weather. An important argument for anthropogenic forcing of recent Arctic change is the model predicted rather uniform increases in Arctic temperatures, in contrast to more regional temperature maximums associated with intrinsic climate variability patterns such as those which occurred during the 1930s Arctic warming. Sea-ice-free areas at the end of summer are allowing: added heat and moisture transport into the troposphere as documented during the recent Japanese vessel Mirai cruises, decreased boundary layer stratification, and modification of wind flow through thermal wind processes. Winter 2009-2010 and December 2010 showed a unique connectivity between the Arc...
A difficult Arctic science issue: Midlatitude weather linkages
Polar Science, 2016
There is at present unresolved uncertainty whether Arctic amplification (increased air temperatures and loss of sea ice) impacts the location and intensities of recent major weather events in midlatitudes. There are three major impediments. The first is the null hypothesis where the shortness of time series since major amplification (~15 years) is dominated by the variance of the physical process in the attribution calculation. This makes it impossible to robustly distinguish the influence of Arctic forcing of regional circulation from random events. The second is the large chaotic jet stream variability at midlatitudes producing a small Arctic forcing signal-to-noise ratio. Third, there are other potential external forcings of hemispheric circulation, such as teleconnections driven by tropical and midlatitude sea surface temperature anomalies. It is, however, important to note and understand recent emerging case studies. There is evidence for a causal connection of Barents-Kara sea ice loss, a stronger Siberian High, and cold air outbreaks into eastern Asia. Recent cold air penetrating into the southeastern United States was related to a shift in the long-wave atmospheric wind pattern and reinforced by warmer temperatures west of Greenland. Arctic Linkages is a major research challenge that benefits from an international focus on the topic.
Characteristics of Atmospheric Circulation Associated with Variability of Sea Ice in the Arctic
Geosciences
The paper investigates the role of atmospheric circulation in the surface layer in forming the Arctic ice structure. For the analysis, the empirical orthogonal function (EOF) method of decomposition of the surface wind field is used, and the reaction of ice to changes in the principal components of leading EOF modes is investigated using statistical methods. Analyzing the rate of ice change in the Arctic associated with the Arctic ocean oscillation mode, we concluded that this mode’s variability leads to the formation of a seesaw in the ice field between two regions. From the one side, it is the region of the central deep-water part of the Arctic, including the East Siberian Sea, and from the other side, it is all other marginal seas. The second (“dipole”) mode is most associated with an increase/decrease in the ice thickness at the Arctic exit through the Fram Strait, as well as the formation of the so-called “ice factory” in the coastal region of the Beaufort Sea in the positive p...
The arctic ocean response to the North Atlantic oscillation
2010
The climatically sensitive zone of the Arctic Ocean lies squarely within the domain of the North Atlantic oscillation (NAO), one of the most robust recurrent modes of atmospheric behavior. However, the specific response of the Arctic to annual and longer-period changes in the NAO is not well understood. Here that response is investigated using a wide range of datasets, but concentrating on the winter season when the forcing is maximal and on the postwar period, which includes the most comprehensive instrumental record. This period also contains the largest recorded low-frequency change in NAO activity-from its most persistent and extreme low index phase in the 1960s to its most persistent and extreme high index phase in the late 1980s/early 1990s. This longperiod shift between contrasting NAO extrema was accompanied, among other changes, by an intensifying storm track through the Nordic Seas, a radical increase in the atmospheric moisture flux convergence and winter precipitation in this sector, an increase in the amount and temperature of the Atlantic water inflow to the Arctic Ocean via both inflow branches (Barents Sea Throughflow and West Spitsbergen Current), a decrease in the late-winter extent of sea ice throughout the European subarctic, and (temporarily at least) an increase in the annual volume flux of ice from the Fram Strait.
Feedbacks between the Arctic and the global climate system
1] By means of simulations with a global coupled AOGCM it is shown that changes in the polar energy sink region can exert a strong influence on the mid-and high-latitude climate by modulating the strength of the mid-latitude westerlies and storm tracks. It is found, that a more realistic sea-ice and snow albedo treatment changes the ice-albedo feedback and the radiative exchange between the atmosphere and the ocean-sea-ice system. The planetary wave energy fluxes in the middle troposphere of mid-latitudes between 30 and 50°N are redistributed, which induces perturbations in the zonal and meridional planetary wave trains from the tropics over the mid-latitudes into the Arctic. It is shown, that the improved parameterization of Arctic sea-ice and snow albedo can trigger changes in the Arctic and North Atlantic Oscillation pattern with strong implications for the European climate. Citation: Dethloff, K., et al. (2006), A dynamical link between the Arctic and the global climate system, Geophys. Res. Lett., 33, L03703,
Atmospheric Research, 2011
The Arctic has undergone substantial changes over the last few decades in various cryospheric and derivative systems and processes. Of these, the Arctic sea ice regime has seen some of the most rapid change and is one of the most visible markers of Arctic change outside the scientific community. This has drawn considerable attention not only from the natural sciences, but increasingly, from the political and commercial sectors as they begin to grapple with the problems and opportunities that are being presented. The possible impacts of past and projected changes in Arctic sea ice, especially as it relates to climatic response, are of particular interest and have been the subject of increasing research activity. A review of the current knowledge of the role of sea ice in the climate system is therefore timely. We present a review that examines both the current state of understanding, as regards the impacts of sea-ice loss observed to date, and climate model projections, to highlight hypothesised future changes and impacts on storm tracks and the North Atlantic Oscillation. Within the broad climate-system perspective, the topics of storminess and large-scale variability will be specifically considered. We then consider larger-scale impacts on the climatic system by reviewing studies that have focused on the interaction between sea-ice extent and the North Atlantic Oscillation. Finally, an overview of the representation of these topics in the literature in the context of IPCC climate projections is presented. While most agree on the direction of Arctic sea-ice change, the rates amongst the various projections vary greatly. Similarly, the response of storm tracks and climate variability are uncertain, exacerbated possibly by the influence of other factors. A variety of scientific papers on the relationship between sea-ice changes and atmospheric variability have brought to light important aspects of this complex topic. Examples are an overall reduction in the number of Arctic winter storms, a northward shift of mid-latitude winter storms in the Pacific and a delayed negative NAO-like response in autumn/winter to a reduced Arctic sea-ice cover (at least in some months). This review paper discusses this research and the disagreements, bringing about a fresh perspective on this issue.