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1

Warming Arctic, weakening polar vortex and winter cooling  

NASA Astrophysics Data System (ADS)

Spatiotemporal patterns of air temperature trends (1958-2012) are evaluated using reanalysis datasets and radiosonde data. Our analysis demonstrates large discrepancies between the reanalysis datasets, possibly due to differences in the data assimilation procedures as well as sparseness and inhomogeneity of high-latitude observations. A change of sign in the winter temperature trend from negative to positive in the mid- to late 1980s is documented in the upper troposphere/ lower stratosphere with a maximum over the Canadian Arctic. This change from cooling to warming tendency is associated with weakening of the stratospheric polar vortex and shift of its center toward the Siberian coast and possibly can be explained by the changes in the dynamics of the Arctic Oscillation. This pattern is likely linked to the observed multi-decadal variability in the Arctic with implications for recently observed winter cooling in Siberia and continental United States. Possible dynamical mechanisms linking the weakening of the polar vortex and weather in mid-latitudes are demonstrated in a number of model frameworks.

Alexeev, Vladimir; Esau, Igor; Outten, Stephen

2014-05-01

2

Development of the polar vortex in the 1999-2000 Arctic winter stratosphere  

NASA Technical Reports Server (NTRS)

The 1999-2000 Arctic stratospheric vortex was unusually cold, especially in the early winter lower stratosphere, with a larger area near polar stratospheric cloud formation temperatures in Dec and Jan, and much lower temperatures averaged over Nov-Jan, than any previously observed Arctic winter.

Manney, G. L.; Sabutis, J. L.

2000-01-01

3

MLS CLO observations and arctic polar vortex temperatures  

NASA Technical Reports Server (NTRS)

Analysis of Upper Altmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) observations in early January 1992 shows a clear relationship between predicted polar stratospheric cloud formation along the back trajectory and elevated ClO amounts. These findings are in good agreement with aircraft observations. The MLS observed variation of ClO amounts within the vortex also fits the pattern of ClO change as a result of air parcel solar exposure and nitric acid photolysis. Outside the polar vortex, the occasional highly elevated ClO appear statistically consistent with MLS measurement noise.

Schoeberl, M. R.; Stolarski, R. S.; Douglass, A. R.; Newman, P. A.; Lait, L. R.; Waters, J. W.; Froidevaux, L.; Ready, W. G.

1993-01-01

4

Stratospheric meterological conditions in the Arctic polar vortex, 1991 to 1992  

SciTech Connect

Stratospheric meterological conditions during the Airborne Arctic Stratospheric Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 k) should have formed over small regions in early December. The temperatures in the polar vortex warmed beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures.

Newman, P.; Lait, L.R.; Schoeberl, M. (National Aeronautics and Space Administration, Greenbelt, MD (United States)); Nash, E.R. (Applied Research Corp., Landover, MD (United States)); Kelly, K.; Fahey, D.W. (National Oceanic and Atmospheric Administration, Boulder, CO (United States)); Nagatani, R. (National Meteorological Center, Washington, DC (United States)); Toohey, D.; Avallone, L. (Univ. of California, Irvine, CA (United States)); Anderson, J. (Harvard Univ., Cambridge, MA (United States))

1993-08-27

5

Stratospheric meteorological conditions in the Arctic polar vortex, 1991 to 1992  

NASA Technical Reports Server (NTRS)

Stratospheric meteorological conditions during the Airborne Arctic Stratospheric Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 K) should have formed over small regions in early December. The temperatures in the polar vortex warmed beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures.

Newman, P.; Lait, L. R.; Schoeberl, M.; Nash, E. R.; Kelly, K.; Fahey, D. W.; Nagatani, R.; Toohey, D.; Avallone, L.; Anderson, J.

1993-01-01

6

Stratospheric meteorological conditions in the arctic polar vortex, 1991 to 1992.  

PubMed

Stratospheric meteorological conditions during the Airborne Arctic Stratospheric Expedition II (AASE II) presented excellent observational opportunities from Bangor, Maine, because the polar vortex was located over southeastern Canada for significant periods during the 1991-1992 winter. Temperature analyses showed that nitric acid trihydrates (NAT temperatures below 195 k) should have formed over small regions in early December. The temperatures in the polar vortex warmed beyond NAT temperatures by late January (earlier than normal). Perturbed chemistry was found to be associated with these cold temperatures. PMID:17790348

Newman, P; Lait, L R; Schoeberl, M; Nash, E R; Kelly, K; Fahey, D W; Nagatani, R; Toohey, D; Avallone, L; Anderson, J

1993-08-27

7

Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter  

NASA Technical Reports Server (NTRS)

Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (0-450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(y)) had also been removed, with layers of enhanced NO(y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (approximately 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 microns) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range of 0 is estimated to have been dehydrated in this event.

Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

1998-01-01

8

Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter  

NASA Technical Reports Server (NTRS)

Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta approximately 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(y)) had also been removed, with layers of enhanced NO(y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (approximately 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 micrometers) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range Transport of theta is estimated to have been dehydrated in this event.

Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

1998-01-01

9

Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter  

NASA Technical Reports Server (NTRS)

Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta = 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NOy) had also been removed, with layers of enhanced NOy at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (approx. 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 micrometers) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range of theta is estimated to have been dehydrated in this event.

Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoerberl, M. R.; Elkins, J. W.; Wamsley, P. R.

1998-01-01

10

Dehydration and Denitrification in the Arctic Polar Vortex During the 1995-1996 Winter  

NASA Technical Reports Server (NTRS)

Dehydration of more than 0.5 ppmv water was observed between 18 and 19 km (theta about 450-465 K) at the edge of the Arctic polar vortex on February 1, 1996. More than half the reactive nitrogen (NO(sub y)) had also been removed, with layers of enhanced (sub y) at lower altitudes. Back trajectory calculations show that air parcels sampled inside the vortex had experienced temperatures as low as 188 K within the previous 12 days, consistent with a small amount of dehydration. The depth of the dehydrated layer (about 1 km) and the fact that trajectories passed through the region of ice saturation in one day imply selective growth of a small fraction of particles to sizes large enough (>10 micron) to be irreversibly removed on this timescale. Over 25% of the Arctic vortex in a 20-30 K range of theta is estimated to have been dehydrated in this event.

Hintsa, E. J.; Newman, P. A.; Jonsson, H. H.; Webster, C. R.; May, R. D.; Herman, R. L.; Lait, L. R.; Schoeberl, M. R.; Elkins, J. W.; Wamsley, P. R.; Dutton, G. S.; Bui, T. P.; Kohn, D. W.; Anderson, J. G.

1998-01-01

11

Weakening of the stratospheric polar vortex by Arctic sea-ice loss.  

PubMed

Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes. PMID:25181390

Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

2014-01-01

12

Weakening of the stratospheric polar vortex by Arctic sea-ice loss  

NASA Astrophysics Data System (ADS)

Successive cold winters of severely low temperatures in recent years have had critical social and economic impacts on the mid-latitude continents in the Northern Hemisphere. Although these cold winters are thought to be partly driven by dramatic losses of Arctic sea-ice, the mechanism that links sea-ice loss to cold winters remains a subject of debate. Here, by conducting observational analyses and model experiments, we show how Arctic sea-ice loss and cold winters in extra-polar regions are dynamically connected through the polar stratosphere. We find that decreased sea-ice cover during early winter months (November-December), especially over the Barents-Kara seas, enhances the upward propagation of planetary-scale waves with wavenumbers of 1 and 2, subsequently weakening the stratospheric polar vortex in mid-winter (January-February). The weakened polar vortex preferentially induces a negative phase of Arctic Oscillation at the surface, resulting in low temperatures in mid-latitudes.

Kim, Baek-Min; Son, Seok-Woo; Min, Seung-Ki; Jeong, Jee-Hoon; Kim, Seong-Joong; Zhang, Xiangdong; Shim, Taehyoun; Yoon, Jin-Ho

2014-09-01

13

Polar Vortex Conditions During the 1995-96 Arctic Winter: MLS CL0 and HNO(sub 3)  

NASA Technical Reports Server (NTRS)

Microwave Limb Sounder (MLS) measurements of lower stratospheric CLO and HNO(sub 3) during the 1995-96 Arctic winter are presented. The 1995-96 Arctic winter was both colder and more persistently cold than usual, leading to an enhancement in lower stratospheric CLO of greater magnitude, vertical extent, and duration than has been previously observed in the Arctic. Vortex concentrations of HNO(sub 3) in mid-December were large due to diabetic decent. Trajectory calculations indicate that localized severe depletions of gas-phase HNO(sub 3) in mid-February and early March did not arise from intrainment of midlatitude air into the vortex and were therefore probably related to polar stratospheric cloud (PSC) formation.

Santee, M. L.; Manney, G. L.; Read, W. G.; Froidevaux, L.; Waters, J. W.

1996-01-01

14

Polar Vortex Conditions During The 1995-96 Arctic Winter: MLS ClO and HNO3  

NASA Technical Reports Server (NTRS)

Microwave Limb Sounder (MLS) measurements of lower stratospheric ClO and HNO3 during the 1995-96 Arctic winter are presented. The 1995-96 Arctic winter was both colder and more persistently cold than usual, leading to an enhancement in lower stratospheric ClO of greater magnitude, vertical extent, and duration than previously observed in the Arctic. Vortex concentrations of HNO3 in mid-December were large due to diabatic descent. Trajectory calculations indicate that localized severe depletions of gas-phase HNO3 in mid-February and early March did not arise from entrainment of midlatitude air into the vortex and were therefore probably related to polar stratospheric cloud (PSC) formation. A strong correlation between temperature and gas-phase HNO3 was evident, consistent with recurring PSC condensation and evaporation cycles.

Santee, M. L.; Manney, G. L.; Read, W. G.; Froidevaux, L.; Waters, J. W.

1996-01-01

15

The anomalous Arctic lower stratospheric polar vortex of 1992-1993  

NASA Technical Reports Server (NTRS)

Potential vorticity (PV) gradients defining the lower stratospheric vortex during the 1992-1993 winter were anomalously strong and persistent compared to those during the last 16 Arctic winters. For approximately equal to 3 months PV gradients were closer to typical Antarctic values than to most Arctic values. Air motion diagnostics computed for 3-dimensional air parcels confirm that the 1992-1993 Arctic lower stratospheric vortex was substantially more isolated than is typical. Such isolation will delay and reduce the export of the higher ozone typical of the winter lower stratospheric vortex to mid-latitudes. This may have contributed to the record-low total ozone amounts observed in northern mid-latitudes in 1993.

Manney, G. L.; Zurek, R. W.; Gelman, M. E.; Miller, A. J.; Nagatani, R.

1994-01-01

16

Enhancements of the refractory submicron aerosol fraction in the Arctic polar vortex: feature or exception?  

NASA Astrophysics Data System (ADS)

In situ measurements with a 4-channel stratospheric condensation particle counter (CPC) were conducted at up to 20 km altitude on board the aircraft M-55 Geophysica from Kiruna, Sweden, in January through March (EUPLEX 2003; RECONCILE 2010) and in December (ESSenCe, 2011). During all campaigns air masses from the upper stratosphere and mesosphere were subsiding inside the Arctic winter vortex, thus transporting refractory aerosol into the lower stratosphere (Θ<500 K) by vertical dispersion. The strength and extent of this downward transport varied between the years depending on the dynamical evolution of the vortex. Inside the vortex and at altitudes of potential temperatures Θ ? 450 K as many as eight of eleven particles per cm3 contained refractory material, thermally stable residuals with diameters from 10 nm to a few ?m which endure heat exposure of 250 °C. Particle mixing ratios (up to 150 refractory particles per milligram of air) and fractions of non-volatile particles (up to 75% of totally detected particles) reach highest values in air masses with lowest content of nitrous oxide (N2O, down to 70 nmol mol-1). This indicates that refractory aerosol originates from the upper stratosphere or the mesosphere. From mixing ratios of the long lived tracer N2O (simultaneously measured in situ) an empirical index was derived which serves to differentiate air masses according to their origin from inside the vortex, the vortex edge region, and outside the vortex. Previously, observed high fractions of refractory submicron aerosol in the 2003 Arctic vortex were ascribed to unusually strong subsidence during that winter. Measurements under perturbed vortex conditions in 2010 and during early winter in December 2011, however, revealed similarly high values. Thus, the abundance of refractory aerosol at high levels appears to be a feature rather than the exception for the Arctic vortices. During December, the import from aloft into the lower stratosphere appears to be developing; thereafter the abundance of refractory aerosol inside the vortex reaches its highest levels until March. A measurement-based estimate of the total mass of refractory aerosol inside the vortex is provided for each campaign. Based on the derived increase of particle mass in the lower stratospheric vortex (100-67 hPa pressure altitude) on the order of 32 × 106 kg between early and late winter and assuming a mesospheric origin, we estimate the total mass of mesospheric particles deposited in the Arctic vortex and compare it to the expected atmospheric influx of meteoritic material (110 ± 55 × 103 kg per day). Such estimates at present still hold considerable uncertainties which are discussed in detail. Nevertheless, the results strongly suggest that the Arctic vortex easily achieves the drainage of all meteoric material deposited on the upper atmosphere.

Weigel, R.; Volk, C. M.; Kandler, K.; Hösen, E.; Günther, G.; Vogel, B.; Grooß, J.-U.; Khaykin, S.; Belyaev, G. V.; Borrmann, S.

2014-04-01

17

Ozone depletion in filaments of the Arctic Polar Vortex observed during the first Global Hawk UAS science mission  

NASA Astrophysics Data System (ADS)

One of the important potential uses of the NASA Global Hawk Unmanned Aircraft System (UAS) in scientific research is to study stratospheric ozone (O3) depletion in polar regions. Manned flights involve remote and hazardous duty, which pose great risks to pilots, crew, and scientists. Arctic ozone depletion observed in the spring of 2010 by satellites, manned aircraft campaigns, ground-base stations was less severe than that observed this year (2011). The Global Hawk UAS flight on 23 April 2010 was the first to observe ozone-depleted air with a UAS platform. Temperatures in the polar vortex were cold enough for Type II Polar Stratospheric Clouds (PSC) to form for a short period (days) at 50 hPa in 2010, and cold temperatures existed for almost 2 months for Type I PSC formation. Based on the NOAA Unmanned aircraft systems Chromatograph for Atmospheric Trace Species (UCATS) ozone versus nitrous oxide tracer correlation plot (below), there is 21% less ozone in air from a polar filament sampled on 7 April 2010 compared to the Arctic air sampled later on 23 April 2010. The NOAA UAS Fast Ozone Instrument showed a similar pattern with respect to N2O. Age-of-air values derived from on board SF6 observations were about 5 years in the filament versus about 3 years outside the filament in the subsequent polar flight. The Global Hawk UAS flights were part of the Global Hawk Pacific Experiment (GloPac), which demonstrated flights up to 28.6 hr duration, altitudes as high as 19.8 km and a maximum range of 9200 nm while carrying a payload of in situ and remote instrumentation for atmospheric chemical and aerosol tracers. This first science mission of the NASA Global Hawk UAS demonstrated its huge potential for stratospheric ozone research over remote and hazardous polar areas.

Elkins, J. W.; Hintsa, E. J.; Dutton, G. S.; Hall, B. D.; Moore, F. L.; Gao, R.; Oltmans, S. J.; Patrick, L.; Johnson, B. J.; Ray, E. A.; Nance, D.; Fahey, D. W.; Newman, P. A.

2011-12-01

18

Observations of the Mars Polar Vortex  

NASA Technical Reports Server (NTRS)

The winter season, westerly circumpolar flow of the Martian atmosphere, and of the terrestrial stratosphere, is concentrated into a jet whose latitude falls between 60 and 80 degrees. This jet is known as the polar vortex. The terrestrial polar vortex has been understood to be the dynamical controlling mechanism for ozone depletion in the polar stratosphere for more than a decade. More recently, the earth's stratospheric annular modes, which are essentially a weakening/strengthening oscillation of the polar vortex jet, have been shown to be coupled to and possibly even a driving mechanism for, the tropospheric Arctic Oscillation (AO) / North Atlantic Oscillation (NAO) phenomenon.

McConnochie, T. H.; Conrath, B. J.; Gierasch, P. J.; Banfield, D.; Smith, M. D.

2003-01-01

19

Chemical loss of ozone in the Arctic polar vortex in the winter of 1991-1992  

SciTech Connect

In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meterological tracer, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double.

Salawitch, R.J.; Wofsy, Gottlieb, E.W.; Anderson, J.G. (Harvard Univ., Cambridge, MA (United States)); Lait, L.R.; Newman, P.A.; Schoeberl, M.R.; Strahan, S.E. (National Aeronautics and Space Administration, Greenbelt, MD (United States)); Loewenstein, M.; Podolske, J.R.; Chan, K.R. (NASA Ames Research Center, Moffett Field, CA (United States)); Proffitt, M.H.; Fahey, D.W.; Kelly, K.K. (National Oceanic and Atmospheric Administration, Boulder, CO (United States)); Webster, C.R.; May, R.D. (Jet Propulsion Lab., Pasadena, CA (United States)); Baumgardner, D.; Dye, J.E. (National Center for Atmospheric Research, Boulder, CO (United States)); Wilson, J.C. (Univ. of Denver, CO (United States)); Elkins, J.W. (NOAA Climate Monitoring and Diagnostics Lab., Boulder, CO (United States))

1993-08-27

20

Chemical loss of ozone in the arctic polar vortex in the winter of 1991-1992.  

PubMed

In situ measurements of chlorine monoxide, bromine monoxide, and ozone are extrapolated globally, with the use of meteorological tracers, to infer the loss rates for ozone in the Arctic lower stratosphere during the Airborne Arctic Stratospheric Expedition II (AASE II) in the winter of 1991-1992. The analysis indicates removal of 15 to 20 percent of ambient ozone because of elevated concentrations of chlorine monoxide and bromine monoxide. Observations during AASE II define rates of removal of chlorine monoxide attributable to reaction with nitrogen dioxide (produced by photolysis of nitric acid) and to production of hydrochloric acid. Ozone loss ceased in March as concentrations of chlorine monoxide declined. Ozone losses could approach 50 percent if regeneration of nitrogen dioxide were inhibited by irreversible removal of nitrogen oxides (denitrification), as presently observed in the Antarctic, or without denitrification if inorganic chlorine concentrations were to double. PMID:17790349

Salawitch, R J; Wofsy, S C; Gottlieb, E W; Lait, L R; Newman, P A; Schoeberl, M R; Loewenstein, M; Podolske, J R; Strahan, S E; Proffitt, M H; Webster, C R; May, R D; Fahey, D W; Baumgardner, D; Dye, J E; Wilson, J C; Kelly, K K; Elkins, J W; Chan, K R; Anderson, J G

1993-08-27

21

Titan's Winter Polar Vortex  

NASA Technical Reports Server (NTRS)

Titan's atmosphere has provided an interesting study in contrasts and similarities with Earth's. While both have N$_2$ as the dominant constituent and comparable surface pressures $\\sim1$ bar, Titan's next most abundant molecule is CH$_4$, not O$_2$, and the dissociative breakup of CH$_4$ and N$_2$ by sunlight and electron impact leads to a suite of hydrocarbons and nitriles, and ultimately the photochemical smog that enshrouds the moon. In addition, with a 15.95-day period, Titan is a slow rotator compared to Earth. While the mean zonal terrestrial winds are geostrophic, Titan's are mostly cyclostrophic, whipping around the moon in as little as 1 day. Despite the different dynamical regime, Titan's winter stratosphere exhibits several characteristics that should be familiar to terrestrial meteorologists. The cold winter pole near the 1 -mbar level is circumscribed by strong winds (up to 190 m/s) that act as a barrier to mixing with airmasses at lower latitudes. There is evidence of enhancement of several organic species over the winter pole, indicating subsidence. The adiabatic heating associated with this subsidence gives rise to a warm anomaly at the 0.01-mbar level, raising the stratopause two scale heights above its location at equatorial latitudes. Condensate ices have been detected in Titan's lower stratosphere within the winter polar vortex from infrared spectra. Although not always unambiguously identified, their spatial distribution exhibits a sharp gradient, decreasing precipitously across the vortex away from the winter pole. The interesting question of whether there is important heterogeneous chemistry occurring within the polar vortex, analogous to that occurring in the terrestrial polar stratospheric clouds in the ozone holes, has not been addressed. The breakup of Titan's winter polar vortex has not yet been observed. On Earth, the polar vortex is nonlinearly disrupted by interaction with large-amplitude planetary waves. Large-scale waves have not been identified in Titan's atmosphere, so the decay of its polar vortex may be more gradual than on Earth. Observations from an extended Cassini mission into late northern spring should provide critical data indicating whether the vortex goes away with a bang or just fades away.

Flasar, F.M.; Achterberg, R.K.; Schinder, P.J.

2008-01-01

22

The potential for ozone depletion in the arctic polar stratosphere.  

PubMed

The nature of the Arctic polar stratosphere is observed to be similar in many respects to that of the Antarctic polar stratosphere, where an ozone hole has been identified. Most of the available chlorine (HCl and ClONO(2)) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl(2)O(2) throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO(3), and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15% at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8% losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50% over the next two decades, ozone losses recognizable as an ozone hole may well appear. PMID:17842951

Brune, W H; Anderson, J G; Toohey, D W; Fahey, D W; Kawa, S R; Jones, R L; McKenna, D S; Poole, L R

1991-05-31

23

In situ observations of HO2 and OH obtained on the NASA ER-2 in the high-ClO conditions of the 1999/2000 Arctic polar vortex  

NASA Astrophysics Data System (ADS)

Extensive observations of OH and HO2 obtained aboard the NASA ER-2 inside the Arctic polar vortex during the SAGE III Ozone loss and Validation Experiment (SOLVE) provide the opportunity to identify and test interferences during the measurement of HO2 in the presence of high concentrations of ClO. In-flight calibrations are consistent with small interferences from CH3O2 (8%) and from ClO (3%) to the total signal on average inside the vortex. Measurements of HO2, OH, ClO, and O3 are used with rate constants derived from laboratory measurements to test the consistency of the reactions that control HO2/OH. Inside the vortex the calculated HO2/OH under predicts the observed HO2/OH by 7% with the JPL-00 rate constants and over-predicts the observations by 23% when recent laboratory rates are used. Measurements of HO2 and ClO are used to calculate ozone loss rates and concentrations of HOCl with uncertainties determined from the analysis of HO2/OH. The calculated concentration of HOCl is 52-28+50 pptv, or 0.07 × ClO on average in the vortex. The ozone loss rate from the two cycles controlled by HO2 + ClO is ˜1.5-0.5+1.2 ppbv d-1 in early March.

Hanisco, T. F.; Smith, J. B.; Stimpfle, R. M.; Wilmouth, D. M.; Anderson, J. G.; Richard, E. C.; Bui, T. P.

2002-10-01

24

Trace Gas Transport in the Arctic Vortex Inferred from ATMOS ATLAS-2 Observations During April 1993  

NASA Technical Reports Server (NTRS)

Measurements of the long-lived tracers CH4, N2O, and HF from the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument during the Atmospheric Laboratory for Science and Applications-2 (ATLAS-2) Space Shuttle mission in April 1993 are used to infer average winter descent rates ranging from 0.8 km/month at 20 km to 3.2 km/month at 40 km in the Arctic polar vortex during the 1992-93 winter. Descent rates in the mid-stratosphere are similar to those deduced for the Antarctic vortex using ATMOS/ATLAS-3 measurements in November 1994, but the shorter time period of descent in the Arctic leads to smaller total distances of descent. Strong horizontal gradients observed along the vortex edge indicate that the Arctic vortex remains a significant barrier to transport at least until mid-April in the lower to middle stratosphere.

Abrams, M. C.; Manney, G. L.; Gunson, M. R.; Abbas, M. M.; Chang, A. Y.; Goldman, A.; Irion, F. W.; Michelsen, H. A.; Newchurch, M. J.; Rinsland, C, P,; Salawitch, R. J.; Stiller, G. P.; Zander, R.

1996-01-01

25

Airborne lidar observations in the wintertime Arctic stratosphere: Polar stratospheric clouds  

Microsoft Academic Search

Polar stratospheric cloud (PSC) distributions in the wintertime Arctic stratosphere and their optical characteristics were measured with a multi-wavelength airborne lidar system as part of the 1989 Airborne Arctic Stratospheric Expedition. PSCs were observed on 10 flights between January 6 and February 2, 1989, into the polar vortex. The PSCs were found in the 14-27 km altitude range in regions

E. V. Browell; S. Ismail; A. F. Carter; N. S. Higdon; C. F. Butler; P. A. Robinette; O. B. Toon; M. R. Schoeberl; A. F. Tuck

1990-01-01

26

Synoptic Evolution of the Arctic Vortex During Elevated Stratopause Events: WACCM vs. Observations  

NASA Astrophysics Data System (ADS)

The structure of the Arctic polar vortex is diagnosed during 15 elevated stratopause (ES) events using 40 years of output from the Whole Atmosphere Community Climate Model (WACCM). For each event, stratopause height maxima are interpreted in the context of the structure of the Arctic vortex. The WACCM results are compared to the 2006, 2009, 2012, and 2013 ES events observed by the Microwave Limb Sounder (MLS) and the Arctic vortex in the Goddard Earth Observing System (GEOS) version 5 analyses. The stratopause first reforms at high altitudes over confined geographic regions before it becomes elevated over the entire polar cap. Thus, defining the day that the stratopause reformed using polar cap averaged temperatures results in a later date than if polar maps of stratopause height are used. Even once an ES event has started based on polar cap mean temperatures, the ES is not at a uniform altitude over the polar cap. Complex patterns change rapidly from day-to-day. ES events simulated by WACCM are zonally asymmetric 33% of the time due to large amplitude planetary waves in the upper stratosphere. This frequency agrees with observations in that the 2012 ES event was zonally asymmetric. For the 66% of ES events that are zonally symmetric in a monthly mean following each event, there are significant periods when zonal symmetry is violated and the vortex structure tilts westward with height over 270o in longitude.

Harvey, V.; Collins, R. L.; Randall, C. E.

2013-12-01

27

Microphysical properties of synoptic-scale polar stratospheric clouds: in situ measurements of unexpectedly large HNO3-containing particles in the Arctic vortex  

NASA Astrophysics Data System (ADS)

In January 2010 and December 2011, synoptic-scale polar stratospheric cloud (PSC) fields were probed during seven flights of the high-altitude research aircraft M-55 Geophysica within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interaction) and the ESSenCe (ESSenCe: ESA Sounder Campaign) projects. Particle size distributions in a diameter range between 0.46 and 40?m were recorded by four different optical in situ instruments. Three of these particle instruments are based on the detection of forward-scattered light by single particles. The fourth instrument is a grayscale optical array imaging probe. Optical particle diameters of up to 35?m were detected with particle number densities and total particle volumes exceeding previous Arctic measurements. Also, gas-phase and particle-bound NOy was measured, as well as water vapor concentrations. The optical characteristics of the clouds were measured by the remote sensing lidar MAL (Miniature Aerosol Lidar) and by the in situ backscatter sonde MAS (Multiwavelength Aerosol Scatterometer), showing the synoptic scale of the encountered PSCs. The particle mode below 2?m in size diameter has been identified as supercooled ternary solution (STS) droplets. The PSC particles in the size range above 2?m in diameter are considered to consist of nitric acid hydrates, and the particles' high HNO3 content was confirmed by the NOy instrument. Assuming a particle composition of nitric acid trihydrate (NAT), the optically measured size distributions result in particle-phase HNO3 mixing ratios exceeding available stratospheric values. Therefore the measurement uncertainties concerning probable overestimations of measured particle sizes and volumes are discussed in detail. We hypothesize that either a strong asphericity or an alternate particle composition (e.g., water ice coated with NAT) could explain our observations. In particular, with respect to the denitrification by sedimentation of large HNO3-containing particles, generally considered to be NAT, our new measurements raise questions concerning composition, shape and nucleation pathways. Answering these would improve the numerical simulation of PSC microphysical processes like cloud particle formation, growth and denitrification, which is necessary for better predictions of future polar ozone losses, especially under changing global climate conditions. Generally, it seems that the occurrence of large NAT particles - sometimes termed "NAT rocks" - are a regular feature of synoptic-scale PSCs in the Arctic.

Molleker, S.; Borrmann, S.; Schlager, H.; Luo, B.; Frey, W.; Klingebiel, M.; Weigel, R.; Ebert, M.; Mitev, V.; Matthey, R.; Woiwode, W.; Oelhaf, H.; Dörnbrack, A.; Stratmann, G.; Grooß, J.-U.; Günther, G.; Vogel, B.; Müller, R.; Krämer, M.; Meyer, J.; Cairo, F.

2014-10-01

28

Observations of filamentary structures near the vortex edge in the Arctic winter lower stratosphere  

NASA Astrophysics Data System (ADS)

The CRISTA-NF (Cryogenic Infrared Spectrometers and Telescope for the Atmosphere - New Frontiers) instrument is an airborne infrared limb sounder operated aboard the Russian research aircraft M55-Geophysica. The instrument successfully participated in a large Arctic aircraft campaign within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) project in Kiruna (Sweden) from January to March 2010. This paper concentrates on the measurements taken during one flight of the campaign, which took place on 2 March in the vicinity of the polar vortex. We present two-dimensional cross-sections of derived volume mixing ratios for the trace gases CFC-11, O3, and ClONO2 with an unprecedented vertical resolution of about 500 to 600 m for a large part of the observed altitude range (? 6-19 km) and a dense horizontal sampling along flight direction of ? 15 km. The trace gas distributions show several structures, for example a part of the polar vortex and a vortex filament, which can be identified by means of O3-CFC-11 tracer-tracer correlations. The observations made during this flight are interpreted using the chemistry and transport model CLaMS (Chemical Lagrangian Model of the Stratosphere). Comparisons of the observations with the model results are used to assess the performance of the model with respect to advection, mixing, and the chemistry in the polar vortex. These comparisons confirm the capability of CLaMS to reproduce even very small-scale structures in the atmosphere, which partly have a vertical extent of only 1 km. Based on the good agreement between simulation and observation, we use artificial (passive) tracers, which represent different air mass origins (e.g. vortex, tropics), to further analyse the CRISTA-NF observations in terms of the composition of air mass origins. These passive tracers clearly illustrate the observation of filamentary structures that include tropical air masses. A characteristic of the Arctic winter 2009/10 was a sudden stratospheric warming in December that led to a split of the polar vortex. The vortex re-established at the end of December. Our passive tracer simulations suggest that large parts of the re-established vortex consisted to about 45% of high- and mid-latitude air.

Kalicinsky, C.; Grooß, J.-U.; Günther, G.; Ungermann, J.; Blank, J.; Höfer, S.; Hoffmann, L.; Knieling, P.; Olschewski, F.; Spang, R.; Stroh, F.; Riese, M.

2013-11-01

29

Vortex polarization states in nanoscale ferroelectric arrays.  

PubMed

Two-dimensional arrays of ferroelectric lead zirconate titanate (PZT) nanodots were fabricated using pulsed laser deposition through ultrathin anodic aluminum oxide membrane stencil masks. The static distribution of polarization configurations was investigated using in- and out-of-plane piezoresponse force microscopy (PFM). The observed presence of an in-plane polarization component in nominally (001) oriented PZT suggests the existence of a significant deviation from the regular tetragonal structure that allows the formation of complex core-polarization states. Core-polarization states may indicate the presence of quasi-toroidal polarization ordering. The experimental results are compared with a theoretical model to determine the fingerprint of a vortex polarization state in PFM. PMID:19191502

Rodriguez, B J; Gao, X S; Liu, L F; Lee, W; Naumov, I I; Bratkovsky, A M; Hesse, D; Alexe, M

2009-03-01

30

On the Origin of Polar Vortex Air  

NASA Technical Reports Server (NTRS)

The existence of the multi-year HALOE CH4 data set, together with some comparisons of forward with back trajectory calculations which we have carried out, has motivated us to reexamine the question of polar vortex descent. Three-dimensional diabatic trajectory calculations have been carried out for the seven month fall to spring period in both the northern hemisphere (NH) and southern hemisphere (SH) polar stratosphere for the years 1992-1999. These computations are compared to fixed descent computations where the parcels were fixed at their latitude-longitude locations and allowed to descend without circulating. The forward trajectory computed descent is always less than the fixed descent due to horizontal parcel motions and variations in heating rates with latitude and longitude. Although the forward calculations estimate the maximum amount of descent that can occur, they do not necessarily indicate the actual origin of springtime vortex air. This is because more equator-ward air can be entrained within the vortex during its formation. To examine the origin of the springtime vortex air, the trajectory model was run backward for seven months from spring to fall. The back trajectories show a complex distribution of parcels in which one population originates in the upper stratosphere and mesosphere and experiences considerable descent in the polar regions, while the remaining parcels originate at lower altitudes of the middle and lower stratosphere and are mixed into the polar regions during vortex formation without experiencing as much vertical transport. The amount of descent experienced by the first population shows little variability from year to year, while the computed descent and mixing of the remaining parcels show considerable interannual variability due to the varying polar meteorology. Because of this complex parcel distribution it is not meaningful to speak of a net amount of descent experienced over the entire winter period. Since the back trajectories indicate that much of the air can come from lower altitudes than would be implied by the forward calculations, using a comparison between pre-winter and post-winter tracer profiles to estimate the amount of descent over this period will give erroneous descent amounts. In order to evaluate the computed descent, spring methane amounts were computed by mapping HALOE fall observations onto the final latitude-altitude locations of the back trajectories. These locations indicate the origin of the spring vortex air. The agreement between the computed means and the spring HALOE means is generally within 0.1-0.2 ppmv in the NH and 0.1-0.4 ppmv in the SH.

Rosenfield, J. E.; Schoeberl, M. R.; Einaudi, Franco (Technical Monitor)

2001-01-01

31

Venus's southern polar vortex reveals precessing circulation.  

PubMed

Initial images of Venus's south pole by the Venus Express mission have shown the presence of a bright, highly variable vortex, similar to that at the planet's north pole. Using high-resolution infrared measurements of polar winds from the Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument, we show the vortex to have a constantly varying internal structure, with a center of rotation displaced from the geographic south pole by ~3 degrees of latitude and that drifts around the pole with a period of 5 to 10 Earth days. This is indicative of a nonsymmetric and varying precession of the polar atmospheric circulation with respect to the planetary axis. PMID:21474710

Luz, D; Berry, D L; Piccioni, G; Drossart, P; Politi, R; Wilson, C F; Erard, S; Nuccilli, F

2011-04-29

32

Microphysical properties of synoptic scale polar stratospheric clouds: in situ measurements of unexpectedly large HNO3 containing particles in the Arctic vortex  

NASA Astrophysics Data System (ADS)

In January 2010 and December 2011 synoptic scale PSC fields were probed during seven flights of the high altitude research aircraft M-55 Geophysica within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interaction.) and the ESSenCe (ESSenCe: ESA Sounder Campaign) projects. Particle size distributions in a diameter range between 0.46 ?m and 40 ?m were recorded simultaneously by up to four different optical in situ instruments. Three of these particle instruments are based on the detection of forward scattered light by single particles. The fourth instrument is a grey scale optical array imaging probe. Optical particle diameters of up to 35 ?m were detected with particle number densities and total particle volumes exceeding previous Arctic measurements. Also, gas phase and particle bound NOy were measured, as well as water vapor concentrations, and other variables. Two remote sensing particle instruments, the Miniature Aerosol Lidar (MAL) and the backscatter sonde (MAS, Multiwavelenght Aerosol Scatterometer) showed the synoptic scale of the encountered PSCs. The particle mode below 2 ?m in size diameter has been identified as supercooled ternary solution droplets (STS). The PSC particles in the size range above 2 ?m in diameter are considered to consist of nitric acid hydrates or ice, and the particles' high HNO3 content was confirmed by the NOy instrument. Assuming a particle composition of nitric acid trihydrate (NAT), the optically measured size distributions result in particle-phase HNO3 mixing ratios exceeding available stratospheric values. In particular, with respect to the denitrification by sedimentation of large HNO3-contaning particles, generally considered as NAT, our new measurements raise questions concerning composition, shape and nucleation pathways. Measurement uncertainties are discussed concerning probable overestimations of measured particle sizes and volumes. We hypothesize that either a strong asphericity or the particle composition (e.g. water-ice coated with NAT) could explain our observations.

Molleker, S.; Borrmann, S.; Schlager, H.; Luo, B.; Frey, W.; Klingebiel, M.; Weigel, R.; Ebert, M.; Mitev, V.; Matthey, R.; Woiwode, W.; Oelhaf, H.; Dörnbrack, A.; Stratmann, G.; Grooß, J.-U.; Günther, G.; Vogel, B.; Müller, R.; Krämer, M.; Meyer, J.; Cairo, F.

2014-05-01

33

Dynamics of Saturn's south polar vortex.  

PubMed

The camera onboard the Cassini spacecraft has allowed us to observe many of Saturn's cloud features. We present observations of Saturn's south polar vortex (SPV) showing that it shares some properties with terrestrial hurricanes: cyclonic circulation, warm central region (the eye) surrounded by a ring of high clouds (the eye wall), and convective clouds outside the eye. The polar location and the absence of an ocean are major differences. It also shares properties with the polar vortices on Venus, such as polar location, cyclonic circulation, warm center, and long lifetime, but the Venus vortices have cold collars and are not associated with convective clouds. The SPV's combination of properties is unique among vortices in the solar system. PMID:18369142

Dyudina, Ulyana A; Ingersoll, Andrew P; Ewald, Shawn P; Vasavada, Ashwin R; West, Robert A; Del Genio, Anthony D; Barbara, John M; Porco, Carolyn C; Achterberg, Richard K; Flasar, F Michael; Simon-Miller, Amy A; Fletcher, Leigh N

2008-03-28

34

Loss of ozone in the Arctic vortex for the winter of 1989  

NASA Technical Reports Server (NTRS)

Measurements of ClO (Brune et al., 1990) acquired during the Airborne Arctic Stratospheric Expedition are used to infer concentrations of reactive chlorine (ClO + 2 x Cl2O2). Observed fields of potential temperature and potential vorticity are used to extrapolate in situ data to larger regions of the vortex. Calculated values of the loss rate of O3, based on estimates of reactive chlorine and measurements of BrO (Toohey et al., 1990), suggest that the loss of O3 was abut 12 pct for levels of the atmosphere with potential temperatures between 440 and 470 K over the 39 day duration of the ER-2 flights into the polar vortex. Calculated loss rates agree with observed rates of removal of O3, although significant uncertainties exist for each.

Salawitch, Ross J.; Mcelroy, Michael B.; Yatteau, John H.; Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Chan, K. Roland; Loewenstein, Max; Podolske, James R.; Strahan, Susan E.

1990-01-01

35

Defining the Polar Vortex Edge from a N20: Potential Temperature Correlation  

NASA Technical Reports Server (NTRS)

A prerequisite to studying phenomena in the winter stratospheric polar vortex is the separation of measurements inside and outside the dynamical barrier of the vortex edge. We describe a technique to accurately determine the inner edge of the vortex boundary region from measurements of potential temperature and a trace gas, such as N2O, and apply it to in situ aircraft and balloon measurements from the SOLVE/THESEO 2000 Arctic campaign. The method may be used to refine the Nash algorithm, which, due to the inherently coarser resolution of potential vorticity on which it is dependent, may misidentify the inner edge by more than 400 km and omit the identification of small, extravortex filaments within the vortex.

Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Bui, T. Paul; Hurst, Dale F.; Elkins, James W.; Herman, Robert L.; Webster, Christopher R.; Schauffler, Sue M.

2002-01-01

36

Polar Stratospheric Descent of NO(y) and CO and Arctic Denitrification During Winter 1992-1993  

NASA Technical Reports Server (NTRS)

Observations inside the November 1994 Antarctic stratospheric vortex and inside the April 1993 remnant Arctic stratospheric vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer are reported. In both instances, elevated volume mixing ratios (VMRS) of carbon monoxide (CO) were measured. A peak Antarctic CO VMR of 60 ppbv (where 1 ppbv = 10(exp -9) per unit Volume) was measured at a potential temperature of 710 K (about 27 km), about 1 km below the altitude of a pocket of elevated NO(y) (total reactive nitrogen) at a deep minimum in N2O (<5 ppbv). The Arctic observations also show a region of elevated vortex CO with a peak VMR of 90 ppbv it 630-670 K (-25 km) but no corresponding enhancement in NO(sub y) perhaps because of stronger dynamical activity in the northern hemisphere polar winter and/or interannual variability in the production of mesospheric or lower thermospheric NO. By comparing vortex and extravortex observations of NO(y) obtained at the same N2O VMR, Arctic vortex denitrification of 5 +/- 2 ppbv at 470 K (at approximately 18 km) is inferred. We show that our conclusion of substantial Arctic winter 1992-1993 denitrification is robust by comparing our extravortex observations with previous polar measurements obtained over a wide range of winter conditions. Correlations of NO(y) with N2O measured at the same potential temperature by ATMOS in the Arctic vortex and at midlatitudes on board the ER-2 aircraft several weeks later lie along the same mixing line. The result demonstrates the consistency of the two data sets and confirms that the ER-2 sampled fragments of the denitrified Arctic vortex following its breakup. An analysis of the ATMOS Arctic measurements of total hydrogen shows no evidence for significant dehydration inside the vortex.

Rinsland, C. P.; Salawitch, R. J.; Gunson, M. R.; Solomon, S.; Zander, R.; Mahieu, E.; Goldman, A.; Newchurch, M. J.; Irion, F. W.; Chang, A. Y.

1999-01-01

37

Hyperbolic lines and the stratospheric polar vortex.  

PubMed

The necessary and sufficient conditions for Lagrangian hyperbolicity recently derived in the literature are reviewed in the light of older concepts of effective local rotation in strain coordinates. In particular, we introduce the simple interpretation of the necessary condition as a constraint on the local angular displacement in strain coordinates. These mathematically rigorous conditions are applied to the winter stratospheric circulation of the southern hemisphere, using analyzed wind data from the European Center for Medium-Range Weather Forecasts. Our results demonstrate that the sufficient condition is too strong and the necessary condition is too weak, so that both conditions fail to identify hyperbolic lines in the stratosphere. However a phenomenological, nonrigorous, criterion based on the necessary condition reveals the hyperbolic structure of the flow. Another (still nonrigorous) alternative is the finite-size Lyapunov exponent (FSLE) which is shown to produce good candidates for hyperbolic lines. In addition, we also tested the sufficient condition for Lagrangian ellipticity and found that it is too weak to detect elliptic coherent structures (ECS) in the stratosphere, of which the polar vortex is an obvious candidate. Yet, the FSLE method reveals a clear ECS-like barrier to mixing along the polar vortex edge. Further theoretical advancement is needed to explain the apparent success of nonrigorous methods, such as the FSLE approach, so as to achieve a sound kinematic understanding of chaotic mixing in the winter stratosphere and other geophysical flows. (c) 2002 American Institute of Physics. PMID:12779568

Koh, Tieh-Yong; Legras, Bernard

2002-06-01

38

The Arctic influences sub-polar wind patterns and European climate  

NSDL National Science Digital Library

An atmosphere-ocean general circulation model run over 500 years was used to look for the feedback mechanism related to the extent to which sea ice impacts the Earth�s albedo. Detailed analysis of the first nine years of simulations showed that although warming may occur in the mid-latitudes, Arctic cooling will result from a polar vortex churning cold air from the Rockies northward. This indicates that the Arctic exerts a strong influence on the mid- and high-latitude climate, because of its ability to modulate the strength of sub-polar westerlies and storm tracks.

Al., Dethloff E.; Agu

39

Computations of diabatic descent in the stratospheric polar vortex  

NASA Technical Reports Server (NTRS)

A radiation model, together with National Meteorological Center temperature observations, was used to compute daily net heating rates in the northern hemisphere (NH) for the Arctic late fall and winter periods of both 1988-1989 and 1991-1992 and in the southern hemisphere (SH) for the Antarctic fall and winters of 1987 and 1992. The heating rates were interpolated to potential temperature (theta) surfaces between 400 K and 2000 K and averaged within the polar vortex, the boundary of which was determined by the maximum gradient in potential vorticity. The averaged heating rates were used in a one-dimensional vortex interior descent model to compute the change in potential temperature with time of air parcels initialized at various theta values, as well as to compute the descent in log pressure coodinates. In the NH vortex, air parcels which were initialized at 18 km on November 1, descended about 6 km by March 21, while air initially at 25 km descended 9 km in the same time period. this represents an average descent rate in the lower stratosphere of 1.3 to 2 km per month. Air initialized at 50 km descended 27 km between November 1 and March 21. In the SH vortex, parcels initialized at 18 km on March 1, descended 3 km, while air at 25 km descended 5-7 km by the end of October. This is equivalent to an average descent in the lower stratosphere of 0.4 to 0.9 km per month during this 8-month period. Air initialized at 52 km descended 26-29 km between March 1 and October 31. In both the NH and the SH, computed descent rates increased markedly with height. The descent for the NH winter of 1992-1993 and the SH winter of 1992 computed with a three-dimensional trajectory model using the same radiation code was within 1 to 2 km of that calculated by the one-dimensional model, thus validating the vortex averaging procedure. The computed descent rates generally agree well with observations of long-lived tracers, thus validating the radiative transfer model.

Rosenfield, Joan E.; Newman, Paul A.; Schoeberl, Mark R.

1994-01-01

40

Microphysical simulations of polar stratospheric clouds during the 2010-2011 Arctic Winter  

NASA Astrophysics Data System (ADS)

Polar stratospheric clouds (PSCs) form in the lower stratosphere during the polar night due to the cold temperature inside the polar vortex. PSCs are important to understand because they are one of the important factors for the formation of the Antarctic ozone hole and the "mini" ozone hole over the Arctic during the winter of 2010-2011. In this work, We explore the formation and evolution of STS particles (Super-cooled Ternary Solution) and NAT (Nitric-acid Trihydrate ) particles using the SD-WACCM/CARMA model for 2010-2011 Arctic winter. SD-WACCM/CARMA is the Whole Atmosphere Community Climate Model coupled with the microphysics model (CARMA) using Specific Dynamics. The 2010-2011 Arctic winter is special because a cold Arctic vortex lasted from December until the end of March [Manney et al., 2011]. The long length of this cold period resulted in a prolonged presence of PSCs and consequently strong ozone depletion. This work includes comparison of the simulated microphysical features of PSCs with historical observations. Also, simulations and observations from MLS and Calipso showing the evolution of temperature, PSCs and related chemical species (HNO3, H2O) in 2010-2011 Arctic winter are presented.

Zhu, Y.; Toon, O. B.; Kinnison, D. E.; Lambert, A.; Brakebusch, M.

2013-12-01

41

Satellite observation of dehydration in the Arctic Polar stratosphere  

E-print Network

Satellite observation of dehydration in the Arctic Polar stratosphere L. L. Pan,1 W. J. Randel,1 H 2002. [1] We report the first space-borne observation of dehydration in the Arctic polar stratosphere between 23 and 26 km. In some cases, the dehydrated air was downwind from mountain wave induced Polar

Pan, Laura

42

Influence of projected Arctic sea ice loss on polar stratospheric ozone and circulation in spring  

NASA Astrophysics Data System (ADS)

The impact of projected Arctic sea ice loss on the stratosphere is investigated using the Whole Atmosphere Community Climate Model (WACCM), a state-of-the-art coupled chemistry climate model. Two 91-year simulations are conducted: one with a repeating seasonal cycle of Arctic sea ice for the late twentieth-century, taken from the fully coupled WACCM historical run; the other with Arctic sea ice for the late twenty-first century, obtained from the fully coupled WACCM RCP8.5 run. In response to Arctic sea ice loss, polar cap stratospheric ozone decreases by 13 DU (34 DU at the North Pole) in spring, confirming the results of Scinocca et al (2009 Geophys. Res. Lett. 36 L24701). The ozone loss is dynamically initiated in March by a suppression of upward-propagating planetary waves, possibly related to the destructive interference between the forced wave number 1 and its climatology. The diminished upward wave propagation, in turn, weakens the Brewer-Dobson circulation at high latitudes, strengthens the polar vortex, and cools the polar stratosphere. The ozone reduction persists until the polar vortex breaks down in late spring.

Sun, Lantao; Deser, Clara; Polvani, Lorenzo; Tomas, Robert

2014-08-01

43

Chemical ozone loss in the Arctic vortex in the winter 199596: HALOE measurements in conjunction with other observations  

E-print Network

Chemical ozone loss in the Arctic vortex in the winter 1995±96: HALOE measurements in conjunction / Accepted: 12 May 1998 Abstract. Severe chemical ozone loss has been detected in the Arctic in the winter Atmosphere Research Satellite in the Arctic vortex. Here, we discuss further aspects of the HALOE

Paris-Sud XI, Université de

44

ACE-FTS measurements across the edge of the winter 2004 Arctic vortex  

NASA Astrophysics Data System (ADS)

Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) solar occultation measurements have been used to create volume mixing ratio (VMR) profiles of H2O, CH4, and N2O inside and outside the 2004 Arctic vortex. Using derived meteorological quantities such as potential vorticity, we have classified 450 occultations (from February and March 2004 spanning 0 to 79.8°N) as vortex, vortex edge, or extravortex. We plot [CH4] versus [N2O] correlations to display the distinct patterns observed for measurements of different air masses and use these correlations to further classify the extravortex occultations as tropical, subtropical, or midlatitude. Using comparisons between high latitude profiles of [N2O], [CH4], and [H2O] inside and outside the Arctic vortex, we estimate upper stratospheric and lower mesospheric descent rates and find that descent in the winter 2004 Arctic vortex was rapid, with evidence of descent at higher altitudes than in past years.

Nassar, Ray; Bernath, Peter F.; Boone, Chris D.; Manney, Gloria L.; McLeod, Sean D.; Rinsland, Curtis P.; Skelton, Randall; Walker, Kaley A.

2005-06-01

45

ATMOS Profile Structure, Filamentation, and Transport Around the 1994 Arctic Proto-Vortex  

NASA Technical Reports Server (NTRS)

Many long-lived trace gas profiles observed by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument around the developing polar vortex (the proto-vortex) during early November 1994 show distinctive minimum/maximum pairs (laminae).

Manney, G.; Michaelsen, H.; Irion, F.; Gunson, M.

1999-01-01

46

Defining the Polar Vortex Edge Using an N2O: Potential Temperature Correlation Versus the Nash Criterion: A Comparison  

NASA Technical Reports Server (NTRS)

A prerequisite to study phenomena in the winter stratospheric polar vortex is the separation of measurements inside and outside the dynamical barrier of the vortex edge. We describe a technique to accurately determine the inner edge of the vortex boundary region from measurements of potential temperature and a trace gas, such as N2O, and apply it to in situ aircraft and balloon measurements from the SOLVE/THESE02000 Arctic campaign. The method may be used to refine the Nash algorithm, which, due to the inherently coarser resolution of potential vorticity on which it is dependent, may misidentify the inner edge by up to 466 km, and omit the identification of small, extra-vortex filaments within the vortex.

Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Bui, T. Paul; Hurst, Dale F.; Elkins, James W.; Herman, Robert L.; Webster, Christopher R.; Schauffler, Sue M.; Hipskind, R. Stephen (Technical Monitor)

2001-01-01

47

Potential Vorticity as a Diagnostic for the Mars Polar Vortex  

NASA Astrophysics Data System (ADS)

Polar vortices dominate the dynamics of the winter mid- and polar latitudes in the martian atmosphere as well as in the terrestrial stratosphere. Polar vortices have also been observed on Venus (Taylor, 2002), Jupiter (Orton, 2002), Saturn (Fletcher, 2008), and Titan (Teanby, 2008). Potential vorticity is the analysis quantity of choice for the terrestrial polar vortices because its vertical component distills the most important features of the wind and temperature fields into a single scalar variable; because it is a conserved tracer under adiabatic conditions; because it serves as the medium for Rossby waves; and because steep potential vorticity gradients are observed to be correlated with steep gradients in the concentrations of chemical species. Using potential vorticity derived from Mars Global Surveyor Thermal Emission Spectrometer (TES) temperature soundings, we compare the structure of the martian polar vortices to those of the earth. We find that the northern martian winter polar vortex, just like its terrestrial conterpart, is bounded by a region of very steep potential vorticity gradients and is surrounded by a "surf zone", a region of low potential vorticity and very low potential vorticity gradients. The surf zone concept, as first described for the terrestrial stratosphere by McIntyre and Palmer (1983), implies persistent Rossby wave breaking. In the vicinity of the northern polar vortex, the TES data set provides some examples of local gradient reversals that are suggestive of wave breaking. There is also one case of possible large-scale wave breaking accompanied by an abrupt polar warming. The martian southern polar vortex, unlike its terrestrial counterpart and unlike the northern martian polar vortex, lacks a distinct boundary between the polar vortex and a surf zone. Instead, the potential vorticity field is highly disorganized with local gradient reversals throughout the middle and polar latitudes. In the zonal mean, the southern winter potential vorticity gradient ends up being relatively uniform, although it is somewhat enhanced near 60 degrees latitude.

McConnochie, T. H.; Conrath, B. J.; Gierasch, P. J.; Banfield, D.; Smith, M. D.

2009-05-01

48

Arctic polar stratospheric cloud measurements by means of a four wavelength depolarization lidar  

NASA Technical Reports Server (NTRS)

A four wavelength depolarization backscattering lidar has been operated during the European Arctic Stratospheric Ozone Experiment (EASOE) in Sodankyl, in the Finnish Arctic. The lidar performed measurements during the months of December 1991, January, February and March 1992. The Finnish Meteorological Institute during the same period launched regularly three Radiosondes per day, and three Ozone sondes per week. Both Mt. Pinatubo aerosols and Polar Stratospheric Clouds were measured. The use of four wavelengths, respectively at 355 nm, 532 nm , 750 nm, and 850 nm permits an inversion of the lidar data to determine aerosol particle size. The depolarization technique permits the identification of Polar Stratospheric Clouds. Frequent correlation between Ozone minima and peaks in the Mt. Pinatubo aerosol maxima were detected. Measurements were carried out both within and outside the Polar Vortex.

Stefanutti, L.; Castagnoli, F.; Delguasta, M.; Flesia, C.; Godin, S.; Kolenda, J.; Kneipp, H.; Kyro, Esko; Matthey, R.; Morandi, M.

1994-01-01

49

Nighttime OClO in the Winter Arctic Vortex  

NASA Technical Reports Server (NTRS)

We show that a nighttime profile of OClO in the Arctic vortex during the winter of 2000 is overestimated, by nearly a factor of 2, using an isentropic trajectory model constrained by observed profiles of ClOx (ClO + 2 X ClOOCl) and BrO. Calculated abundances of nighttime OClO are shown to be sensitive to the abundance of BrOx (BrO + BrCl), details of the air parcel history during the most recent sunrise/sunset transitions, and the BrCl yield from the reaction BrO + ClO. Many uncertainties are considered, and the discrepancy between measured and modeled nighttime OClO appears to be robust. This discrepancy suggests that production of OClO occurs more slowly than implied by standard photochemistry. If the yield of BrCl from the reaction of BrO + ClO is increased from 7% (JPL 2002 value) to 11% (near the upper limit of the uncertainty), good agreement is found between measured and modeled nighttime OClO. This study highlights the importance of accurate knowledge of BrO + ClO reaction kinetics as well as air parcel trajectories for proper interpretation of nighttime OClO. These factors have a considerably smaller impact on the interpretation of OClO observations obtained during twilight (90(deg) <=SZA <= 92(deg)), when photolytic processes are still active.

Canty, T.; Riviere, E. D.; Salawitch, R. J.; Berthet, G.; Renard, J. -B.; Pfeilsticker, K.; Dorf, M.; Butz, A.; Bosch, H.; Stimpfle, R. M.; Wilmouth, D. M.; Richard, E. C.; Fahey, D. W.; Popp, P. J.; Schoeberl, M. R.; Lait, L. R.; Bui, T. P.

2005-01-01

50

Transport, mixing and ozone loss in the 2010 Arctic vortex region from in-situ tracer observations during RECONCILE  

NASA Astrophysics Data System (ADS)

The 2009/2010 Arctic stratospheric vortex was dynamically very active, splitting and reforming twice, first in mid December and then again in mid February. We use in-situ measurements of tracers and ozone both in- and outside the Arctic vortex during the 2010 RECONCILE campaign to investigate isentropic transport and irreversible mixing in the vortex region and to assess chemical ozone loss. N2O and CFC-11, along with CO2, CFC-12, H-1211, CH4, SF6 and H2 were simultanously measured by the High Altitude Gas Analyser (HAGAR) during 13 Geophysica flights between mid January and mid March. Ozone was measured onboard the M55 Geophysica aircraft by the Fast Ozone Analyser (FOZAN). Early winter reference profiles for a number of tracers are provided by the satellite instrument ACE-FTS. We derive an empirical "vortex index" from the observed isentropic distribution of N2O as an altitude-independent tracer of origin with respect to the vortex. This index is used to identify the origin of the observed air masses and to diagnose recent transport of air between distinct regions. Irreversible mixing of air masses, typically following such transport, is diagnosed from the evolution of the CFC-11/N2O correlation. Simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) are used for comparison and to better understand the meteorological context of the observed transport and mixing. Intrusions of extra-vortex air into the vortex are evident already during January, however much stronger effects are observed after the vortex split in late February and its reformation in early March. The N2O-derived "vortex index" suggests strong transport of subtropical air into the polar region above 470 K and a corresponding shift of the CFC-11/N2O correlation indicates that this air has already mixed irreversibly with high-latitude air. A further partial shift of the correlation is evidence for irreversible mixing of mid-latitude air inside the newly formed vortex. The CLaMS simulation captures these signatures of transport and mixing mostly well. We finally discuss the implications of the unusual transport situation on the derivation of ozone loss via the O3-N2O correlation method.

Hösen, E.; Volk, C. M.; vom Scheidt, M.; Wintel, J.; Ulanovsky, A.; Ravegnani, F.; Grooß, J. U.; Günther, G.; Walker, K. A.

2012-04-01

51

Balloon-borne In-Situ Measurements of ClO and ClONO2 in the late 2010/2011 Arctic Polar Vortex: Instrument Calibration and Results  

NASA Astrophysics Data System (ADS)

Since 1995 we have carried out balloon-borne in-situ measurements of ClO and BrO. Lately we have designed an upgraded balloon instrument to additionally measure the ClO dimer and the reservoir species ClONO2. The halogen oxide measurements are carried out employing the chemical conversion resonance fluorescence technique (Brune et al., 1989) in a fast flow through two parallel ducts generated by modified roots blowers. The inlet of one duct is equipped with a dedicated heating element enabling controlled air temperatures in excess of 550K at pressures lower than 50 hPa. This causes the ClO dimer to thermolyze forming two ClO molecules at around 380K as well as additional thermolysis of ClONO2 to ClO and NO2 at around 540K. The ClO generated within the thermolysis is then detected on top of the ambient ClO. Temperature cycling and intercomparisons with the first unheated duct allow the differentiation of the chlorine species. Details of the instrumental setup, instrument calibration, and performance will be discussed. Profiles for ClO and ClONO2 from a flight carried out from ESRANGE near Kiruna, Sweden, on April-01-2011 in the edge region of the degrading arctic vortex will be presented marking the first ClONO2 in-situ measurements above research aircraft altitudes (20km). Brune, W. H., et al., Insitu Observations Of ClO In The Antarctic - Er-2 Aircraft Results From 54-Degrees-S To 72-Degrees-S Latitude, Journal Of Geophysical Research-Atmospheres, 94, 16649-16663, 1989.

Stroh, F.; Heinecke, F.; Afchine, A.; Barthel, J.; Engel, A.; Grooß, J.; von Hobe, M.; Richter, A.; Schönfeld, A.; Suminska, O.; Tan, V.

2011-12-01

52

On the motion of air through the stratospheric polar vortex  

NASA Technical Reports Server (NTRS)

Trajectory calculations using horizontal winds from the U.K. Meteorological Office data assimilation system and vertical velocities from a radiation calculation are used to simulate the three-dimensional motion of air through the stratospheric polar vortex for Northern Hemisphere (NH) and Southern Hemisphere (SH) winters since the launch of the Upper Atmosphere Research Satellite (UARS). Throughout the winter, air from the upper stratosphere moves poleward and descends into the middle stratosphere. In the SH lower to middle stratosphere, strongest descent occurs near the edge of the polar vortex, with that edge defined by mixing characteristics. The NH shows a similar pattern in late winter, but in early winter strongest descent is near the center of the vortex, except when wave activity is particularly strong. Strong barriers to latitudinal mixing exist above about 420 K throughout the winter. Below this, the polar night jet is weak in early winter, so air descending below that level mixes between polar and middle latitudes. In late winter, parcels descend less and the polar night jet moves downward, so there is less latitudinal mixing. The degree of mixing in the lower stratosphere thus depends strongly on the position and evolution of the polar night jet and on the amount of descent experienced by the air parcels; these characteristics show considerable interannual variability in both hemispheres. The computed trajectories provide a three-dimensional picture of air motion during the final warming. Large tongues of air are drawn off the vortex and stretched into increasingly long and narrow tongues extending into low latitudes. This vortex erosion process proceeds more rapidly in the NH than in he SH. In the lower stratosphere, the majority of air parcels remain confined within a lingering region of strong potential vorticity gradients into December in the SH and April in the NH, well after the vortex breaks up in the midstratosphere.

Manney, G. L.; Zurek, R. W.; O'Neill, A.; Swinbank, R.

1994-01-01

53

Interannual Variability of the North Polar Vortex in the Lower Stratosphere During the UARS Mission  

NASA Technical Reports Server (NTRS)

Northern winters since the 1991 launch of UARS are compared to earlier years (1978 -1991) with respect to the potential for formation of Polar Stratospheric Clouds and for isolation of the north polar vortex. Daily NMC temperature minima at 465 K late in the winter of 1993-94 and again in December 1994 were the lowest values experienced during these times of the year (since 1978). Northern PV gradients were unusually strong in 1991-92 prior to late January and throughout the winter in both 1992-93 and 1994-95. Of all northern winters since 1978, 1994-95 with its early extended cold spell and persistently strong PV gradients most resembled the Antarctic winter lower stratosphere. Even so, temperatures was never as low, nor was the polar vortex as large, as during a typical southern winter. Judged by daily temperature minima and PV gradients at 465 K, meteorological conditions in the Arctic winter lower stratosphere during the UARS period were more conducive to vortex ozone loss by heterogeneous chemistry than in most previous winters since 1978-79.

Zurek, R. W.; Manney, G. L.; Miller, A. J.; Gelman, M. E.; Nagatani, R. M.

1996-01-01

54

Comparison of measurements and models in stratospheric polar vortex studies  

NASA Technical Reports Server (NTRS)

An overview will be given of recent studies comparing model results with observations of stratospheric meteorological and trace gas fields, focusing on the polar vortex during winter. Studies comparing process-oriented (e.g., stability) model, mechanistic (i.e., forced lower boundary near the tropopause) model and general circulation model (GCM) simulations of the dynamics of the polar winter stratosphere with analyzed or assimilated meteorological datasets are reviewed.

Manney, G.

2002-01-01

55

Transport into the south polar vortex in early spring  

NASA Technical Reports Server (NTRS)

The effect of transport on the springtime decline in ozone in the southern polar vortex was investiated using data on long-lived gas tracers (N2O, CH4, CCl4, CH3CCl3, CO, CFC-11, CFC-12, and CFC-113) obtained by the ER-2 aircraft in the period between August 23 and September 22 during the Airborne Antarctic Ozone Experiment. It was found that, while the concentrations of long-lived trace gases remained relatively constant for fixed potential temperature and latitude, the ozone mixing ratio over the same period declined by more than 50 percent inside the polar vortex near 18-km altitude. These data indicate a substantial photochemical sink of ozone. The evidence of the zero or negative time tendencies for long-lived trace gases and the meridional and vertical gradients of ozone imply that transport is supplying ozone to the polar region during springtime.

Hartmann, D. L.; Heidt, L. E.; Loewenstein, M.; Podolske, J. R.; Vedder, J.

1989-01-01

56

Arctic Weather Patterns  

NSDL National Science Digital Library

This webpage focuses on the different patterns that occur in the Arctic. Detailed explanations and examples are given about Cyclones, anticyclones, the polar vortex, Semipermanent high's and low's, polar lows, the arctic as "heat sink", the arctic oscillation, feedback loops, and climate change.For example, the explanation on the semipermanent high's and low's includes information on the different ones all over the world, like the North American high and the Icelandic low

2000-01-01

57

Measuring ozone inside the polar vortex  

NSDL National Science Digital Library

Ozone profiles with and without the Polar Ozone and Aerosol Measurement (POAM) III satellite data were compared to measurements taken from ground and air stations in the South Pole and surrounding Antarctic. Results indicate that the satellite information helps produce a much more accurate estimate of the region's ozone distribution.

Stajner, Ivanka; Wargan, Krzysztof; Agu

58

Evolution of MLS Ozone and the Polar Vortex During Winter  

NASA Technical Reports Server (NTRS)

The evolution of polar ozone observed by the Upper Atmosphere Research Satellite Microwave Limb Sounder is described for the northern hemisphere (NH) winters of 1991/1992, 1992/1993, and 1993/1994, and the southern hemisphere (SH) winters of 1992 and 1993. Ozone in the mid-stratospheric vortex increases over the winter, with largest increases associated with stratospheric warmings, and a much larger increase in the NH than in the SH.

Manney, G. L.; Froidevaux, L.; Waters, J. W.; Zurek, R. W.

1994-01-01

59

Study of the winter 2005 Antarctica polar vortex  

E-print Network

During winter and springtime, the flow above Antarctica at high altitude (upper troposphere and stratosphere) is dominated by the presence of a vortex centered above the continent. It lasts typically from August to November. This vortex is characterized by a strong cyclonic jet centered above the polar high. In a recent study of our group (Hagelin et al., 2008) of four different sites in the Antarctic internal plateau (South Pole, Dome C, Dome A and Dome F), it was made the hypothesis that the wind speed strength in the upper atmosphere should be related to the distance of the site to the center of the Antarctic polar vortex. This high altitude wind is very important from an astronomical point of view since it might trigger the onset of the optical turbulence and strongly affect other optical turbulence parameters. What we are interested in here is to localize the position of the minimum value of the wind speed at high altitude in order to confirm the hypothesis of Hagelin et al. (2008).

Lascaux, F; Hagelin, S; Stoesz, J; 10.1051/eas/1040013

2010-01-01

60

Venusian Polar Vortex reproduced in an Atmospheric General Circulation Model  

NASA Astrophysics Data System (ADS)

The Venus atmosphere has a polar vortex rotating in the retrograde direction with a period of about three days. The vortex has a warm feature surrounded by a cold collar (e.g., Taylor et al. 1980; Piccioni et al. 2006). Although the Venusian polar vortex has been reported by many observations, its mechanism is still unknown. Elson (1982, 1989) examined the structure of the polar vortex by linear calculations. However, the background zonal wind assumed in the calculations was much stronger or weaker than those retrieved in the previous measurements (e.g., Peralta et al. 2008; Kouyama et al. 2012). Lee et al. (2010) and Yamamoto and Takahashi (2012) performed numerical simulations with general circulation models (GCMs) of the Venus atmosphere and obtained vertical structure in the polar region. However, the models included artificial forcing of Kelvin and/or Rossby waves. We have developed a new Venusian GCM by modifying the Atmospheric GCM For the Earth Simulator (Sugimoto et al. 2012; 2013). The basic equations of the GCM are primitive ones in the sigma coordinate on a sphere without topography. The model resolution is T42 (i.e., about 2.8 deg x 2.8 deg grids) and L60 (Deltaz is about 2 km). Rayleigh friction (sponge layer) in the upper layer (>80 km) is applied to prevent the reflection of waves, whose effect increases gradually with height. In the model, the atmosphere is dry and forced by the solar heating and Newtonian cooling. The vertical profile of the solar heating is based on Crisp (1986), and zonally averaged distribution is used. In addition diurnal component of the solar heating, which excites the diurnal and semi-diurnal tides, is also included. Newtonian cooling relaxes the temperature to the zonally uniform basic temperature which has a virtual static stability of Venus with almost neutral layers, and its coefficient is based on Crisp (1986). To prevent numerical instability, the biharmonic hyper-diffusion is included with 0.8 days of e-folding time for the truncation wavenumber. The coefficient of the vertical eddy diffusion is 0.15 m (2) s (-1) . A fast zonal wind in a solid-body rotation and the temperature field that balances with the zonal wind (gradient wind balance) is given as the initial state. Time integrations are performed until the solution achieves a statistically steady state. In this study we analyzed the data of 300 days of the last from getting to the quasi-steady state. The temporal and zonal mean wind and temperature fields are almost consistent with those obtained in previous studies (e.g., Kouyama et al. 2012; Tellmann et al. 2009). Barotropic or baroclinic instability occurs at the polar region, and zonal wavenumber one component is the most dominant in the polar vortex, followed by wavenumber two. It rotates the pole with the period of 4-5 days. These features are almost consistent with recent measurements (e.g. Lopez et al. 2013). We also calculated the potential vorticity distribution and found that it sometimes shows the filament structure, which is similar to the cloud morphology observed in recent imaging measurements (e.g. Piccioni et al. 2006). The vertical structure of each zonal wavenumber component has the common feature that the phase stands upright within the polar vortex and seems to shift at the top of the neutral stable layer. In this presentation, we will also compare the vertical structure seen in our calculation with that examined by radio occultation measurements in Venus Express mission.

Ando, Hiroki; Imamura, Takeshi; Takagi, Masahiro; Sugimoto, Norihiko; Kashimura, Hiroki

61

Development and testing of Polar Weather Research and Forecasting model: 2. Arctic Ocean  

E-print Network

Development and testing of Polar Weather Research and Forecasting model: 2. Arctic Ocean David H over the Arctic Ocean with a western Arctic grid using 25-km resolution. The model is based upon WRF tool for studies of Arctic Ocean meteorology. Citation: Bromwich, D. H., K. M. Hines, and L.-S. Bai

Howat, Ian M.

62

MRO Aerobraking: Observations of the Martian Southern Polar Vortex  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor spacecraft Horizon Sensor Assembly (MHSA) has been in continuous operation since arrival at Mars in 1997, providing 15 µm band atmospheric brightness temperature information for nadir orientation of the spacecraft and incidentally for science. These data now have supported the aerobraking of MRO as well as MGS itself and Odyssey by monitoring global thermal behavior, to provide early detection of dust storms that could cause 'blooming' of the atmosphere, affecting densities at altitudes near 100 km where aerobraking occurs. We now have data on the southern fall-winter polar vortex for 3 Mars years (2002-2006, Ls 35-105), defined by the locus of steepest latitudinal temperature gradient. The data refer to the lower atmosphere between about 5-30km altitude. The vortex is modeled as a wave 1 and 2 phenomenon. Wave one is generally dominant, with a highly consistent minimum latitude near 50° E. longitude; Hellas is thought to be the cause of this behavior. The vortex diminishes in size with season. Wave 2 is more variable but also consistent between years. This research was funded by the Mars Reconnaissance Orbiter project and carried out by the Jet Propulsion Laboratory, California Institute of Technology.

Martin, Terry Z.; Sengstacken, A.

2006-09-01

63

Ozone laminae near the edge of the stratospheric polar vortex  

NASA Technical Reports Server (NTRS)

Analysis of ozonesonde data collected at high northern latitudes in winter and spring shows that laminae of enhanced and depleted ozone are associated with the polar vortex. In January and February, they are most common at all latitudes in the potential temperature range 370-430 K, but are abundant up to 500 K between 60 and 70 deg N. In March and April they occur most frequently northward of 75 deg N, and are abundant up to 520 K, whereas they are largely confined to the range 320-440 K at lower latitudes. Analysis of ozone lidar data obtained during AASE-1 depicts clearly the extrusion of laminae of enhanced ozone concentration from the polar regions in the altitude range 13-15 km. These extrusions form a class of laminae which transport ozone equatorward in the lowest levels of the stratosphere.

Reid, S. J.; Vaughan, Geraint

1994-01-01

64

A quantitative measure of polar vortex strength using the function M  

NASA Astrophysics Data System (ADS)

Changes in the dynamics of the stratospheric polar vortices can significantly affect the composition of air in the polar stratosphere, with the dynamics of the vortex barrier being particularly important. The "Function M" is a recently proposed measure for quantifying transport in dynamical systems. We show that it can be used not only to visualize the structure of the stratospheric polar region in detail but also to provide a basis for quantitative measures capturing important aspects of vortex dynamics. Two such measures have been calculated daily for August-October 2009 and 2010 in the Southern Hemisphere for potential temperatures of 600, 700, and 900 K, as well as for three different Northern Hemisphere winter periods for 900 K. We discuss a measure of vortex barrier strength and permeability based on the average value of the function M near the vortex edge. The second measure, associated with vortex barrier area, is obtained by calculating the area associated with values of M above a threshold. Both measures are found to be potentially useful, with the area-based measure providing the most convincing results. The measures are based on a Lagrangian framework and follow the vortex edge, allowing periods when the vortex retains its dynamical integrity to be identified even when the vortex is greatly distorted. We also discuss a strong linear correlation near the vortex edge between values of the function M calculated over different time periods, suggesting that the structure of the polar vortex is coherent over periods of at least 30 days.

Smith, Madeleine L.; McDonald, Adrian J.

2014-05-01

65

Stratospheric polar vortex as a possible reason for temporal variations of solar activity and galactic cosmic ray effects on the lower atmosphere circulation  

NASA Astrophysics Data System (ADS)

Possible reasons for the temporal instability of long-term effects of solar activity (SA) and galactic cosmic ray (GCR) variations on the lower atmosphere circulation were studied. It was shown that the detected earlier ?60-year oscillations of the amplitude and sign of SA/GCR effects on the troposphere pressure at high and middle latitudes (Veretenenko and Ogurtsov, Adv.Space Res., 2012) are closely related to the state of a cyclonic vortex forming in the polar stratosphere. The intensity of the vortex was found to reveal a roughly 60-year periodicity affecting the evolution of the large-scale atmospheric circulation and the character of SA/GCR effects. An intensification of both Arctic anticyclones and mid-latitudinal cyclones associated with an increase of GCR fluxes at minima of the 11-year solar cycles is observed in the epochs of a strong polar vortex. In the epochs of a weak polar vortex SA/GCR effects on the development of baric systems at middle and high latitudes were found to change the sign. The results obtained provide evidence that the mechanism of solar activity and cosmic ray influences on the lower atmosphere circulation involves changes in the evolution of the stratospheric polar vortex.

Veretenenko, S.; Ogurtsov, M.

2014-12-01

66

Chlorine chemistry on polar stratospheric cloud particles in the Arctic winter  

SciTech Connect

Simultaneous in situ measurements of hydrochloric acid (HCl) and chlorine monoxide (ClO) in the Arctic winter vortex showed large HCl losses, of up to 1 part per billion by volume (ppbv), which were correlated with high ClO levels of up to 1.4 ppbv. Air parcel trajectory analysis identified that this conversion of inorganic chlorine occurred at air temperatures of less than 196 [plus minus]4 kelvin. High ClO was always accompanied by loss of HCl mixing ratios equal to 1/2(ClO + 2Cl[sub 2]O[sub 2]). These data indicate that the heterogeneous reaction HCl + ClONO[sub 2] [yields] Cl[sub 2] + HNO[sub 3] on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO[sub 2], not HCl.

Webster, C.R.; May, R.D. (California Institute of Technology, Pasadena, CA (United States)); Toohey, D.W. (Univ. of California, Irvine, CA (United States)); Avallone, L.M.; Anderson, J.G. (Harvard Univ., Cambridge, MA (United States)); Newman, P.; Lait, L.; Schoeberl, M.R. (National Aeronautics and Space Administration, Greenbelt, MD (United States)); Elkins, J.W. (National Oceanographic and Atmospheric Agency, Boulder, CO (United States)); Chan, K.R. (NASA Ames Research Center, Moffett Field, CA (United States))

1993-08-27

67

Chlorine chemistry on polar stratospheric cloud particles in the arctic winter.  

PubMed

Simultaneous in situ measurements of hydrochloric acid (HCl) and chlorine monoxide (ClO) in the Arctic winter vortex showed large HCl losses, of up to 1 part per billion by volume (ppbv), which were correlated with high ClO levels of up to 1.4 ppbv. Air parcel trajectory analysis identified that this conversion of inorganic chlorine occurred at air temperatures of less than 196 +/- 4 kelvin. High ClO was always accompanied by loss of HCI mixing ratios equal to (1/2)(ClO + 2Cl(2)O(2)). These data indicate that the heterogeneous reaction HCl + ClONO(2) --> Cl(2) + HNO(3) on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO(2), not HCl. PMID:17790344

Webster, C R; May, R D; Toohey, D W; Avallone, L M; Anderson, J G; Newman, P; Lait, L; Schoeberl, M R; Elkins, J W; Chan, K R

1993-08-27

68

On the Role of the Arctic Ocean in Polar Amplification  

NASA Astrophysics Data System (ADS)

Understanding oceanic effects on climate in the Arctic region requires knowledge of the mean circulation and its seasonal to decadal variability in the region. We synthesize results from a hierarchy of climate models together with available observations in the pan-Arctic region to better understand potential oceanic contributions to polar amplification. In particular, results from a version of the Regional Arctic System Model (RASM) forced with multi-decadal reanalysis data are analyzed with the main focus on the annual cycle and interannual to decadal variability of the upper ocean heat content in relation to the decline of the Arctic sea ice cover and warming climate. The motivation for this study is the increase of heat accumulation in the upper ocean, which has been observed and simulated by some model since the late 1990s. We investigate the circulation patterns and their seasonal to decadal variability controlling inflow of volume and properties into the Arctic Ocean. In addition, we examine critical processes governing the outflow of warm water, including coastal runoff, from the shelves into basin, for their impact on retreat and thinning of sea ice cover. Finally, the transport due to the boundary current along the slope and eddies in the basin are considered for their redistribution of heat within the upper ocean and contribution to the overall state of sea ice cover. The main goal of this study is to advance a system-level understanding of critical processes and feedbacks in the Arctic and their links with the Earth System. The secondary, yet an equally important objective, is to identify important areas from which to obtain new or additional observations to better understand some of these processes and to help constrain models.

Maslowski, Wieslaw; Osinski, Robert; Clement Kinney, Jaclyn

2014-05-01

69

Coexistence of toroidal and polar domains in ferroelectric systems: A strategy for switching ferroelectric vortex  

NASA Astrophysics Data System (ADS)

Phase field simulations have been conducted to investigate the vortex domain structure in ferroelectric nanodots epitaxially grown on ferroelectric nanofilm. It is found that the nanodot region has great impact on the domain evolution of the whole system. At suitable conditions (e.g., geometry, size, temperature, external strain, and electric field), the nanodot adopts a vortex domain pattern while the nanofilm maintains a polar domain. Interestingly, the vortex domain pattern of the nanodot can be switched by controlling the direction of the adjacent polar domain. Our study indicates an alternative strategy for controlling the chirality of vortex domain structure in nano-ferroelectrics.

Chen, W. J.; Zheng, Yue; Wang, Biao; Liu, J. Y.

2014-06-01

70

The evolution of AAOE observed constituents with the polar vortex  

NASA Technical Reports Server (NTRS)

One of the difficulties in determining constituent trends from the ER-2 flight data is the large amount of day to day variability generated by the motion of the polar vortex. To reduce this variability, the observations have been transformed into the conservative (Lagrangian) reference frames consisting of the coordinate pairs, potential temperature (PT) and potential vorticity (PV), or PT and N2O. The requirement of only two independent coordinates rests on the assumption that constituent distributions and their chemical processes are nearly zonal in that coordinate system. Flight data is used everywhere for these transformation except for potential vorticity. Potential vorticity is determined from level flight segments, and NMC PV values during flight dives and takeoffs are combined with flight data in a smooth fashion.

Schoeberl, Mark R.; Lait, Leslie R.; Newman, P. A.; Martin, R.; Loewenstein, M.; Podolske, J. R.; Anderson, J.; Proffitt, M. H.

1988-01-01

71

Visualization of stratospheric ozone depletion and the polar vortex  

NASA Technical Reports Server (NTRS)

Direct analysis of spacecraft observations of stratospheric ozone yields information about the morphology of annual austral depletion. Visual correlation of ozone with other atmospheric data illustrates the diurnal dynamics of the polar vortex and contributions from the upper troposphere, including the formation and breakup of the depletion region each spring. These data require care in their presentation to minimize the introduction of visualization artifacts that are erroneously interpreted as data features. Non geographically registered data of differing mesh structures can be visually correlated via cartographic warping of base geometries without interpolation. Because this approach is independent of the realization technique, it provides a framework for experimenting with many visualization strategies. This methodology preserves the fidelity of the original data sets in a coordinate system suitable for three-dimensional, dynamic examination of atmospheric phenomena.

Treinish, Lloyd A.

1995-01-01

72

Arctic Ocean during the Last Glacial Maximum: Atlantic and polar domains of surface water  

E-print Network

Arctic Ocean during the Last Glacial Maximum: Atlantic and polar domains of surface water mass for the Fram Strait and the eastern and central Arctic Ocean. Sediment composition and stable isotope data the total inflow of Atlantic Water into the Arctic Ocean may have been reduced during the LGM, its impact

Ingólfsson, �lafur

73

Tracer-Based Determination of Vortex Descent in the 1999-2000 Arctic Winter  

NASA Technical Reports Server (NTRS)

A detailed analysis of available in situ and remotely sensed N2O and CH4 data measured in the 1999-2000 winter Arctic vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences in potential temperature (theta) among balloon and aircraft vertical profiles (an average of 19-23 K on a given N2O or CH4 isopleth) indicated significant vortex inhomogeneity in late fall as compared with late winter profiles. A composite fall vortex profile was constructed for November 26, 1999, whose error bars encompassed the observed variability. High-latitude, extravortex profiles measured in different years and seasons revealed substantial variability in N2O and CH4 on theta surfaces, but all were clearly distinguishable from the first vortex profiles measured in late fall 1999. From these extravortex-vortex differences, we inferred descent prior to November 26: 397+/-15 K (1sigma) at 30 ppbv N2O and 640 ppbv CH4, and 28+/-13 K above 200 ppbv N2O and 1280 ppbv CH4. Changes in theta were determined on five N2O and CH4 isopleths from November 26 through March 12, and descent rates were calculated on each N2O isopleth for several time intervals. The maximum descent rates were seen between November 26 and January 27: 0.82+/-0.20 K/day averaged over 50-250 ppbv N2O. By late winter (February 26-March 12), the average rate had decreased to 0.10+/-0.25 K/day. Descent rates also decreased with increasing N2O; the winter average (November 26-March 5) descent rate varied from 0.75+/-0.10 K/day at 50 ppbv to 0.40+/-0.11 K/day at 250 ppbv. Comparison of these results with observations and models of descent in prior years showed very good overall agreement. Two models of the 1999-2000 vortex descent, SLIMCAT and REPROBUS, despite theta offsets with respect to observed profiles of up to 20 K on most tracer isopleths, produced descent rates that agreed very favorably with the inferred rates from observation.

Greenblatt, Jeffery B.; Jost, Hans-Juerg; Loewenstein, Max; Podolske, James R.; Hurst, Dale F.; Elkins, James W.; Schauffler, Sue M.; Atlas, Elliot L.; Herman, Robert L.; Webster, Christopher R.

2001-01-01

74

Ozone loss inside the Northern polar vortex during the 1991-1992 winter  

SciTech Connect

Measurements made in the outer ring of the northern polar vortex from October 1991 through March 1992 reveal an altitude-dependent change in ozone, with a decrease at the bottom of the vortex and a substantial increase at the highest altitudes accessible to measurement. The increase is the result of ozone-rich air entering the vortex, and the decrease reflects ozone loss accumulated after the descent of the air through high concentrations of reactive chlorine. The depleted air that is released out of the bottom of the vortex is sufficient to significantly reduce column ozone at mid-latitudes.

Proffitt, M.H.; Aikin, K. (National Oceanic and Atmospheric Administration, Boulder, CO (United States) Univ. of Colorado, Boulder, CO (United States)); Margitan, J.J. (California Institute of Technology, Pasadena, CA (United States)); Loewenstein, M.; Podolske, J.R.; Weaver, A.; Chan, K.R. (National Aeronautics and Space Administration, Moffett Field, CA (United States)); Fast, H. (Atmospheric Environmental Service, Downsview, Ontario (Canada)); Elkins, J.W. (National Oceanic and Atmospheric Administration, Boulder, CO (United States))

1993-08-27

75

Ozone loss inside the northern polar vortex during the 1991-1992 winter.  

PubMed

Measurements made in the outer ring of the northern polar vortex from October 1991 through March 1992 reveal an altitude-dependent change in ozone, with a decrease at the bottom of the vortex and a substantial increase at the highest altitudes accessible to measurement. The increase is the result of ozone-rich air entering the vortex, and the decrease reflects ozone loss accumulated after the descent of the air through high concentrations of reactive chlorine. The depleted air that is released out of the bottom of the vortex is sufficient to significantly reduce column ozone at mid-latitudes. PMID:17790350

Proffitt, M H; Aikin, K; Margitan, J J; Loewenstein, M; Podolske, J R; Weaver, A; Chan, K R; Fast, H; Elkins, J W

1993-08-27

76

Impact of sudden Arctic sea-ice loss on stratospheric polar ozone recovery  

E-print Network

Impact of sudden Arctic sea-ice loss on stratospheric polar ozone recovery 1234567 89A64BC7DEF72B4BE647 #12;Impact of sudden Arctic sea-ice loss on stratospheric polar ozone recovery J. F. Scinocca,1 there is rapid loss of Arctic summer sea ice in the first half of the 21st century. The issue is addressed

Wirosoetisno, Djoko

77

The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions.  

PubMed

Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. Both of these conditions are produced within the stratospheric winter polar vortex. Recent aircraft missions have provided new information about the structure of polar vortices during winter and their relation to polar ozone depletions. The aircraft data show that gradients of potential vorticity and the concentration of conservative trace species are large at the transition from mid-latitude to polar air. The presence of such sharp gradients at the boundary of polar air implies that the inward mixing of heat and constituents is strongly inhibited and that the perturbed polar stratospheric chemistry associated with the ozone hole is isolated from the rest of the stratosphere until the vortex breaks up in late spring. The overall size of the polar vortex thus limits the maximum areal coverage of the annual polar ozone depletions. Because it appears that this limit has not been reached for the Antarctic depletions, the possibility of future increases in the size of the Antarctic ozone hole is left open. In the Northern Hemisphere, the smaller vortex and the more restricted region of cold temperatures suggest that this region has a smaller theoretical maximum for column ozone depletion, about 40 percent of the currently observed change in the Antarctic ozone column in spring. PMID:17778602

Schoeberl, M R; Hartmann, D L

1991-01-01

78

Determination of magnetic vortex polarity from a single Lorentz Fresnel image.  

SciTech Connect

Nanoscale confinement of the magnetization in a magnetic element often results in the creation of a vortex structure. The vortex equilibrium state is characterized by the curling of the in-plane magnetization (chirality) and an out-of-plane core magnetization. The polarity of the vortex core can point up or down, independent of the chirality, and, thus, magnetic elements with a vortex core are interesting as four-state logic elements. We present an easy-to-use, quantitative method for the determination of both chirality and polarity from a single Fresnel image. This method offers direct evidence of the three-dimensional structure of a magnetic vortex and has significant advantages over the more complex methods currently in use.

Phatak, C.; Tanase, M.; Petford-Long, A. K.; De Graef, M.; Materials Science Division; Carnegie Mellon Univ.

2009-01-01

79

The Distribution of Ozone in the Early Stages of Polar Vortex Development  

NASA Technical Reports Server (NTRS)

Previous analysis has shown that the distribution of O3 at high northern latitudes in the lower-to-middle stratosphere at the beginning of the winter season, 1999-2000 has a characteristic distribution, which is consistent between in situ and satellite measurements [Kawa et al., The Interaction Between Dynamics and Chemistry of Ozone in the Set-up Phase of the Northern Hemisphere Polar Vortex, submitted manuscript, 2001 ]. Initial O3 profiles in the vortex are similar to each other and are quite different from outside the vortex at the same latitude and also from a zonal mean climatology. In the vortex, O3 is nearly constant from 500 to above 800 K with a value at 3 ppmv +/- approx.10%. Values outside the vortex are up to a factor of 2 higher and increase significantly with potential temperature. The seasonal time series of POAM data shows that relatively low O3 mixing ratios, which characterize the vortex in late fall, are already present at high latitudes at the end of summer in September before the vortex circulation sets up. This suggests a possible feedback role between O3 chemistry and the formation of the vortex, which is dominated by the seasonal radiation balance. Here we show that these characteristic O3 distributions are consistent from year to year and between the hemispheres. We will attempt to determine whether variations in fall vortex O3 are related in any way to O3 abundances and vortex structure later during winter and into spring.

Kawa, S. R.; Newman, P. A.; Schoeberl, M. R.; Bevilacqua, R.; Bhartia, P. K. (Technical Monitor)

2002-01-01

80

Chasing air masses in the Arctic vortex: An evaluation of trajectory calculations using an active Match  

NASA Astrophysics Data System (ADS)

During the RECONCILE campaign in the Arctic winter 2009/10, an active Match experiment was performed sampling the same air masses up to three times during two consecutive flights of the high-altitude research aircraft M55-Geophysica from Kiruna (67.83 N, 20.42 E). The first flight was westbound and its flightpath designed to resample the air masses from the outbound leg during the return to Kiruna with a time difference of up to 3 hours. Another match was attempted during a second flight 72 hours later when the air masses had moved into the Geophysica's range again. Flightplans were designed using trajectory calculations driven by ECMWF wind fields. In situ measurements of N2O and NOy revealed strong gradients inside the vortex thus allowing us to examine the accuracy of such trajectory calculations with wind fields in different spatial and temporal resolution.

Wegner, T.; Grooss, J.; Mueller, R.; Stroh, F.; Lehmann, R.; Volk, C.; Hösen, E.; Vom Scheidt, M.; Wintel, J.; Riediger, O.; Schlager, H.; Scheibe, M.; Stock, P.; Ravegnani, F.; Ulanovsky, A.; Yushkov, V. A.; von Hobe, M.

2010-12-01

81

Observations of Arctic haze during polar flights from Alaska to Norway  

NASA Astrophysics Data System (ADS)

Arctic haze observed during polar flights from Anchorage, Alaska, to Thule, Greenland, and Thule to Bodo, Norway, during March 1983, was widespread over the entire Arctic region flown. The distribution of this haze exhibited strong horizontal and vertical variability resulting from the synopticmeteorological situations encountered: e.g. the presence of fronts and haze transport zones. Condensation nuclei concentrations of about 500 cm -3 and aerosol scattering extinction values of about 4 × 10 -5m-1 were typical for Arctic haze layers. Intrusions of stratospheric air into the Arctic troposphere through tropopause folds were observed twice, suggesting that these events might occur quite frequently in the springtime Arctic atmosphere.

Raatz, Wolfgang E.; Schnell, Russell C.; Bodhaine, Barry A.; Oltmans, Samuel J.

82

Barotropic simulation of large-scale mixing in the Antarctic Polar Vortex  

SciTech Connect

Theory and observations suggest that the Antarctic polar vortex is relatively isolated from midlatitudes, although others have interpreted the observations to indicate that there is substantial mixing from the interior of the vortex into middle latitudes. The equivalent barotropic model of Salby et al. is used to study quasi-horizontal mixing by the large-scale flow in the lower stratosphere during Southern Hemisphere spring, which is when the Antarctic ozone hole appears and disappears. The model is forced by relaxation to observed climatological monthly mean zonal-mean winds and by an idealized wave 1 or 2 forcing at the lower boundary. Mixing and transport and diagnosed primarily through Lagrangian tracer trajectories. For September, October, and November basic states, there is little or no mixing in the interior of the vortex. Mixing occurs near the critical lines for the waves: in the tropics and subtropics for a stationary wave 1, and in midlatitudes on the equatorward flank of the jet for an eastward-moving wave 2. For the December basic state, the wave 2 forcing rapidly mixes the interior of the vortex. Mixing of Lagrangian tracer particles can be significant even when the waves do not [open quotes]break,[close quotes] as evidenced by the potential vorticity field. In the model there does not appear to be any significant transport of air out of the interior of the polar vortex prior to the vortex breakdown. The principal factor that leads to the vortex breakdown and mixing of the vortex interior is the deceleration of the jet to the factor that leads to the vortex breakdown and mixing of the vortex interior is the deceleration of the get to the point where winds in the interior of the vortex are close to phase velocity of the wavenumber 2 forcing. The tracer transport is very similar to many aspects of the behavior of the total ozone field during the spring season. 37 refs., 14 figs., 1 tab.

Bowman, K.P. (Texas A M Univ., College Station, TX (United States))

1993-09-01

83

Large-scale isentropic mixing properties of the Antarctic polar vortex from analyzed winds  

NASA Technical Reports Server (NTRS)

Winds derived from analyzed geopotential height fields are used to study quasi-horizontal mixing by the large-scale flow in the lower stratosphere during austral spring. This is the period when the Antarctic ozone hole appears and disappears. Trajectories are computed for large ensembles of particles initially inside and outside the main polar vortex. Mixing and transport are diagnosed through estimates of finite time Lyapunov exponents and Lagrangian dispersion statistics of the tracer trajectories. At 450 K and above prior to the vortex breakdown: Lyapunov exponents are a factor of 2 smaller inside the vortex than outside; diffusion coefficients are an order of magnitude smaller inside than outside the vortex; and the trajectories reveal little exchange of air across the vortex boundary. At lower levels (425 and 400 K) mixing is greater, and there is substantial exchange of air across the vortex boundary. In some years there are large wave events that expel small amounts of vortex air into the mid-latitudes. At the end of the spring season during the vortex breakdown there is rapid mixing of air across the vortex boundary, which is evident in the mixing diagnostics and the tracer trajectories.

Bowman, Kenneth P.

1993-01-01

84

Aircraft deployment, and airborne arctic stratospheric expedition  

NASA Technical Reports Server (NTRS)

The Airborne Arctic Stratospheric Expedition had two primary objectives: to study the production and loss mechanisms of ozone in the north polar stratosphere and to study the effect on ozone distribution of the Arctic Polar Vortex and of the cold temperatures associated with the formation of Polar Stratospheric Clouds. Two specially instrumented NASA aircraft were flown over the Arctic region. Each aircraft flew to acquire data on the meteorological, chemical and cloud physical phenomena that occur in the polar stratosphere during winter. The chemical processes which occur in the polar stratosphere during winter were also observed and studied. The data acquired are being analyzed.

Condon, Estelle; Tuck, Adrian; Hipskind, Steve; Toon, Brian; Wegener, Steve

1990-01-01

85

Measurement of the vortex core in sub-100 nm Fe dots using polarized neutron scattering  

E-print Network

OFFPRINT Measurement of the vortex core in sub-100 nm Fe dots using polarized neutron scattering neutron scattering Igor V. Roshchin1,2 , Chang-Peng Li2(a) , Harry Suhl2 , Xavier Batlle3 , S. Roy2(b diffraction and scattering Abstract ­ We use polarized neutron scattering to obtain quantitative information

Roshchin, Igor V.

86

Analytical Predictions for Zonally Symmetric Equilibrium States of the Stratospheric Polar Vortex  

Microsoft Academic Search

Equilibrium states of initially barotropically unstable polar vortices are predicted using two different approaches: minimum enstrophy and maximum entropy theories, which have been extended to include flows evolving on the surface of a sphere.Minimum enstrophy theory shows very good agreement with an ensemble of direct numerical integrations of a polar vortex that mixes vorticity mainly on a spherical cap. For

Ricardo Prieto; Wayne H. Schubert

2001-01-01

87

In-situ measurements of changes in stratospheric aerosol and the N2O-aerosol relationship inside and outside of the polar vortex  

NASA Technical Reports Server (NTRS)

Two optical particle counters on the ER-2, together covering a particle size diameter range from 0.1 microns to 23 microns, were used to measure the aerosol bulk quantities integral number, aerosol surface and volume, as well as detailed size distributions inside and outside of the polar vortex in the lower stratosphere. While AAES I (Arctic Airborne Stratospheric Expedition, (Dec. 88 - Feb. 89) was conducted in a period of relative volcanic quiescence, enhancements in aerosol number, surface and volume of factors around 10, 25 and 100 were observed during AASE 2 (Aug. 91 - Mar. 92) due to the eruption of Mt. Pinatubo. The changes in these bulk quantities as well as in the size distributions measured both outside and inside the polar vortex are presented and compared with those obtained in polar stratospheric cloud events (AASE I). Except for a shift towards larger aerosol mixing ratios the general shape of correlograms between the measured N2O and particle mixing ratios remain similar before and after the eruption. Similar correlograms are used to interpret data from vertical profiles inside and outside of the polar vortex.

Borrmann, S.; Dye, J. E.; Baumgardner, D.; Wilson, J. C.; Jonsson, H. H.; Brock, C. A.; Loewenstein, M.; Podolske, J. R.; Ferry, G. V.; Barr, K. S.

1993-01-01

88

In-Situ Measurements of Changes in Stratospheric Aerosol and the N2O - Aerosol Relationship inside and outside of the Polar Vortex  

NASA Technical Reports Server (NTRS)

Two optical particle counters on the ER-2, together covering a particle size diameter range from 0.1 micrometers to 23 micrometers, were used to measure the aerosol bulk quantities integral number, aerosol surface and volume, as well as detailed size distributions inside and outside of the polar vortex in the lower stratosphere. While AASE I (Arctic Airborne Stratospheric Expedition, (Dec. 1988 - Feb. 1989) was conducted in a period of relative volcanic quiescence, enhancements in aerosol number, surface and volume of factors around 10, 25 and 100 were observed during AASE II (Aug. 1991 - Mar. 1992) due to the eruption of Mt. Pinatubo. The changes in these bulk quantities as well as in the size distributions measured both outside and inside the the polar vortex are presented and compared with those obtained in polar stratospheric cloud events (AASE I). Except for a shift towards larger aerosol mixing ratios the general shape of correlograms between the measured N2O and particle mixing ratios remain similar before and after the eruption. Similar correlograms are used to interpret data from vertical profiles inside and outside of the polar vortex.

Borrmann, S.; Dye, J. E.; Baumgardner, D.; Wilson, J. C.; Jonsson, H. H.; Brock, C. A.; Loewenstein, M.; Podolske, J. R.; Ferry, G. V.; Barr, K. S.

1993-01-01

89

Control of magnetic vortex chirality and polarization in indented and notched nanomagnetic disks  

NASA Astrophysics Data System (ADS)

Magnetic vortex dynamics in nanoscale structures is currently a topic of intensive research not only from a fundamental physics point of view but also for their potential use in future generation spintronics and magnetic random access memories. We propose a method, where one can independently control the magnetic vortex polarization and chirality states by a combination of fine-tuning the applied magnetic field and breaking the geometrical symmetry of the magnetic nanostructure. Numerical simulations corroborate our proposal of achieving vortex switchability for the two different geometries we investigate: the indented disk and notched disk structures. Our results suggest that the notched disk structure offers more robust vortex dynamics and better switching characteristics, which makes this geometry ideal for use as a vortex-based magnetic memory device.

El-Mezeini, Ahmed M.; Flack, Tim J.; Welland, Mark E.

2014-12-01

90

On the nature and location of the proposed twin vortex systems in Saturn's polar upper atmosphere  

NASA Astrophysics Data System (ADS)

Twin vortices in Saturn's northern and southern polar ionospheres have been proposed as the drivers of the ˜10.7 h periodicities in the magnetosphere. We critically analyze this model from an atmospheric perspective, identifying two broad problems: first, the difficulty in reconciling a ˜10.7 h periodicity with the strongly subcorotational flows that are observed in the polar ionosphere; second, the very large energy requirement for sustaining the vortices against Joule dissipation. We propose a model in which the twin vortex originates neither in the plasma nor in the thermosphere but deeper in the atmosphere, around 750 km altitude. At this altitude the gas is expected to be close to corotation, and Joule dissipation is low. A twin vortex system at this altitude blowing laterally across the Hall conductance gradient at the main auroral oval generates field-aligned currents which are qualitatively similar to those driven by a plasma vortex or thermospheric vortex at higher altitudes.

Smith, C. G. A.

2014-07-01

91

Evolution of microwave limb sounder ozone and the polar vortex during winter  

NASA Technical Reports Server (NTRS)

The evolution of polar ozone observed by the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) is described for the northern hemisphere (NH) winters of 1991/1992, 1992/1993, and 1993/1994 and the southern hemisphere (SH) winters of 1992 and 1993. Imterannual and interhemispheric variability in polar ozone evolution are closely related to differences in the polar vortex and to the frequency, duration and strength of stratospheric sudden warmings. Ozone in the midstratospheric vortices increases during the winter, with largest increases associated with stratospheric warmings and a much larger increase in the NH than in the SH. A smaller NH increase was observed in 1993/1994, when the middle stratospheric vortex was stronger. During strong stratospheric warmings in the NH, the upper stratospheric vortex may be so much eroded that it presents little barrier to poleward transport; in contrast, the SH vortex remains strong throughout the stratosphere during wintertime warmings, and ozone increases only below the mixing ratio peak, due to enhanced diabatic descent. Ozone mixing ratios decrease rapidly in the lower stratosphere in both SH late winters, as expected from chemical destruction due to enhanced reactive chlorine. The interplay between dynamics and chemistry is more complex in the NH lower stratosphere and interannual variability is greater. Evidence has previously been shown for chemical ozone destruction in the 1991/1992 and 1992/1993 winters. We show here evidence suggesting some chemical destruction in late February and early March 1994. In the NH late winter lower stratosphere the pattern of high-ozone values (typical of the vortex) seen in mid-latitudes is related to the strength of the lower-stratospheric vortex, with the largest areal extent of high ozone outside the vortex in 1994, when the lower stratospheric vortex is relatively weak, and the least extent in 1993 when the lower stratospheric vortex is strongest.

Manney, G. L.; Froidevaux, L.; Waters, J. W.; Zurek, R. W.

1995-01-01

92

Assessment of the Breakup of the Antarctic Polar Vortex in Two New Chemistry-Climate Models  

NASA Technical Reports Server (NTRS)

Successful simulation of the breakup of the Antarctic polar vortex depends on the representation of tropospheric stationary waves at Southern Hemisphere middle latitudes. This paper assesses the vortex breakup in two new chemistry-climate models (CCMs). The stratospheric version of the UK Chemistry and Aerosols model is able to reproduce the observed timing of the vortex breakup. Version 2 of the Goddard Earth Observing System (GEOS V2) model is typical of CCMs in that the Antarctic polar vortex breaks up too late; at 10 hPa, the mean transition to easterlies at 60 S is delayed by 12-13 days as compared with the ERA-40 and National Centers for Environmental Prediction reanalyses. The two models' skill in simulating planetary wave driving during the October-November period accounts for differences in their simulation of the vortex breakup, with GEOS V2 unable to simulate the magnitude and tilt of geopotential height anomalies in the troposphere and thus underestimating the wave driving. In the GEOS V2 CCM the delayed breakup of the Antarctic vortex biases polar temperatures and trace gas distributions in the upper stratosphere in November and December.

Hurwitz, M. M.; Newman, P. A.; Oman, L. D.; Li, F.; Morgenstern, O.; Braesicke, P.; Pyle, J. A.

2010-01-01

93

Autocatalytic release of bromine from Arctic snow pack during polar sunrise  

Microsoft Academic Search

Measurements and modeling studies strongly suggest that spring time depletion of ozone in the Arctic planetary boundary layer (PBL) is due to catalytic destruction by bromine atoms. However, the source of the bromine is uncertain. In this note, we propose that the source of the bromine at polar sunrise is the snow pack on the ice covering Arctic ocean and

T. Tang; J. C. McConnell

1996-01-01

94

Barotropic simulation of large-scale mixing in the Antarctic polar vortex  

NASA Technical Reports Server (NTRS)

Theory and observations suggest that the Antarctic polar vortex is relatively isolated from midlatitudes, although others have interpreted the observations to indicate that there is substantial mixing from the interior of the vortex into middle latitudes. The equivalent barotropic model of Salby et al. is used to study quasi-horizontal mixing by the large-scale flow in the lower stratosphere during Southern Hemisphere spring, which is when the Antarctic ozone hole appears and disappears. The model is forced by relaxation to observed climatological monthly mean zonal-mean winds and by an idealized wave 1 or 2 forcing at the lower boundary. Mixing and transport are diagnosed primarily through Lagrangian tracer trajectories. For September, October, and November basic states, there is little or no mixing in the interior of the vortex. Mixing occurs near the critical lines for the waves: in the tropics and subtropics for a stationary wave 1, and in midlatitudes on the equatorial flank of the jet for an eastward-moving wave 2. For the December basic state, the wave 2 forcing rapidly mixes the interior of the vortex. Mixing of Lagrangian tracer particles can be significant even when the waves do not `break', as evidenced by the potential vorticity field. In the model there does not appear to be any significant transport of air out of the interior of the polar vortex prior to the vortex breakdown. The principal factor that leads to the vortex breakdown and mixing of the vortex interior is the deceleration of the jet to the point where winds in the interior of the vortex are close to the phase velocity of the wavenumber 2 forcing. The tracer transport is very similar to many aspects of the behavior of the total ozone field during the spring season.

Bowman, Kenneth P.

1993-01-01

95

The January 30, 1989 Arctic polar stratospheric clouds (PSC) event - Evidence for a mechanism of dehydration  

NASA Technical Reports Server (NTRS)

In-situ particle measurements made aboard the NASA ER-2 in the Arctic on 890130 (YYMMDD) show Type 1 PSC particles over much of the flight, with instances of embedded Type 2 PSCs. The Type 2 particles were observed at temperatures warmer than the local frost-point temperature of water; extended up to the upper size cutoff of the instrument (about 24-micron diameter); and are shown to contain too large a volume to be primarily NAT. Based on measured vertical temperature profiles, it is concluded that the Type 2 particles observed on this day were formed above the aircraft in a region where saturation with respect to ice was achieved and were sufficiently large to have fallen into the path of the ER-2. Although the amount of material in the particles, expressed as water, is small by comparison to the total (vapor + aerosol) water concentration, the flux of water from the falling particles is of sufficient magnitude, if sustained, to lead to dehydration of the source region. These observations verify the mechanism for dehydration of polar vortex air masses by precipitation of ice particles.

Gandrud, B. W.; Dye, J. E.; Baumgardner, D.; Ferry, G. V.; Loewenstein, M.; Chan, K. R.; Sanford, L.; Gary, B.

1990-01-01

96

Nonorographic generation of Arctic polar stratospheric clouds during December 1999  

NASA Astrophysics Data System (ADS)

During December 1999, polar stratospheric clouds (PSCs) were observed in the absence of conditions conducive to generation by topographic gravity waves. The possibility is explored that PSCs can be generated by inertia gravity waves (IGW) radiating from breaking synoptic-scale Rossby waves on the polar front jet. The aerosol features on 7 and 12 December are selected for comparison with theory and with simulations using the University of Wisconsin Nonhydrostatic Modeling System (UWNMS). Consistent with Rossby adjustment theory, a common feature in the UWNMS simulations is radiation of IGW from the tropopause polar front jet, especially from sectors which are evolving rapidly in the Rossby wave breaking process. Packets of gravity wave energy radiate upward and poleward into the cold pool, while individual wave crests propagate poleward and downward, causing mesoscale variations in vertical motion and temperature. On 12 December the eastbound DC-8 lidar observations exhibited a fairly uniform field of six waves in aerosol enhancement in the 14-20 km layer, consistent with vertical displacement by a field of IGW propagating antiparallel to the flow, with characteristic horizontal and vertical wavelengths of ˜300 and ˜10 km. UWNMS simulations show emanation of a field of IGW upward and southwestward from a northward incursion of the polar front jet. The orientation and evolution of the aerosol features on 7 December are consistent with a single PSC induced by an IGW packet propagating from a breaking Rossby wave over western Russia toward the northeast into the coldest part of the base of the polar vortex, with characteristic period ˜9 hours, vertical wavelength ˜12 km, and horizontal wavelength ˜1000 km. Linear theory shows that for both of these cases, IGW energy propagates upward at ˜1 km/hour and horizontally at ˜100 km/hour, with characteristic trace speed ˜30 m/s. The spatial orientation of the PSC along IGW phase lines is contrasted with the nearly horizontal filamentary structures in the PSC, which are indicative of flow streamlines. It is suggested that vertical displacement is a crucial factor in determining whether a PSC will form and that most PSCs are relatable to specific synoptic and mesoscale motions.

Hitchman, Matthew H.; Buker, Marcus L.; Tripoli, Gregory J.; Browell, Edward V.; Grant, William B.; McGee, Thomas J.; Burris, John F.

2003-03-01

97

EOS Microwave Limb Sounder Observations of the Antarctic Polar Vortex Breakup in 2004  

NASA Technical Reports Server (NTRS)

Observations from the Microwave Limb Sounder (MLS) on NASA's new Aura satellite give an unprecedentedly detailed picture of the spring Antarctic polar vortex breakup throughout the stratosphere. HCl is a particularly valuable tracer in the lower stratosphere after chlorine deactivation. MLS HCl, N2O, H2O broke up in the upper stratosphere by early October, in the midstratosphere by early November, and in the lower stratosphere by late December. The subvortex broke up just a few days later than the lower stratospheric vortex. Vortex remnants persisted in the midstratosphere through December, but only through early January 2005 in the lower stratosphere. MLS N2O observations show diabatic descent continuing throughout November, with evidence of weak ascent after late October in the lower stratospheric vortex core.

Manney, G. L.; Santee, M. L.; Livesey, N. J.; Froidevaux, L.; Read, W. G.; Pumphrey, H. C.; Waters, J. W.; Pawson, S.

2005-01-01

98

Arctic Climatology and Meteorology Primer for Newcomers to the North  

NSDL National Science Digital Library

This primer introduces basic concepts about the arctic, including weather and climate, synoptic meteorology, and optical and acoustic phenomena. Sections on factors affecting arctic weather and climate include: latitude, land/sea distribution, solar radiation, air temperature and pressure, winds, humidity, clouds, precipitation, and arctic energy budget. Sections on factors affecting weather patterns cover: cyclones, anticyclones, the polar vortex, semipermanent highs and lows, polar lows, the arctic as a heat sink, arctic oscillation, feedback loops, and climate change. There is also a photo gallery based on life on a Russian North Pole drifting station.

99

Observations of Hydration and Dehydration in the Winter 2000 Arctic Stratosphere  

NASA Technical Reports Server (NTRS)

During the January 2000 deployment of the SAGE III Ozone Loss Validation Experiment (SOLVE), the NASA ER-2 aircraft intercepted air parcels with unusual water mixing ratios within the the Arctic polar vortex.

Herman, R.; Webster, C.; Ordla, K.; Bui, P.; Gandrud, B.

2000-01-01

100

The possible biotic origin of polar sunrise Arctic "bromine explosion"  

E-print Network

The Arctic phenomenon of the sunrise bromine explosion in atmospheric boundary layer is likely to belong to the group of the global atmosphere and climate factors. The global atmosphere and climate factors are identified as the most crucial and fundamental processes in Earth atmosphere and climate evolution. They affect normal climate and are able to control climate changes over geological time scales. This study deals with the hypothesis of the microbial origin of natural Arctic bromine emissions. Most of Arctic surface is permafrost. Some of the Arctic permafrost is very old. It contains huge amounts of viable ancient microbial life forms survived over geological times. The erosion of permafrost is a hypothetical precursor to bromine injection to Arctic troposphere. The controlled experiment has been suggested. GOME satellite data from 1996 to 2000 has been discussed. Bromine biosphere atmosphere ascertaining would require the interdisciplinary research of experimental findings and observations in extreme A...

Iudin, M

2008-01-01

101

Stereographical visualization of a polarization state using weak measurements with an optical-vortex beam  

NASA Astrophysics Data System (ADS)

We propose a stereographical-visualization scheme for a polarization state by two-dimensional imaging of a weak value with a single setup. The key idea is to employ Laguerre-Gaussian modes or an optical vortex beam for a probe state in weak measurement. Our scheme has the advantage that we can extract information on the polarization state from the single image in which the zero-intensity point of the optical vortex beam corresponds to a stereographic projection point of the Poincaré sphere. We experimentally perform single-setup weak measurement to validate the stereographical relationship between the polarization state on the Poincaré sphere and the location of the zero-intensity point.

Kobayashi, Hirokazu; Nonaka, Koji; Shikano, Yutaka

2014-05-01

102

Nonlinear magnetic vortex dynamics in a circular nanodot excited by spin-polarized current  

NASA Astrophysics Data System (ADS)

We investigate analytically and numerically nonlinear vortex spin torque oscillator dynamics in a circular magnetic nanodot induced by a spin-polarized current perpendicular to the dot plane. We use a generalized nonlinear Thiele equation including spin-torque term by Slonczewski for describing the nanosize vortex core transient and steady orbit motions and analyze nonlinear contributions to all forces in this equation. Blue shift of the nano-oscillator frequency increasing the current is explained by a combination of the exchange, magnetostatic, and Zeeman energy contributions to the frequency nonlinear coefficient. Applicability and limitations of the standard nonlinear nano-oscillator model are discussed.

Guslienko, Konstantin Y.; Sukhostavets, Oksana V.; Berkov, Dmitry V.

2014-08-01

103

An International Polar Year Adventure in the Arctic  

NASA Astrophysics Data System (ADS)

RAHI, the Rural Alaska Honors Institute at the University of Alaska Fairbanks began in 1983 after a series of meetings between the Alaska Federation of Natives and the University of Alaska, to discuss the retention rates of Alaska Native and rural students. RAHI is a six-week college-preparatory summer bridge program on the University of Alaska Fairbanks campus for Alaska Native and rural high school juniors and seniors. The program's student body is approximately 94 percent Alaska Native. RAHI students take classes that earn them seven to ten college credits, thus giving them a head start on college. Courses include: writing, study skills, desk top publishing, Alaska Native dance or swimming, and a choice of biochemistry, math, business, or engineering. A program of rigorous academic activity combines with social, cultural, and recreational activities to make up the RAHI program of early preparation for college. Students are purposely stretched beyond their comfort levels academically and socially to prepare for the big step from home or village to a large culturally western urban campus. They are treated as honors students and are expected to meet all rigorous academic and social standards set by the program. All of this effort and activity support the principal goal of RAHI: promoting academic success for rural students in college. Over 26 years, 1,200 students have attended the program. Sixty percent of RAHI's alumni have entered four-year academic programs. Over 245 have earned a bachelor's degree, thirty-one have earned master's degrees, and seven have graduated with professional degrees (J.D., Pharm., or M.D.), along with 156 associate degrees and certificates. In looking at the RAHI cohort, removing those students who have not been in college long enough to obtain a degree, 27.3 percent of RAHI alums have received a bachelor's degree. An April 2006 report by the American Institutes for Research through the National Science Foundation found that: Rural Native students in the UA system who participated in RAHI are nearly twice as likely to earn a bachelor's degree, than those who did not attend RAHI. The past two summers, in celebration of the International Polar Year, in collaboration with Ilisagvik College, at the completion of the traditional RAHI program, ten RAHI students flew to Barrow for an additional two weeks of study. Five students participated in an archaeological dig and five students performed research with the Barrow Arctic Science Consortium scientists studying climate change. And another student was the Alaskan delegate to the Students on Ice, a 2-week ship-based adventure in northern Canada. In addition, ten students from Greenland visited the program, with plans to more fully participate next summer. This added dimension to the program has proved successful, allowing the students to compare and contrast between their own countries and indigenous perspectives. Global warming was an issue that was hotly debated, as its effects are so evident in the Polar Regions. In the Arctic, one's life is directly tied to the ice and snow. As the ice disappears and/or changes, the Indigenous people have to adapt. RAHI would like to share with you some of the results of this past summer's IPY activities.

Wartes, D.

2008-12-01

104

Production of dicarboxylic acids in the arctic atmosphere at polar sunrise  

SciTech Connect

The authors report measurements which reveal the presence of a homologous series of dicarboxylic acids in the arctic atmophere. Their results show a marked peak in the densities at the time of the polar sunrise. They attribute these acids to the photochemical oxidation of pollutants which have been transported into the arctic via long range transport processes. The appearance of these acids correlates with tropospheric ozone depletions which occur in concert with the appearance of bromine particles.

Kimitaka Kawamura; Hideki Kasukabe; Osamu Yasui [Tokyo Metropolitan Univ. (Japan)] [Tokyo Metropolitan Univ. (Japan)

1995-05-15

105

Production of dicarboxylic acids in the arctic atmosphere at polar sunrise  

Microsoft Academic Search

An homologous series of low molecular weight dicarboxylic acids (C2-C11) have been measured in the arctic aerosol samples collected from July 1987 to June 1988 in Alert. Oxalic acid (C2) was found as the dominant species followed by malonic (C3) or succinic (C4) acid. At the time of polar sunrise, certain dicarboxylic acids in arctic haze aerosols became 5 to

Kimitaka Kawamura; Hideki Kasukabe; Osamu Yasui; Leonard A. Barrie

1995-01-01

106

Polarization-selective vortex-core switching by tailored orthogonal Gaussian-pulse currents  

SciTech Connect

We experimentally demonstrate low-power-consumption vortex-core switching in magnetic nanodisks using tailored rotating magnetic fields produced with orthogonal and unipolar Gaussian-pulse currents. The optimal width of the orthogonal pulses and their time delay are found, from analytical and micromagnetic numerical calculations, to be determined only by the angular eigenfrequency {omega}{sub D} for a given vortex-state disk of polarization p, such that {sigma}=1/{omega}{sub D} and ?{Delta}t={pi}/2 p/{omega}{sub D} . The estimated optimal pulse parameters are in good agreement with the experimental results. This work lays a foundation for energy-efficient information recording in vortex-core cross-point architecture.

Jung, H.; Choi, Y. -S.; Yoo, M. -W.; Im, M. -Y.; Kim, S. -K.

2010-10-13

107

Large amplitude spin torque vortex oscillations at zero external field using a perpendicular spin polarizer  

NASA Astrophysics Data System (ADS)

We investigate the microwave response of a spin transfer vortex based oscillator in a magnetic tunnel junction with an in-plane reference layer combined with a spin valve with an out-of-plane magnetization spin polarizing layer. The main advantage of this perpendicular spin polarizer is to induce a large spin transfer force even at zero magnetic field, thus leading to a record emitted power (up to 0.6 ?W) associated to a very narrow spectral linewidth of a few hundreds of kHz. The characteristics of this hybrid vortex based spin transfer nano-oscillator obtained at zero field and room temperature are of great importance for applications based on rf spintronic devices as integrated and tunable microwave source and/or microwave detector.

Dussaux, A.; Grimaldi, E.; Rache Salles, B.; Jenkins, A. S.; Khvalkovskiy, A. V.; Bortolotti, P.; Grollier, J.; Kubota, H.; Fukushima, A.; Yakushiji, K.; Yuasa, S.; Cros, V.; Fert, A.

2014-07-01

108

Impact of mixing and chemical change on ozone-tracer relations in the polar vortex  

Microsoft Academic Search

Tracer-tracer relations have been used for a long time to separate physico-chemical change from change caused by transport processes. In particular, for more than a decade, ozone-tracer relations have been used to quantify chemical ozone loss in the polar vortex. The application of ozone-tracer relations for quantifying ozone loss relies on two hypotheses; that a compact ozone-tracer relation is established

R. Müller; S. Tilmes; P. Konopka; J.-U. Grooß; H.-J. Jost

2005-01-01

109

Impact of mixing and chemical change on ozone-tracer relations in the polar vortex  

Microsoft Academic Search

Tracer-tracer relations have been used for a long time to separate physico-chemical change from change caused by transport processes. In particular, for more than a decade, ozone-tracer relations have been used to quantify chemical ozone loss in the polar vortex. The application of ozone-tracer relations for quantifying ozone loss relies on two hypotheses: that a compact ozone-tracer relation is es-

S. Tilmes; P. Konopka; J.-U. Grooß; H.-J. Jost

2005-01-01

110

Observations of deformation and mixing of the total ozone field in the Antaractic Polar Vortex  

SciTech Connect

Total Ozone Mapping Spectrometer (TOMS) images of the springtime Southern Hemisphere commonly show concentric layers in the total ozone field outside the Antarctic polar vortex. The layering appears to result from horizontal folding and stretching of regions on the equatorward flank of the polar vortex near the midlatitude ozone maximum. This folding and stretching interleaves low and high ozone air from the subtropics and midlatitudes, respectively. Occasional large amplitude wave events can extract very low ozone air from the interior of the polar vortex (the Antarctic ozone hole), but the folding and stretching results in relatively rapid horizontal mixing of the atmosphere on the equatorward flank of the jet. This type of lagrangian behavior may be common in the atmosphere, but is only visible when local tracer gradients are large and observations with high spatial resolution are available. Also, experimentation has shown that gray-scale images of TOMS data show the details of the spatial distribution of ozone much more clearly than contour maps of false-color images. 22 refs., 3 figs., 2 tabs.

Bowman, K.P. (Texas A M Univ., College Stations, TX (United States)); Mangus, N.J. (Univ of Illinois, Urbana-Champaign (United States))

1993-09-01

111

Polar bear maternal den habitat in the Arctic National Wildlife Refuge, Alaska  

USGS Publications Warehouse

Polar bears (Ursus maritimus) give birth during mid-winter in dens of ice and snow. Denning polar bears subjected to human disturbances may abandon dens before their altricial young can survive the rigors of the Arctic winter. Because the Arctic coastal plain of Alaska is an area of high petroleum potential and contains existing and planned oil field developments, the distribution of polar bear dens on the plain is of interest to land managers. Therefore, as part of a study of denning habitats along the entire Arctic coast of Alaska, we examined high-resolution aerial photographs (n = 1655) of the 7994 km2 coastal plain included in the Arctic National Wildlife Refuge (ANWR) and mapped 3621 km of bank habitat suitable for denning by polar bears. Such habitats were distributed uniformly and comprised 0.29% (23.2 km2) of the coastal plain between the Canning River and the Canadian border. Ground-truth sampling suggested that we had correctly identified 91.5% of bank denning habitats on the ANWR coastal plain. Knowledge of the distribution of these habitats will help facilitate informed management of human activities and minimize disruption of polar bears in maternal dens.

Durner, G. M.; Amstrup, S. C.; Ambrosius, K. J.

2006-01-01

112

Polar Energy: Where Did Arctic People Get Metal?  

NSDL National Science Digital Library

This Why Files article investigates trading, sources, and use of metal by Arctic peoples. Until recently, metal was seldom found at Arctic archeological digs. In 1994, a group of scientists found many iron and copper objects by simply using a metal detector. By analyzing isotopes, scientists were able to show that both iron and copper came from few sources that were traded widely. Starting around 1,000 AD, iron that came from a meteorite found in Cape York, Greenland was used in preference to flaking stone. Much of the copper came from the Coronation Gulf-Coppermine River area along Canada's central Arctic coast. Other metals may have been traded across the Bering Strait. Archeologist Allen McCartney was interviewed for this article.

Tenenbaum, David

113

Chemical Depletion of Lower Stratospheric Ozone in the 1992-1993 Northern Winter Vortex  

NASA Technical Reports Server (NTRS)

Satellite observations of ozone and chlorine monoxide in the Arctic lower stratosphere during winter 1992-1993 are compared with observations during other winters, observations of long-lived tracers and the evolution of the polar vortex. Chlorine in the lower stratospheric vortex during February 1993 was mostly in chemically reactive forms.

Manney, G. L.; Froidevaux, L.; Waters, J. W.; Zurek, R. W.; Read, W. G.; Elson, L. S.; Kumer, J. B.; Mergenthaler, J. L.; Roche, A. E.; O'Neill, A.; Harwood, R. S.; MacKenzie, I.; Swinbank, R.

1994-01-01

114

Generation of Vortex Beams with Strong Longitudinally Polarized Magnetic Field by Using a Metasurface  

E-print Network

A novel method of generation and synthesis of azimuthally E-polarized vortex beams is presented. Along the axis of propagation such beams have a strong longitudinally polarized magnetic field where ideally there is no electric field. We show how these beams can be constructed through the interference of Laguerre-Gaussian beams carrying orbital angular momentum. As an example, we present a metasurface made of double-split ring slot pairs and report a good agreement between simulated and analytical results. Both a high magnetic-to-electric-field contrast ratio and a magnetic field enhancement are achieved. We also investigate the metasurface physical constraints to convert a linearly polarized beam into an azimuthally E- polarized beam and characterize the performance of magnetic field enhancement and electric field suppression of a realistic metasurface. These findings are potentially useful for novel optical spectroscopy related to magnetic dipolar transitions and for optical manipulation of particles with sp...

Veysi, Mehdi; Capolino, Filippo

2014-01-01

115

Three-dimensional thermal structure of the South Polar Vortex of Venus  

NASA Astrophysics Data System (ADS)

We have analyzed thermal infrared images provided by the VIRTIS-M instrument aboard Venus Express (VEX) to obtain high resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. The maps investigate three different dynamical configurations of the polar vortex including its classical dipolar shape, a regularly oval shape and a transition shape between the different configurations of the vortex. We apply the atmospheric model described by García Muñoz et al. (2013) and a variant of the retrieval algorithm detailed in Grassi et al. (2008) to obtain maps of temperature over the Venus south polar region in the quoted altitude range. These maps are discussed in terms of cloud motions and relative vorticity distribution obtained previously (Garate-Lopez et al. 2013). Temperature maps retrieved at 55 – 63 km show the same structures that are observed in the ~5 µm radiance images. This altitude range coincides with the optimal expected values of the cloud top altitude at polar latitudes and magnitudes derived from the analysis of ~5 µm images are measured at this altitude range. We also study the imprint of the vortex on the thermal field above the cloud level which extends up to 80 km. From the temperature maps, we also study the vertical stability of different atmospheric layers. The cold collar is clearly the most statically stable structure at polar latitudes, while the vortex and subpolar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex at 55-63 km exhibit lower values of static stability than their immediate surroundings.ReferencesGarate-Lopez et al. Nat. Geosci. 6, 254–257 (2013).García Muñoz et al. Planet. Space Sci. 81, 65–73 (2013).Grassi, D. et al. J. Geophys. Res. 113, 1–12 (2008).AcknowledgementsWe thank ESA for supporting Venus Express, ASI, CNES and the other national space agencies supporting VIRTIS on VEX and their principal investigators G. Piccioni and P. Drossart. This work was supported by projects AYA2012-36666 with FEDER support, PRICI-S2009/ESP-1496, Grupos Gobierno Vasco IT-765-13 and by UPV/EHU through program UFI11/55. IGL and AGM acknowledge ESA/RSSD for hospitality and access to ‘The Grid’ computing resources.

Hueso, Ricardo; Garate-Lopez, Itziar; Garcia-Muñoz, Antonio; Sánchez-Lavega, Agustín

2014-11-01

116

Growth and variation in the bacula of polar bears (Ursus maritimus) in the Canadian Arctic  

Microsoft Academic Search

Structure and growth of the baculum (os penis) in arctoid carnivores have been well described for many species. This study presents the first extensive analysis of bacular growth and variation for bears (Ursidae), based on 871 bacula of polar bears Ursus maritimus (858 of known age) that were shot in the Canadian Arctic from 1994 to 1997. Bacular length, maximal

Markus G. Dyck; Jackie M. Bourgeois; Edward H. Miller

2004-01-01

117

Spatial variation of ozone depletion rates in the springtime antarctic polar vortex  

SciTech Connect

An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O{sub 3}. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. There is tentative evidence for quasi-periodic O{sub 3} fluctuations in the collar and for upwelling of tropospheric air in late spring. A simplified photochemical model of O{sub 3} loss and the temporal evolution of the area-mapped polar O{sub 3} are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The concentrations required to account for the observed loss of O{sub 3} are higher than those previously reported by Anderson et al. but are comparable to their recently revised values. However, the O{sub 3} loss rates could be larger than deduced here because of underestimates of total O{sub 3} by TOMS near the terminator. This uncertainty, together with the uncertainties associated with measurements acquired during the Airborne Antarctic Ozone Experiment, suggests that in early spring, closer to the vortex center, there may be even larger ClO concentrations than have yet been detected.

Yung, Y.L.; Allen, M.; Crisp, D.; Zurek, R.W.; Sander, S.P. (California Institute of Technology, Pasadena (USA))

1990-05-11

118

Spatial variation of ozone depletion rates in the springtime Antarctic polar vortex.  

PubMed

An area-mapping technique, designed to filter out synoptic perturbations of the Antarctic polar vortex such as distortion or displacement away from the pole, was applied to the Nimbus-7 TOMS (Total Ozone Mapping Spectrometer) data. This procedure reveals the detailed morphology of the temporal evolution of column O3. The results for the austral spring of 1987 suggest the existence of a relatively stable collar region enclosing an interior that is undergoing large variations. There is tentative evidence for quasi-periodic (15 to 20 days) O3 fluctuations in the collar and for upwelling of tropospheric air in late spring. A simplified photochemical model of O3 loss and the temporal evolution of the area-mapped polar O3 are used to constrain the chlorine monoxide (ClO) concentrations in the springtime Antarctic vortex. The concentrations required to account for the observed loss of O3 are higher than those previously reported by Anderson et al. but are comparable to their recently revised values. However, the O3 loss rates could be larger than deduced here because of underestimates of total O3 by TOMS near the terminator. This uncertainty, together with the uncertainties associated with measurements acquired during the Airborne Antarctic Ozone Experiment, suggests that in early spring, closer to the vortex center, there may be even larger ClO concentrations than have yet been detected. PMID:11538181

Yung, Y L; Allen, M; Crisp, D; Zurek, R W; Sander, S P

1990-05-11

119

Optimally coherent sets in geophysical flows: a transfer-operator approach to delimiting the stratospheric polar vortex.  

PubMed

The "edge" of the Antarctic polar vortex is known to behave as a barrier to the meridional (poleward) transport of ozone during the austral winter. This chemical isolation of the polar vortex from the middle and low latitudes produces an ozone minimum in the vortex region, intensifying the ozone hole relative to that which would be produced by photochemical processes alone. Observational determination of the vortex edge remains an active field of research. In this paper, we obtain objective estimates of the structure of the polar vortex by introducing a technique based on transfer operators that aims to find regions with minimal external transport. Applying this technique to European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-40 three-dimensional velocity data, we produce an improved three-dimensional estimate of the vortex location in the upper stratosphere where the vortex is most pronounced. This computational approach has wide potential application in detecting and analyzing mixing structures in a variety of atmospheric, oceanographic, and general fluid dynamical settings. PMID:21230580

Santitissadeekorn, Naratip; Froyland, Gary; Monahan, Adam

2010-11-01

120

Ross Ice Shelf airstream driven by polar vortex cyclone  

NASA Astrophysics Data System (ADS)

The powerful air and ocean currents that flow in and above the Southern Ocean, circling in the Southern Hemisphere's high latitudes, form a barrier to mixing between Antarctica and the rest of the planet. Particularly during the austral winter, strong westerly winds isolate the Antarctic continent from heat, energy, and mass exchange, bolstering the scale of the annual polar ozone depletion and driving the continent's record-breaking low temperatures. Pushing through this wall of high winds, the Ross Ice Shelf airstream (RAS) is responsible for a sizable amount of mass and energy exchange from the Antarctic inland areas to lower latitudes. Sitting due south of New Zealand, the roughly 470,000-square-kilometer Ross Ice Shelf is the continent's largest ice shelf and a hub of activity for Antarctic research. A highly variable lower atmospheric air current, RAS draws air from the inland Antarctic Plateau over the Ross Ice Shelf and past the Ross Sea. Drawing on modeled wind patterns for 2001-2005, Seefeldt and Cassano identify the primary drivers of RAS.

Schultz, Colin

2012-07-01

121

Potential Arctic sea ice refuge for sustaining a remnant polar bear population (Invited)  

NASA Astrophysics Data System (ADS)

Polar bears depend on sea ice as a platform from which they capture seals. Sea ice availability must be spatially and temporally adequate for birth and weaning of seal pups, and to maximize seal hunting opportunities for polar bears. Projected declines in the spatial and temporal extent of summer and autumn sea ice could potentially limit the ability of polar bears to build up body stores sufficient to maintain reproductive fitness. General circulation models, however, suggest that summer and autumn sea ice may persist in the shelf waters of the Canadian Archipelago and northern Greenland adjacent to the Arctic basin. While winter-formed ice is important, a primary mechanism for sea ice accumulation in this region is by mechanical thickening of the sea ice facilitated by convergent forces from the Beaufort Gyre and the Transpolar Drift Stream. Collectively these areas could provide a polar bear refugium when other regions have lost the sea ice necessary to support viable populations. The potential for a polar bear refugium, however, must include other resource considerations. Projected declines of sea ice in the Northwest Passage may expose polar bears to hazards related to increase shipping and other commerce. Increasing global demands and limited opportunities elsewhere make the Arctic an increasingly attractive area for petroleum exploration. The Canadian Archipelago coincides with the Sverdrup basin, where petroleum accumulations have already been discovered but as yet are undeveloped. The Lincoln Sea Basin offshore of northern Greenland has the geological possibility of significant petroleum accumulations, and northeastern Greenland is one of the most prospective areas in the Arctic for undiscovered oil. Activities associated with commerce and petroleum development could reduce the potential viability of the region as a polar bear refugium. Hence, if the goal is a sustainable (albeit reduced) polar bear population, important considerations include commerce, hydrocarbon extraction and polar bear habitat.

Durner, G. M.; Amstrup, S. C.; Douglas, D. C.; Gautier, D. L.

2010-12-01

122

Polar Bears in the Arctic National Wildlife Refuge  

Microsoft Academic Search

The Beaufort Sea population of polar bears in Alaska is estimated to be between 2000 and 2500. Based on the analysis of over 30 years of data, scientists found that a bit less than half of the polar bear maternity dens were located on the coastal mainland or on ice attached to the mainland. 1 Of these land dens, about

123

Troposphere-Stratosphere Dynamic Coupling Under Strong and Weak Polar Vortex Conditions  

NASA Technical Reports Server (NTRS)

The relationship between Northern Hemisphere (NH) tropospheric and stratospheric wave-like anomalies of spherical zonal wave number (ZWN) 1 is studied by applying Canonical Correlation Analysis (CCA). A lag-correlation technique is used with 10-day lowpass filtered daily time series of 50- and 500-hPa geopotential heights. Generally stratospheric circulation is determined by ultralong tropospheric planetary waves. During winter seasons characterized either by any anomalously strong or weak polar winter vortex different propagation characteristics for waves of ZWN 1 are observed. The non-linear perspective of the results have implications for medium range weather forecast and climate sensitivity experiments.

Perlwitz, Judith; Graf, Hans-F.; Hansen, James E. (Technical Monitor)

2001-01-01

124

IHY-IPY conference report from Polar Gateways Arctic Circle Sunrise 2008  

NASA Astrophysics Data System (ADS)

Polar, heliophysical, and planetary science topics related to the International Heliophysical and Polar Years 2007-2009 were addressed during this unique circumpolar conference hosted January 23-29, 2008 at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium in Barrow, Alaska. Science presentations spanned the solar system from the polar Sun and heliospheric environment to Earth, Moon, Mars, Jupiter, Saturn, the Kuiper Belt, and the solar wind termination shock now crossed by both Voyager spacecraft. Many of the science presentations were made remotely via video conference or teleconference from Sweden, Norway, Russia, Canada, Antarctica, and the United States, spanning up to thirteen time zones (Alaska to Russia) at various times during the conference. U.S. remote contributions came from the University of Alaska at Fairbanks, the University of California at Berkeley, the University of Arizona, NASA Jet Propulsion Laboratory, and NASA Goddard Space Flight Center. Convening during the first week of 2008 Arctic sunrise at Barrow, this conference served as a prelude that year to international Sun-Earth Day celebrations for IHY, while also commemorating Barrow scientific and native cultural support for the first International Polar Year 1882-1883. Extensive educational outreach activities were conducted with the local Barrow and Alaska North Slope communities and through the NASA Digital Learning Network live from the "top of the world" at Barrow. The conference proceedings are Internet accessible via the home page at http://polargateways2008.org/.

Cooper, John; Kauristie, Kirsti; Weatherwax, Allan; Thompson, Barbara; Sheehan, Glenn; Smith, Roger; Sandahl, Ingrid

125

Lower Stratospheric Temperature Differences Between Meteorological Analyses in two cold Arctic Winters and their Impact on Polar Processing Studies  

NASA Technical Reports Server (NTRS)

A quantitative intercomparison of six meteorological analyses is presented for the cold 1999-2000 and 1995-1996 Arctic winters. The impacts of using different analyzed temperatures in calculations of polar stratospheric cloud (PSC) formation potential, and of different winds in idealized trajectory-based temperature histories, are substantial. The area with temperatures below a PSC formation threshold commonly varies by approximately 25% among the analyses, with differences of over 50% at some times/locations. Freie University at Berlin analyses are often colder than others at T is less than or approximately 205 K. Biases between analyses vary from year to year; in January 2000. U.K. Met Office analyses were coldest and National Centers for Environmental Prediction (NCEP) analyses warmest. while NCEP analyses were usually coldest in 1995-1996 and Met Office or NCEP[National Center for Atmospheric Research Reanalysis (REAN) warmest. European Centre for Medium Range Weather Forecasting (ECMWF) temperatures agreed better with other analyses in 1999-2000, after improvements in the assimilation model. than in 1995-1996. Case-studies of temperature histories show substantial differences using Met Office, NCEP, REAN and NASA Data Assimilation Office (DAO) analyses. In January 2000 (when a large cold region was centered in the polar vortex), qualitatively similar results were obtained for all analyses. However, in February 2000 (a much warmer period) and in January and February 1996 (comparably cold to January 2000 but with large cold regions near the polar vortex edge), distributions of "potential PSC lifetimes" and total time spent below a PSC formation threshold varied significantly among the analyses. Largest peaks in "PSC lifetime" distributions in January 2000 were at 4-6 and 11-14 days. while in the 1996 periods, they were at 1-3 days. Thus different meteorological conditions in comparably cold winters had a large impact on expectations for PSC formation and on the discrepancies between different meteorological analyses. Met Office. NCEP, REAN, ECMWF and DAO analyses are commonly used for trajectory calculations and in chemical transport models; the choice of which analysis to use can strongly influence the results of such studies.

Manney, Gloria L.; Sabutis, Joseph L.; Pawson, Steven; Santee, Michelle L.; Naujokat, Barbara; Swinbank, Richard; Gelman, Melvyn E.; Ebisuzaki, Wesley; Atlas, Robert (Technical Monitor)

2001-01-01

126

Observational constraints on the tropospheric and near-surface winter signature of the Northern Hemisphere stratospheric polar vortex  

NASA Astrophysics Data System (ADS)

A composite analysis of Northern Hemisphere's mid-winter tropospheric anomalies under the conditions of strong and weak stratospheric polar vortex was performed on NCEP/NCAR reanalysis data from 1948 to 2013 considering, as additional grouping criteria, the coincidental states of major seasonally relevant climate phenomena, such as El Niño-Southern Oscillation (ENSO), Quasi Biennial Oscillation and strong volcanic eruptions. The analysis reveals that samples of strong polar vortex nearly exclusively occur during cold ENSO states, while a weak polar vortex is observed for both cold and warm ENSO. The strongest tropospheric and near-surface anomalies are found for warm ENSO and weak polar vortex conditions, suggesting that internal tropospheric circulation anomalies related to warm ENSO constructively superpose on dynamical effects from the stratosphere. Additionally, substantial differences are found between the continental winter warming patterns under strong polar vortex conditions in volcanically-disturbed and volcanically-undisturbed winters. However, the small-size samples obtained from the multi-compositing prevent conclusive statements about typical patterns, dominating effects and mechanisms of stratosphere-troposphere interaction on the seasonal time scale based on observational/reanalysis data alone. Hence, our analysis demonstrates that patterns derived from observational/reanalysis time series need to be taken with caution as they not always provide sufficiently robust constraints to the inferred mechanisms implicated with stratospheric polar vortex variability and its tropospheric and near-surface signature. Notwithstanding this argument, we propose a limited set of mechanisms that together may explain a relevant part of observed climate variability. These may serve to define future numerical model experiments minimizing the sample biases and, thus, improving process understanding.

Graf, Hans-F.; Zanchettin, Davide; Timmreck, Claudia; Bittner, Matthias

2014-03-01

127

Quantifying transport into the Arctic lowermost stratosphere  

NASA Astrophysics Data System (ADS)

In the Arctic winter 2003, in-situ measurements of the long-lived trace gases N2O, CFC-11 (CCl3F), H-1211 (CBrClF2), CH4, O3 and H2O have been performed on board the high-altitude aircraft M55 Geophysica. The data are presented and used to study transport into the lowermost stratosphere (LMS). The LMS can be regarded as a mixture of fractions of air originating in (i) the troposphere, (ii) the extra-vortex stratosphere above 400 K and (iii) the Arctic vortex above 400 K. These fractions are determined using a simple mass balance calculation. The analysis exhibits a strong tropospheric influence of 50% ± 15% or more in the lowest 20 K of the high-latitude LMS. Above this region the LMS is dominated by air masses having descended from above 400 K. Below the Arctic vortex region at potential temperatures above 360 K, air in the LMS is a mixture of extra-vortex stratospheric and vortex air masses. The vortex fraction increases from about 40% ± 15% at 360 K to 100% at 400 K for equivalent latitudes >70° N. This influence of air masses descending through the bottom of the polar vortex increases over the course of the winter. By the end of winter a significant fraction of 30% ± 10% vortex air in the LMS is found even at an equivalent latitude of 40° N. Since the chemical and dynamical history of vortex air is distinct from that of mid-latitude stratospheric air masses, this study implies that the composition of the mid- to high-latitude LMS during late winter and spring is significantly influenced by the Arctic vortex.

Werner, A.; Volk, C. M.; Ivanova, E. V.; Wetter, T.; Schiller, C.; Schlager, H.; Konopka, P.

2010-12-01

128

Dielectric meta-reflectarray for broadband linear polarization conversion and optical vortex generation.  

PubMed

Plasmonic metasurfaces have recently attracted much attention due to their ability to abruptly change the phase of light, allowing subwavelength optical elements for polarization and wavefront control. However, most previously demonstrated metasurface designs suffer from low coupling efficiency and are based on metallic resonators, leading to ohmic loss. Here, we present an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane. We experimentally demonstrate that this meta-reflectarray can be used to realize linear polarization conversion with more than 98% conversion efficiency over a 200 nm bandwidth in the short-wavelength infrared band. We also demonstrate optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile. The vortex beam generation is shown to have high efficiency over a wavelength range from 1500 to 1600 nm. The use of dielectric resonators in place of their plasmonic counterparts could pave the way for ultraefficient metasurface-based devices at high frequencies. PMID:24547692

Yang, Yuanmu; Wang, Wenyi; Moitra, Parikshit; Kravchenko, Ivan I; Briggs, Dayrl P; Valentine, Jason

2014-03-12

129

Changes in the polarization and coherence of a stochastic electromagnetic vortex beam propagating through a misaligned optical system with aperture  

NASA Astrophysics Data System (ADS)

An analytical expression for the elements of the cross-spectral density matrix of a stochastic electromagnetic vortex beam passing through a misaligned optical system with aperture is derived. Some analyses are illustrated by numerical examples relating to changes in the spectral degree of polarization and the spectral degree of coherence for a stochastic electromagnetic vortex beam passing through such an optical system. It was found that the topological charge, the radius of the aperture and the displacement have different influences on the changes in the spectral degree of polarization and the spectral degree of coherence.

Luo, Meilan; Zhao, Daomu

2014-10-01

130

Organochlorine contaminants in arctic marine food chains: identification, geographical distribution, and temporal trends in polar bears  

Microsoft Academic Search

Contamination of Canadian arctic and subarctic marine ecosystems by organochlorine (OC) compounds was measured by analysis of polar bear (Ursus maritimus) tissues collected from 12 zones between 1982 and 1984. PCB congeners (S-PCB), chlordanes, DDT and metabolites, chlorobenzenes (S-CBz), hexachlorocyclohexane isomers (S-HC-H), and dieldrin were identified by high-resolution gas chromatography-mass spectrometry. Nonachlor-III, a nonachlor isomer in technical chlordane, was positively

Ross J. Norstrom; Mary Simon; Derek C. G. Muir; Ray E. Schweinsburg

1988-01-01

131

Ozone and aerosol changes during the 1991-1992 airborne arctic stratospheric expedition.  

PubMed

Stratospheric ozone and aerosol distributions were measured across the wintertime Arctic vortex from January to March 1992 with an airborne lidar system as part of the 1992 Airborne Arctic Stratospheric Expedition (AASE II). Aerosols from the Mount Pinatubo eruption were found outside and inside the vortex with distinctly different distributions that clearly identified the dynamics of the vortex. Changes in aerosols inside the vortex indicated advection of air from outside to inside the vortex below 16 kilometers. No polar stratospheric clouds were observed and no evidence was found for frozen volcanic aerosols inside the vortex. Between January and March, ozone depletion was observed inside the vortex from 14 to 20 kilometers with a maximum average loss of about 23 percent near 18 kilometers. PMID:17790351

Browell, E V; Butler, C F; Fenn, M A; Grant, W B; Ismail, S; Schoeberl, M R; Toon, O B; Loewenstein, M; Podolske, J R

1993-08-27

132

Saturn's North Polar Vortex Revealed by Cassini/VIMS: Zonal Wind Structure and Constraints on Cloud Distributions  

NASA Astrophysics Data System (ADS)

We present the first high-spatial resolution, near-nadir imagery and movies of Saturn's north polar region that reveal the wind structure of a north polar vortex. Obtained by Cassini/VIMS on June 15, 2008 from high over Saturn's polar region (sub-spacecraft latitude of 65 degrees N. lat) at an altitude of 0.42 million km during the long polar night, these 210-per-pixel images of the polar region north of 73 degrees N. latitude show several concentric cloud rings and hundreds of individual cloud features in silhouette against the 5-micron background thermal glow of Saturn's deep atmosphere. In contrast to the clear eye of the south polar vortex, the north polar vortex sports a central cloud feature about 650-km in diameter. Zonal winds reach a maximum of 150 m/s near 88 degrees N. latitude (planetocentric) - comparable to the south polar vortex maximum of 190 m/s near 88 degrees S. latitude - and fall off nearly monotonically to 10 m/s near 80 degrees N. latitude. At slightly greater distance from the pole, inside the north polar hexagon in the 75-77 degree N. latitude region, zonal winds increase dramatically to 130 m/s, as silhouetted clouds are seen speeding aroud the "race track” of the hexagonal feature. VIMS 5-micron thermal observations over a 1.6-year period from October 29, 2006 to June 15, 2008 are consistent with the polar hexagon structure itself remaining fixed in the Voyager-era radio rotation rate (Desch and Kaiser, Geophys. Res. Lett, 8, 253-256, 1981) to within an accuracy of 3 seconds per rotational period. This agrees with the stationary nature of the wave in this rotation system found by Godfrey (Icarus 76, 335-356, 1988), but is inconsistent with rotation rates found during the current Cassini era.

Baines, Kevin H.; Momary, T. W.; Fletcher, L. N.; Buratti, B. J.; Roos-Serote, M.; Showman, A. P.; Brown, R. H.; Clark, R. N.; Nicholson, P. D.

2008-09-01

133

Arctic Forecasts Available from Polar Bear Exhibit as an Example of Formal/Informal Collaboration  

NASA Astrophysics Data System (ADS)

A subset of the general population enjoys and frequents informal education venues, offering an opportunity for lifelong learning that also enhances and supports formal education efforts. The Byrd Polar Research Center (BPRC) at The Ohio State University collaborated with the Columbus Zoo & Aquarium (CZA) in the development of their Polar Frontier exhibit, from its initial planning to the Grand Opening of the exhibit, through the present. Of course, the addition to the Zoo of polar bears and Arctic fox in the Polar Frontier has been very popular, with almost a 7% increase in visitors in 2010 when the exhibit opened. The CZA and BPRC are now investigating ways to increase the climate literacy impact of the exhibit, and to increase engagement with the topics through follow-on activities. For example, individuals or classes anywhere in the world can check forecasts from the Polar Weather and Research Forecasting model and compare them to observed conditions-- allowing deep investigation into changes in the Arctic. In addition, opportunities exist to adapt the Zoo School experience (affecting several Central Ohio school districts) and/or to enable regular participation through social media such as Facebook, Twitter, and other forms of digital communication. BPRC's sustained engagement with the CZA is an example of a trusted and meaningful partnership where open dialogue exists about providing the best learning experience for visitors. This presentation will share some of the lessons learned from this unique partnership, and strategies that are adopted to move it forward.

Landis, C. E.; Cervenec, J.

2012-12-01

134

Different temperature adaptation in Arctic and Atlantic heterotrophic bacteria in the Barents Sea Polar Front region  

NASA Astrophysics Data System (ADS)

In the northern Barents Sea, at and around the Polar Front, carbon cycle variables were investigated during 2 weeks in late summer of 2007. Arctic Water primary production in the experimental period averaged 50 mmol C m- 2 day- 1, as estimated from satellite sensed chlorophyll. In Atlantic waters, which appeared to just have passed the culmination of a late summer bloom, primary production was 125 mmol C m- 2 day- 1. Total organic carbon (TOC) averaged 82.4 ?M C in the mixed layer, and the values showed a gradient with highest values to the southeast and lowest to the northwest. The distribution of TOC was not related to the distribution of Atlantic and Arctic waters, although the highest values were found in Atlantic Water. Integrated bacterial production in the mixed layer, as estimated from thymidine incorporation rates, averaged 6.3% of primary production. In Atlantic Water, over the depth of the mixed layer, bacterial production rate averaged 0.40 mmol C m- 3 day- 1, which was 6.6 times the average in Arctic Water and 2.3 times the average in the front regions. Below 30 m depth, bacterial production rates were generally higher in the Arctic Water than in the Atlantic Water. Moreover, when production rates of bacteria were compared according to temperature, the rates in Arctic Water were systematically higher than the rates in Atlantic Water. This difference implies that the heterotrophic bacteria from the Arctic have adapted towards higher growth efficiency than the bacteria in Atlantic Water.

Børsheim, Knut Yngve; Drinkwater, Kenneth F.

2014-02-01

135

The Arctic Human Health Initiative: a legacy of the International Polar Year 2007-2009  

PubMed Central

Background The International Polar Year (IPY) 2007–2008 represented a unique opportunity to further stimulate cooperation and coordination on Arctic health research and increase the awareness and visibility of Arctic regions. The Arctic Human Health Initiative (AHHI) was a US-led Arctic Council IPY coordinating project that aimed to build and expand on existing International Union for Circumpolar Health (IUCH) and Arctic Council human health interests. The project aimed to link researchers with potential international collaborators and to serve as a focal point for human health research, education, outreach and communication activities during the IPY. The progress of projects conducted as part of this initiative up until the end of the Arctic Council Swedish chairmanship in May 2013 is summarized in this report. Design The overall goals of the AHHI was to increase awareness and visibility of human health concerns of Arctic peoples, foster human health research, and promote health strategies that will improve health and well-being of all Arctic residents. Proposed activities to be recognized through the initiative included: expanding research networks that will enhance surveillance and monitoring of health issues of concern to Arctic peoples, and increase collaboration and coordination of human health research; fostering research that will examine the health impact of anthropogenic pollution, rapid modernization and economic development, climate variability, infectious and chronic diseases, intentional and unintentional injuries, promoting education, outreach and communication that will focus public and political attention on Arctic health issues, using a variety of publications, printed and electronic reports from scientific conferences, symposia and workshops targeting researchers, students, communities and policy makers; promoting the translation of research into health policy and community action including implementation of prevention strategies and health promotion; and promoting synergy and strategic direction of Arctic human health research and health promotion. Results As of 31 March, 2009, the official end of the IPY, AHHI represented a total of 38 proposals, including 21 individual Expressions of Intent (EoI), and 9 full proposals (FP), submitted to the IPY Joint Committee for review and approval from lead investigators from the US, Canada, Greenland, Norway, Finland, Sweden and the Russian Federation. In addition, there were 10 National Initiatives (NI-projects undertaken during IPY beyond the IPY Joint Committee review process). Individual project details can be viewed at www.arctichealth.org. The AHHI currently monitors the progress of 28 individual active human health projects in the following thematic areas: health network expansion (5 projects), infectious disease research (7 projects), environmental health research (7 projects), behavioral and mental health research (4 projects), and outreach education and communication (5 projects). Conclusions While some projects have been completed, others will continue well beyond the IPY. The IPY 2007–2008 represented a unique opportunity to further stimulate cooperation and coordination on Arctic health research and increase the awareness and visibility of Arctic regions. PMID:23971017

Parkinson, Alan J.

2013-01-01

136

Imaging polarimetry of the fogbow: polarization characteristics of white rainbows measured in the high Arctic.  

PubMed

The knowledge on the optics of fogbows is scarce, and their polarization characteristics have never been measured to our knowledge. To fill this gap we measured the polarization features of 16 fogbows during the Beringia 2005 Arctic polar research expedition by imaging polarimetry in the red, green and blue spectral ranges. We present here the first polarization patterns of the fogbow. In the patterns of the degree of linear polarization p, fogbows and their supernumerary bows are best visible in the red spectral range due to the least dilution of fogbow light by light scattered in air. In the patterns of the angle of polarization ? fogbows are practically not discernible because their ?-pattern is the same as that of the sky: the direction of polarization is perpendicular to the plane of scattering and is parallel to the arc of the bow, independently of the wavelength. Fogbows and their supernumeraries were best seen in the patterns of the polarized radiance. In these patterns the angular distance ? between the peaks of the primary and the first supernumerary and the angular width ? of the primary bow were determined along different radii from the center of the bow. ? ranged between 6.08° and 13.41°, while ? changed from 5.25° to 19.47°. Certain fogbows were relatively homogeneous, meaning small variations of ? and ? along their bows. Other fogbows were heterogeneous, possessing quite variable ?- and ?-values along their bows. This variability could be a consequence of the characteristics of the high Arctic with open waters within the ice shield resulting in the spatiotemporal change of the droplet size within the fog. PMID:22016248

Horváth, Gábor; Hegedüs, Ramón; Barta, András; Farkas, Alexandra; Åkesson, Susanne

2011-10-01

137

Introduction to the Arctic Climatology and Meterology Primer  

NSDL National Science Digital Library

This publication gives students and teachers valuable information on the Arctic. Topics like Synoptic meteorology, Arctic Climate, and the difference between weather and climate is discussed in the introductory part section of the page. The next section focuses on the factors that affect weather and climate, like latitude, sea level, air pressure, air temperature, and wind. The following section discusses weather patterns such as cyclones, feedback loops, and the polar vortex. A very useful tool on this website is the glossary, which has definitions for all the terms related to climate and weather. There is a gallery on the arctic and life there, as well as a detailed map of the arctic.

2000-01-01

138

Vulnerability of polar oceans to anthropogenic acidification: comparison of arctic and antarctic seasonal cycles.  

PubMed

Polar oceans are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique CO2 system observations covering complete annual cycles at an Arctic (Amundsen Gulf) and Antarctic site (Prydz Bay). The Arctic site experiences greater seasonal warming (10 vs 3°C), and freshening (3 vs 2), has lower alkalinity (2220 vs 2320 ?mol/kg), and lower summer pH (8.15 vs 8.5), than the Antarctic site. Despite a larger uptake of inorganic carbon by summer photosynthesis, the Arctic carbon system exhibits smaller seasonal changes than the more alkaline Antarctic system. In addition, the excess surface nutrients in the Antarctic may allow mitigation of acidification, via CO2 removal by enhanced summer production driven by iron inputs from glacial and sea-ice melting. These differences suggest that the Arctic system is more vulnerable to anthropogenic change due to lower alkalinity, enhanced warming, and nutrient limitation. PMID:23903871

Shadwick, E H; Trull, T W; Thomas, H; Gibson, J A E

2013-01-01

139

Analysis of UARS data in the Southern Polar Vortex n September, 1992 Using a Chemical Transport Model  

NASA Technical Reports Server (NTRS)

We have used a new, isentropic-coordinate three-dimensional chemical transport model to investigate the decay of C1O and evolution of other species in the Antarctic polar vortex during September, 1992. The model simulations cover the same southern hemisphere period studied in a companion data paper by Santee et al.

Chipperfield, M. P.; Santee, M. L.; Froidevaux, L.; Manney, G. L.; Read, W. G.; Waters, J. W.; Roche, A. E.; Russel, J. M.

1996-01-01

140

Polar Vortex Conditions during the 1995-96 Artic Winter: Meteorology and MLS Ozone  

NASA Technical Reports Server (NTRS)

The 1995-96 northern hemisphere (NH) 205 winter stratosphere was colder than in any of the previous 17 winters, with lower stratospheric temperatures continuously below the type 1 (primarily HN03) polar stratospheric cloud (PSC) threshold for over 2 1/2 months. Upper tropospheric ridges in late Feb and early Mar 1996 led to the lowest observed NH lower stratospheric temperatures, and the latest observed NH temperatures below the type 2 (water ice) PSC threshold. Consistent with the unusual cold and chemical processing on PSCS, Upper Atmosphere Research Satellite (UARS) MLS observed a greater decrease in lower stratospheric ozone (03) in 1995-96 than in any of the previous 4 NH winters. 03 decreased throughout the vortex over an altitude range nearly as large as that typical of the southern hemisphere (SH). The decrease between late Dec 1995 and early Mar 1996 was about 2/3 of that over the equivalent SH period. As in other NH winters, temperatures in 1996 rose above the PSC threshold before the spring equinox, ending chemical processing in the NH vortex much earlier than is usual in the SH. A downward trend in column 03 above 100 hPa during Jan and Feb 1996 appears to be related to the lower stratospheric 03 depletion.

Manney, G. L.; Santee, M. L.; Froidevaux, L.; Waters, J. W.; Zurek, R. W.

1996-01-01

141

Atmospheric chemistry of formaldehyde in the Arctic troposphere at Polar Sunrise, and the influence of the snowpack  

Microsoft Academic Search

The role of formaldehyde in the atmospheric chemistry of the Arctic marine boundary layer has been studied during both polar day and night at Alert, Nunavut, Canada. Formaldehyde concentrations were determined during two separate field campaigns (PSE 1998 and ALERT2000) from polar night to the light period. The large differences in the predominant chemistry and transport issues in the dark

A. l. Sumner; P. b. Shepson; A. m. Grannas; J. w. Bottenheim; K. g. Anlauf; D. Worthy; W. h. Schroeder; A. Steffen; F. Domine; S. Perrier; S. Houdier

2002-01-01

142

Using Polarization Shaped Optical Vortex Traps for Single-Cell Nanosurgery  

PubMed Central

Single-cell nanosurgery and the ability to manipulate nanometer-sized subcellular structures with optical tweezers has widespread applications in biology, but so far has been limited by difficulties in maintaining the functionality of the transported subcellular organelles. This difficulty arises because of the propensity of optical tweezers to photodamage the trapped object. To address this issue, this paper describes the use of a polarization-shaped optical vortex trap, which exerts less photodamage on the trapped particle than conventional optical tweezers, for carrying out single-cell nanosurgical procedures. This method is also anticipated to find broad use in the trapping of any nanoparticles that are adversely affected by high-intensity laser light. PMID:17298009

Jeffries, Gavin D.M.; Edgar, J. Scott; Zhao, Yiqiong; Shelby, J. Patrick; Fong, Christine; Chiu, Daniel T.

2008-01-01

143

Quaternary Science Reviews 25 (2006) 13831400 Last Interglacial Arctic warmth confirms polar amplification  

E-print Network

Atlantic Drift, combined to reduce Arctic Ocean sea ice, allow expansion of boreal forest to the Arctic). In addition, the margins of permanent Arctic Ocean sea ice retracted well into the Arctic Ocean basin and boreal forests advanced to the Arctic Ocean coast across vast regions of the Arctic currently occupied

Ingólfsson, �lafur

144

Chinese Journal of Polar Science, Vol. 19,No. 2,159 -167, December 2008 Modeling Arctic Ocean heat transport and warming episodes in  

E-print Network

Chinese Journal of Polar Science, Vol. 19,No. 2,159 -167, December 2008 Modeling Arctic Ocean heat and Hydrological Institute, Sweden Received September 20, 2008 Abstract This study investigates the Arctic Ocean temperature (AWCT) in the Arctic Ocean and shows that four largest decadal- scale warming episodes occurred

145

Section Head, Arctic Sciences Section, ES-1301, OD/OPP (Closes: 09/21/2005)  

NSF Publications Database

... marine polar biology, polar oceanography, sea ice, Arctic Social Science, and Arctic System Science ... marine polar biology, polar oceanography, sea ice, social sciences, and Arctic System Science.) 2 ...

146

Section Head, Arctic Sciences Section, ES-1301, OD/OPP (Closes: 10/21/2005)  

NSF Publications Database

... marine polar biology, polar oceanography, sea ice, Arctic Social Science, and Arctic System Science ... marine polar biology, polar oceanography, sea ice, social sciences, and Arctic System Science.) 2 ...

147

Section Head, Arctic Sciences Section, ES-1301, OD/OPP (Closes: 09/21/2005)  

NSF Publications Database

... marine polar biology, polar oceanography, sea ice, Arctic Social Sciences, and Arctic System Science ... marine polar biology, polar oceanography, sea ice, social sciences, and Arctic System Science.) 2 ...

148

Section Head, Arctic Sciences Section, ES-1301, OD/OPP (Closes: 10/21/2005)  

NSF Publications Database

... marine polar biology, polar oceanography, sea ice, Arctic Social Sciences, and Arctic System Science ... marine polar biology, polar oceanography, sea ice, social sciences, and Arctic System Science.) 2 ...

149

On the Stability of the Southern Hemisphere Stratospheric Polar Vortex and Influence of Topographically-Forced Inertia-Gravity Waves  

NASA Astrophysics Data System (ADS)

While it is well known that topographically forced Rossby waves may propagate into the stratosphere under certain conditions and strongly affect the polar vortex, the stability of the polar vortex under the influence of topographically-forced inertia gravity waves is less well understood. In particular, in the Southern Andes, there is a strong gravity wave source region, and AIRS satellite measurements have indicated that these waves propagate into the stratosphere with large amplitudes. A remaining question is whether or not theses waves can significantly perturb the Southern Hemisphere stratospheric polar vortex, leading to distortion and mixing. This question is examined in the following manner. First, using the ERA-Interim reanalysis data from 1999-2009, the observed evolution of the winter vortex is characterized, with particular focus on the evolution during periods of strong mesoscale wave activity in the Southern Andes region. Next, idealized modeling experiments are conducted with a shallow water model using unbalanced perturbations based upon the observed characteristics of the inertia-gravity waves. Finally, full-physics numerical simulations are conducted using a regional model with and without topography.

Hendricks, E. A.; Doyle, J.; Jiang, Q.; Reinecke, A.

2012-12-01

150

Observations of the Martian atmosphere: THEMIS-VIS calibration, mesospheric clouds, and the polar vortex  

NASA Astrophysics Data System (ADS)

We present observations of the Martian atmosphere derived from two instruments: the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor spacecraft, and the visible light subsystem of the Thermal Emission Imaging System (THEMIS- VIS) on the Mars Odyssey spacecraft. For TES, we start with vertically resolved temperatures derived as described by Conrath et al. (2000, JGR, 105), and from them we derive horizontal winds and Ertel potential vorticity on a time series of regular three-dimensional grids. The Ertel potential vorticity is used as a dynamical tracer and diagnostic tool to study the behavior of the martian polar vortices. We find that, in contrast to the terrestrial polar vortices, the martian polar vortices' Ertel potential vorticity typically has an annular maximum well away from the pole. We also find that the martian northern winter vortex is better organized than the southern winter vortex, and thus is likely to be a more effective barrier to mixing. For THEMIS-VIS we develop a complete radiometric calibration pipeline. This pipeline is used for standard data processing to convert Engineering Data Records (EDRs) to the Reduced Data Records (RDRs) released by NASAs Planetary Data System. We use THEMIS-VIS nadir-pointed images to detect clouds in the 40 km to 80 km altitude range, measuring altitude from parallax and velocity from cross-track motion during the imaging sequence. We have observed 5 cases of aphelion season equatorial high-altitude clouds during late afternoon, all located in the eastern Tharsis/Valles Marineris region, and 30 cases of high- altitude cloud features in the northern winter (perihelion season) mid- latitudes, all but one in the Acidalia region. A simple radiative transfer model yields optical depths greater than 0.2 for the equatorial clouds, as well as constraints on their composition. The mid-latitude high-altitude features are visible only in twilight, a geometry for which our simple plane parallel radiative transfer model is not valid. Comparing the zonal velocity of the clouds with a radiative transfer model, we find good agreement in the northern winter mid-latitudes, but poorer agreement for equatorial clouds.

McConnochie, Timothy Hubbard

151

Arctic and Antarctic exploration including the contributions of physicians and effects of disease in the polar regions.  

PubMed

A history of Arctic and Antarctic exploration, whether to find a Northwest Passage, North Pole, or South Pole, is a story of triumph and tribulation. The hardship experienced by polar explorers in the last 1000 years permeates the tales of achievement. Physicians and surgeons have played prominent roles in all major polar explorations. No significant Arctic voyage, particularly in the last 300 years, was made without a member of the party trained in the management of medical emergencies and in basic surgery. During times of health, surgeons functioned as the voyage naturalists with expertise in biology, botany, zoology, and the writing of scientific catalogs. Spurred by our interest and fascination with the history of polar exploration, we reviewed the roles of physicians and natural scientists in Arctic and Antarctic adventures. PMID:10232525

Fodstad, H; Kondziolka, D; Brophy, B P; Roberts, D W; Girvin, J P

1999-05-01

152

Geographical distribution of organochlorine pesticides (OCPs) in polar bears (Ursus maritimus) in the Norwegian and Russian Arctic  

USGS Publications Warehouse

Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, ??-HCH, ??-HCH and p,p???-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of ??- and ??-HCH. The lowest ??-HCH concentration was found in bears from Kara Sea. In all the bears, ???HCHs was dominated by ??-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p???-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research. ?? 2002 Elsevier Science B.V. All rights reserved.

Lie, E.; Bernhoft, A.; Riget, F.; Belikov, S. E.; Boltunov, A. N.; Derocher, A. E.; Garner, G. W.; Wiig, O.; Skaare, J. U.

2003-01-01

153

El Chichon volcanic debris in an Arctic tropopause fold  

Microsoft Academic Search

A research flight with the NOAA WP-3D aircraft revealed evidence for stratospheric-tropospheric exchange within the Arctic through tropopause folding on the flank of the polar vortex. Observations showed descent of the tropopause and of stratospheric ozone to 700 mb along the west coast of Greenland. Measurements of condensation nuclei and analysis of high volume impactor samples documented the presence of

M. A. Shapiro; R. C. Schnell; F. P. Parungo; S. J. Oltmans; B. A. Bodhaine

1984-01-01

154

The impact of volcanic aerosol on the Northern Hemisphere stratospheric polar vortex: mechanisms and sensitivity to forcing structure  

NASA Astrophysics Data System (ADS)

Observations and simple theoretical arguments suggest that the Northern Hemisphere (NH) stratospheric polar vortex is stronger in winters following major volcanic eruptions. However, recent studies show that climate models forced by prescribed volcanic aerosol fields fail to reproduce this effect. We investigate the impact of volcanic aerosol forcing on stratospheric dynamics, including the strength of the NH polar vortex, in ensemble simulations with the Max Planck Institute Earth System Model. The model is forced by four different prescribed forcing sets representing the radiative properties of stratospheric aerosol following the 1991 eruption of Mt. Pinatubo: two forcing sets are based on observations, and are commonly used in climate model simulations, and two forcing sets are constructed based on coupled aerosol-climate model simulations. For all forcings, we find that temperature and zonal wind anomalies in the NH high latitudes are not directly impacted by anomalous volcanic aerosol heating. Instead, high latitude effects result from robust enhancements in stratospheric residual circulation, which in turn result, at least in part, from enhanced stratospheric wave activity. High latitude effects are therefore much less robust than would be expected if they were the direct result of aerosol heating. While there is significant ensemble variability in the high latitude response to each aerosol forcing set, the mean response is sensitive to the forcing set used. Significant differences, for example, are found in the NH polar stratosphere temperature and zonal wind response to two different forcing data sets constructed from different versions of SAGE II aerosol observations. Significant strengthening of the polar vortex, in rough agreement with the expected response, is achieved only using aerosol forcing extracted from prior coupled aerosol-climate model simulations. Differences in the dynamical response to the different forcing sets used imply that reproducing the polar vortex responses to past eruptions, or predicting the response to future eruptions, depends on accurate representation of the space-time structure of the volcanic aerosol forcing.

Toohey, M.; Krüger, K.; Bittner, M.; Timmreck, C.; Schmidt, H.

2014-06-01

155

Mercury speciation in brain tissue of polar bears (Ursus maritimus) from the Canadian Arctic.  

PubMed

Methylmercury (MeHg) is a neurotoxicant that has been found at elevated concentrations in the Arctic ecosystem. Little is known about its internal dose in wildlife such as polar bears. We measured concentrations of mercury (Hg) in three different brain regions (cerebellum, frontal lobe and brain stem) of 24 polar bears collected from the Nunavik, Canada between 2000 and 2003. Speciation of Hg was measured by High Performance Liquid Chromatography coupled to Inductively Coupled Plasma Mass Spectroscopy (HPLC-ICP-MS). Concentrations of mean total Hg in brain tissue were up to 625 times lower (0.28 ± 0.07 mg kg(-1) dry weight (dw) in frontal lobe, 0.23 ± 0.07 mg kg(-1) dw in cerebellum and 0.12 ± 0.0 3mg kg(-1) dw in brain stem) than the mean total Hg concentration previously reported in polar bear liver collected from Eastern Baffin Island. Methylmercury (MeHg) accounted for 100% of the Hg found in all three brain regions analyzed. These results suggest that polar bear might reduce the toxic effects of Hg by limiting the uptake into the brain and/or decrease the rate of demethylation so that Hg can be excreted from the brain more easily. The toxicokinetics and the blood-brain-barrier mechanisms of polar bears are still unknown and further research is required. PMID:22406289

Krey, Anke; Kwan, Michael; Chan, Hing Man

2012-04-01

156

The last polar dinosaurs: high diversity of latest Cretaceous arctic dinosaurs in Russia  

NASA Astrophysics Data System (ADS)

A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous-Tertiary mass extinction event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest Cretaceous dinosaur taxa could reproduce in polar region and were probably year-round residents of high latitudes. Palaeobotanical data suggest that these polar dinosaurs lived in a temperate climate (mean annual temperature about 10°C), but the climate was apparently too cold for amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian dinosaurs in high latitudes, where ectotherms are absent, strongly questions hypotheses according to which dinosaur extinction was a result of temperature decline, caused or not by the Chicxulub impact.

Godefroit, Pascal; Golovneva, Lina; Shchepetov, Sergei; Garcia, Géraldine; Alekseev, Pavel

2009-04-01

157

The Interaction Between Dynamics and Chemistry of Ozone in the Set-Up Phase of the Northern Hemisphere Polar Vortex  

NASA Technical Reports Server (NTRS)

Understanding stratospheric ozone loss to the point of accurately predicting ozone in the future requires correctly distinguishing chemical from transport-induced changes in ozone. For example, evaluating the impact of chlorine reduction in controlling stratospheric ozone loss requires estimating the amount of ozone lost in chemical reactions in the polar winter and spring. The Northern Hemisphere winter polar region is a particularly crucial and interesting area because it appears that the Northern vortex may currently be poised near the threshold of extreme ozone destruction such as that which now occurs annually in the Antarctic ozone "hole." In this presentation we explore the interaction of ozone transport and chemistry through the Northern late summer and fall seasons as the vortex circulation becomes established. This phase of the seasonal cycle determines the starting point for heterogeneous processes and chlorine-driven loss that take control in the winter vortex. Using a combination of profile data from POAM, HALOE, and in situ measurements, we show that relatively low ozone at high latitudes in the middle stratosphere is associated with vortex airmasses and that these ozone abundances evolve photochemically from characteristically higher values at the end of the summer. The zonal variance of ozone mixing ratio also increases greatly at this time consistent with increasing wave-driven transport. Comparison with a three-dimensional chemistry-transport model is used to generalize the findings from the limited set of observations and quantify the relative roles of transport and chemistry in determining the ozone mixing ratio distributions.

Kawa, S.R.; Douglass, A. R.; Bevilacqua, R.; Margitan, J. J.; Sen, B.; Einaudi, Franco (Technical Monitor)

2000-01-01

158

Hematology of southern Beaufort Sea polar bears (2005-2007): Biomarker for an arctic ecosystem health sentinel  

USGS Publications Warehouse

Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ???5, than lactating adult females ages ???5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel. ?? 2010 International Association for Ecology and Health.

Kirk, C. M.; Amstrup, S.; Swor, R.; Holcomb, D.; O'Hara, T. M.

2010-01-01

159

Polar vision or tunnel vision the making of Canadian Arctic waters policy : The making of Canadian Arctic waters policy  

Microsoft Academic Search

This article examined the manner by which Canadian maritime Arctic policy is formulated. It suggests that this policy is largely the result of an ad hoc and reactive process. In general, the policy tends to be the product of a specific event initiated by a non-Canadian actor in the Canadian Arctic. In the early 1970s, this event was the voyages

Rob Huebert

1995-01-01

160

Simultaneous control of vortex polarity and chirality in thickness-modulated [Co/Pd]n/Ti/Ni80Fe20 disks  

NASA Astrophysics Data System (ADS)

Simultaneous vortex chirality and polarity control are observed in thickness-modulated [Co/Pd]n/Ti/Ni80Fe20 disks using magnetic force microscopy by applying a proper sequence of in-plane and out-of-plane reset fields. The thickness modulation in the NiFe layer introduces an additional shape anisotropy, which defines the vortex chirality during the in-plane reset field, while the [Co/Pd]n underlayer produces a large out-of-plane stray field, which stabilizes the vortex polarity in the NiFe layer. Micromagnetic simulations are compared with experiment results.

Shimon, G.; Ravichandar, V.; Adeyeye, A. O.; Ross, C. A.

2014-10-01

161

Sailing the Open Polar Sea...Again: What Are You Teaching Your Children about the Arctic Ocean?  

ERIC Educational Resources Information Center

Relates how a blunder about the Arctic Ocean and the polar ice cap made by the author in his first year of teaching led to a successful learning experience. Lists five important discussion topics that social studies teachers should use to teach about this remote, but strategic, part of the world. (LS)

Stockard, James W. Jr.

1989-01-01

162

SYNTHESIS The future of soil invertebrate communities in polar regions: different climate change responses in the Arctic and Antarctic?  

E-print Network

climate change responses in the Arctic and Antarctic? Uffe N. Nielsen1,2 and Diana H. Wall1 1 Natural The polar regions are experiencing rapid climate change with implications for terrestrial ecosystems. Here to predicted twenty-first century climate change. Geographic and environmental differences suggest that climate

Wall, Diana

163

Influence of Arctic sea ice extent on polar cloud fraction and vertical structure and implications for regional climate  

Microsoft Academic Search

Recent satellite lidar measurements of cloud properties spanning a period of 5 years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anticorrelation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over

Stephen P. Palm; Sara T. Strey; James Spinhirne; Thorsten Markus

2010-01-01

164

Molecular halogens before and during ozone depletion events in the Arctic at polar sunrise: concentrations and sources  

Microsoft Academic Search

The molecular halogens Br2, BrCl and Cl2 were monitored from 9 February to 13 March 2000 as part of the ALERT 2000 campaign to investigate the causes of ozone depletion at polar sunrise. The measurements were performed over the transition period from winter to spring in the high Arctic, at Alert, on northern Ellesmere Island in Nunavut, Canada. The measurement

Chester W. Spicer; Robert A. Plastridge; Krishna L. Foster; Barbara J Finlayson-Pitts; Jan W. Bottenheim; Amanda M. Grannas; Paul B Shepson

2002-01-01

165

Effect of polar day on plasma profiles of melatonin, testosterone, and estradiol in high-Arctic Lapland Longspurs.  

PubMed

In polar habitats, continuous daylight (polar day) can prevail for many weeks or months around the summer solstice. In the laboratory, continuous light conditions impair or disrupt circadian rhythms in many animals. To determine whether circadian rhythms are disrupted under natural polar day conditions in a species that is only a summer resident in polar regions we analyzed diel rhythms in plasma concentrations of melatonin, testosterone (T), and 17-beta estradiol (E(2)) during the summer solstice in Arctic-breeding Lapland Longspurs (Calcarius lapponicus). We compared these profiles to those of conspecifics housed in outdoor aviaries at a mid-latitude site in Seattle, Washington, during spring, summer, fall, and winter. Under polar day conditions plasma melatonin concentrations of Lapland Longspurs were strongly suppressed, but still showed a significant diel rhythm. Likewise, plasma T in males, and E(2) in females, showed significant diel changes in Arctic birds. Lapland Longspurs housed at mid-latitude in Seattle showed high-amplitude melatonin cycles at all times of the year, and the duration of the nightly melatonin secretion was positively correlated with the duration of the dark phase. We found no diel changes in plasma T in Seattle males in May, but Seattle females showed significant day/night differences in plasma E(2) in May. The data suggest that even under polar day conditions diel rhythms can persist. The maintenance of hormone rhythms could provide a physiological basis to reports of rhythmic behavior in many birds during the Arctic summer. PMID:11944971

Hau, Michaela; Romero, L Michael; Brawn, Jeff D; Van't Hof, Thomas J

2002-03-01

166

A Proposed Arctic Ocean Field Program During the International Polar Year 2007-2008  

Microsoft Academic Search

The Arctic Ocean represents a glaring void of measurements appropriate for monitoring and understanding the climate changes currently occurring in the Arctic region. We propose a field program in the central Arctic Ocean to develop and improve methods for the long-term monitoring of the Arctic atmosphere, ice, and ocean and the interactions among them, and to study physical processes crucial

O. P. Persson

2004-01-01

167

Late Cretaceous Extreme Polar Warmth recorded by Vertebrate Fossils from the High Canadian Arctic  

NASA Astrophysics Data System (ADS)

A vertebrate fossil assemblage from Late Cretaceous (Coniacian-Turonian, ~92 to 86 Ma) rocks on Axel Heiberg Island in the High Canadian Arctic reflects what was once a diverse community of freshwater fishes and reptiles. Paleomagnetic data indicate a paleolatitude of ~71° N for the site; the fossils are from non-migratory fauna, so they can provide insight into Late Cretaceous polar climate. The fossil assemblage includes large (> 2.4 m long) champsosaurs (extinct crocodilelike reptiles). The presence of large champsosaurs suggests a mean annual temperature > 14 °C (and perhaps as great as 25 °C). Here we summarize findings and analyses following the discovery of the fossil-bearing strata in 1996. Examination of larger fish elements, isolated teeth and SEM studies of microstructures indicates the presence of lepisosteids, amiids and teleosts (Friedman et al., 2003) Interestingly, the only other known occurrence of amiids and lepisosteids, fossil or recent, are from intervals of extreme warmth during the Tertiary. Turtles present in the assemblage include Boreralochelys axelheibergensis, a generically indeterminate eucryptodire and a trioychid (Brinkman and Tarduno, 2005). The level of turtle diversity is also comparable to mid-latitude assemblages with a mean annual paleotemperature of at least 14 °C. A large portion of the champsosaur fossil assemblage is comprised of elements from subadults. This dominance of subadults is similar to that seen from low latitude sites. Because of the sensitivity of juveniles to ice formation, the make-up of the Arctic champsosaur population further indicates that the Late Cretaceous saw an interval of extreme warmth and low seasonality. We note the temporal coincidence of these fossils with volcanism at large igneous provinces (including high Arctic volcanism) and suggest that a pulse in volcanic carbon dioxide emissions helped cause the global warmth.

Vandermark, D.; Tarduno, J. A.; Brinkman, D.

2006-12-01

168

Autocatalytic release of bromine from Arctic snow pack during polar sunrise  

SciTech Connect

Measurements and modeling studies strongly suggest that spring time depletion of ozone in the Arctic planetary boundary layer (PBL) is due to catalytic destruction by bromine atoms. However, the source of the bromine is uncertain. In this note, we propose that the source of the bromine at polar sunrise is the snow pack on the ice covering Arctic ocean and that it is released auto-catalytically, stimulated by a bromine seed from one of the brominated organic compounds, such as CHBr{sub 3}, by photolysis. In this manner {approximately}100 pptv of bromine can be transferred to the atmosphere where it can reside in the gas phase or, by scavenging, be partitioned in the aerosol or ice crystal phase. Moreover, it appears that heterogeneous recycling of bromine may be a process that self-terminates as ozone depletes to low levels. We also have included chlorine chemistry in the model in order to simulate inferred levels of chlorine atoms. This is important as it results in the production of HCHO which acts to convert post ozone depletion active bromine into HBr which is then returned to the snow pack or scavenged by aerosols or ice crystals. {copyright} American Geophysical Union 1996

Tang, T. [Dept. of Phys. & Astron., York Univ., Ont. (Canada)] [Dept. of Phys. & Astron., York Univ., Ont. (Canada); McConnell, J.C. [Dept. of Earth & Atmos. Sci., York Univ., Ont. (Canada)] [Dept. of Earth & Atmos. Sci., York Univ., Ont. (Canada)

1996-09-01

169

Accuracy of Modelled Stratospheric Temperatures in the Winter Arctic Vortex from Infra Red Montgolfier Long Duration Balloon Measurements  

NASA Technical Reports Server (NTRS)

The temperature of the stratosphere has been measured in the Arctic vortex every 9-10 minutes along the trajectory of four Infra Red Montgolfier long duration balloons flown for 7 to 22 days during the winters of 1997 and 1999. From a number of comparisons to independent sensors, the accuracy of the measurements is demonstrated to be plus or minus 0.5 K during nighttime and at altitude below 28 km (10 hPa). The performances of the analyses of global meteorological models, European Center for Medium Range Weather Forecasts (ECMWF) 31 and 50 levels, United Kingdom Meteorological Office (UKMO), Data Assimilation Office (DAO), National Climatic Prediction Center (NCEP) and NCEP/NCAR reanalysis, used in photochemical simulations of ozone destruction and interpretation of satellite data, are evaluated by comparison to this large (3500 data points) and homogeneous experimental data set. Most of models, except ECMWF31 in 1999, do show a smal1 average warm bias of between 0 and 1.6 K, with deviations particularly large, up to 20 K at high altitude (5hPa) in stratospheric warming conditions in 1999. Particularly wrong was ECMWF 31 levels near its top level at 10 hPa in 1999 where temperature 25 K colder than the real atmosphere were reported. The average dispersion between models and measurements varies from plus or minus 1.0 to plus or minus 3.0 K depending on the model and the year. It is shown to be the result of three contributions. The largest is a long wave modulation likely caused by the displacement of the temperature field in the analyses compared to real atmosphere. The second is the overestimation of the vertical gradient of temperature particularly in warming conditions, which explains the increase of dispersion from 1997 to 1999. Unexpectedly, the third and smallest (plus or minus 0.6-0.7 K) is the contribution of meso and subgrid scale vertical and horizontal features associated to the vertical propagation of orographic or gravity waves. Compared to other models, the newly available ECMWF 50 levels version assimilating the high vertical resolution radiances of the space borne Advanced Microwave Sounding Unit, performs significantly better (0.03 plus or minus 1.12 K on average between 10 and 140 hPa in 1999) than other models.

Pommereau, J.-P.; Garnier, A.; Knudson, B. M.; Letrenne, G.; Durand, M.; Cseresnjes, M.; Nunes-Pinharanda, M.; Denis, L.; Newman, P. A.; Einaudi, Franco (Technical Monitor)

2000-01-01

170

Cooling of the Arctic and Antarctic polar stratospheres due to ozone depletion  

SciTech Connect

Long time records of stratospheric temperatures indicate that substantial cooling has occurred during spring over polar regions of both hemispheres. These cooling patterns are coincident with observed recent ozone depletions. Time series of temperature from radiosonde, satellite, and National Centers for Environmental Prediction reanalysis data are analyzed in order to isolate the space-time structure of the observed temperature changes. The Antarctic data show strong cooling (of order 6--10 K) in the lower stratosphere ({approximately} 12--21 km) since approximately 1985. The cooling maximizes in spring (October--December), with small but significant changes extending throughout Southern Hemisphere summer. No Antarctic temperature changes are observed during midwinter. Significant warming is found during spring at the uppermost radiosonde data level (30 mb, {approximately} 24 km). These observed temperature changes are all consistent with model predictions of the radiative response to Antarctic polar ozone depletion. Winter and spring temperatures in Northern Hemisphere polar regions also indicate a strong cooling in the 1990s, and the temperature changes are coherent with observed ozone losses. The overall space-time patterns are similar between both hemispheres, suggesting that the radiative response to ozone depletion is an important component of the Arctic cooling as well.

Randel, W.J.; Wu, F. [National Center for Atmospheric Research, Boulder, CO (United States)] [National Center for Atmospheric Research, Boulder, CO (United States)

1999-05-01

171

The future of soil invertebrate communities in polar regions: different climate change responses in the Arctic and Antarctic?  

PubMed

The polar regions are experiencing rapid climate change with implications for terrestrial ecosystems. Here, despite limited knowledge, we make some early predictions on soil invertebrate community responses to predicted twenty-first century climate change. Geographic and environmental differences suggest that climate change responses will differ between the Arctic and Antarctic. We predict significant, but different, belowground community changes in both regions. This change will be driven mainly by vegetation type changes in the Arctic, while communities in Antarctica will respond to climate amelioration directly and indirectly through changes in microbial community composition and activity, and the development of, and/or changes in, plant communities. Climate amelioration is likely to allow a greater influx of non-native species into both the Arctic and Antarctic promoting landscape scale biodiversity change. Non-native competitive species could, however, have negative effects on local biodiversity particularly in the Arctic where the communities are already species rich. Species ranges will shift in both areas as the climate changes potentially posing a problem for endemic species in the Arctic where options for northward migration are limited. Greater soil biotic activity may move the Arctic towards a trajectory of being a substantial carbon source, while Antarctica could become a carbon sink. PMID:23278945

Nielsen, Uffe N; Wall, Diana H

2013-03-01

172

Aura-OMI Ozone Hole from September 12, 2004 to November 15,2004 with Polar Vortex Demarced  

NSDL National Science Digital Library

Data from NASA satellites establishes a 40 year record of stratospheric ozone measurements. The stratospheric ozone layer shields life on Earth from harmful solar ultraviolet (UV) radiation. Research shows that excess exposure to UV radiation causes skin cancer and eye problems and impacts plant growth. Global stratospheric ozone has decreased by 3 percent globally between 1980 and 2000 and has thinned by 50 percent over Antarctica in winter and spring. Depletion of the ozone layer allows more UV radiation to reach the Earths surface. This animation shows the ozone layer blocking harmful UV radiation from the Earths surface. The hole in the ozone is seen in purple. The location, size, and shape of the polar vortex is derived from potential vorticity data, PV. The pv, shown in white at 550 degrees Kelvin, is an atmospheric regional event that isolates polar air from the air at lower latitudes, producing conditions favorable for wintertime polar ozone depletion. The animation shows that most of the low-temperature and chemically-perturbed region is confined within the polar vortex during the Antarctic winter.

Perkins, Lori; Shirah, Greg; Snodgrass, Stuart; Hilsenrath, Ernest; Schoeberl, Mark; Douglass, Anne

2004-12-13

173

Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard  

PubMed Central

Background Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81°N, 10-33°E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. Results A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 × 104 to 1.6 × 106 colony forming units (cfu)/ml for the rectum swabs and 4.0 × 103 to 1.0 × 105 cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic ?-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. Conclusion The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations. PMID:20074323

2010-01-01

174

The Interaction Between Dynamics and Chemistry of Ozone in the Set-up Phase of the Northern Hemisphere Polar Vortex  

NASA Technical Reports Server (NTRS)

The morphology and evolution of the stratospheric ozone (O3) distribution at high latitudes in the Northern Hemisphere (NH) are examined for the late summer and fall seasons of 1999. This time period sets the O3 initial condition for the SOLVE/THESEO field mission performed during winter 1999-2000. In situ and satellite data are used along with a three-dimensional model of chemistry and transport (CTM) to determine the key processes that control the distribution of O3 in the lower-to-middle stratosphere. O3 in the vortex at the beginning of the winter season is found to be nearly constant from 500 to above 800 K with a value at 3 ppmv +/- approx. 10%. Values outside the vortex are up to a factor of 2 higher and increase significantly with potential temperature. The seasonal time series of data from POAM shows that relatively low O3 mixing ratios, which characterize the vortex in late fall, are already present at high latitudes at the end of summer before the vortex circulation sets up. Analysis of the CTM output shows that the minimum O3 and increase in variance in late summer are the result of: 1) stirring of polar concentric O3 gradients by nascent wave-driven transport, and 2) an acceleration of net photochemical loss with decreasing solar illumination. The segregation of low O3 mixing ratios into the vortex as the circulation strengthens through the fall suggests a possible feedback role between O3 chemistry and the vortex formation dynamics. Trajectory calculations from O3 sample points early in the fall, however, show only a weak correlation between initial O3 mixing ratio and potential vorticity later in the season consistent with order-of-magnitude calculations for the relative importance of O3 in the fall radiative balance at high latitudes. The possible connection between O3 chemistry and the dynamics of vortex formation does suggest that these feedbacks and sensitivities need to be better understood in order to make confident predictions of the recovery of NH O3.

Kawa, S. R.; Bevilacqua, R.; Margitan, J. J.; Douglass, A. R.; Schoeberl, M. R.; Hoppel, K.; Sen, B.; Bhartia, P. K. (Technical Monitor)

2001-01-01

175

Assessment and Consequences of the Delayed Breakup of the Antarctic Polar Vortex in Two Versions of the GEOS Chemistry-Climate Model  

NASA Technical Reports Server (NTRS)

In mid-winter, winds circle the globe at speeds greater than 200 km/hr (approximately 130mph) in the middle atmosphere. This strong jet bounds the region known as the polar vortex. The presence of the Antarctic polar vortex is a key ingredient in the formation of the 'ozone hole', because the air inside the vortex is cold and isolated from lower latitudes, creating ideal conditions for large-scale chemical ozone depletion. Many atmospheric models are not able to reproduce observed winds in the middle atmosphere. Specifically, the polar vortices tend to break down too late and peak wind speeds are higher than observed. Hurwitz et al. find that the delayed break-up of the Antarctic polar vortex is due to weaker-than-observed wave driving from the lower atmosphere during the October-November period. The delayed break-up of the Antarctic polar vortex changes the temperature structure of the middle atmosphere, which biases the amount of chemical ozone depletion that can occur in late winter and spring. Also, the extended lifetime of the polar vortex strengthens the 'overturning' circulation cell in the middle atmosphere, changing the amount of ozone, methane and other chemical species that is transported from low to high latitudes. As greenhouse gas concentrations continue to rise, the atmospheric temperature structure and resulting wind structure are expected to change. Clearly, if models cannot duplicate the observed late 20th century high-latitude winds, their ability to simulate the polar vortices in future must be poor. Understanding model weaknesses and improving the modeled polar vortices will be necessary for accurate predictions of ozone recovery in the coming century.

Hurwitz, M.M.; Newman, P.A.; Li, F.

2008-01-01

176

Denitrification in the Arctic mid-winter 2004/2005 observed by airborne submillimeter radiometry  

NASA Technical Reports Server (NTRS)

We present measurements of unusually low mixing ratios of HNO3 in the exceptionally cold Arctic vortex of late-January and early-February 2005. The measurements were obtained by the airborne submillimeter radiometer ASUR during the polar aura validation experiment (PAVE). The distribution of HNO3 inside the vortex reaches minima below 4 ppbv around 22 km altitude and maxima above 13 ppbv around 16 km altitude, with a considerable spatial variability.

Kleinbohl, Armin; Bremer, Holger; Kullmann, Harry; Kuttippurath, Jayanarayanan; Browell, Edward V.; Canty, Timothy; Salawitch, Ross J.; Toon, Geoffrey C.; Nothol, Justus

2005-01-01

177

Interannual Variability of Ozone in the Polar Vortex during the Fall Season  

NASA Technical Reports Server (NTRS)

Previous analysis has shown that the distribution of O3 at high northern latitudes in the lower-to-middle stratosphere at the beginning of the winter season has a characteristic distribution, which is consistent between in situ and satellite measurements. Initial O3 profiles in the vortex are similar to each other and are quite different from outside the vortex at the same latitude and also from a zonal mean climatology. In the vortex, O3 is nearly constant from 500 to above 800 K with a value near 3 ppmv. Values outside the vortex are up to a factor of 2 higher and increase significantly with potential temperature. Model analysis indicates that the characteristic vortex O3 profiles arise from a combination of seasonally accelerated photochemical loss at high latitudes and minimal transport of air from lower latitudes. Analysis of the relatively high-resolution POAM data shows that these characteristic O3 distributions are consistent from year to year and between the hemispheres. Here we emphasize analysis of the 24-year time series of O3 data from SBUV in the lower-to-middle stratosphere at high latitudes in the fall vortex. We find that the variability of O3 from SBUV is relatively small in this regime and no significant trend is detectable. The implications of the findings for stratospheric O3 chemistry and transport will be explored.

Bhartia, P. K. (Technical Monitor); Kawa, S. R.; Newman, P. A.; Schoeberl, M. R.; Stolarski, R. S.; Bevilacqua, R.

2002-01-01

178

Vortexwide denitrification of the Arctic polar stratosphere in winter 1999/2000 determined by remote observations  

NASA Astrophysics Data System (ADS)

Denitrification has been studied using measurements of stratospheric HNO3 and N2O by the Airborne Submillimeter Radiometer (ASUR), operated on board the NASA DC-8 during SOLVE/THESEO 2000. Lidar measurements taken on board the same aircraft have been used to distinguish between temporary uptake of HNO3 in polar stratospheric clouds (PSCs) and denitrification events. To derive an NOy budget, ClNO3 data by balloonborne and ground-based Fourier transform infrared measurements and a model estimate of NOx + 2N2O5 have been considered. The HNO3 profiles of sporadic ASUR measurements without PSC coverage in January suggest that denitrification had started in the vortex core region by then. Vortexwide denitrification was found in mid-March 2000. Corrected for diabatic descent using the N2O measurements, a vortex-averaged NOy deficit between 1.2 ± 0.9 ppb at about 16 km altitude and 5.3 ± 2.7 ppb at about 20.5 km altitude was derived compared to December 1999, based on an observed decrease in HNO3 between 2.2 and 3.5 ppb during this time period. A shift in the NOy partitioning from HNO3 toward ClNO3 of about 0.4 to 0.7 ppb was observed in mid-March compared to December, indicating that chlorine deactivation was occurring. Comparisons with the SLIMCAT three-dimensional chemical transport model applying denitrification schemes based on ice and nitric acid trihydrate particles in equilibrium, respectively, reveal agreement within the error bars at higher altitudes (˜19 km) but show discrepancies at lower altitudes (˜16 km). It is suggested that more sophisticated denitrification schemes are needed to generally describe denitrification processes.

KleinböHl, Armin; Bremer, Holger; von KöNig, Miriam; Küllmann, Harry; Künzi, Klaus F.; Goede, Albert P. H.; Browell, Edward V.; Grant, William B.; Toon, Geoffrey C.; Blumenstock, Thomas; Galle, Bo; Sinnhuber, BjöRn-Martin; Davies, Stewart

2002-03-01

179

Vortexwide denitrification of the Arctic polar stratosphere in winter 1999/2000 determined by remote observations  

NASA Astrophysics Data System (ADS)

Denitrification has been studied using measurements of stratospheric HNO3 and N2O by the Airborne Submillimeter Radiometer (ASUR), operated on board the NASA DC-8 during SOLVE/THESEO 2000. Lidar measurements taken on board the same aircraft have been used to distinguish between temporary uptake of HNO3 in polar stratospheric clouds (PSCs) and denitrification events. To derive an NOy budget, ClNO3 data by balloonborne and ground-based Fourier transform infrared measurements and a model estimate of NOx + 2N2O5 have been considered. The HNO3 profiles of sporadic ASUR measurements without PSC coverage in January suggest that denitrification had started in the vortex core region by then. Vortexwide denitrification was found in mid-March 2000. Corrected for diabatic descent using the N2O measurements, a vortex-averaged NOy deficit between 1.2 +/- 0.9 ppb at about 16 km altitude and 5.3 +/- 2.7 ppb at about 20.5 km altitude was derived compared to December 1999, based on an observed decrease in HNO3 between 2.2 and 3.5 ppb during this time period. A shift in the NOy partitioning from HNO3 toward ClNO3 of about 0.4 to 0.7 ppb was observed in mid-March compared to December, indicating that chlorine deactivation was occurring. Comparisons with the SLIMCAT three-dimensional chemical transport model applying denitrification schemes based on ice and nitric acid trihydrate particles in equilibrium, respectively, reveal agreement within the error bars at higher altitudes (~19 km) but show discrepancies at lower altitudes (~16 km). It is suggested that more sophisticated denitrification schemes are needed to generally describe denitrification processes.

Kleinböhl, Armin; Bremer, Holger; von König, Miriam; Küllmann, Harry; Künzi, Klaus F.; Goede, Albert P. H.; Browell, Edward V.; Grant, William B.; Toon, Geoffrey C.; Blumenstock, Thomas; Galle, Bo; Sinnhuber, Björn-Martin; Davies, Stewart

2003-03-01

180

A case study of high Arctic anthropogenic disturbance to polar desert permafrost and ecosystems  

NASA Astrophysics Data System (ADS)

One of the indirect impacts of climate change on Arctic ecosystems is the expected increase of industrial development in high latitudes. The scale of terrestrial impacts cannot be known ahead of time, particularly due to a lack of long-term impact studies in this region. With one of the slowest community recovery rates of any ecosystem, the high Artic biome will be under a considerable threat that is exacerbated by a high susceptibility to change in the permafrost thermal balance. One such area that provides a suitable location for study is an old airstrip near Eureka, Ellesmere Island, Nunavut (80.0175°N, 85.7340°W). While primarily used as an ice-runway for winter transport, the airstrip endured a yearly summer removal of vegetation that continued from 1947 until its abandonment in 1951. Since then, significant vegetative and geomorphic differences between disturbed and undisturbed areas have been noted in the literature throughout the decades (Bruggemann, 1953; Beschel, 1963; Couture and Pollard, 2007), but no system wide assessment of both the ecosystem and near-surface permafrost has been conducted. Key to our study is that the greatest apparent geomorphic and vegetative changes have occurred and persisted in areas where underlying ice-wedges have been disturbed. This suggests that the colonizing communities rapidly filled new available thermokarst niches and have produced an alternative ice-wedge stable state than the surrounding polar desert. We hypothesize that disturbed areas will currently have greater depths of thaw (deeper active layers) and degraded ice-wedges, with decreased vegetation diversity but higher abundance due to a changed hydrological balance. To test this a comprehensive set of near-surface active layer and ecosystem measurements were conducted. Permafrost dynamics were characterized using probing and high-frequency Ground Penetrating Radar (500 MHz) to map the near-surface details of ice-wedges and active layer. Vegetation was measured using quadrat sampling for species richness and abundance. Soil measures consisted of temperature at depth, moisture content, and bioavailable nutrients, all augmented with hourly microclimate data. NMDS ordination was performed as an exploratory analysis of clustering between disturbed/undisturbed microsite differences. Further statistical analysis showed that disturbed polygon tops have an active layer 30% deeper than other microsites (p < .001) despite having no greater vegetation cover than undisturbed polygon tops. Conversely, disturbed troughs show no difference in active layer, but their soils have double the water content of other microsites (p < .001), likely accounting for a significantly greater, but less-diverse, biomass that may be buffering the active layer from further development. Our results suggest that a disturbance to the thermal regime of high Arctic ice-wedge polygon systems results in long-lasting and significant effects on the polar desert landscape. Understanding how the polar desert responds to disturbance after 60 years of ';recovery' will provide useful information for applying conceptual thermal models of landscape disturbance in the high Arctic, as well as information to governments and industries hoping to plan and minimize their impacts.

Becker, M. S.; Pollard, W. H.

2013-12-01

181

Arctic aerosol size-segregated chemical observations in relation to ozone depletion during Polar Sunrise Experiment 1992  

Microsoft Academic Search

During Polar Sunrise Experiment 1992 at Alert in the Canadian high Arctic, size-fractionated observations of aerosol constituents (halogens, Na, V, As, Sb, Zn, Al, Ca, SO=4, Sm, K, Mn, and Mg) were made using a low-pressure cascade impactor and a high-volume virtual impactor (HVVI). Over 80% of the mass of V, Br, I, As, Sb, Zn, and SO=4 was in

L. A. Barrie; R. Staebler; D. Toom; B. Georgi; G. den Hartog; S. Landsberger; D. Wu

1994-01-01

182

Fine and coarse modes of dicarboxylic acids in the Arctic aerosols collected during the Polar Sunrise Experiment 1997  

Microsoft Academic Search

Fine (1 ?m) aerosol particles were collected at Alert, Canada (82°27?N, 62°30?W), during the Arctic spring as part of the Polar Sunrise Experiment 1997 and were analyzed for low molecular weight dicarboxylic acids (C2–C11) using gas chromatography with flame ionization detector (GC-FID) and GC\\/mass spectrometry (GC\\/MS). More than 80% of total diacids were detected in the fine fraction, suggesting the

M. Narukawa; K. Kawamura; K. G. Anlauf; L. A. Barrie

2003-01-01

183

Leveraging scientific credibility about Arctic sea ice trends in a polarized political environment  

PubMed Central

This work argues that, in a polarized environment, scientists can minimize the likelihood that the audience’s biased processing will lead to rejection of their message if they not only eschew advocacy but also, convey that they are sharers of knowledge faithful to science’s way of knowing and respectful of the audience’s intelligence; the sources on which they rely are well-regarded by both conservatives and liberals; and the message explains how the scientist arrived at the offered conclusion, is conveyed in a visual form that involves the audience in drawing its own conclusions, and capsulizes key inferences in an illustrative analogy. A pilot experiment raises the possibility that such a leveraging–involving–visualizing–analogizing message structure can increase acceptance of the scientific claims about the downward cross-decade trend in Arctic sea ice extent and elicit inferences consistent with the scientific consensus on climate change among conservatives exposed to misleadingly selective data in a partisan news source. PMID:25225380

Hall Jamieson, Kathleen; Hardy, Bruce W.

2014-01-01

184

Subsidence, Mixing and Denitrification of Polar Vortex Air Measured During Polaris  

NASA Technical Reports Server (NTRS)

We use the correlation between CH(sub 4) and N(sub 2)O as measured during the POLARIS campaign in spring 1997 to estimate the degree of mixing between descended air masses from the vortex and air masses from mid-latitudes.

Rex, M.; Salawitch, R.; Toon, G.; Sen, B.; Margitan, J.; Osterman, G.; Blavier, J.; Gao, R.; Del Negro, L.; Donnelly, S.; Keim, E.; Neuman, J.; Fahey, D.; Webster, C.; Scott, D.; Herman, B.; May, R.; Moyer, L.; Gunson, M.; Irion, F.; Chang, A.; Rinsland, R.; Bui, P.; Loewenstein, M.

1998-01-01

185

What Controls the Arctic Lower Stratosphere Temperature?  

NASA Technical Reports Server (NTRS)

The temperature of the Arctic lower stratosphere is critical for understanding polar ozone levels. As temperatures drop below about 195 K, polar stratospheric clouds form, which then convert HCl and ClONO2 into reactive forms that are catalysts for ozone loss reactions. Hence, the lower stratospheric temperature during the March period is a key parameter for understanding polar ozone losses. The temperature is basically understood to be a result of planetary waves which drive the polar temperature away from a cold "radiative equilibrium" state. This is demonstrated using NCEP/NCAR reanalysis calculations of the heat flux and the mean polar temperature. The temperature during the March period is fundamentally driven by the integrated impact of large scale waves moving from the troposphere to the stratosphere during the January through February period. We will further show that the recent cold years in the northern polar vortex are a result of this weakened wave driving of the stratosphere.

Newman, Paul A.; Nash, Eric R.; Einaudi, Franco (Technical Monitor)

2001-01-01

186

Space weather monitoring by ground-based means carried out in Polar Geophysical Center at Arctic and Antarctic Research Institute  

NASA Astrophysics Data System (ADS)

A real-time information on geophysical processes in polar regions is very important for goals of Space Weather monitoring by the ground-based means. The modern communication systems and computer technology makes it possible to collect and process the data from remote sites without significant delays. A new acquisition equipment based on microprocessor modules and reliable in hush climatic conditions was deployed at the Roshydromet networks of geophysical observations in Arctic and is deployed at observatories in Antarctic. A contemporary system for on-line collecting and transmitting the geophysical data from the Arctic and Antarctic stations to AARI has been realized and the Polar Geophysical Center (PGC) arranged at AARI ensures the near-real time processing and analyzing the geophysical information from 11 stations in Arctic and 5 stations in Antarctic. The space weather monitoring by the ground based means is one of the main tasks standing before the Polar Geophysical Center. As studies by Troshichev and Janzhura, [2012] showed, the PC index characterizing the polar cap magnetic activity appeared to be an adequate indicator of the solar wind energy that entered into the magnetosphere and the energy that is accumulating in the magnetosphere. A great advantage of the PC index application over other methods based on satellite data is a permanent on-line availability of information about magnetic activity in both northern and southern polar caps. A special procedure agreed between Arctic and Antarctic Research Institute (AARI) and Space Institute of the Danish Technical University (DTUSpace) ensures calculation of the unified PC index in quasi-real time by magnetic data from the Thule and Vostok stations (see public site: http://pc-index.org). The method for estimation of AL and Dst indices (as indicators of state of the disturbed magnetosphere) based on data on foregoing PC indices has been elaborated and testified in the Polar Geophysical Center. It is demonstrated that the PC index can be successfully used to monitor the state of the magnetosphere (space weather monitoring) and the readiness of the magnetosphere to producing substorm or storm (space weather nowcasting).

Janzhura, Alexander

187

Polar vision or tunnel vision the making of Canadian Arctic waters policy  

Microsoft Academic Search

This article examined the manner by which Canadian maritime Arctic policy is formulated. It suggests that this policy is largely the result of an ad hoc and reactive process. In general, the policy tends to be the product of a specific event initiated by a non-Canadian actor in the Canadian Arctic. In the early 1970s, this event was the voyages

Rob Huebert

1995-01-01

188

Opportunities and Challenges for Arctic Geoscience in the IPY (International Polar Year)  

Microsoft Academic Search

Anyone who has seen a weather map of the northern hemisphere understands that the Arctic Ocean has a climatic and oceanographic influence far beyond its limited geographic extent. This influence is not matched by our understanding of the basin history. For example, we do not know when sea ice first covered the Arctic Basin. The detailed geologic composition and history

B. Coakley; Y. Kristoffersen; M. Edwards; L. Johnson

2003-01-01

189

The Temperature of the Arctic and Antarctic Lower Stratosphere  

NASA Technical Reports Server (NTRS)

The temperature of the polar lower stratosphere during spring is the key factor in changing the magnitude of ozone loss in the polar vortices. In this talk, we will review the results of Newman et al. [2000] that quantitatively demonstrate that the polar lower stratospheric temperature is primarily controlled by planetary-scale waves. In particular, the tropospheric eddy heat flux in middle to late winter (January--February) is highly correlated with the mean polar stratospheric temperature during March. Strong midwinter planetary wave forcing leads to a warmer spring Arctic lower stratosphere in early spring, while weak midwinter forcing leads to cooler spring Arctic temperatures. In addition, this planetary wave driving also has a strong impact on the strength of the polar vortex. These results from the Northern Hemisphere will be contrasted with the Southern Hemisphere.

Newman, Paul A.; Nash, Eric R.; Bhartia, P. K. (Technical Monitor)

2002-01-01

190

ArtArctic Science: a polarTREC effort to educate about Antarctica through art  

NASA Astrophysics Data System (ADS)

Formal scientific education is as important as ever for raising awarness about Antarctic issues, but some people resistance to learning about scienctific issues demands novel approaches for reaching people who are not in the classroom. ArtArctic Science is an interactive exhibit of photography and paintings presented at the Overture Center for the Arts, in Madison, WI by Monona Grove High School students and a science teacher that attempts to educate the general audience about Antarctic science. The exhibit explores art as a form of perceiving and understanding the world around us, and as a way of igniting the spark of curiosity that can lead to scientific inquiries. Antarctica has inspired explorers and scientists for over 100 years, and we add our work to efforts that share scientific results with common people. Antarctica offers stunning views of amazing geometric ice structures complemented and contrasted by the organisms that inhabit it that fascinate most everyone. We probe these scenes through photography and paintings knowing that there is more in each image than what the eye can 'see'. We invite the viewer to discover these secrets by engaging the observer in a mimicking of the scientific method (observation, questioning, finding an explanation, revising the explanation). Each art piece has a question and a scientific explanation hidden under a wooden lid. The observer is invited to explore the scene, involve itself with the scientific query, come up with an answer, and compare his or her idea with the hidden explanation. The exhibit is inspired by an Antarctic PolarTREC expedition in which our science teacher participated as a member of a scientific research team. In this presentation we share the knowledge acquired through this experience in hopes that it will help others attempting a similar Project.

Botella, J.; Racette, B.

2013-12-01

191

The generation of a complete spiral spot and multi split rings by focusing three circularly polarized vortex beams  

NASA Astrophysics Data System (ADS)

We demonstrate that a complete right-handed or left-handed spiral-shaped focus can be created by focusing circularly polarized and three spatially shifted vortex beams through high numerical objective. By dividing the back aperture into multi annular zones and applying an additional phase term, the multi focal spots aligned along z axis of individual three dimensional focal shapes can be generated. The spiral shaped focus provides a pathway of manipulating the micro-particles in a curved trajectory and opens up a possibility of measuring mechanical torque of biological large molecules such as DNA by chemically binding one end on the cover-glass. The multi focal spots aligned along the z axis can eliminate the need of z axis scanning in the direct laser writing fabrication of some metamaterials which is composed of three-dimensional array of specific shapes of building blocks.

Chen, Jiannong; Gao, Xiumin; Zhu, Linwei; Xu, Qinfeng; Ma, Wangzi

2014-05-01

192

Arctic chemical Ozone Loss Observed by the AROTEL Instrument during the SOLVE Campaign, December 1999 - March 2000  

NASA Technical Reports Server (NTRS)

During the winter of 1999-2000, the AROTEL instrument was deployed on the NASA DC-8 at Kiruna, Sweden for the SAGE III Ozone Loss Validation Experiment (SOLVE). Measurements of ozone, temperature and aerosols were made on 18 local science flights from December to March. Extremely low temperatures were observed throughout most of the Arctic vortex and polar stratospheric clouds were observed throughout the Arctic area during January. Significant ozone loss was measured after the sun began to rise on the vortex area in February. Ozone mixing ratios as low as 800 ppbv were observed during flights in March.

McGee, Thomas J.; Burris, John F.; Hoegy, Walter; Newman, Paul; Heaps,William; Silbert, Donald; Lait, Leslie; Sumnicht, Grant; Twigg, Laurence

2000-01-01

193

4, 66676689, 2004 Arctic ozone  

E-print Network

ACPD 4, 6667­6689, 2004 Arctic ozone depletion 2002/2003 T. Christensen et al. Title Page Abstract Discussions Vortex-averaged Arctic ozone depletion in the winter 2002/2003 T. Christensen 1 , B. M. Knudsen 1 6667 #12;ACPD 4, 6667­6689, 2004 Arctic ozone depletion 2002/2003 T. Christensen et al. Title Page

Paris-Sud XI, Université de

194

Persistence of the Lower Stratospheric Polar Vortices  

NASA Technical Reports Server (NTRS)

The persistence of the Arctic and Antarctic lower stratospheric vortices is examined over the period 1958 to 1998. Three different vortex-following diagnostics (two using potential vorticity and one based solely on the zonal winds) are compared, and shown to give very similar results for the break up date. The variability in the timing of the breakup of each vortex is qualitatively the same: there are large interannual variations together with smaller decadal-scale variations and there is a significant increase in the persistence since the mid-1980s (all variations are larger for the Arctic vortex). Also, in both hemispheres there is a high correlation between the persistence and the strength and coldness of the spring vortex, with all quantities having the same interannual and decadal variability. However, there is no such correlation between the persistence and the characteristics of the mid-winter vortex. In the northern hemisphere there is also a high correlation between the vortex persistence and the upper tropospheric/lower stratospheric eddy heat flux averaged over the two months prior to the breakup. This indicates that the variability in the wave activity entering the stratosphere over late-winter to early-spring plays a key role in the variability of the vortex persistence (and spring polar temperatures) on both interannual and decadal time scales. However, the decadal variation in the Arctic vortex coldness and persistence for the 1990's falls outside the range of natural variability, while this is not the case for the eddy heat flux. This suggests that the recent increase in vortex persistence is not due solely to changes in the wave activity entering the stratosphere.

Waugh, Darryn W.; Randel, William J.; Pawson, Steven; Newman, Paul A.; Nash, Eric R.

1999-01-01

195

Spatiotemporal analysis of the January Northern Hemisphere circumpolar vortex over the contiguous United States  

NASA Astrophysics Data System (ADS)

2014 will be remembered for the sensationalized media usage of the term "polar vortex" which coincided with several polar air outbreaks. A United States polar vortex (USPV) perspective is presented to better understand the January spatial and temporal variability of this regional component of the Northern Hemisphere circumpolar vortex. Use of the monthly mean 5460 m isohypse to represent the location of the USPV extent and area revealed that the spatial features of the January 2014 USPV were not extreme relative to certain 1948-2013 Januaries. Furthermore, the Arctic Oscillation (AO), Pacific-North American (PNA) Pattern, and Pacific Decadal Oscillation (PDO) are all linked to southernmost latitude of the USPV trough, but the PDO and PNA are most closely associated with the longitude at which this latitude occurs. The AO is closely related to the area of the United States enclosed within the USPV.

Ballinger, Thomas J.; Allen, Michael J.; Rohli, Robert V.

2014-05-01

196

Archaeal Ammonia Oxidizers and Total Production of N2O and CH4 in Arctic Polar Desert Soils  

NASA Astrophysics Data System (ADS)

Ammonia-oxidizing Archaea are abundant in Arctic desert soils and appear to be responsible for the majority of ammonia oxidation activity in these cold and dry ecosystems. We used DNA microarrays to characterize the microbial community consisting of ammonia-oxidizing Archaea and methane-oxidizing Bacteria in three polar deserts from Ellesmere Island, Canada. Patterns of net greenhouse gas production, including production and consumption of CO2, CH4, and N2O were compared with community relative richness and abundance in a structural equation model that tested causal hypotheses relating edaphic factors to the biological community and net gas production. We extracted and amplified DNA sequences from soils collected at three polar deserts on Ellesmere Island in the Canadian high Arctic, and characterized the community structure using DNA microarrays. The functional genes Archaeal AmoA and pMMO were used to compare patterns of biological community structure to the observed patterns of net greenhouse gas production from those soils, as measured in situ. Edaphic factors including water content, bulk density, pH, and nutrient levels such as nitrate, ammonia, and extractable organic carbon were also measured for each soil sample, resulting in a highly multivariate dataset. Both concentration and net production of the three greenhouse gases were correlated, suggesting underlying causal factors. Edaphic factors such as soil moisture and pH had important, direct effects on the community composition of both functional groups of microorganisms, and pH further had a direct effect on N2O production. The structural relationship between the examined microbial communities and net production of both N2O and CH4 was strong and consistent between varying model structures and matrices, providing high confidence that this model relationship accurately reflects processes occurring in Arctic desert soils.

Brummell, Martin; Robert, Stan; Bodrossy, Levente; Abell, Guy; Siciliano, Steven

2014-05-01

197

POLAR-UVI and other Coordinated Observations of a Traveling Convection Vortex Event Observed on 24 July 1996  

NASA Technical Reports Server (NTRS)

Coordinated analysis of data from the POLAR UVI instrument, ground magnetometers, incoherent scatter radar, solar wind monitors IMP-8 and WIND, and DMSP satellite is focused on a traveling convection vortex (TCV) event on 24 July 1966. Starting at 10:48 UT, ground magnetometers in Greenland and eastern Canada measure pulsations consistent with the passing overhead of a series of alternating TCV field-aligned current pairs. Sondrestrom incoherent scatter radar measures strong modulation of the strength and direction of ionospheric plasma flow, The magnetometer pulsations grow in magnitude over the next hour, peaking in intensity at 11:39 UT, at which time the UVI instrument measures a localized intensification of auroral emissions over central and western Greenland. Subsequent images show the intensification grow in strength and propagate westward (tailward) until approximately 11:58 UT at which time the emissions fade. These observations are consistent with the westward passage of two pairs of moderately intense TCVs over central Greenland followed by a third very intense TCV pair. The intensification of auroral emissions at 11:39 UT is associated with the trailing vortex of the third TCV pair, thought to be the result of an upward field-aligned current. Measurements of the solar wind suggest that a pressure change may be responsible for triggering the first two pairs of TCVS, and that a subsequent sudden change in orientation of the IMF may have produced the intensification of the third TCV pair and the associated aurora] brightening. DMSP particle data indicate that the TCVs occur on field lines which map to the boundary plasma sheet or outer edge of the low latitude boundary layer.

Clauer, C. R.; Baker, J. B.; Ridley, A. J.; Sitar, R. J.; Papitashvili, V. O.; Cumnock, J.; Spann, J. F., Jr.; Brittnacher, M. J.; Parks, G. K.

1997-01-01

198

Examining the Quasi-Biennial Oscillation Modulation of Rossby Waves and the Northern Hemisphere Stratospheric Polar Vortex Using Ertel's Potential Vorticity  

NASA Astrophysics Data System (ADS)

It is recognised that the strength of the northern hemisphere winter stratospheric polar vortex is related to the phase of the equatorial quasi-biennial oscillation (QBO). When the QBO at 50hPa is in its westerly phase (QBOw), the vortex is stronger and colder. When the QBO is in its easterly phase (QBOe), the vortex becomes weaker and warmer. Previous studies have suggested that Rossby waves, especially those of planetary scale, play a critical role in linking the QBO to the polar vortex strength, although the mechanism which explains this modulation is unclear. In this study, we investigate the QBO modulation of planetary and synoptic waves using Ertel's potential vorticity (PV). It is known that the ability of a Rossby wave to propagate in the stratosphere depends on a positive background meridional PV gradient existing. We examine three PV diagnostics, each of which is based, in part, on this gradient. These diagnostics include a Rossby wave breaking criterion, a wave activity density quantity and the frequency of reversals in PV gradient. Together, they enable us to identify the key regions where wave breaking, wave propagation and wave-mean flow interaction occur in response to the two phases of the QBO. These three diagnostics are calculated using the high resolution, ECMWF ERA-Interim reanalysis PV data on nine isentropic surfaces in the stratosphere over the period 1979-2012. We find that the QBO affects planetary and synoptic waves in different ways, with preferential latitudes and different zonal structures in the stratosphere. For the first time, we find that an enhanced poleward advection of the negative PV gradient anomalies from low latitudes to high latitudes is associated with QBOw in the middle stratosphere and lower stratosphere, where the QBO excites barotropic instability and generates synoptic waves in the subtropics. In the middle stratosphere, the residual meridional circulation transports these tropical anomalies to middle latitudes to affect the polar vortex directly. In the lower stratosphere, this poleward advection indirectly affects the strength of the vortex by modulating the ability of planetary waves to propagate vertically into the stratosphere. At high latitudes, the QBOw conditions modulate planetary waves by enhancing the wave density and also wave breaking at ~35N, whilst reducing wave activity at ~65N. Under QBOe conditions, the opposite effect occurs. These results suggest that the QBO modulation of the polar vortex occurs via a combined effect of synoptic wave-mean flow interaction in the subtropical to middle latitudes and a modulation of planetary waves at middle to high latitudes.

White, Ian; Lu, Hua; Mitchell, Nicholas

2014-05-01

199

Flame retardants and methoxylated and hydroxylated polybrominated diphenyl ethers in two Norwegian Arctic top predators: glaucous gulls and polar bears.  

PubMed

The brominated flame retardants have been subject of a particular environmental focus in the Arctic. The present study investigated the congener patterns and levels of total hexabromocyclododecane (HBCD), polybrominated biphenyls, polybrominated diphenyl ethers (PBDEs), as well as methoxylated (MeO) and hydroxylated (OH) PBDEs in plasma samples of glaucous gulls (Larus hyperboreus) and polar bears (Ursus maritimus) from the Norwegian Arctic. The analyses revealed the presence of total HBCD (0.07-1.24 ng/g wet wt) and brominated biphenyl 101 (< 0.13-0.72 ng/g wet wt) in glaucous gull samples whereas these compounds were generally found at nondetectable or transient concentrations in polar bears. Sum (sigma) concentrations of the 12 PBDEs monitored in glaucous gulls (range: 8.23-67.5 ng/g wet wt) surpassed largely those of polar bears (range: 2.65-9.72 ng/g wet wt). Two higher brominated PBDEs, BDE183 and BDE209, were detected, and thus bioaccumulated to a limited degree, in glaucous gulls with concentrations ranging from < 0.03 to 0.43 ng/g wet wt and from < 0.05 to 0.33 ng/g wet wt, respectively. In polar bear plasma, BDE183 was < 0.04 ng/g wet wt for all animals, and BDE209 was only detected in 7% of the samples at concentrations up to 0.10 ng/g wet wt. Of the 15 MeO-PBDEs analyzed in plasma samples, 3-MeO-BDE47 was consistently dominant in glaucous gulls (sigmaMeO-PBDE: 0.30-4.30 ng/g wet wt) and polar bears (sigmaMeO-PBDE up to 0.17 ng/g wet wt), followed by 4'-MeO-BDE49 and 6-MeO-BDE47. The 3-OH-BDE47, 4'-OH-BDE49, and 6-OH-BDE47 congeners were also detected in glaucous gulls (sigmaOH-PBDE up to 1.05 ng/g wet wt), although in polar bears 4'-OH-BDE49 was the only congener quantifiable in 13% of the samples. The presence of MeO- and OH-PBDEs in plasma of both species suggests possible dietary uptake from naturally occurring sources (e.g., marine sponges and green algae), but also metabolically derived biotransformation of PBDEs such as BDE47 could be a contributing factor. Our findings suggest that there are dissimilar biochemical mechanisms involved in PCB and PBDE metabolism and accumulation/elimination and/or OH-PBDE accumulation and retention in glaucous gulls and polar bears. PMID:16173559

Verreault, Jonathan; Gabrielsen, Geir W; Chu, Shaogang; Muir, Derek C G; Andersen, Magnus; Hamaed, Ahmad; Letcher, Robert J

2005-08-15

200

The Influence of Planetary Wave Transport on Arctic Ozone as Observed by POAM III  

NASA Technical Reports Server (NTRS)

Three recent Arctic winters have been unusually warm or cold compared to the 1979-2001 mean, resulting in either a warm, disturbed vortex or a cold, quiet vortex. Interannual differences n ozone transport in the lower stratospheric Arctic vortex are investigated using data from the Polar Ozone and Aerosol Measurement (POAM) III satellite instrument obtained between May 1998 and April 2001. Time series of probability distribution functions (PDFs) of the FOAM data are used to identify seasonal and interannual variations in the transport processes controlling polar ozone. A major warming occurred in December, 1998, that caused the middle stratospheric vortex to be displaced from the pole for nearly a month and dissipate. Ozone transport is inferred from the PDFs and supported by potential vorticity (PV) analyses. The vortex reformed in January, 1999, filled with high O3 air from lower latitudes, which then cooled and descended. As a result, by the end of winter 1999, ozone at 500K in the vortex was 0.5-1.0 ppm higher than in the cold winter of 2000. The winter of 2000-1 had frequent wave disturbances, beginning with a fairly large event in November. However, at the end of this wave activity, the high PV core of the vortex was still intact, and by February, 03 in the vortex looked the same as in 2000. This study demonstrates that interannual variability in the 03-PV relationship can be caused by transport, independent of 03 loss by polar stratospheric clouds (PSCs). Ozone in the vortex in a very disturbed winter does not necessarily represent'pre-PSC' O3 levels in other years.

Strahan, Susan; Atlas, Robert (Technical Monitor)

2002-01-01

201

The Martian Dust Chronicle and the Impact on the Atmospheric Polar Vortex  

NASA Astrophysics Data System (ADS)

In this paper, we describe the chronicle of the dust distribution from martian year 24 to MY 31, and we analyze the impact of large-scale dust storms on the dynamics of the atmospheric polar vortices, as an example of effect at distance.

Montabone, L.; Forget, F.; Millour, E.; Wilson, R. J.; Mitchell, D.; Thomson, S. I.; Lewis, S. R.; Read, P. L.

2014-07-01

202

The International Polar Year, 2007-2008, an opportunity to focus on infectious diseases in Arctic regions.  

PubMed

On 3 occasions over the past 125 years, scientists from around the world have worked together to organize scientific and exploration activities in polar regions (www.ipy.org). The first International Polar Year (IPY) in 1881-1884 marked the first major coordinated international scientific initiative to collect standardized meteorological and geophysical data in polar regions. Fifteen expeditions led by 12 nations amassed a large amount of data, but the scientific value was diminished by disjointed publication efforts and lack of long-term institutional commitment; lessons were learned and corrected in subsequent polar years. The second IPY began in 1932. Forty-four nations led expeditions in the Arctic and Antarctic, resulting in greater understanding of the aurora, magnetism, and meteorology. Air and marine navigation, radio operations, and weather forecasting were greatly improved as a result. The third IPY, in 1957-58, was renamed the International Geophysical Year and capitalized on technologic advances developed during World War II. Technologic and scientific momentum was redirected toward research, particularly to studies of the upper atmosphere, a legacy that continues to the present day. Notable achievements included launching the first satellite, measurement of atmospheric greenhouse gases, delineating the system of mid-ocean ridges, and confirming the theory of plate tectonics. PMID:18258069

Parkinson, Alan J

2008-01-01

203

Observational Evidence Against Mountain-Wave Generation of Ice Nuclei as a Prerequisite for the Formation of Three Solid Nitric Acid Polar Stratospheric Clouds Observed in the Arctic in Early December 1999  

NASA Technical Reports Server (NTRS)

A number of recently published papers suggest that mountain-wave activity in the stratosphere, producing ice particles when temperatures drop below the ice frost point, may be the primary source of large NAT particles. In this paper we use measurements from the Advanced Very High Resolution Radiometer (AVHRR) instruments on board the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites to map out regions of ice clouds produced by stratospheric mountain-wave activity inside the Arctic vortex. Lidar observations from three DC-8 flights in early December 1999 show the presence of solid nitric acid (Type Ia or NAT) polar stratospheric clouds (PSCs). By using back trajectories and superimposing the position maps on the AVHRR cloud imagery products, we show that these observed NAT clouds could not have originated at locations of high-amplitude mountain-wave activity. We also show that mountain-wave PSC climatology data and Mountain Wave Forecast Model 2.0 (MWFM-2) raw hemispheric ray and grid box averaged hemispheric wave temperature amplitude hindcast data from the same time period are in agreement with the AVHRR data. Our results show that ice cloud formation in mountain waves cannot explain how at least three large scale NAT clouds were formed in the stratosphere in early December 1999.

Pagan, Kathy L.; Tabazadeh, Azadeh; Drdla, Katja; Hervig, Mark E.; Eckermann, Stephen D.; Browell, Edward V.; Legg, Marion J.; Foschi, Patricia G.

2004-01-01

204

High Bacterial Diversity of Biological Soil Crusts in Water Tracks over Permafrost in the High Arctic Polar Desert  

PubMed Central

In this study we report the bacterial diversity of biological soil crusts (biocrusts) inhabiting polar desert soils at the northern land limit of the Arctic polar region (83° 05 N). Employing pyrosequencing of bacterial 16S rRNA genes this study demonstrated that these biocrusts harbor diverse bacterial communities, often as diverse as temperate latitude communities. The effect of wetting pulses on the composition of communities was also determined by collecting samples from soils outside and inside of permafrost water tracks, hill slope flow paths that drain permafrost-affected soils. The intermittent flow regime in the water tracks was correlated with altered relative abundance of phylum level taxonomic bins in the bacterial communities, but the alterations varied between individual sampling sites. Bacteria related to the Cyanobacteria and Acidobacteria demonstrated shifts in relative abundance based on their location either inside or outside of the water tracks. Among cyanobacterial sequences, the proportion of sequences belonging to the family Oscillatoriales consistently increased in relative abundance in the samples from inside the water tracks compared to those outside. Acidobacteria showed responses to wetting pulses in the water tracks, increasing in abundance at one site and decreasing at the other two sites. Subdivision 4 acidobacterial sequences tended to follow the trends in the total Acidobacteria relative abundance, suggesting these organisms were largely responsible for the changes observed in the Acidobacteria. Taken together, these data suggest that the bacterial communities of these high latitude polar biocrusts are diverse but do not show a consensus response to intermittent flow in water tracks over high Arctic permafrost. PMID:23967218

Steven, Blaire; Lionard, Marie; Kuske, Cheryl R.; Vincent, Warwick F.

2013-01-01

205

Small-scale transport structures in the Arctic winter 2009/2010  

NASA Astrophysics Data System (ADS)

The CRISTA-NF (Cryogenic Infrared Spectrometers and Telescope for the Atmosphere - New Frontiers) instrument is an airborne infrared limb sounder operated aboard the Russian research aircraft M55-Geophysica. The instrument successfully participated in a large Arctic aircraft campaign within the RECONCILE (Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) project from January to March 2010 in Kiruna, Sweden. This paper concentrates on the measurements during one flight of the campaign, which took place on 2 March in the vicinity of the polar vortex. We present two-dimensional cross-sections of volume mixing ratios for the trace gases CFC-11, O3, and ClONO2 with an unprecedented vertical resolution of about 500 to 600 m for a large part of the observed altitude range and a dense horizontal sampling along flight direction of ? 15 km. The trace gas distributions show several structures like the polar vortex and filaments composed of air masses of different origin. The situation during the analysed flight is simulated by the chemistry and transport model CLaMS (Chemical Lagrangian Model of the Stratosphere) and compared with the measurements to assess the performance of the model with respect to advection, mixing, and the chemistry in the polar vortex. These comparisons confirm the capability of CLaMS to reproduce even very small-scale structures in the atmosphere. Based on the good agreement between simulation and observation, we use a model concept utilising artificial tracers to further analyse the CRISTA-NF observations in terms of air mass origin. A characteristic of the Arctic winter 2009/10 was a sudden stratospheric warming in early December that led to a split of the polar vortex. The vortex re-established at the end of December. Our passive tracer simulations suggest that large parts of the re-established vortex consisted to about 45% of high- and mid-latitude air.

Kalicinsky, C.; Grooß, J.-U.; Günther, G.; Ungermann, J.; Blank, J.; Höfer, S.; Hoffmann, L.; Knieling, P.; Olschewski, F.; Spang, R.; Stroh, F.; Riese, M.

2013-04-01

206

Multi-Instrument Analysis of a Traveling Convection Vortex Event on July 24, 1996 Coordinated with the Polar UVI  

NASA Technical Reports Server (NTRS)

We present the analysis of a coordinated set of observations from the POLAR Ultraviolet Imager (UVI), ground magnetometers, incoherent scatter radar, solar wind monitors, DMSP and GOES satellites, focused on a traveling convection vortex (TCV) event on 24th July 1996. Starting at approximately 10:48 UT, around magnetometers in Greenland and northern Canada observe pulsations consistent with the passing overhead of a series of alternating TCV filed-aligned current pairs. Azimuthal scans by the Sondrestrom incoherent scatter radar located near Kangerlussuaq (formerly Sondrestrom), Greenland, at this time show strong modulation in the strength and direction of ionospheric plasma flow. The magnetometer pulsations grow in magnitude over the next hour, peaking in intensity at 11:39 UT, at which time images form the UVI instrument show a localized intensification of auroral emissions over central and western Greenland. Subsequent images show the intensification grow in strength and propagate westward (tailward) until approximately 11:58 UT at which time the intensification fades. These observations are consistent with the westward passage of two pairs of moderately intense TCVs over central Greenland followed by a third very intense TCV pair. The intensification of auroral emissions at 11:39 UT is associated with the trailing vortex of the third TCV pair, thought to be the result of an upward field aligned current. The modulated flow observed by the radar is the result of the strong electric fields associated with the impulsive TCV related field aligned current systems as they pass through the field of view of the radar. Measurements of the solar wind from the V;IND and IMP-8 spacecraft suggest that a pressure change may be responsible for triggering the first two pairs of TCVS, and that a subsequent sudden change in the orientation of the interplanetary magnetic field may have produced the intensification of the third TCV pair and the associated auroral brightening. Magnetometer data from the GOES satellite located over the eastern United States at geostationary orbit is consistent with a series of field-aligned moving tailward past the satellite. DMSP particle data indicated that the TCVs occur on field lines which map to the boundary plasma sheet (BPS).

Sitar, R. J.; Clauer, C. R.; Baker, J. B.; Ridley, A. J.; Cumnock, J.; Germany, G. A.; Spann, J. F., Jr.; Brittnacher, M. J.; Parks, G. K.

1998-01-01

207

The Effect of Tropospheric Jet Latitude on Rossby Wave Breaking and on Coupling between the Stratospheric Polar Vortex and the Troposphere  

NASA Astrophysics Data System (ADS)

A dry General Circulation Model is used to investigate how the latitude of the tropospheric jet affects (1) coupling between the stratospheric polar vortex and the extratropical tropospheric circulation, and (2) Rossby wave breaking. The tropospheric response to an identical stratospheric vortex configuration is shown to be strongest for a jet centered near 40° and weaker for jets near either 30° or 50° by more than a factor of three. Stratosphere-focused mechanisms based on stratospheric potential vorticity inversion, eddy phase speed, and planetary wave reflection, as well as arguments based on tropospheric eddy heat flux and zonal length scale, appear to be incapable of explaining the differences in the magnitude of the jet shift. In contrast, arguments based purely on tropospheric variability involving the strength of eddy-zonal mean flow feedbacks and jet persistence, and related changes in the synoptic eddy momentum flux, appear to explain this effect. The dependence of coupling between the stratospheric polar vortex and the troposphere on tropospheric jet latitude found here is consistent with (1) the observed variability in the North Atlantic and the North Pacific, and (2) the trend in the Southern Hemisphere as projected by comprehensive models. The shift in wavebreaking per degree latitude of jet shift is then compared for three different sources of jet movement: the baroclinic forcing imposed by the equator-to-pole temperature gradient, the imposition of a stratospheric polar vortex, and the internal variability of the mid-latitude eddy driven jet. It is demonstrated that all three sources of jet movement produce a similar change in Rossby wave breaking frequency per degree of jet shift. Hence, it is difficult (if not impossible) to isolate the ultimate cause behind the shift in Rossby wave breaking in response to the two external forcings.

Garfinkel, Chaim; Waugh, Darryn; Gerber, Edwin

2014-05-01

208

Simultaneous traveling convection vortex events and Pc1 wave bursts at cusp latitudes observed in Arctic Canada and Svalbard  

NASA Astrophysics Data System (ADS)

convection vortices (TCVs), which appear in ground magnetometer records at near-cusp latitudes as solitary ~5 mHz pulses, are a signature of dynamical processes in the ion foreshock upstream of the Earth's bow shock that can stimulate transient compressions of the dayside magnetosphere. These compressions can also increase the growth rate of electromagnetic ion cyclotron (EMIC) waves, which appear in ground records at these same latitudes as bursts of Pc1 pulsations. In this study we have identified TCVs and simultaneous Pc1 burst events in two regions, Eastern Arctic Canada and Svalbard, using a combination of fluxgate magnetometers and search coil magnetometers in each region. By looking for the presence of TCVs and Pc1 bursts in two different sequences, we have found that the distribution of Pc1 bursts was more tightly clustered near local noon than that of TCV events, that neither TCVs nor Pc1 bursts were always associated with the other, and even when they occurred simultaneously their amplitudes showed little correlation. Magnetometer data from GOES-12 were also used to characterize the strength of the magnetic compressions at geosynchronous orbit near the magnetic equator. Compressions > 2 nT at GOES-12 occurred during 57% of the Canadian TCV events, but during ~85% of the simultaneous TCV/Pc1 burst events. There was again little evident correlation between TCV and GOES-12 compression amplitudes. We have also documented unusually low EMIC wave activity during this deep solar minimum interval, and we attribute the low occurrence percentage of combined events in this study to this minimum.

Posch, J. L.; Engebretson, M. J.; Witte, A. J.; Murr, D. L.; Lessard, M. R.; Johnsen, M. G.; Singer, H. J.; Hartinger, M. D.

2013-10-01

209

Spectroscopic measurement of bromine oxide and ozone in the high Arctic during Polar Sunrise Experiment 1992  

Microsoft Academic Search

Bromine oxide (BrO) is proposed to be an important agent for tropospheric ozone depletion, as observed in the high Arctic during springtime. In this paper we report measurements of bromine oxide and ozone by Long Path Differential Optical Absorption Spectroscopy (LPDOAS), 8.6-km light path), performed in April 1992 in Alert (82.3°N, 62.2°W). BrO mixing ratios were found between the detection

M. Hausmann; U. Platt

1994-01-01

210

Chemical depletion of Arctic ozone in winter 1999/2000  

NASA Astrophysics Data System (ADS)

During Arctic winters with a cold, stable stratospheric circulation, reactions on the surface of polar stratospheric clouds (PSCs) lead to elevated abundances of chlorine monoxide (ClO) that, in the presence of sunlight, destroy ozone. Here we show that PSCs were more widespread during the 1999/2000 Arctic winter than for any other Arctic winter in the past two decades. We have used three fundamentally different approaches to derive the degree of chemical ozone loss from ozonesonde, balloon, aircraft, and satellite instruments. We show that the ozone losses derived from these different instruments and approaches agree very well, resulting in a high level of confidence in the results. Chemical processes led to a 70% reduction of ozone for a region ˜1 km thick of the lower stratosphere, the largest degree of local loss ever reported for the Arctic. The Match analysis of ozonesonde data shows that the accumulated chemical loss of ozone inside the Arctic vortex totaled 117 ± 14 Dobson units (DU) by the end of winter. This loss, combined with dynamical redistribution of air parcels, resulted in a 88 ± 13 DU reduction in total column ozone compared to the amount that would have been present in the absence of any chemical loss. The chemical loss of ozone throughout the winter was nearly balanced by dynamical resupply of ozone to the vortex, resulting in a relatively constant value of total ozone of 340 ± 50 DU between early January and late March. This observation of nearly constant total ozone in the Arctic vortex is in contrast to the increase of total column ozone between January and March that is observed during most years.

Rex, M.; Salawitch, R. J.; Harris, N. R. P.; von der Gathen, P.; Braathen, G. O.; Schulz, A.; Deckelmann, H.; Chipperfield, M.; Sinnhuber, B.-M.; Reimer, E.; Alfier, R.; Bevilacqua, R.; Hoppel, K.; Fromm, M.; Lumpe, J.; Küllmann, H.; KleinböHl, A.; Bremer, H.; von KöNig, M.; Künzi, K.; Toohey, D.; VöMel, H.; Richard, E.; Aikin, K.; Jost, H.; Greenblatt, J. B.; Loewenstein, M.; Podolske, J. R.; Webster, C. R.; Flesch, G. J.; Scott, D. C.; Herman, R. L.; Elkins, J. W.; Ray, E. A.; Moore, F. L.; Hurst, D. F.; Romashkin, P.; Toon, G. C.; Sen, B.; Margitan, J. J.; Wennberg, P.; Neuber, R.; Allart, M.; Bojkov, B. R.; Claude, H.; Davies, J.; Davies, W.; de Backer, H.; Dier, H.; Dorokhov, V.; Fast, H.; Kondo, Y.; Kyrö, E.; Litynska, Z.; Mikkelsen, I. S.; Molyneux, M. J.; Moran, E.; Nagai, T.; Nakane, H.; Parrondo, C.; Ravegnani, F.; Skrivankova, P.; Viatte, P.; Yushkov, V.

2002-10-01

211

Zero-Field Vortex-Induced Hall Effect and Polar Kerr Effect in Chiral p-Wave Superconductors near Kosterlitz-Thouless Transition  

NASA Astrophysics Data System (ADS)

In this work, we investigate polar Kerr effect and Ohmic conductivity induced by vortex dynamics in a chiral p-wave superconducting thin film near Kosterlitz-Thouless (KT) transition without explicitly applying magnetic field. Due to the broken time reversal symmetry in the superconducting state and the breaking of Galilean invariance by forces originated from impurities, a conductivity tensor with nonzero off-diagonal element is expected. We generalize the dynamical theory developed by Ambegaokar, Halperin, Nelson, and Siggia to obtain a matrix dielectric function describing vortex screening, which is further related to the conductivity tensor. Polar Kerr effect due to the nonzero Hall conductivity is studied. The corresponding Kerr angle is shown to be proportional to the imaginary part of off-diagonal component of the dielectric function in certain parameter regime. While the frequency and temperature dependence of dissipation in chiral p-wave context behave similarly to those of s-wave results, the Kerr angle exhibits some novel features near the KT transition. As a result, Kerr angle measurement in experiment can provide a probe of vortex dynamics described in this work.

Chung, C. K.; Kato, Y.

2014-04-01

212

Ice navigation studies in the Alaskan Arctic using POLAR Class icebreakers  

Microsoft Academic Search

The operational capability of the U.S. Coast Guard's POLAR Class icebreakers is reviewed for Alaskan ice covered waters. Operational capability is defined in terms of three distinct geographic areas: the Bering, Chukchi, and Beaufort Seas. POLAR Class icebreakers have successfully operated in each of these areas since 1979. As a result of the deployments, it is possible to draw conclusions

L. Brigham; R. Voelker

1985-01-01

213

Climate Change and Arctic Ecosystems  

NSDL National Science Digital Library

In this activity, students learn about how climate change is affecting the Arctic ecosystem and then investigate how this change is impacting polar bear populations. Students analyze maps of Arctic sea ice, temperature graphs, and polar bear population data to answer questions about the impact of climate change on the Arctic ecosystem.

Change, Project A.; University, Purdue

214

Spectroscopic measurement of bromine oxide and ozone in the high Arctic during Polar Sunrise Experiment 1992  

SciTech Connect

The authors report the measurement of BrO radical densities and ozone in the Arctic troposphere by means of differential optical absorption using very long paths. They observed levels of BrO which varied from below the detection limit to 17 ppt. Such concentrations alone cannot account for the catalytic destruction of ozone observed during periods of episodic ozone variation. The authors offer a model which involves BrO catalyzed reactions, advection, and atmospheric mixing which they argue could account for the observed ozone depletions.

Hausmann, M.; Platt, U. [Universitaet Heidelberg (Germany)] [Universitaet Heidelberg (Germany)

1994-12-20

215

Polarization of 'water-skies' above arctic open waters: how polynyas in the ice-cover can be visually detected from a distance  

NASA Astrophysics Data System (ADS)

The foggy sky above a white ice-cover and a dark water surface (permanent polynya or temporary lead) is white and dark gray, phenomena called the 'ice-sky' and the 'water-sky,' respectively. Captains of icebreaker ships used to search for not-directly-visible open waters remotely on the basis of the water sky. Animals depending on open waters in the Arctic region may also detect not-directly-visible waters from a distance by means of the water sky. Since the polarization of ice-skies and water-skies has not, to our knowledge, been studied before, we measured the polarization patterns of water-skies above polynyas in the arctic ice-cover during the Beringia 2005 Swedish polar research expedition to the North Pole region. We show that there are statistically significant differences in the angle of polarization between the water-sky and the ice-sky. This polarization phenomenon could help biological and man-made sensors to detect open waters not directly visible from a distance. However, the threshold of polarization-based detection would be rather low, because the degree of linear polarization of light radiated by water-skies and ice-skies is not higher than 10%.

Hegedüs, Ramón; Åkesson, Susanne; Horváth, Gábor

2007-01-01

216

Polar bears exhibit genome-wide signatures of bioenergetic adaptation to life in the arctic environment.  

PubMed

Polar bears (Ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (U. arctos). We have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate whether polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. We observed increased evolutionary rates in the mitochondrial cytochrome c oxidase I gene in polar but not brown bears. An amino acid substitution occurred near the interaction site with a nuclear-encoded subunit of the cytochrome c oxidase complex and was predicted to lead to a functional change, although the significance of this remains unclear. The nuclear genomes of brown and polar bears demonstrate different adaptations related to cellular respiration. Analyses of the genomes of brown bears exhibited substitutions that may alter the function of proteins that regulate glucose uptake, which could be beneficial when feeding on carbohydrate-dominated diets during hyperphagia, followed by fasting during hibernation. In polar bears, genes demonstrating signatures of functional divergence and those potentially under positive selection were enriched in functions related to production of nitric oxide (NO), which can regulate energy production in several different ways. This suggests that polar bears may be able to fine-tune intracellular levels of NO as an adaptive response to control trade-offs between energy production in the form of adenosine triphosphate versus generation of heat (thermogenesis). PMID:24504087

Welch, Andreanna J; Bedoya-Reina, Oscar C; Carretero-Paulet, Lorenzo; Miller, Webb; Rode, Karyn D; Lindqvist, Charlotte

2014-01-01

217

Aboveground activity rhythm in Arctic black-capped marmot ( Marmota camtschatica bungei Katschenko 1901) under polar day conditions  

NASA Astrophysics Data System (ADS)

Daily aboveground activity of wild black-capped marmots of Yakutia ( Marmota camtschatica bungei) was recorded under 'polar day' conditions at 71°56' N and 127°19' E (north of the Polar Circle). From the beginning of May until the end of August, the sun was permanently above or close to the horizon. However under this condition of continuous lighting, the aboveground activity of these arctic hibernating mammals was periodic. Onset and end of activity showed marked changes throughout the seasons. Activity time increased strongly from hibernation emergence until the end of July and then decreased slowly until onset of hibernation. Below daily mean temperatures of 5 °C, activity started when the sun was 35° above the horizon, and ended when it dropped below 28°. When daily mean temperatures were above 5 °C, activity onset was synchronised with a solar altitude around 17-18° and activity ended at 10°. Activity onset was more precise relative to the solar altitude than the end of activity. This may be explained by late feeding bouts, following a midday thermal stress. In absence of rapid natural light-dark (LD) transitions that occur at civil twilight, our results suggest that the activity pattern of black-capped marmots may be synchronised by the light cycle through the solar altitude and ambient temperature.

Semenov, Youri; Ramousse, Raymond; Le Berre, Michel; Vassiliev, Vladimir; Solomonov, Nikita

2001-04-01

218

Gaia Paradigm: A Biotic Origin Of The Polar Sunrise Arctic Bromine Explosion  

E-print Network

The main attention is given to discussion of the natural causes and regularities of the Arctic bromine pollution. We make notice of marine microbial organisms and their metabolism as a prime driving force for the elemental biogeochemical cycles. One of the important conclusions of this study is on similarity between ocean bromine concentrating as by-product of the marine microbial activities and nitrogen fixation by soil bacteria. In both cases, microbial organisms and their food webs maintain the sustainability of the superficial environments throughout the geological ages of the biotic Earth. Phenomenology of bromine explosion points on synchronization of the biogeochemical processing upon the solar factor. Spatial-temporal extent and statistical properties of the Arctic BrO cloud make the bromine explosion phenomena an exceptionally valuable for modeling. In our analysis of of the interannual (Solar Cycle 23) variability of the BrO cloud, we rely on on the processed from GOME satellite data and on the ground observations. Sustainability of the earth superficial environments is impossible without ozone-oxygen transformations. Bromine pollution activate catalytic depletion of ozone, which leads to the intensification of oxygen fluxes and atmosphere-ocean exchange and to the stimulation of the seasonal production of the superficial Northern Hemisphere's biota. The biotic bromine explosion illustrates the major concepts of Gaia hypothesis and yields on the foundational principle of multiple unity of the Earth's life and planetary operations.

M. Iudin

2008-12-28

219

POLAR-PALOOZA Polar Researchers and Arctic Residents Engage, Inform and Inspire Diverse Public Audiences by sharing Polar Science and Global Connections during the International Polar Year, using a New Model of Informal Science Education  

NASA Astrophysics Data System (ADS)

(Please note that the POLAR-PALOOZA initiative described in this Abstract is-as of 9/7/2006-"pending" for possible support from NSF and NASA as part of this year's IPY solicitation. Subject to decisions expected by 9/30, this presentation would either be withdrawn, or amplified with specific participants, locations and dates.) Despite the success of well-regarded movies like "March of the Penguins", the polar regions remain a great unknown for most people. Public knowledge about the Arctic and Antarctic, and the critical role of the Poles in the entire Earth system, is nonexistent, incomplete or burdened with misperceptions. The International Polar Years of 2007-2009-and associated "I*Y" science years such as IHY, IYPE and eGY-present a unique opportunity to change this. The people who can best effect this change are those who know the Poles best, through living or working there. Based on innovative but proven models, POLAR-PALOOZA will use three complementary strategies to engage, inform and inspire large public audiences. (1) A national tour, under the working title "Stories from a Changing Planet", will include in-person presentations at science centers, museums, libraries and schools across North America, including Canada and Mexico. The presentations will be augmented by High Definition Video taped on location at the Poles, audio and video podcasts, and special education and outreach activities for targeted audiences. "Stories from a Changing Planet" will provide diverse audiences with an exciting opportunity to meet and interact directly with polar experts, and to appreciate why the Poles and the research done there are directly relevant to their lives. (2) The "HiDef Video Science Story Capture Corps" is a team of professional videographers, using the latest generation of low-cost, high-quality cameras, deployed to both Poles. They will document the work of multiple researchers and projects, rather than focusing on one topic for a single broadcast program. The resulting HD footage will be cataloged, archived and made available as public domain material, accessible to government research agencies for media releases, to the researchers and their home universities, and to science centers and museums. (3) POLAR- PALOOZA will edit short video and audio podcasts from this archive, and distribute them non-exclusively through an open network of websites, including iTunes, YouTube, Google, Yahoo, and the official IPY, US-IPY, NSF and NASA websites. Project design targets underserved groups and regions, and has developed a detailed strategy by which to reach out to under-served minorities and mid-sized and smaller communities over the entire two years of IPY. A balanced cadre of researchers, both male and female, young and old, ethnically-diverse and representing the many disciplines engaged in polar research, has already been identified, and over twenty five scientists, engineers, artists and journalists have committed to participating. The project's Advisors include members of the National Academy's Polar Research Board, and the two U.S. representatives to the international IPY Education and Outreach Committee.

Haines-Stiles, G.; Akuginow, E.

2006-12-01

220

7, 1023510285, 2007 High Arctic in  

E-print Network

ACPD 7, 10235�10285, 2007 High Arctic in extreme winters G. L. Manney et al. Title Page Abstract Discussions The high Arctic in extreme winters: vortex, temperature, and MLS and ACE-FTS trace gas evolution G (manney@mls.jpl.nasa.gov) 10235 #12;ACPD 7, 10235�10285, 2007 High Arctic in extreme winters G. L. Manney

Paris-Sud XI, Université de

221

In-Situ Measurements of BrO in the early 2011/2012 Arctic Polar Vortex  

NASA Astrophysics Data System (ADS)

The Bromine Monoxide radical was measured along with Chlorine Monoxide with the HALOX instrument during two flights of the M55-Geophysica high-altitude research aircraft from Kiruna (Sweden) employing the Chemical Conversion Resonance Fluorescence (CCRF) Technique, first demonstrated on aircraft by Brune et al., 1989. In the effort to narrow down the remaining uncertainties for the inorganic Bromine loading (Bry) of the stratosphere, In-Situ BrO data provide valuable information, as BrO is the most abundant inorganic Bromine species in sunlit stratospheric air. The BrO detection limit was lowered by recent modifications of the optical setup in the HALOX instrument aiming at the reduction of stray light. However a closer look at the stray light problem also revealed the need for an improved instrument calibration. A concept for a reliable calibration was developed. The new method will be applied to the new dataset and compared to the former calibration. The results from the acquired BrO data along the flight track will be discussed and compared to earlier measurements. Based on the demonstrated field performance the potential of the CCRF technique to quantify the extremely low BrO concentrations in the UTLS and TTL regions in future tropical field measurements will be evaluated. Brune, W. H., J. G. Anderson, and K. R. Chan (1989), In Situ Observations of BrO Over Antarctica: ER-2 Aircraft Results From 54°S to 72°S Latitude, J. Geophys. Res., 94(D14), 16,639-16,647, doi:10.1029/JD094iD14p16639.

Heinecke, F.; Afchine, A.; von Hobe, M.; Richter, A.; Schönfeld, A.; Steinert, C.; Suminska, O.; Tan, V.; Stroh, F.

2012-04-01

222

Photochemical production and loss of organic acids in high Arctic aerosols during long-range transport and polar sunrise ozone depletion events  

Microsoft Academic Search

Unique daily measurements of water-soluble organics in fine (<2?m) and coarse (>2?m) aerosols were conducted at Alert in the Canadian Arctic in winter to spring of 1992. They yield insight into photochemical production and loss of organics during long-range transport and ozone depletion events following polar sunrise. Comprehensive analyses of ?, ?-dicarboxylic acids (C2–C12), ?-oxocarboxylic acids (C2–C9) and ?-dicarbonyls (C2,

Kimitaka Kawamura; Yoshie Imai; Leonard A. Barrie

2005-01-01

223

IMMOBILIZATION OF POLAR BEARS (URSUS MARITIMUS) WITH TELAZOL#{174} IN THE CANADIAN ARCTIC  

Microsoft Academic Search

In 1986, 213 polar bears (Ursus maritimus) were immobilized with Telazol#{174} on the sea ice of the eastern Beaufort Sea during April and May, and 106 along the western coast of Hudson Bay near Churchill, Manitoba (Canada) in September. No animals died from handling. The efficacy of this drug at different seasons and the physiological responses of the immobilized bears

I. Stirling; C. Spencer; D. Andriashek

1989-01-01

224

Infrared Measurements Throughout Polar Night using Two AERIs in the Arctic  

E-print Network

, Madison, Wisconsin, USA 8 ABB, Quebec City, Canada 9 NOAA / National Severe Storms Laboratory, Norman Network for the Detection of Atmospheric Change (CANDAC) has equipped the Polar Environment Atmospheric. Remote Sensing of Clouds and the Atmosphere XVII; and Lidar Technologies, Techniques, and Measurements

Strong, Kimberly

225

Cooling of the Arctic and Antarctic Polar Stratospheres due to Ozone Depletion  

Microsoft Academic Search

Long time records of stratospheric temperatures indicate that substantial cooling has occurred during spring over polar regions of both hemispheres. These cooling patterns are coincident with observed recent ozone depletions. Time series of temperature from radiosonde, satellite, and National Centers for Environmental Prediction reanalysis data are analyzed in order to isolate the space-time structure of the observed temperature changes. The

William J. Randel; Fei Wu

1999-01-01

226

Arctic Ecosystems  

NSDL National Science Digital Library

Scientists predict that the climate in most parts of the world will warm dramatically in the next century, with change expected to occur earliest and be most pronounced in polar regions. In light of this, there is an urgent need to understand different aspects of the Earth's climate system, including the role that Arctic ecosystems play in regulating the Earth's climate and how food webs are affected by the changing climate. This module explores the Arctic Ocean ecosystem through interaction with a model that simulates how phytoplankton and zooplankton interact and respond to changes in season, sea ice, and nutrients.

Byrd, Greg

2010-01-01

227

Interhemispheric Differences in Polar Stratospheric HNO3, H2O, CIO, and O3.  

PubMed

Simultaneous global measurements of nitric acid (HNO(3)), water (H(2)O), chlorine monoxide (CIO), and ozone (O(3)) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO(3) was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H(2)O after mid-July. By mid-August, near the time of peak CIO, abundances of gas-phase HNO(3) and H(2)O were extremely low. The concentrations of HNO(3) and H(2)O over Antarctica remained depressed into November, well after temperatures in the lower stratosphere had risen above the evaporation threshold for polar stratospheric clouds, implying that denitrification and dehydration had occurred. No large decreases in either gas-phase HNO(3) or H(2)O were observed in the 1992-1993 Arctic winter vortex. Although CIO was enhanced over the Arctic as it was over the Antarctic, Arctic O(3) depletion was substantially smaller than that over Antarctica. A major factor currently limiting the formation of an Arctic ozone "hole" is the lack of denitrification in the northern polar vortex, but future cooling of the lower stratosphere could lead to more intense denitrification and consequently larger losses of Arctic ozone. PMID:17813911

Santee, M L; Read, W G; Waters, J W; Froidevaux, L; Manney, G L; Flower, D A; Jarnot, R F; Harwood, R S; Peckham, G E

1995-02-10

228

Investigation of Polar Stratospheric Cloud Solid Particle Formation Mechanisms Using ILAS and AVHRR Observations in the Arctic  

NASA Technical Reports Server (NTRS)

Satellite observations of denitrification and ice clouds in the Arctic lower stratosphere in February 1997 are used with Lagrangian microphysical box model calculations to evaluate nucleation mechanisms of solid polar stratospheric cloud (PSC) particles. The occurrences of ice clouds are not correlated in time and space with the locations of back trajectories of denitrified air masses, indicating that ice particle surfaces are not always a prerequisite for the formation of solid PSCs that lead to denitrification. In contrast, the model calculations incorporating a pseudoheterogeneous freezing process occurring at the vapor-liquid interface can quantitatively explain most of the observed denitrification when the nucleation activation free energy for nitric acid dihydrate formation is raised by only approx.10% relative to the current published values. Once nucleated, the conversion of nitric acid dihydrate to the stable trihydrate phase brings the computed levels of denitrification closer to the measurements. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0320 Atmospheric Composition and SblctureC: loud physics and chemistry; 0340 Atmospheric Composition and Structure: Middle atmosphere-composition and chemistry

Irie, H.; Pagan, K. L.; Tabazadeh, A.; Legg, M. J.; Sugita, T.

2004-01-01

229

A Composite View of Ozone Evolution in the 1995-96 Northern Winter Polar Vortex Developed from Airborne Lidar and Satellite Observations  

NASA Technical Reports Server (NTRS)

The processes which contribute to the ozone evolution in the high latitude lower stratosphere are evaluated using a three dimensional model simulation and ozone observations. The model uses winds and temperatures from the Goddard Earth Observing System Data Assimilation System. The simulation results are compared with ozone observations from three platforms: the differential absorption lidar (DIAL) which was flown on the NASA DC-8 as part of the Vortex Ozone Transport Experiment; the Microwave Limb Sounder (MLS) on the Upper Atmosphere Research Satellite; and the Polar Ozone and Aerosol Measurement (POAM II) solar occulation instrument, on board the French Satellite Pour I'Observations de la Terre. Comparisons of the different data sets with the model simulation are shown to provide complementary information and a consistent view of the ozone evolution. The model ozone in December and January is shown to be sensitive to the ozone vertical gradient and the model vertical transport, and only weakly sensitive to the model photochemistry. The most consistent comparison between observed and modeled ozone evolution is found for a simulation where the vertical profiles between 12 and 20 km within the polar vortex closely match December DIAL observations. Diabatic trajectory calculations are used to estimate the uncertainty due to vertical advection quantitatively. The transport uncertainty is significant, and should be accounted for when comparing observations with model ozone. The model ozone evolution during December and January is broadly consistent with the observations when these transport uncertainties are taken into account.

Douglass, Anne R.; Schoeberl, M. R.; Kawa, S. R.

2000-01-01

230

A Composite View of Ozone Evolution in the 1995-1996 Northern Winter Polar Vortex Developed from Airborne Lidar and Satellite Observations  

NASA Technical Reports Server (NTRS)

The processes which contribute to the ozone evolution in the high latitude northern lower stratosphere are evaluated using a three dimensional model simulation and ozone observations. The model uses winds and temperatures from the Goddard Earth Observing System Data Assimilation System. The simulation results are compared with ozone observations from three platforms: the differential absorption lidar (DIAL) which was flown on the NASA DC-8 as part of the Vortex Ozone Transport Experiment; the Microwave Limb Sounder (MLS); the Polar Ozone and Aerosol Measurement (POAM II) solar occultation instrument. Time series for the different data sets are consistent with each other, and diverge from model time series during December and January. The model ozone in December and January is shown to be much less sensitive to the model photochemistry than to the model vertical transport, which depends on the model vertical motion as well as the model vertical gradient. We evaluate the dependence of model ozone evolution on the model ozone gradient by comparing simulations with different initial conditions for ozone. The modeled ozone throughout December and January most closely resembles observed ozone when the vertical profiles between 12 and 20 km within the polar vortex closely match December DIAL observations. We make a quantitative estimate of the uncertainty in the vertical advection using diabatic trajectory calculations. The net transport uncertainty is significant, and should be accounted for when comparing observations with model ozone. The observed and modeled ozone time series during December and January are consistent when these transport uncertainties are taken into account.

Douglass, A. R.; Schoeberl, M. R.; Kawa, S. R.; Browell, E. V.

2000-01-01

231

New space technology advances knowledge of the remote polar regions. [Arctic and Antarctic regions  

NASA Technical Reports Server (NTRS)

The application of ERTS-1 imagery is rapidly increasing man's knowledge of polar regions. Products compiled from this imagery at scales of 1:250,000, 1:500,000 and 1:1,000,000 are already providing valuable information to earth scientists working in Antarctica. Significant finds detected by these bench mark products were glaciological changes, advancement in ice fronts, discovery of new geographic features, and the repositioning of nunataks, islands, and ice tongues. Tests conducted in Antarctica have proven the feasibility of tracking Navy navigation satellites to establish ground control for positioning ERTS-1 imagery in remote areas. ERTS imagery coupled with satellite geodesy shows great promise and may prove to be the most practical and cost effective way to meet the small-scale cartographic requirements of the polar science community.

Macdonald, W. R.

1974-01-01

232

Mark-Recapture and Stochastic Population Models for Polar Bears of the High Arctic  

Microsoft Academic Search

We used mark-recapture data and population viability analysis (PVA) to estimate demographic parameters, abundance, and harvest risks for two adjacent populations of polar bears (Ursus maritimus) inhabiting Lancaster Sound and Norwegian Bay, Canada. Analyses were based on data from 1871 bears that were uniquely marked during the period 1972 - 97. Our best-fitting mark-recapture model specified sex and age effects

MITCHELL K. TAYLOR; JEFF LAAKE; PHILIP D. McLOUGHLIN; H. DEAN CLUFF; FRANÇOIS MESSIER

2008-01-01

233

Organic and inorganic bromine compounds and their composition in the Arctic troposphere during polar sunrise  

Microsoft Academic Search

Particle and gas phase inorganic bromine, total organic bromine, and several individual organic bromine species were measured in the troposphere during the Polar Sunrise Experiment at Alert, Northwest Territories, Canada, during January 18 to April 21, 1992. The measurements revealed the following: (1) Particle bromide increased gradually from about 10 ng(Br)\\/m³ during the dark period to >20 ng(Br)\\/m³ during the

Shao-Meng Li; Y. Yokouchi; L. A. Barrie; K. Muthuramu; P. B. Shepson; J. W. Bottenheim; W. T. Sturges; S. Landsberger

1994-01-01

234

The Severe Arctic Ozone Depletion 2010/11 - Implications for UV Radiation in Europe and North America  

NASA Astrophysics Data System (ADS)

The Arctic winter 2010/11 saw record ozone depletion in the northern polar vortex with column ozone dropping below 250 DU by the end of the winter. One question of concern is, how strongly such a winter affects surface UV radiation in high and mid-latitudes and in particular in central Europe and North America. This obviously depends not only on the degree of ozone depletion but also on the spatial extent and the position of the depleted vortex. Besides, surface UV levels are influenced by other factors such as cloudiness, aerosol loading and variations in the solar flux. Here, monthly average as well as maximum erythemal UV doses are calculated for spring and early summer over different regions in Europe and North America for Arctic winters between 1980 and 2011, using data from the Ozone Monitoring Instrument (OMI) onboard the EOS Aura satellite and the Total Ozone Mapping Spectrometer onboard Nimbus-7, Meteor-3 and Earth-Probe. The comparison of UV data from Arctic winters with very different degrees of polar vortex ozone loss allows to estimate the extent, to which large vortex ozone losses translate directly into higher surface UV in certain areas in high and mid-latitudes. Special attention is given to the 2010/11 winter.

von Hobe, M.; Griessbach, S.; Wegner, T.

2011-12-01

235

Arctic stratospheric dehydration - Part 1: Unprecedented observation of vertical redistribution of water  

NASA Astrophysics Data System (ADS)

We present high-resolution measurements of water vapour, aerosols and clouds in the Arctic stratosphere in January and February 2010 carried out by in-situ instrumentation on balloon-sondes and high-altitude aircraft combined with satellite observations. The measurements provide unparalleled evidence of dehydration and rehydration due to gravitational settling of ice particles. An extreme cooling of the Arctic stratospheric vortex during the second half of January 2010 resulted in a rare synoptic-scale outbreak of ice PSCs (polar stratospheric clouds) detected remotely by the lidar aboard the CALIPSO satellite. The widespread occurrence of ice clouds was followed by sedimentation and consequent sublimation of ice particles, leading to vertical redistribution of water inside the vortex. A sequence of balloon and aircraft soundings with chilled mirror and Lyman-? hygrometers (CFH, FISH, FLASH) and backscatter sondes (COBALD) conducted in January 2010 within the LAPBIAT and RECONCILE campaigns captured various phases of this phenomenon: ice formation, irreversible dehydration and rehydration. Consistent observations of water vapour by these independent measurement techniques show clear signatures of irreversible dehydration of the vortex air by up to 1.6 ppmv in the 20-24 km altitude range and rehydration by up to 0.9 ppmv in a 1 km-thick layer below. Comparison with space-borne Aura MLS water vapour observations allow the spatiotemporal evolution of dehydrated air masses within the Arctic vortex to be derived and upscaled.

Khaykin, S. M.; Engel, I.; Vömel, H.; Formanyuk, I. M.; Kivi, R.; Korshunov, L. I.; Krämer, M.; Lykov, A. D.; Meier, S.; Naebert, T.; Pitts, M. C.; Santee, M. L.; Spelten, N.; Wienhold, F. G.; Yushkov, V. A.; Peter, T.

2013-05-01

236

Evaluation of the SKYHI general circulation model using aircraft N2O measurements. 1: Polar winter stratospheric meteorology and tracer morphology  

SciTech Connect

Winter polar stratospheric nitric oxide (N2O) measurements made during two NASA polar aircraft field campaigns are used to evaluate the dynamics of the Geophysical Fluid Dynamics Laboratory's 'SKYHI' general circulation model. SKYHI has 1 deg latitude by 1.2 deg longitude grid spacing and 40 vertical levels (up to 80 km) and precscribed N2O dissociation coefficients. The model has been integrated a total of 20 months, producing one Antarctic and two Artic winters. The climatologies of these winters are compared with the known northern and southern hemisphere climatologies and to the meteorological conditions durng the time of the field campaigns. The two Arctic SKYHI winters show considerable interannual variability. In the lower stratosphere, SKYHI realistically simulates the magnitude and variability of winds and temperatures both inside and outside the polar vortex and can produce a credible sudden warming. In the Antarctic the magnitude and variablity of winds and temperatures around the polar vortex are quite realistic, but inside the vortex, temperatures are too low. Flight data from each mission have been averaged together to produce a contour map showing N2O morphology in and around the vortex. Because the N2O distribution in the lower stratosphere is under dynamical control, the mean N2O field can be used to interpret the dynamics of the polar stratosphere. At the Arctic vortex edge, Airborne Arctic Stratospheric Experiment (AASE) data show large gradients of N2O on isentropic surfaces. SKYHI vortex edge gradients are nearly as large, and model mixing ratios between 400 and 500 K (potential temperature) are similar to the observations. In the Antarctic, model mixing ratios are too high everywhere and the edge gradients are flatter than the observed gradients. The comparison of mean N2O fields suggests realistic wave activity in the SKYHI Arctic winter but inadequate wave activity in the SKYHI Antarctic winter.

Strahan, S.E.; Mahlman, J.D. (Princeton Univ., NJ (United States) NOAA Geophysical Fluid Dynamics Lab, Princeton, NJ (United States))

1994-05-01

237

Chemical ozone depletion during Arctic winter 1997/98 derived from ground based millimeter-wave observations  

NASA Astrophysics Data System (ADS)

We present ground based millimeter-wave measurements of Arctic stratospheric ozone at Ny-Ålesund, Spitsbergen (79N, 12E), for winter 1997/98. Vortex averaged chemical ozone depletion rates around the 475 K isentropic level were derived from our observations using measured ozone trends for 20 day periods and calculations of diabatic descent inside the vortex. Back trajectory calculations for air-parcels crossing Ny-Ålesund show that measurements at Ny-Ålesund were representative for vortex air-masses. Significant chemical ozone depletion was observed during one period at the end of February 1998 with loss rates of 32 ppb/day around the 475 K isentropic level. During this period the loss rate was higher than in February 1997. Due to the early breakup of the polar vortex, the chemical ozone depletion stopped in March and the accumulated loss is found to be 0.64±0.2 ppm in 1997/98.

Langer, J.; Barry, B.; Klein, U.; Sinnhuber, B.-M.; Wohltmann, I.; Künzi, K. F.

238

Polar Bears  

NSDL National Science Digital Library

Use the following websites to answer questions about the rapid disappearance of polar bears in the Arctic region. Polar Bear picture Polar Bear Tracker 1: What region in the world has the fewest polar bears? 2: Using the internet as a resource, provide some reasons as to why this region is suffering from the most polar bear differences? Polar Bears Change Diet 1: Why are polar bears having to change their diets? 2: List some other factors (besides diet) in the ...

Thomas, Mr.

2010-09-27

239

Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic.  

PubMed

Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems. PMID:24500172

Iverson, Samuel A; Gilchrist, H Grant; Smith, Paul A; Gaston, Anthony J; Forbes, Mark R

2014-03-22

240

Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic  

PubMed Central

Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears’ ability to meet their energetic demands. In this study, we examined polar bears’ use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010–2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator–prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems. PMID:24500172

Iverson, Samuel A.; Gilchrist, H. Grant; Smith, Paul A.; Gaston, Anthony J.; Forbes, Mark R.

2014-01-01

241

Vortex–Vortex Interactions in the Winter Stratosphere  

Microsoft Academic Search

This paper examines the interaction of oppositely signed vortices in the compressible (non-Boussinesq) quasigeostrophic system, with a view to understanding vortex interactions in the polar winter stratosphere. A series of simplifying approximations leads to a two-vortex system whose dynamical properties are de- termined principally by two parameters: the ratio of the circulation of the vortices and the vertical sepa- ration

R. K. Scott; D. G. Dritschel

2006-01-01

242

Global Hawk dropsonde observations of the Arctic atmosphere during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) field campaign  

NASA Astrophysics Data System (ADS)

In February and March of 2011, the Global Hawk unmanned aircraft system (UAS) was deployed over the Pacific Ocean and the Arctic during the WISPAR field campaign. The WISPAR science missions were designed to: (1) improve our understanding of Pacific weather systems and the polar atmosphere; (2) evaluate operational use of unmanned aircraft for investigating these atmospheric events; and (3) demonstrate operational and research applications of a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind information between the stratosphere and surface. The 35 m wingspan Global Hawk, which can soar for ~ 31 h at altitudes up to ~ 20 km, was remotely operated from NASA's Dryden Flight Research Center at Edwards AFB in California. During the 25 h polar flight on 9-10 March 2011, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude marking the first UAS Arctic dropsonde mission of its kind. The polar flight transected an unusually cold polar vortex, notable for an associated record-level Arctic ozone loss, and documented polar boundary layer variations over a sizable ocean-ice lead feature. Comparison of dropsonde observations with atmospheric reanalyses reveal that for this day, large-scale structures such as the polar vortex and air masses are captured by the reanalyses, while smaller-scale features, including low-level jets and inversion depths, are mischaracterized. The successful Arctic dropsonde deployment demonstrates the capability of the Global Hawk to conduct operations in harsh, remote regions. The limited comparison with other measurements and reanalyses highlights the value of Arctic atmospheric dropsonde observations where routine in situ measurements are practically non-existent.

Intrieri, J. M.; de Boer, G.; Shupe, M. D.; Spackman, J. R.; Wang, J.; Neiman, P. J.; Wick, G. A.; Hock, T. F.; Hood, R. E.

2014-04-01

243

Early Triassic magnetic polarity time scale—integration of magnetostratigraphy, ammonite zonation and sequence stratigraphy from stratotype sections (Canadian Arctic Archipelago)  

NASA Astrophysics Data System (ADS)

Stratotypes defining the stages of the Early Triassic (Griesbachian, Dienerian, Smithian and Spathian) are located on Ellesmere and Axel Heiberg islands in the northern Canadian Arctic. Ammonite-rich horizons are within a clastic outer shelf-to-slope facies of thick progradational wedges of mudstones and siltstones. Three sections were sampled for magnetostratigraphy and interpreted for transgressive and regressive pulses of sedimentation. Using the ammonite zonation as a guide, the transgressive-regressive cycles and magnetostratigraphies have been correlated among the sections and to the published Triassic sequence stratigraphy time scale, thus enabling definition of the magnetic polarity pattern for the upper Griesbachian to Smithian stages in multiple sections. The magnetic polarity and associated sequence stratigraphy pattern for the lower Griesbachian and for the Spathian were derived from single sections. The Griesbachian and Dienerian stages each have two pairs of normal- and reversed-polarity chrons; the Smithian is predominantly of normal polarity, and the Spathian is predominantly of reversed polarity. This magnetic polarity time scale may help to resolve age correlations of North American redbed facies and to define the Permian-Triassic boundary. After correction for variable structural orientations, the mean directions of magnetization from the three sites converge at 296° declination, 57° inclination ( k = 60, ? 95 = 16.5° ; equivalent pole = 41°N, 161°E; paleolatitude = 38°N), which is consistent with the pole derived from nearby Early Permian volcanics and supports a postulated post-Early Triassic, pre-Tertiary counterclockwise rotation of this region with respect to cratonic North America.

Ogg, James G.; Steiner, Maureen B.

1991-10-01

244

Organic and inorganic bromine compounds and their composition in the Arctic troposphere during polar sunrise  

SciTech Connect

Particle and gas phase inorganic bromine, total organic bromine, and several individual organic bromine species were measured in the troposphere during the Polar Sunrise Experiment at Alert, Northwest Territories, Canada, during January 18 to April 21, 1992. The measurements revealed the following: (1) Particle bromide increased gradually from about 10 ng(Br)/m{sup 3} during the dark period to >20 ng(Br)/m{sup 3} during the light period, with a marked peak of 120 ng(Br)/m{sup 3} corresponding to a strong O{sub 3} depletion event. (2) Inorganic gaseous bromine (InorgBr) was about 60 ng(Br)/m{sup 3} during the dark period and relatively constant. A major peak, up to 280 ng(Br)/m{sup 3}, before sunrise accompanied a similar peak in the total organic bromine. After sunrise the peaks in InorgBr corresponded to O{sub 3} depletion periods. InorgBr appeared to be the sum of HBr, HOBr, and Br{sub 2}. (3) Total organic bromine was relatively constant before sunrise at 100 ng(Br)/m{sup 3} but more variable afterward, up to 280 ng(Br)/m{sup 3}. Individual species include CHBr{sub 3} with levels of 7-60 ng(Br)/m{sup 3}. CH{sub 2}Br{sub 2}, CH{sub 2}ClBr, CHClBr{sub 2}, and CHCl{sub 2}Br levels were lower at 0.5-7.5 ng(Br)/m{sup 3}. CHBr{sub 3} was the largest contributor to total organic bromine of the five species, on average accounting for 23%, while the other four species amounted to less than 5% on average. (4) CHBr{sub 3}, CHClBr{sub 2} and CHCl{sub 2}Br were significantly correlated. The ratio CHClBr{sub 2}/CHBr{sub 3} decreased linearly with increasing ln(CHBr{sub 3}), with a steeper decrease after sunrise than before. The decreases suggest different rates of destruction with CHBr{sub 3} having a larger rate constant than CHClBR{sub 2}. A similar relationship existed between the ratio CHCl{sub 2}Br/CHClBr{sub 2}, but the dark period slope was near zero, indicating a greater difference in rates in the two species in the light period. 37 refs., 9 figs., 3 tabs.

Li, S.M.; Barrie, L.A.; Bottenheim, J.W. [Atmospheric Environment Service, Ontario (Canada)] [and others

1994-12-20

245

Microwave measurements of arctic chlorine monoxide and computed chemical ozone loss in spring 2000  

NASA Astrophysics Data System (ADS)

The University of Bremen (Germany) operates a microwave radiometer for the detection of stratospheric chlorine monoxide at 204 GHz, ozone at 142 GHz and water vapor at 22 GHz. The radiometer for atmospheric measurements (RAM) is located at the primary Arctic station of the Network for the Detection of Stratospheric Change - NDSC - in Ny-Ålesund, Spitsbergen at 79° North and 12° East. We observed a maximum chlorine monoxide (ClO) volume mixing ratio (VMR) of 1.2 ± 0.2 ppb in early March 2000 inside the polar vortex. The observed ClO decreased almost linearly to background values until late March. The vortex averaged chemical ozone loss derived from our observations accumulated to 45% at the 475 K isentropic level over the complete vortex existence period from December 1999 to March 2000.

Klein, U.; Lindner, K.; Bagdohn, S.; Wohltmann, I.; Künzi, K. F.

246

Unraveling the empirical relationship between Arctic stratospheric ozone loss and temperature  

NASA Astrophysics Data System (ADS)

Ever since the discovery of the Antarctic ozone hole it has been recognized that cold temperatures play a key role in fostering strong ozone depletion in the polar stratosphere. Compact negative correlations between total winter ozone loss and vortex area exposed to temperatures below certain threshold values have been demonstrated (e.g. Harris et al., 2010; Rex et al., 2006; Rex et al., 2004). The most commonly used threshold is the NAT equilibrium temperature, but other choices have been suggested, such as the temperature when the rate of chlorine activation on liquid aerosols exceeds a certain limit. Interestingly, both thresholds relate to critical temperatures in the context of heterogeneous chlorine activation, and Harris et al., 2010, stated that original activation (i.e. the activation in early winter) is the most important factor influencing ozone loss. But at least two other key processes - catalytic ozone loss and denitrification - depend directly on temperature, and temperature also controls the stability and therefore the persistence of the polar vortex. Here, we investigate such "vortex area" correlations for a number of different temperature thresholds, as well as direct correlations with vortex mean temperature and with the date of the final warming. We also carry out sensitivity studies using the Chemical Lagrangian Model of the Stratosphere (CLaMS) to investigate the response of ozone loss to temperature modifications for particle formation and growth, surface reaction probabilities and gas phase reactivity separately. Rex et al., Arctic ozone loss and climate change, Geophys. Res. Lett., 31, L04116, 2004. Rex et al., Arctic winter 2005: Implications for stratospheric ozone loss and climate change, Geophys. Res. Lett., 33, L23808, 2006. Harris et al., A closer look at Arctic ozone loss and polar stratospheric clouds, Atmos. Chem. Phys., 10, 8499-8510, 2010.

von Hobe, Marc; Grooß, Jens-Uwe; Müller, Rolf

2014-05-01

247

Polar stratospheric ozone: interactions with climate change, results from the EU project RECONCILE, and the 2010/11 Arctic ozone hole  

NASA Astrophysics Data System (ADS)

One of the most profound and well known examples of human impacts on atmospheric chemistry is the so called ozone hole. During the second half of the 20th century, anthropogenic emissions of chlorofluorocarbons (CFCs) led to a significant increase in stratospheric chlorine levels and hence the rate of ozone removal by catalytic cycles involving chlorine. While CFCs were essentially banned by the 1987 Montreal Protocol and its subsequent amendments, and stratospheric chlorine levels have recently started to decline again, another anthropogenic influence may at least delay the recovery of the stratospheric ozone layer: climate change, with little doubt a result of human emissions of carbon dioxide and other greenhouse gases, has led to changes in stratospheric temperature and circulation. The large ozone losses that typically occur in polar regions in spring are particularly affected by these changes. Here, we give an overview of the ozone-climate interactions affecting polar stratospheric ozone loss, and present latest results from the international research project RECONCILE funded by the European Commission. Remaining open questions will be discussed including the possible impacts of recently suggested geoengineering concepts to artificially enhance the stratospheric aerosol loading. A special focus will also be put on the 2010/11 Arctic winter that saw the first Arctic Ozone hole, including an impact study on surface UV radiation in the densely populated northern mid-latitudes.

von Hobe, Marc

2013-04-01

248

Effects of environmental variation and spatial distance on Bacteria, Archaea and viruses in sub-polar and arctic waters  

PubMed Central

We investigated the influence of environmental parameters and spatial distance on bacterial, archaeal and viral community composition from 13 sites along a 3200-km long voyage from Halifax to Kugluktuk (Canada) through the Labrador Sea, Baffin Bay and the Arctic Archipelago. Variation partitioning was used to disentangle the effects of environmental parameters, spatial distance and spatially correlated environmental parameters on prokaryotic and viral communities. Viral and prokaryotic community composition were related in the Labrador Sea, but were independent of each other in Baffin Bay and the Arctic Archipelago. In oceans, the dominant dispersal mechanism for prokaryotes and viruses is the movement of water masses, thus, dispersal for both groups is passive and similar. Nevertheless, spatial distance explained 7–19% of the variation in viral community composition in the Arctic Archipelago, but was not a significant predictor of bacterial or archaeal community composition in either sampling area, suggesting a decoupling of the processes regulating community composition within these taxonomic groups. According to the metacommunity theory, patterns in bacterial and archaeal community composition suggest a role for species sorting, while patterns of virus community composition are consistent with species sorting in the Labrador Sea and suggest a potential role of mass effects in the Arctic Archipelago. Given that, a specific prokaryotic taxon may be infected by multiple viruses with high reproductive potential, our results suggest that viral community composition was subject to a high turnover relative to prokaryotic community composition in the Arctic Archipelago. PMID:23552622

Winter, Christian; Matthews, Blake; Suttle, Curtis A

2013-01-01

249

New view of Arctic cyclone activity from the Arctic system reanalysis  

E-print Network

New view of Arctic cyclone activity from the Arctic system reanalysis Natalia Tilinina1,2 , Sergey Byrd Polar Research Center, Ohio State University, Columbus, Ohio, USA Abstract Arctic cyclone activity is analyzed in 11 year (2000­2010), 3-hourly output from the Arctic System Reanalysis (ASR) interim version

Howat, Ian M.

250

Effect of Polar Day on Plasma Profiles of Melatonin, Testosterone, and Estradiol in High-Arctic Lapland Longspurs  

Microsoft Academic Search

In polar habitats, continuous daylight (polar day) can prevail for many weeks or months around the summer solstice. In the laboratory, continuous light conditions impair or disrupt circadian rhythms in many animals. To determine whether circadian rhythms are disrupted under natural polar day conditions in a species that is only a summer resident in polar regions we analyzed diel rhythms

Michaela Hau; L. Michael Romero; Jeff D. Brawn; Thomas J. Van't Hof

2002-01-01

251

Arctic Ocean  

NASA Technical Reports Server (NTRS)

The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that tends to increase its sensitivity to climate change. Its temperature, salinity, and ice cover have all undergone changes in the past several decades, although it is uncertain whether these predominantly reflect long-term trends, oscillations within the system, or natural variability. Major changes include a warming and expansion of the Atlantic layer, at depths of 200-900 m, a warming of the upper ocean in the Beaufort Sea, a considerable thinning (perhaps as high as 40%) of the sea ice cover, a lesser and uneven retreat of the ice cover (averaging approximately 3% per decade), and a mixed pattern of salinity increases and decreases.

Parkinson, Claire L.; Zukor, Dorothy J. (Technical Monitor)

2000-01-01

252

Arctic stratospheric dehydration - Part 1: Unprecedented observation of vertical redistribution of water  

NASA Astrophysics Data System (ADS)

We present high-resolution measurements of water vapour, aerosols and clouds in the Arctic stratosphere in January and February 2010 carried out by in situ instrumentation on balloon sondes and high-altitude aircraft combined with satellite observations. The measurements provide unparalleled evidence of dehydration and rehydration due to gravitational settling of ice particles. An extreme cooling of the Arctic stratospheric vortex during the second half of January 2010 resulted in a rare synoptic-scale outbreak of ice polar stratospheric clouds (PSCs) remotely detected by the lidar aboard the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite. The widespread occurrence of ice clouds was followed by sedimentation and consequent sublimation of ice particles, leading to vertical redistribution of water inside the vortex. A sequence of balloon and aircraft soundings with chilled mirror and Lyman- ? hygrometers (Cryogenic Frostpoint Hygrometer, CFH; Fast In Situ Stratospheric Hygrometer, FISH; Fluorescent Airborne Stratospheric Hygrometer, FLASH) and backscatter sondes (Compact Optical Backscatter Aerosol Detector, COBALD) conducted in January 2010 within the LAPBIAT (Lapland Atmosphere-Biosphere Facility) and RECONCILE (Reconciliation of Essential Process Parameters for an Enhanced Predictability of Arctic Stratospheric Ozone Loss and its Climate Interactions) campaigns captured various phases of this phenomenon: ice formation, irreversible dehydration and rehydration. Consistent observations of water vapour by these independent measurement techniques show clear signatures of irreversible dehydration of the vortex air by up to 1.6 ppmv in the 20-24 km altitude range and rehydration by up to 0.9 ppmv in a 1 km thick layer below. Comparison with space-borne Aura MLS (Microwave Limb Sounder) water vapour observations allow the spatiotemporal evolution of dehydrated air masses within the Arctic vortex to be derived and upscaled.

Khaykin, S. M.; Engel, I.; Vömel, H.; Formanyuk, I. M.; Kivi, R.; Korshunov, L. I.; Krämer, M.; Lykov, A. D.; Meier, S.; Naebert, T.; Pitts, M. C.; Santee, M. L.; Spelten, N.; Wienhold, F. G.; Yushkov, V. A.; Peter, T.

2013-11-01

253

Extensive sampling of polar bears (Ursus maritimus) in the Northwest Passage (Canadian Arctic Archipelago) reveals population differentiation across multiple spatial and temporal scales.  

PubMed

As global warming accelerates the melting of Arctic sea ice, polar bears (Ursus maritimus) must adapt to a rapidly changing landscape. This process will necessarily alter the species distribution together with population dynamics and structure. Detailed knowledge of these changes is crucial to delineating conservation priorities. Here, we sampled 361 polar bears from across the center of the Canadian Arctic Archipelago spanning the Gulf of Boothia (GB) and M'Clintock Channel (MC). We use DNA microsatellites and mitochondrial control region sequences to quantify genetic differentiation, estimate gene flow, and infer population history. Two populations, roughly coincident with GB and MC, are significantly differentiated at both nuclear (F ST = 0.01) and mitochondrial (?ST = 0.47; F ST = 0.29) loci, allowing Bayesian clustering analyses to assign individuals to either group. Our data imply that the causes of the mitochondrial and nuclear genetic patterns differ. Analysis of mtDNA reveals the matrilineal structure dates at least to the Holocene, and is common to individuals throughout the species' range. These mtDNA differences probably reflect both genetic drift and historical colonization dynamics. In contrast, the differentiation inferred from microsatellites is only on the scale of hundreds of years, possibly reflecting contemporary impediments to gene flow. Taken together, our data suggest that gene flow is insufficient to homogenize the GB and MC populations and support the designation of GB and MC as separate polar bear conservation units. Our study also provide a striking example of how nuclear DNA and mtDNA capture different aspects of a species demographic history. PMID:24102001

Campagna, Leonardo; Van Coeverden de Groot, Peter J; Saunders, Brenda L; Atkinson, Stephen N; Weber, Diana S; Dyck, Markus G; Boag, Peter T; Lougheed, Stephen C

2013-09-01

254

Life in a temperate Polar sea: a unique taphonomic window on the structure of a Late Cretaceous Arctic marine ecosystem  

PubMed Central

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75?Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input. PMID:18713718

Chin, Karen; Bloch, John; Sweet, Arthur; Tweet, Justin; Eberle, Jaelyn; Cumbaa, Stephen; Witkowski, Jakub; Harwood, David

2008-01-01

255

Life in a temperate Polar sea: a unique taphonomic window on the structure of a Late Cretaceous Arctic marine ecosystem.  

PubMed

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75 Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input. PMID:18713718

Chin, Karen; Bloch, John; Sweet, Arthur; Tweet, Justin; Eberle, Jaelyn; Cumbaa, Stephen; Witkowski, Jakub; Harwood, David

2008-12-01

256

From polar night to midnight sun: photoperiod, seal predation, and the diel vertical migrations of polar cod ( Boreogadus saida ) under landfast ice in the Arctic Ocean  

Microsoft Academic Search

The winter\\/spring vertical distributions of polar cod, copepods, and ringed seal were monitored at a 230-m station in ice-covered\\u000a Franklin Bay. In daytime, polar cod of all sizes (7–95 g) formed a dense aggregation in the deep inverse thermocline (160–230 m,\\u000a ?1.0 to 0°C). From December (polar night) to April (18-h daylight), small polar cod <25 g migrated into the isothermal cold\\u000a intermediate

Delphine Benoit; Yvan Simard; Jacques Gagné; Maxime Geoffroy; Louis Fortier

2010-01-01

257

Circum-arctic comparison of the hatching season of polar cod Boreogadus saida: A test of the freshwater winter refuge hypothesis  

NASA Astrophysics Data System (ADS)

The hypothesis that salt-related differences in winter sea surface temperature dictate regional differences in the hatching season of polar cod Boreogadus saida is tested by contrasting hatch-date frequency distributions among six oceanographic regions of the Arctic Ocean characterized by different freshwater input. Consistent with the hypothesis, hatching started as early as January and extended to July in seas receiving large river discharge (Laptev/East Siberian Seas, Hudson Bay, and Beaufort Sea). By contrast, hatching was restricted to April-July in regions with little freshwater input (Canadian Archipelago, North Baffin Bay, and Northeast Water). Length (weight) in late-summer (14 August) varied from <10 mm (<0.01 g) in July hatchers to 50 mm (0.91 g) in January hatchers. An earlier ice break-up, more frequent winter polynyas, a warmer surface layer, and increased river discharge linked to climate warming could enhance the survival of juvenile 0+ polar cod by enabling a larger fraction of the annual cohort to hatch earlier and reach a larger size before the fall migration to the deep overwintering grounds. A further test of the hypothesis would require the verification that the early winter hatching of polar cod actually occurs in the thermal refuge provided by under-ice river plumes.

Bouchard, Caroline; Fortier, Louis

2011-07-01

258

Contamination of food by crude oil affects food selection and growth performance, but not appetite, in an Arctic fish the polar cod (Boreogadus saida)  

SciTech Connect

The polar cod (Boreogadus saida) is recognized as a key species in Arctic marine food webs and it may, therefore, be important for the transfer of xenobiotics from lower trophic levels to its main predators, birds and sea mammals. The present work examines the effects of foods contaminated with 200 or 400 ppm crude oil on food selection patterns and appetite-growth relationship in polar cod using X-radiography. It is shown that sexually mature polar cod consumed mixtures of uncontaminated and oil-contaminated foods, and did not show a reduced overall appetite as compared with fish provided with uncontaminated food only. Food selection was, however, influenced by both sex and individual appetite. Male fish selected uncontaminated food when appetite was low, whereas females ingested contaminated and uncontaminated foods equally, irrespective of appetite level. The ingestion of oil-contaminated food led to a significant depression in growth performance in both male and female fish. Food contaminated with oil at a concentration of 500 ppm was completely rejected by both sexes. 6 refs., 4 figs., 2 tabs.

Christiansen, J.S. [Norwegian Institute of Fisheries and Aquaculture, Troms (Norway); George, S.G. [Univ. of Stirling, Scotland (United Kingdom)

1995-04-01

259

The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing  

PubMed Central

In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around ‘climate response functions’ (CRFs), i.e. the response of the climate to ‘step’ changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate. PMID:24891392

Marshall, John; Armour, Kyle C.; Scott, Jeffery R.; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G.; Bitz, Cecilia M.

2014-01-01

260

The ocean's role in polar climate change: asymmetric Arctic and Antarctic responses to greenhouse gas and ozone forcing.  

PubMed

In recent decades, the Arctic has been warming and sea ice disappearing. By contrast, the Southern Ocean around Antarctica has been (mainly) cooling and sea-ice extent growing. We argue here that interhemispheric asymmetries in the mean ocean circulation, with sinking in the northern North Atlantic and upwelling around Antarctica, strongly influence the sea-surface temperature (SST) response to anthropogenic greenhouse gas (GHG) forcing, accelerating warming in the Arctic while delaying it in the Antarctic. Furthermore, while the amplitude of GHG forcing has been similar at the poles, significant ozone depletion only occurs over Antarctica. We suggest that the initial response of SST around Antarctica to ozone depletion is one of cooling and only later adds to the GHG-induced warming trend as upwelling of sub-surface warm water associated with stronger surface westerlies impacts surface properties. We organize our discussion around 'climate response functions' (CRFs), i.e. the response of the climate to 'step' changes in anthropogenic forcing in which GHG and/or ozone-hole forcing is abruptly turned on and the transient response of the climate revealed and studied. Convolutions of known or postulated GHG and ozone-hole forcing functions with their respective CRFs then yield the transient forced SST response (implied by linear response theory), providing a context for discussion of the differing warming/cooling trends in the Arctic and Antarctic. We speculate that the period through which we are now passing may be one in which the delayed warming of SST associated with GHG forcing around Antarctica is largely cancelled by the cooling effects associated with the ozone hole. By mid-century, however, ozone-hole effects may instead be adding to GHG warming around Antarctica but with diminished amplitude as the ozone hole heals. The Arctic, meanwhile, responding to GHG forcing but in a manner amplified by ocean heat transport, may continue to warm at an accelerating rate. PMID:24891392

Marshall, John; Armour, Kyle C; Scott, Jeffery R; Kostov, Yavor; Hausmann, Ute; Ferreira, David; Shepherd, Theodore G; Bitz, Cecilia M

2014-07-13

261

International Polar Year GEOTRACES: an International Study of the Biogeochemical Cycles of Trace Elements and Isotopes in the Arctic and Southern Oceans  

NASA Astrophysics Data System (ADS)

Trace elements and their isotopes play an important role in oceanography as participants in, and as tracers of, processes of fundamental interest. Some trace elements (e.g., Fe, Co, Zn) serve as essential micronutrients, the availability of which influences the physiological state and biochemical activity of marine organisms. This, in turn, controls the structure of ocean ecosystems and their biological productivity. For example, Fe is the key limiting trace nutrient in the Southern Ocean. Moreover several natural stable and radio- isotopes in the oceans serve as tracers of specific ocean processes like mixing, biogenic export, or adsorption. Quantification of such processes is feasible via mass fractionation or decay rate of the selected isotope. In context of worldwide GEOTRACES, scientists of 19 nations are developing an intensive observation program during the International Polar Year to detect and understand a suite of trace elements and isotopes in the Arctic and Antarctic marine environment.

de Baar, H. J.; Anderson, R.

2006-12-01

262

Airborne Arctic Stratospheric Expedition 2: Air Parcel Trajectories  

NASA Technical Reports Server (NTRS)

An overview of Airborne Arctic Stratospheric Expedition 2 is given. Effects of Pinatubo aerosol on stratospheric ozone at mid-latitudes, in situ measurements of ClO and ClO/HCl ratio, balloon-borne measurements of ClO, NO, and O3 in a volcanic cloud, and new observations of the NO(y)/N2O correlation in the lower stratosphere are discussed. Among other topics addressed are the following: in situ tracer correlations of methane, nitrous oxide, and ozone as observed aboard the DC-8, in situ measurements of changes in stratospheric aerosol and the N2O-aerosol relationship inside and outside of the polar vortex, measurements of halogenated organic compounds near the tropical tropopause, and airborne brightness measurements of the polar winter troposphere.

1993-01-01

263

Arctic Research Opportunities  

NSF Publications Database

Arctic research is supported at NSF by the Office of Polar Programs (OPP; http://www.nsf.gov/od/opp) in the Office of the Director, as well as by a number of other programs within the Foundation. Program representatives from OPP and other NSF programs that support arctic research coordinate across NSF, including joint review and funding of arctic proposals, as well as mutual support of special projects with high logistical costs. Crosscutting programs at NSF (http://www.nsf.gov/home/crssprgm/...

264

Teachers, Researchers, and Students Collaborating in Arctic Climate Change Research: The Partnership Between the Svalbard REU and ARCUS PolarTREC programs  

NASA Astrophysics Data System (ADS)

Since 2004, the Arctic Research Consortium of the U.S. (ARCUS) "TREC" program (Teachers and Researchers Exploring and Collaborating, now "PolarTREC") has sent four K-12 teachers to Svalbard, Norway to work alongside researchers and undergraduate students conducting climate change research as part of the Svalbard Research Experiences for Undergraduates (REU) Program. The benefits of this scientist/educator/student partnership are many. Researchers benefit from teacher participation as it increases their understanding of student learning and the roles and responsibilities of K-12 teachers. The TREC teacher contributes to the research by making observations, analyzing data, and carrying heavy loads of equipment. In collaborating with K- 12 teachers, undergraduate student participants discover the importance of teamwork in science and the need for effective communication of scientific results to a broad audience. The questions that K-12 teachers ask require the scientists and students in our program to explain their work in terms that non-specialists can understand and appreciate. The K-12 teacher provides a positive career role model and several Svalbard REU undergraduate students have pursued K-12 teaching careers after graduating. TREC teachers benefit from working alongside the researchers and by experiencing the adventures of real scientific research in a remote arctic environment. They return to their schools with a heightened status that allows them to share the excitement and importance of scientific research with their students. Together, all parties contribute to greatly enhance public outreach. With ARCUS logistical support, TREC teachers and researchers do live web conferences from the field, reaching hundreds of students and dozens of school administrators and even local politicians. Teachers maintain web journals, describing the daily activities and progress of the researcher team. Online readers from around the world write in to ask questions, which the TREC teacher answers after consulting the research team. TREC teachers have developed and distributed teaching modules using real questions and data from the research program. Our collaboration is successful in part because the teachers are well prepared by ARCUS in advance of the field experience and the Svalbard REU leaders treat the TREC teacher as a senior member of the research team. Reliable telephone and internet communication from the field site is also important because it greatly facilitates the daily outreach. Our success is measured by the hundreds of K-12 students exposed to arctic climate change research (some of which are now going to college to pursue geoscience studies!) and the mutual desire for continued collaboration between the Svalbard REU Program and the ARCUS PolarTREC Program.

Roof, S.; Warburton, J.; Oddo, B.; Kane, M.

2007-12-01

265

Arctic aerosol size-segregated chemical observations in relation to ozone depletion during Polar Sunrise Experiment 1992  

SciTech Connect

The authors report measurements of aerosol particle size distributions and chemical compositions in the arctic winter atmosphere by means of two different impactor instruments. They looked at halogens, Na, V, As, Sb, Zn, Al, Ca, SO{sub 4}{sup 2{minus}}, Sm, K, Mn, and Mg. Several of the chemical elements were observed predominantly in particles less than 2.5 {mu}m diameter (V, Br, I, As, Sb, Zn, and SO{sub 4}{sup 2{minus}}). Cl was observed more often in larger particles relative to Na. They observed an anticorrelation between the observed occurance of Br and the measured ozone density during all observations.

Barrie, L.A.; Staebler, R.; Toom, D. [Atmospheric Environment Service, Ontario (Canada)] [and others] [Atmospheric Environment Service, Ontario (Canada); and others

1994-12-20

266

Arctic System Reanalysis David. H. Bromwich1,2  

E-print Network

Arctic System Reanalysis David. H. Bromwich1,2 , and Keith M. Hines1 1 Polar Meteorology Group the recently-observed dramatic changes in Arctic land ice, sea ice, and permafrost regions. In response to the Arctic's importance for climate change, the Study of Environmental Arctic Change (SEARCH) project

Howat, Ian M.

267

Early Paleogene Arctic terrestrial ecosystems affected by the change of polar hydrology under global warming: Implications for modern climate change at high latitudes  

Microsoft Academic Search

Our understanding of both the role and impact of Arctic environmental changes under the current global warming climate is\\u000a rather limited despite efforts of improved monitoring and wider assessment through remote sensing technology. Changes of Arctic\\u000a ecosystems under early Paleogene warming climate provide an analogue to evaluate long-term responses of Arctic environmental\\u000a alteration to global warming. This study reviews Arctic

Qin Leng; Gaytha A. Langlois; Hong Yang

2010-01-01

268

Generation of cylindrical vector vortex beams by two cascaded metasurfaces  

NASA Astrophysics Data System (ADS)

We present a simple and efficient method to generate any cylindrical vector vortex (CVV) beams based on two cascaded metasurfaces. The metasurface works as a space-variant Panchratnam-Berry phase element and can produce any desirable vortex phase and vector polarization. The first metasurface is used to switch the sign of topological charges associated with vortex, and the second metasurface is applied to manipulate the local polarization. This method allows us to simultaneously manipulate polarization and phase of the CVV beams.

Yi, Xunong; Ling, Xiaohui; Zhang, Zhiyou; Li, Ying; Zhou, Xinxing; Liu, Yachao; Chen, Shizhen; Luo, Hailu; Wen, Shuangchun

2014-07-01

269

Polar Bear  

USGS Publications Warehouse

Polar bears are long-lived, late-maturing carnivores that have relatively low rates of reproduction and natural mortality. Their populations are susceptible to disturbance from human activities, such as the exploration and development of mineral resources or hunting. Polar bear populations have been an important renewable resource available to coastal communities throughout the Arctic for thousands of years.

Amstrup, S.D.

1988-01-01

270

Magnetic vortex based transistor operations.  

PubMed

Transistors constitute the backbone of modern day electronics. Since their advent, researchers have been seeking ways to make smaller and more efficient transistors. Here, we demonstrate a sustained amplification of magnetic vortex core gyration in coupled two and three vortices by controlling their relative core polarities. This amplification is mediated by a cascade of antivortex solitons travelling through the dynamic stray field. We further demonstrated that the amplification can be controlled by switching the polarity of the middle vortex in a three vortex sequence and the gain can be controlled by the input signal amplitude. An attempt to show fan-out operation yielded gain for one of the symmetrically placed branches which can be reversed by switching the core polarity of all the vortices in the network. The above observations promote the magnetic vortices as suitable candidates to work as stable bipolar junction transistors (BJT). PMID:24531235

Kumar, D; Barman, S; Barman, A

2014-01-01

271

Magnetic Vortex Based Transistor Operations  

PubMed Central

Transistors constitute the backbone of modern day electronics. Since their advent, researchers have been seeking ways to make smaller and more efficient transistors. Here, we demonstrate a sustained amplification of magnetic vortex core gyration in coupled two and three vortices by controlling their relative core polarities. This amplification is mediated by a cascade of antivortex solitons travelling through the dynamic stray field. We further demonstrated that the amplification can be controlled by switching the polarity of the middle vortex in a three vortex sequence and the gain can be controlled by the input signal amplitude. An attempt to show fan–out operation yielded gain for one of the symmetrically placed branches which can be reversed by switching the core polarity of all the vortices in the network. The above observations promote the magnetic vortices as suitable candidates to work as stable bipolar junction transistors (BJT). PMID:24531235

Kumar, D.; Barman, S.; Barman, A.

2014-01-01

272

Magnetic Vortex Based Transistor Operations  

NASA Astrophysics Data System (ADS)

Transistors constitute the backbone of modern day electronics. Since their advent, researchers have been seeking ways to make smaller and more efficient transistors. Here, we demonstrate a sustained amplification of magnetic vortex core gyration in coupled two and three vortices by controlling their relative core polarities. This amplification is mediated by a cascade of antivortex solitons travelling through the dynamic stray field. We further demonstrated that the amplification can be controlled by switching the polarity of the middle vortex in a three vortex sequence and the gain can be controlled by the input signal amplitude. An attempt to show fan-out operation yielded gain for one of the symmetrically placed branches which can be reversed by switching the core polarity of all the vortices in the network. The above observations promote the magnetic vortices as suitable candidates to work as stable bipolar junction transistors (BJT).

Kumar, D.; Barman, S.; Barman, A.

2014-02-01

273

Rapid development of arctic cyclone in June 2008 simulated by the cloud resolving global model NICAM  

NASA Astrophysics Data System (ADS)

In this study, we conducted a numerical simulation of a rapid development of an arctic cyclone (AC) that appeared in June 2008 using a cloud resolving global model, Nonhydrostatic ICosahedral Atmospheric Model (NICAM). We investigated the three dimensional structure and intensification mechanism of the simulated AC that developed to the minimum sea level pressure of 971 hPa in the model. According to the result, the AC indicates a barotropic structure with a warm core in the lower stratosphere and a cold core in the troposphere. The development of the AC is accompanied by an intense mesoscale cyclone (MC) showing baroclinic structure with a marked local arctic front. The upper level warm core of the AC is formed by an adiabatic heating associated with the downdraft in the lower stratosphere. The rapid development of the AC is caused by the combination of the intensification of the upper level warm core and the merging with the baroclinically growing MC in the lower level. The merging of the AC and MC and the vertical vortex coupling with the upper air polar vortex are the most important mechanisms for the rapid development of the arctic cyclone.

Aizawa, Takuro; Tanaka, H. L.; Satoh, Masaki

2014-11-01

274

The Arctic winter 2010/11 as observed by GOME-2 and SCIAMACHY and its relation to dominant modes of interannual climate variability  

NASA Astrophysics Data System (ADS)

Arctic winter-spring ozone losses in the stratosphere exhibit a large inter annual variability, emphasising that planetary wave driving largely controls magnitude as well as timing of chemically-induced losses in the stratosphere by a maintaining the strength of the polar vortex. In the course of implementing the Montreal Protocol, the release of anthropogenic long-lived ozone depleting substances into the atmosphere was greatly reduced, so that ongoing observations of stratospheric ozone suggest that the declining trend in the global ozone abundance is being reversed. However, through their long-lived nature, the reservoir of ozone killers in the upper atmosphere remains large so that one may expect that those substances may also force severe ozone losses in necessarily cold polar vortices in near future. In this work, we present a comprehensive compilation of SCIAMACHY/ENVISAT stratospheric trace gas (O3, BrO, NO2, OClO) and PSC observations during winter 2010/2011. We compare this situation of the Arctic stratosphere with that during precedent boreal winters within the SCIAMACHY period. Furthermore, we show that severe ozone losses over the Arctic are clearly associated with a characteristic evolution of the planetary wave activity in the stratosphere before and during the formation of the polar vortex, and show that this mode predominated establishes when La Niña occurred in precedent summer month.

Hommel, R.; Eichmann, K.-U.; von Savigny, C.; Weber, M.; Rozanov, A.; Richter, A.; Bramstedt, K.; Wittrock, F.; Noel, S.; Aschmann, J.; Burrows, J. P.; Graf, H. F.; Khosrawi, F.

2012-04-01

275

The Influence of Stratospheric Vortex Displacements and Splits on Surface Climate  

NASA Astrophysics Data System (ADS)

A strong link exists between stratospheric variability and anomalous weather patterns at the Earth's surface. Specifically, during extreme variability of the Arctic polar vortex termed a 'weak vortex event', anomalies can descend from the upper stratosphere to the surface on timescales of weeks. Subsequently the outbreak of cold-air events have been noted in high Northern Latitudes, as well as a quadrapole pattern in surface temperature over the Atlantic and western European sectors and it is currently not understood why certain events descend to the surface while others do not. In this study we compare a new classification technique of weak vortex events, based on the distribution of potential vorticity, with that of an existing technique and demonstrate that the subdivision of such events into vortex displacements and vortex splits has important implications for tropospheric weather patterns on weekly-monthly timescales. Using reanalysis data we find that vortex splitting events are correlated with surface weather and lead to positive temperature anomalies over eastern North-America of more than 1.5K, and negative anomalies over Eurasia of up to -3K. Associated with this is an increase in high-latitude blocking in both the Atlantic and Pacific sectors and a decrease in European blocking. The corresponding signals are weaker during displacement events, although ultimately they are shown to be related to cold-air outbreaks over North America. Owing to the predictability and importance of stratosphere-troposphere coupling for medium-range weather forecasts, our findings suggest the need for forecasting systems to correctly identify the type of stratospheric variability, otherwise surface responses cannot be accurately reproduced.

Mitchell, Dann; Gray, Lesley; Anstey, James; Baldwin, Mark; Charlton-Perez, Andrew

2014-05-01

276

Chemical analysis of polar stratospheric cloud particles  

PubMed

A balloon-borne gondola carrying a particle analysis system, a backscatter sonde, and pressure and temperature sensors was launched from Kiruna, Sweden, on 25 January 1998. Measurements within polar stratospheric cloud layers inside the Arctic polar vortex show a close correlation between large backscatter ratios and enhanced particle-related water and nitric acid signals at low temperatures. Periodic structures in the data indicate the presence of lee waves. The H2O/HNO3 molar ratios are consistently found to be above 10 at atmospheric temperatures between 189 and 192 kelvin. Such high ratios indicate ternary solution particles of H2O, HNO3, and H2SO4 rather than the presence of solid hydrates. PMID:9974386

Schreiner; Voigt; Kohlmann; Arnold; Mauersberger; Larsen

1999-02-12

277

Douglas and Sturm, Page 1 ARCTIC HAZE, MERCURY AND THE CHEMICAL COMPOSITION OF SNOW  

E-print Network

Douglas and Sturm, Page 1 ARCTIC HAZE, MERCURY AND THE CHEMICAL COMPOSITION OF SNOW ACROSS loading (arctic haze) that develops as the Arctic polar front expands southward in March and April. Haze contaminants in northwest Alaska is arctic haze. During late winter and early spring, when the Polar Front

Sturm, Matthew

278

A Observational Study of Mixing in the Arctic Winter Stratosphere.  

NASA Astrophysics Data System (ADS)

Dynamic isolation of the winter Arctic circumpolar vortex is studied using analyzed winds derived from geopotential height fields. Isentropic trajectories are calculated for assemblages of particles initialized on uniform latitude -longitude grids. Transport across isolines of Ertel potential vorticity (PV) is used to characterize the mixing processes of ejection of vortex air and entrainment of midlatitude air into the vortex. During January and February a barrier to mixing, where exchange of air is inhibited, typically forms near the vortex boundary. At 450 K, transport across the barrier is predominantly in the form of thin filaments of particles ejected from the vortex. These filaments tend to wrap around the vortex, creating a layered structure of vortex and midlatitude air at the vortex edge. Near or total splits of the vortex into two or more distinct vortex fragments are quite common based on these trajectory calculations. Significant entrainment deep into the vortex is rare and results from only a limited number of the splitting events. During December and March the mixing barrier is less evident due to nonconservative factors during the spin-up and breakdown of the vortex, respectively. In December both ejection and entrainment are only weakly inhibited by the mixing barrier. Exchange in March is dominated by ejection of air from the vortex. Isolation of the vortex during 1991-1992 through 1993-1994 (the first three northern hemisphere winters of the UARS mission) is compared to the climatological values obtained from the analysis of 16 Arctic winters. A number of unusual features of both winters are discussed. The most notable features are the anomalous isolation experienced by the vortex during December 1992 and the unusual degree of isolation and persistence of the vortex during February and March of both years. The 1992-1993 winter season is the most consistently isolated vortex on record. Only during January 1993, when entrainment is large, is this pattern of extreme isolation broken.

Dahlberg, Steven Paul

1995-01-01

279

Organochlorines in antarctic and arctic avian top predators: a comparison between the South Polar Skua and two species of northern hemisphere gulls.  

PubMed

Different organochlorine compounds (OCs) were measured in the blood of breeding south polar skuas (Catharacta maccormicki) at Svarthamaren, Dronning Maud Land (Antarctica) and compared to those in two species of northern hemisphere gulls: the Arctic glaucous gull (Larus hyperboreus) and the subarctic great black-backed gull (Larus marinus). The skuas had 8% and 29% of the SigmaOC levels (45 ng/g, wet weight) of glaucous gulls (591 ng/g) and great black-backed gulls (158 ng/g), respectively. Polychlorinated biphenyls (PCBs) and p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) were very low in skuas compared to northern gulls, but the mean hexachlorobenzene (HCB) level was 1.7 times higher than in great black-backed gulls and one-third of the glaucous gull level. Mirex levels in skuas were among the highest reported in birds, the mean level being 3 and 26 times higher than those in glaucous gull and great black-backed gulls, respectively. In skuas, the mean levels of HCB, oxychlordane, p,p'-DDE, and PCBs increased by about 30% during a 2-week period, and mirex increased by nearly 60%. In glacuous gulls, HCB, p,p'-DDE, and PCBs increased by 10-20%. For HCB, mirex, and oxychlordane, only a relatively small proportion of the increase in skuas could be explained by changes in lipid pools and the levels at first sampling, compared to glaucous gulls. Thus, skuas were probably accumulating these compounds when present in Antarctica. p,p'-DDE and PCB levels, in contrast, seemed much more stable in the skuas. Relatively high levels of mirex and HCB in south polar skuas are concerning with regard to potential adverse effects. PMID:16683630

Bustnes, Jan O; Tveraa, Torkild; Henden, John A; Varpe, Oystein; Janssen, Kirstin; Skaare, Janneche U

2006-04-15

280

Decadal Time Scale change in terrestrial plant communities in North American arctic and alpine tundra: A contribution to the International Polar Year Back to the Future Project (Invited)  

NASA Astrophysics Data System (ADS)

The International Polar Year-Back to the Future (IPY-BTF) is an endorsed International Polar Year project (IPY project #214). The overarching goal of this program is to determine how key structural and functional characteristics of high latitude/altitude terrestrial ecosystems have changed over the past 25 or more years and assess if such trajectories of change are likely to continue in the future. By rescuing data, revisiting, re-sampling historic research sites and assessing environmental change over time, we aim to provide greater understanding of how tundra is changing and what the possible drivers of these changes are. Resampling of sites established by Patrick J. Webber between 1964 and 1975 in northern Baffin Island, Northern Alaska and in the Rocky Mountains form a key contribution to the BTF project. Here we report on resampling efforts at each of these locations and initial results of a synthesis effort that finds similarities and differences in change between sites. Results suggest that although shifts in plant community composition are detectable at each location, the magnitude and direction of change differ among locations. Vegetation shifts along soil moisture gradients is apparent at most of the sites resampled. Interestingly, however, wet communities seem to have changed more than dry communities in the Arctic locations, while plant communities at the alpine site appear to be becoming more distinct regardless of soil moisture status. Ecosystem function studies performed in conjunction with plant community change suggest that there has been an increase in plant productivity at most sites resampled, especially in wet and mesic land cover types.

Tweedie, C. E.; Ebert-May, D.; Hollister, R. D.; Johnson, D. R.; Lara, M. J.; Villarreal, S.; Spasojevic, M.; Webber, P.

2010-12-01

281

Temporal trends of perfluoroalkyl contaminants in polar bears (Ursus maritimus) from two locations in the North American Arctic, 1972-2002.  

PubMed

Perfluoroalkyl substances are globally distributed anthropogenic contaminants. Their production and use have increased dramatically from the early 1980s. While many recent publications have reported concentrations of perfluorooctane sulfonate (PFOS) and other perfluoroalkyl acids (PFAs) in biotic and abiotic samples, only limited work has addressed temporal trends. In this study we analyzed archived polar bear(Ursus maritimus) livertissue samples from two geographic locations in the North American Arctic, collected from 1972 to 2002. The eastern group, taken from the vicinity of northern Baffin Island, Canada, comprised 31 samples, and the western group, from the vicinity of Barrow, Alaska, comprised 27 samples. Samples were analyzed for perfluorocarboxylic acids (PFCAs) from carbon chain length C8 to C15, perfluorohexane sulfonate, PFOS, the neutral precursor perfluorooctane sulfonamide (PFOSA), as well as 8:2 and 10:2 fluorotelomer acids and their alpha,beta unsaturated acid counterparts. Concentrations of PFOS and PFCAs with carbon chain lengths from C9 to C11 showed an exponential increase between 1972 and 2002 at both locations. Doubling times ranged from 3.6 +/- 0.9 years for perfluorononanoic acid in the eastern group to 13.1 +/- 4.0 years for PFOS in the western group. PFOSA showed decreasing concentrations over time at both locations, while the remaining PFAs showed no significant trends or were not detected in any sample. The doubling time for PFOS was similar to the doubling time of production of perfluoroctylsulfonyl-fluoride-based products during the 1990s. PMID:16572767

Smithwick, Marla; Norstrom, Ross J; Mabury, Scott A; Solomon, Keith; Evans, Thomas J; Stirling, Ian; Taylor, Mitch K; Muir, Derek C G

2006-02-15

282

Chlorinated Hydrocarbon Contaminants in Polar Bears from Eastern Russia, North America, Greenland, and Svalbard: Biomonitoring of Arctic Pollution  

Microsoft Academic Search

.   Adipose tissue samples from polar bears (Ursus maritimus) were obtained by necropsy or biopsy between the spring of 1989 to the spring of 1993 from Wrangel Island in Russia, most\\u000a of the range of the bear in North America, eastern Greenland, and Svalbard. Samples were divided into 16 regions corresponding\\u000a as much as possible to known stocks or management

R. J. Norstrom; S. E. Belikov; E. W. Born; G. W. Garner; B. Malone; S. Olpinski; M. A. Ramsay; S. Schliebe; I. Stirling; M. S. Stishov; M. K. Taylor; Ø. Wiig

1998-01-01

283

Arctic deployment of USCGC Polar Sea - winter 1983. Volume 3. Trafficability tests. Final report, December 1982November 1983  

Microsoft Academic Search

Environmental and ship-performance data were collected aboard the USCGC POLAR SEA during the period March-May 1983 as part of a multi-year program to make an operational assessment on the feasibility of a year-round marine transportation system (including offshore structures) serving Alaska. This is the third volume of a four-volume set and focuses on the performance of the icebreaker from the

R. P. Voelker; F. A. Geisel; K. E. Dane

1983-01-01

284

Vortex methods and vortex statistics  

SciTech Connect

Vortex methods originated from the observation that in incompressible, inviscid, isentropic flow vorticity (or, more accurately, circulation) is a conserved quantity, as can be readily deduced from the absence of tangential stresses. Thus if the vorticity is known at time t = 0, one can deduce the flow at a later time by simply following it around. In this narrow context, a vortex method is a numerical method that makes use of this observation. Even more generally, the analysis of vortex methods leads, to problems that are closely related to problems in quantum physics and field theory, as well as in harmonic analysis. A broad enough definition of vortex methods ends up by encompassing much of science. Even the purely computational aspects of vortex methods encompass a range of ideas for which vorticity may not be the best unifying theme. The author restricts himself in these lectures to a special class of numerical vortex methods, those that are based on a Lagrangian transport of vorticity in hydrodynamics by smoothed particles (``blobs``) and those whose understanding contributes to the understanding of blob methods. Vortex methods for inviscid flow lead to systems of ordinary differential equations that can be readily clothed in Hamiltonian form, both in three and two space dimensions, and they can preserve exactly a number of invariants of the Euler equations, including topological invariants. Their viscous versions resemble Langevin equations. As a result, they provide a very useful cartoon of statistical hydrodynamics, i.e., of turbulence, one that can to some extent be analyzed analytically and more importantly, explored numerically, with important implications also for superfluids, superconductors, and even polymers. In the authors view, vortex ``blob`` methods provide the most promising path to the understanding of these phenomena.

Chorin, A.J.

1993-05-01

285

Arctic Research Opportunities  

NSF Publications Database

... Research Support and Logistics; Arctic Cyberinfrastructure and Sensors; and Arctic Research and ... research in the Arctic including field and modeling studies and data analysis. Arctic research is ...

286

Seasonal variability in physicochemical characteristics of small water bodies across a High Arctic wetland, Polar Bear Pass, Bathurst Island, Nunavut, Canada  

NASA Astrophysics Data System (ADS)

Small water bodies (lakes, ponds) in permafrost environments make up roughly half of the total area of surface water, but their relevance to nutrient and carbon fluxes on a landscape scale still remains largely unknown. Small variations in pond water balance as a result of seasonal changes in precipitation, evaporation, or drainage processes have the potential to produce considerable changes in the carbon and nutrient budgets as small changes in the water level can have a major effect on volumes and surface areas of ponds. The aims of this study were (1) to identify the main characteristics in pond hydrology both seasonally and between years; (2) to identify factors controlling variation in measured physicochemical variables; and (3) to detect seasonal trends in the hydrological and chemical characteristics of ponds located in an extensive low-gradient High Arctic wetland. We conducted detailed limnological surveys of 50 wetland ponds located at Polar Bear Pass (PBP), Bathurst Island, Nunavut, Canada during 2007-2010. The results indicate large seasonal variability in physicochemical parameters that is associated with pond water budget changes, especially for ponds with steady water levels vs. dynamic ponds (fluctuating water levels). Principal component analysis (PCA) of the datasets indicated that major ion content, specifically calcium (Ca2+), was responsible for much of the variability among the ponds in both 2008 and 2009. Additionally in 2009 most of the variability was also due to specific conductivity in the summer and magnesium (Mg2+) in the fall. These trends are typically identified as a result of dilution or evapo-concentration processes in small water bodies. In 2007, a warm and dry year, pH and potassium (K+) were responsible for much of variation between ponds. This is attributed to high vegetation growth in ponds and a longer growing season. While no trend was identified in 2010 (PCA analysis), calculations of greenhouse gas (GHG) emissions from 50 ponds during spring and early summer showed strong variability in fluxes of carbon dioxide (-0.01-2.09 g C m-2 d-1), methane (0.02-13.95 mg C m-2 d-1), and nitrous oxide (-0.15-3.94 mg N m-2 d-1). These differences in GHG fluxes are primarily related to hydrological settings of ponds at PBP. These ponds are strong GHG sources in comparison to ponds in other circumpolar environments. Our findings highlight the importance of water budget dynamics in understanding nutrient and carbon fluxes in Canadian High Arctic ponds and indicate the need for long-term monitoring studies.

Abnizova, A.; Miller, E.; Shakil, S.; Young, K. L.

2012-12-01

287

Generation of broadband terahertz vortex beams.  

PubMed

We propose and demonstrate a method for generating broadband terahertz (THz) vortex beams. We convert a THz radially polarized beam into a THz vortex beam via achromatic polarization optical elements for THz waves and characterize the topological charge of the generated vortex beam by measuring the spatial distribution of the phase of the THz wave at its focal plane. For example, a uniform topological charge of +1 is achieved over a wide frequency range. We also demonstrate that the sign of the topological charge can be easily controlled. By utilizing the orbital angular momentum of the beam, these results open new THz wave technologies for sensing, manipulation, and telecommunication. PMID:24978718

Imai, Ryo; Kanda, Natsuki; Higuchi, Takuya; Konishi, Kuniaki; Kuwata-Gonokami, Makoto

2014-07-01

288

Live from the Arctic  

NASA Astrophysics Data System (ADS)

For reasons of geography and geophysics, the poles of our planet, the Arctic and Antarctica, are places where climate change appears first: they are global canaries in the mine shaft. But while Antarctica (its penguins and ozone hole, for example) has been relatively well-documented in recent books, TV programs and journalism, the far North has received somewhat less attention. This project builds on and advances what has been done to date to share the people, places, and stories of the North with all Americans through multiple media, over several years. In a collaborative project between the Arctic Research Consortium of the United States (ARCUS) and PASSPORT TO KNOWLEDGE, Live from the Arctic will bring the Arctic environment to the public through a series of primetime broadcasts, live and taped programming, interactive virtual field trips, and webcasts. The five-year project will culminate during the 2007-2008 International Polar Year (IPY). Live from the Arctic will: A. Promote global understanding about the value and world -wide significance of the Arctic, B. Bring cutting-edge research to both non-formal and formal education communities, C. Provide opportunities for collaboration between arctic scientists, arctic communities, and the general public. Content will focus on the following four themes. 1. Pan-Arctic Changes and Impacts on Land (i.e. snow cover; permafrost; glaciers; hydrology; species composition, distribution, and abundance; subsistence harvesting) 2. Pan-Arctic Changes and Impacts in the Sea (i.e. salinity, temperature, currents, nutrients, sea ice, marine ecosystems (including people, marine mammals and fisheries) 3. Pan-Arctic Changes and Impacts in the Atmosphere (i.e. precipitation and evaporation; effects on humans and their communities) 4. Global Perspectives (i.e. effects on humans and communities, impacts to rest of the world) In The Earth is Faster Now, a recent collection of comments by members of indigenous arctic peoples, arctic residents speak in eloquent terms of the changes they see around them, manifested in new patterns of vegetation, the melting of permafrost and the absence of game species that used to be abundant. Meanwhile, new satellites and more sophisticated sensors on the ground and in the ice, add scientific testimony that seems to support and even extend native perceptions. Live from the Arctic will unify both perspectives, and use todays most powerful and effective communications media to connect young people and general audiences all across America to researchers and communities living and working in the Arctic. During IPY there will be a level of interest in the Polar regions unprecedented in a generation. Live from the Arctic offers unique resources to satisfy that curiosity, and encourage active participation and engagement in understanding some of Earths most significant peoples, places and rapidly changing conditions.

Haines-Stiles, G.; Warnick, W. K.; Warburton, J.; Sunwood, K.

2003-12-01

289

Evidence for subsidence in the 1989 Arctic winter stratosphere from airborne infrared composition measurements  

NASA Technical Reports Server (NTRS)

Simultaneous measurements of the stratospheric burdens of CO2, HCN, N2O, CH4, OCS, CF2Cl2, CFCl3, CHF2Cl and HF were made by the Jet propulsion Laboratory MkIV interferometer on board the NASA DC-8 aircraft during January and early February 1989 as part of the Airborne Arctic Stratosphere Experiment. Data were acquired on 11 flights at altitudes of up to 12 km over a geographic region covering the NE Atlantic Ocean, Iceland and Greenland. The results obtained show large variations in the burdens of these tracers due to the effects of transport. The tropospheric source gas burdens were reduced inside the polar vortex, suggesting that the air had subsided with respect to the surrounding midlatitude air. Increased HF burdens inside the vortex support this interpretation. The results obtained from the different tracers are highly consistent with each other and indicate that in the 15- to 20-km altitude range inside the vortex, surfaces of constant volume mixing ratio were located some 5-6 km lower in absolute altitude than outside the vortex. The results also indicate that the magnitude of this subsidence increases with altitude. These conclusions are consistent with other measurements.

Toon, G. C.; Farmer, C. B.; Schaper, P. W.; Lowes, L. L.; Norton, R. H.; Schoeberl, M. R.; Lait, L. R.; Newman, P. A.

1992-01-01

290

Vortex methods  

SciTech Connect

Vortex methods originated from the observation that in incompressible inviscid flow vorticity (or, more accurately, circulation) is a conserved quantity, as can be readily deduced from the absence of tangential stresses. Thus, if the vorticity is known at time t=0, one can find the flow at a later time by simply following the vorticity. In this narrow context, a vortex method is a numerical method that follows vorticity. The author restricts himself in these lectures to a special class of numerical vortex methods, those that are based on a Lagrangian transport of vorticity in hydrodynamics by smoothed particles (blobs) and those whose analysis contributes to the understanding of blob methods. Blob methods started in the 1930`s.

Chorin, A.J. [California Univ., Berkeley, CA (United States). Dept. of Mathematics]|[Lawrence Berkeley Lab., CA (United States)

1993-06-01

291

Arctic Intersection  

USGS Multimedia Gallery

The Canadian Coast Guard Ship Louis S. St-Laurent ties up to the Coast Guard Cutter Healy in the Arctic Ocean Sept. 5, 2009. The two ships are taking part in a multi-year, multi-agency Arctic survey that will help define the Arctic continental shelf....

2010-02-19

292

Arctic ozone loss  

SciTech Connect

Scientists have returned from the first comprehensive probe of the Arctic stratosphere with unexpectedly dire results: The winter atmosphere in the north polar region is loaded with the same destructive chlorine compounds that cause the Antarctic ozone hole. Atmospheric researchers who only a few weeks ago were comforted by the thought that the warmer Northern Hemisphere is strongly protected from the processes that lead to massive losses of ozone during spring in Antarctica now see very little standing in the way of an Arctic ozone hole.

Zurer, P.S.

1989-03-06

293

Arctic Research and Writing  

NSDL National Science Digital Library

Recently, senior-level physics students joined thousands of scientists from over 60 nations to examine a wide range of physical, biological, and social research topics as part of the International Polar Year (IPY). Through a National Science Foundation (NSF)-funded research project, these students applied physics concepts to the study of Arctic sea ice. They participated in an authentic proposal writing contest focused on dramatic changes observed in the Arctic environment and developed a research question to examine why these changes are occurring. This article describes their participation in this exciting hands-on project.

Coon, Brian; Englert, Karl; Hinckley, Matt; Pruis, Matt

2009-01-01

294

Building Partnerships in Polar Research and Education. Report from the Arctic Science Education Workshop (New Orleans, Louisiana, April 6-8, 1997).  

ERIC Educational Resources Information Center

To examine the role of arctic science in U.S. primary and secondary education, 58 teachers, researchers, and curriculum specialists met in a workshop in April 1997 in New Orleans. The workshop sought to provide a forum for development of K-12 educational materials investigating the Arctic and to bring current research activities into K-12…

Arctic Research Consortium of the United States, Fairbanks, AK.

295

ATMOS Measurements of H2O + 2CH4 and Total Reactive Nitrogen in the November 1994 Antarctic Stratosphere: Dehydration and Denitrification in the Vortex  

NASA Technical Reports Server (NTRS)

Simultaneous stratospheric volume mixing ratios (VMR's) measured inside and outside the Antarctic vortex by the Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument in November 1994 reveal previously unobserved features in the distributions of total reactive nitrogen (NO(y)) and total hydrogen (H2O + 2CH4). Maximum removal of NO(y) due to sedimentation of polar stratospheric clouds (PSC's) inside the vortex occurred at a potential temperature (Theta) of 500-525 K (approximately 20 km), where values were 5 times smaller than measurements outside. Maximum loss of H2O + 2CH4 due to PSC's occurred in the vortex at 425-450 K, approximately 3 km lower than the peak NO(y) loss. At that level, H2O + 2CH4 VMR's inside the vortex were approximately 70% of corresponding values outside. The Antarctic and April 1993 Arctic measurements by ATMOS show no significant differences in H2O + 2CH4 VMR's outside the vortices in the two hemispheres. Elevated NO(y) VMRs were measured inside the vortex near 700 K. Recent model calculations indicate that this feature results from downward transport of elevated NO(y) produced in the thermosphere and mesosphere.

Rinsland, C. P.; Gunson, M. R.; Salawitch, R. J.; Newchurch, M. J.; Zander, R.; Abbas, M. M.; Abrams, M. C.; Manney, G. L.; Michelsen, H. A.; Chang, A. Y.; Goldman, A.

1996-01-01

296

Canada's Polar Environments: Land  

NSDL National Science Digital Library

This site describes the Arctic lands of Canada, which have been divided into three ecozones: the Arctic Cordillera, which encompasses the northeastern fringe of Nunavut and northern Labrador and is defined by the Arctic Cordillera Mountain Range; the Northern Arctic, which is a polar desert that comprises the non-mountainous portions of the Arctic Islands as well as the northernmost areas of Quebec; and the Southern Arctic, which covers much of the northern mainland of Canada, from the Richardson Mountains in the Yukon Territory to northern Quebec. The site discusses topography, glacial features, freeze/thaw features, geology, and permafrost and soils. The discussion of glaciers includes their origin and classification as well as glaciers, past and present, their retreat and glacial cores. A section called cool facts contrasts the North Magnetic Pole with the geographic North Pole, discusses polar wandering, and tells of the smoking hills where the ground is burning.

297

Islands of the Arctic  

NASA Astrophysics Data System (ADS)

The Arctic islands are characterized by beautiful mountains and glaciers, in which the wildlife lives in delicate balance with its environment. It is a fragile region with a long history of exploration and exploitation that is now experiencing rapid environmental change. All of these themes are explored in Islands of the Arctic, a richly illustrated volume with superb photographs from the Canadian Arctic archipelago, Greenland, Svalbard and the Russian Arctic. It begins with the various processes shaping the landscape: glaciers, rivers and coastal processes, the role of ice in the oceans and the weather and climate. Julian Dowdeswell and Michael Hambrey describe the flora and fauna in addition to the human influences on the environment, from the sustainable approach of the Inuit, to the devastating damage inflicted by hunters and issues arising from the presence of military security installations. Finally, they consider the future prospects of the Arctic islands Julian Dowdeswell is Director of the Scott Polar Research Institute and Professor of Physical Geography at 0he University of Cambridge. He received the Polar Medal from Queen Elizabeth for his contributions to the study of glacier geophysics and the Gill Memorial Award from the Royal Geographical Society. He is chair of the Publications Committee of the International Glaciological Society and head of the Glaciers and Ice Sheets Division of the International Commission for Snow and Ice. Michael Hambrey is Director of the Centre for Glaciology at the University of Wales, Aberystwyth. A past recipient of the Polar Medal, he was also given the Earth Science Editors' Outstanding Publication Award for Glaciers (Cambridge University Press). Hambrey is also the author of Glacial Environments (British Columbia, 1994).

Dowdeswell, Julian; Hambrey, Michael

2002-11-01

298

Venus: further evidence of vortex circulation.  

PubMed

A space-time composite of polar stereographic ultraviolet images of Venus from Mariner 10 shows a remarkable circumpolar vortex. The vortex is characterized by a cloud which appears similar to dense terrestrial stratus having an albedo that is 50 percent higher. Spiral streaks converge into it from low latitudes, akin to the spiral bands of a hurricane. The bright visible polar cloud is not axisymmetric but has roughly an elliptical shape. The high brightness of the polar cloud suggests that it has a different origin from the rest of the Venus cloud cover. PMID:17743631

Suomi, V E; Limaye, S S

1978-09-15

299

Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications  

E-print Network

175 Arctic Sea Ice Decline: Observations, Projections, Mechanisms, and Implications Geophysical Is the Trajectory of Arctic Sea Ice? Harry L. Stern and Ronald W. Lindsay Polar Science Center, Applied Physics space of the Arctic sea ice thickness distribution, in which each dimension or component is the time

Lindsay, Ron

300

Core contribution to magnetotransport of ferromagnetic dots in vortex state  

NASA Astrophysics Data System (ADS)

We study the influence of the vortex core on magnetotransport of ferromagnetic dots in a vortex state. The extraordinary Hall effect generated in the core region has a different field symmetry compared to contributions of anisotropic magnetoresistance and the planar Hall effect, which can be used to detect chirality and polarity of the vortex. We propose a method for realization of two-bit per dot magnetic random access memory, in which two states are contributed by clockwise and counter-clockwise chirality and two by up and down core polarity. Dependence of the signal on vortex location, core diameter, and other parameters is discussed.

Segal, A.; Gerber, A.

2012-04-01

301

Unusually strong nitric oxide descent in the Arctic middle atmosphere in early 2013 as observed by Odin/SMR  

NASA Astrophysics Data System (ADS)

The middle atmosphere was affected by an exceptionally strong midwinter stratospheric sudden warming (SSW) during the Arctic winter 2012/2013. These unusual meteorological conditions led to a breakdown of the polar vortex, followed by the reformation of a strong upper stratospheric vortex associated with particularly efficient descent of air. Measurements by the submillimetre radiometer (SMR), on board the Odin satellite, show that very large amounts of nitric oxide (NO), produced by energetic particle precipitation (EPP) in the mesosphere/lower thermosphere (MLT), could thus enter the polar stratosphere in early 2013. The mechanism referring to the downward transport of EPP-generated NOx during winter is generally called the EPP indirect effect. SMR observed up to 20 times more NO in the upper stratosphere than the average NO measured at the same latitude, pressure and time during three previous winters where no mixing between mesospheric and stratospheric air was noticeable. This event turned out to be the strongest in the aeronomy-only period of SMR (2007-present). Our study is based on a comparison with the Arctic winter 2008/2009, when a similar situation was observed. This outstanding situation is the result of the combination of a relatively high geomagnetic activity and an unusually high dynamical activity, which makes this case a prime example to study the EPP impacts on the atmospheric composition.

Pérot, K.; Urban, J.; Murtagh, D. P.

2014-08-01

302

Super Interglacials and persistent warmth paced Arctic Climate Evolution over the Past 3.6 Myr: Lake El'gygytgyn, Western Beringia, a new polar lens focused on high latitude environmental change  

NASA Astrophysics Data System (ADS)

The Pliocene-Pleistocene climate evolution of the Arctic must have modulated the glacial history of Greenland and the onset of Northern Hemisphere glaciation. Yet what is known from the terrestrial stratigraphy of Arctic climate change comes from sites that are spatially and temporally fragmented. In 2009, International Continental Deep drilling at Lake El'gygytgyn (67o30' N, 172 o 05' E) recovered lacustrine sediments dating back to 3.58 Ma that now provide the first time-continuous Pliocene-Pleistocene Arctic paleoclimate record of alternating glacial-interglacial change. The warmest/wettest Pliocene interval of the lake record occurs from ~3.58-3.34 Ma and is dominated by exceptional tree pollen implying July temperatures nearly 7-8o C warmer than today with nearly ~3 times the annual precipitation. Atmospheric CO2 levels are estimated to have been 360 to 400 ppm implying exceptionally high climate sensitivity and polar amplification. In fact, pollen spectra and modern analog analysis show an unbroken persistence of summers much warmer and wetter than the last interglacial, MIS 5e until nearly 2.2 Ma. Extreme warmth in the Mid Pliocene Arctic occurs at the same time ANDRILL results suggest the West Antarctic Ice Sheet was non-existent. Modeling sensitivity experiments using 300 and 400 ppm CO2 are consistent with sustained forests at Lake El'gygytgyn during this interval and restricted glacial ice over Greenland in both cold and warm boreal summer orbits especially for the PRISM interval. This has implications for reinterpreting the M2 isotopic shift in the North Atlantic suggesting that most of the ice advance at that time was in Antarctica. Using physical, chemical, and biological proxies we find pronounced glacial episodes commenced ~2.6 Ma ago, but the full range of typical Pleistocene glacial/interglacial change wasn't established until ~1.8 Ma ago. Greenland must have also responded to numerous "super interglacials" during the Quaternary record, with maximum summer temperatures and annual precipitation, especially during MIS 9,11 and 31, at Lake El'gygytgyn exceeding that documented for MIS 5e. The correspondence of many of these super-interglacials with retreat of the West Antarctic Ice Sheet (Naish et al. 2009) could coincide with intervals when the Greenland Ice was reduced in size. The climate record from Lake El'gygytgyn, especially the history of past interglacials, provides a fresh means of testing the evolving magnitude of polar amplification over time, and the sensitivity of the Greenland Ice Sheet to extreme warmth in the rest of the Arctic.

Brigham-Grette, Julie; Melles, Martin; Minyuk, Pavel

2013-04-01

303

Uncharted Territory on the Arctic Seafloor  

NSDL National Science Digital Library

This article profiles Dr. Leonid Polyak, a senior research scientist with the Byrd Polar Research Center, The Ohio State University, who studies seafloor sediments from the Arctic Ocean to find clues about the climate conditions of the past.

Landis, Carol

304

Water vapour variability and trends in the Arctic stratosphere  

NASA Astrophysics Data System (ADS)

Water vapour in the upper troposphere-lower stratosphere (UTLS) is a radiatively and chemically important trace gas. Stratospheric water vapour also affects ozone chemistry through odd-hydrogen chemistry and formation of polar stratospheric clouds (PSC). Both transport and chemistry contribute to the extratropical lower stratospheric water vapour distribution and trends. The main sources of stratospheric water vapour are intrusion through the tropical tropopause and production from oxidation of methane. Accurate observations of UTLS water vapour are difficult to obtain due to the strong gradient in the water vapour profile over the tropopause. However, modelling the stratospheric water vapour distribution is challenging and accurate measurements are needed for model validation. Trends in Arctic water vapour will be analysed and explained in terms of contribution from different processes (transport and chemistry), using observations and chemistry transport model (CTM) simulations. Accurate water vapour soundings from Sodankylä will be used to study water vapour within the Arctic polar vortex, including process studies on formation of PSCs and dehydration. Water vapour profiles measured during the LAPBIAT atmospheric sounding campaign in Sodankylä in January 2010 indicated formation of ice clouds and dehydration. Effects on ozone chemistry will also be studied. Global middle atmospheric simulations have been performed with the FinROSE-ctm using ERA-Interim winds and temperatures. The FinROSE-ctm is a global middle atmosphere model that produces the distribution of 30 long-lived species and tracers and 14 short-lived species. The chemistry describes around 110 gas phase reactions, 37 photodissociation processes and the main heterogeneous reactions related to aerosols and polar stratospheric clouds.

Thölix, Laura; Kivi, Rigel; Backman, Leif; Karpechko, Alexey

2014-05-01

305

One more step toward a warmer Arctic  

Microsoft Academic Search

This study was motivated by a strong warming signal seen in mooring-based and oceanographic survey data collected in 2004 in the Eurasian Basin of the Arctic Ocean. The source of this and earlier Arctic Ocean changes lies in interactions between polar and sub-polar basins. Evidence suggests such changes are abrupt, or pulse-like, taking the form of propagating anomalies that can

Igor V. Polyakov; Agnieszka Beszczynska; Eddy C. Carmack; Igor A. Dmitrenko; Eberhard Fahrbach; Ivan E. Frolov; Rüdiger Gerdes; Edmond Hansen; Jürgen Holfort; Vladimir V. Ivanov; Mark A. Johnson; Michael Karcher; Frank Kauker; James Morison; Kjell A. Orvik; Ursula Schauer; Harper L. Simmons; Øystein Skagseth; Vladimir T. Sokolov; Michael Steele; Leonid A. Timokhov; David Walsh; John E. Walsh

2005-01-01

306

Quasi-biennial oscillation and solar cycle influences on winter Arctic total ozone  

NASA Astrophysics Data System (ADS)

total column ozone (TCO) observed from satellites and assimilated in the European Centre for Medium-Range Weather Forecasts since 1979 is used as an atmospheric tracer to study the modulations of the winter Arctic stratosphere by the quasi-biennial oscillation (QBO) and the solar cycle. It is found that both the QBO and solar forcings in low latitudes can perturb the late winter polar vortex, likely via planetary wave divergence, causing an early breakdown of the vortex in the form of sudden stratospheric warming. As a result, TCO within the vortex in late winter can increase by ~60 Dobson unit during either a solar maximum or an easterly phase of the QBO, or both, relative to the least perturbed state when the solar cycle is minimum and the QBO is in the westerly phase. In addition, from the solar maximum to the solar minimum during the QBO easterly phase, the change in TCO is found to be statistically insignificant. Therefore, the "reversal" of the Holton-Tan effect, reported in some previous studies using lower stratospheric temperature, is not evident in the TCO behavior of both observation and assimilation.

Li, King-Fai; Tung, Ka-Kit

2014-05-01

307

Arctic Region Supercomputing Center  

NSDL National Science Digital Library

Based at the University of Alaska-Fairbanks, The Arctic Region Supercomputing Center (ARSC) provides high-performance supercomputing for the Arctic region. Visitors to ARSC's Science and Engineering pages can learn about computer-based research projects on arctic, polar regions, and high latitudes (e.g., ice-tide interaction of the Arctic Ocean, imaging the Bering Glacier surge, volcanic ash plume simulation) along with other computer-based techniques (e.g., visualization of MRI data or atmospheric aerosol monitoring). Atmospheric Sciences, Engineering and Environmental Sciences, Geophysics, Medical and Health Related Research, Oceanography and Marine Sciences, and Space Physics are the subcategories of the Science and Engineering section. On these pages, a wide range of items are available: articles from ARSC's newsletter Challenges, animations of computer models and simulations (MPEG, .gif), satellite images, links to laboratories, and more. Summaries of research techniques and specific projects describe the issues driving research, the hows and whys of models used, and brief overviews of the results (if available). Other highlights of the site include an index of the center's software with descriptions and links, an image map and text description of the ARSC computer system, and the newsletter, Challenges, providing fresh, illustrated articles on computer modeling research. Those in the Fairbanks area might also be interested in the daily local weather reports. ARSC's Website is a good place to take a brief look at the numerous computer modeling and simulation research techniques in use today, especially those dealing with high latitude regions.

308

Airborne arctic stratospheric expedition II: An overview  

SciTech Connect

The sudden onset of ozone depletion in the antarctic vortex set a precedent for both the time scale and the severity of global change. The Airborne Antarctic Ozone Experiment (AAOE), staged from Punta Arenas, Chile, in 1987, established that CFCs, halons, and methyl bromide, the dominant sources of chlorine and bromine radicals in the stratosphere, control the rate of ozone destruction over the Antarctic; that the vortex is depleted in reactive nitrogen and water vapor; and that diabatic cooling during the antarctic winter leads to subsidence within the vortex core, importing air from higher altitudes and lower latitudes. This last conclusion is based on observed dramatic distortion in the tracer fields, most notably N[sub 2]O. In 1989, the first Airborne Arctic Stratospheric Expedition (AASE-I), staged from Stavanger, Norway, and using the same aircraft employed for AAOE (the NASA ER-2 and the NASA DC-8), discovered that while NO[sub x] and to some degree NO[sub y] were perturbed within the arctic vortex, there was little evidence for desiccation. Under these (in contrast to the antarctic) marginally perturbed conditions, however, ClO was found to be dramatically enhanced such that a large fraction of the available (inorganic) chlorine resided in the form of ClO and its dimer ClOOCl. This leaves two abiding issues for the northern hemisphere and the mission of the second Airborne Arctic Stratospheric Expedition (AASE-II): (1) Will significant ozone erosion occur within the arctic vortex in the next ten years as chlorine loading in the stratosphere exceeds four parts per billion by volume (2) Which mechanisms are responsible for the observed ozone erosion poleward of 30[degrees]N in the winter/spring northern hemisphere reported in satellite observations 12 refs., 2 tabs.

Anderson, J.G. (Harvard Univ., Cambridge, MA (United States)); Toon, O.B. (NASA Ames Research Center, Moffett Field, CA (United States))

1993-11-19

309

Beyond Penguins and Polar Bears: Polar Geography  

NSDL National Science Digital Library

Our presenters provide an overview of the geography of the Arctic and Antarctic regions and featured resources from the Beyond Penguins and Polar Bears cyberzine, a resource for elementary educators. This cyberzine focuses on strategies and content to integrate science and literacy through the study of the polar regions. Recorded on May 27, 2008, Beyond Penguins and Polar Bears: Integrating Science and Literacy, Seminar 1: Polar Geography, NSDL featured our experts from The Ohio State University, Jessica Fries-Gaither, Project Director for Beyond Penguins and Polar Bears and Elementary Resource Specialist at the Ohio Resource Center and Dr. Carol Landis, Education Coordinator at the Byrd Polar Research Center.

Payo, Robert

310

Summer at-sea distribution of seabirds and marine mammals in polar ecosystems: a comparison between the European Arctic seas and the Weddell Sea, Antarctica  

Microsoft Academic Search

The summer at-sea distribution of seabirds and marine mammals was quantitatively established both in Antarctica (Weddell Sea) and in the European Arctic: Greenland, Norwegian and Barents seas. Data can directly be compared, since the same transect counts were applied by the same team from the same icebreaking ship in both regions. The main conclusion is that densities of seabirds and

Claude R Joiris

2000-01-01

311

The Arctic and Antarctic Circles  

NSDL National Science Digital Library

This website is part of National Geographic's Xpeditions Hall and includes lesson plans and activities related to the topic of the Arctic and Antarctic regions. Students compare and contrast these regions to learn more about the flora and fauna found there, as well as environmental issues facing the polar regions. These lesson plans were written by educators and have been tested in the classroom.

312

EOS MLS observations of ozone loss in the 2004-2005 Arctic winter  

NASA Astrophysics Data System (ADS)

Earth Observing System Microwave Limb Sounder O3 and N2O are used to examine transport and chemical O3 loss in the unusually cold 2004-2005 Arctic winter. The vortex was dynamically active, with episodic mixing events throughout the winter; descent was the dominant transport process only through late January. Before the onset of lower stratospheric chemical loss, O3 was higher near the vortex edge than in the vortex core, causing different effects of mixing depending on the vortex region and time, either masking or mimicking chemical loss. O3 loss ceased by 10 March because of an early final warming. Rough estimates suggest maximum vortex-averaged O3 loss of 1.2-1.5 ppmv between 450 and 500 K, with up to ~2 ppmv loss in the outer vortex near 500 K. Despite record cold, chemical O3 loss was less in 2004-2005 than in previous cold Arctic winters.

Manney, G. L.; Santee, M. L.; Froidevaux, L.; Hoppel, K.; Livesey, N. J.; Waters, J. W.

2006-02-01

313

Aerosols and polar stratospheric clouds measurements during the EASOE campaign  

NASA Technical Reports Server (NTRS)

Preliminary results of observations performed using two different lidar systems during the EASOE (European Arctic Stratospheric Ozone Experiment), which has taken place in the winter of 1991-1992 in the northern hemisphere lattitude regions, are presented. The first system is a ground based multiwavelength lidar intended to perform measurements of the ozone vertical distribution in the 5 km to 40 km altitude range. It was located in Sodankyla (67 degrees N, 27 degrees E) as part of the ELSA experiment. The objectives of the ELSA cooperative project is to study the relation between polar stratospheric cloud events and ozone depletion with high vertical resolution and temporal continuity, and the evolution of the ozone distribution in relation to the position of the polar vortex. The second system is an airborne backscatter lidar (Leandre) which allows for the study of the 3-D structure and the optical properties of polar stratospheric clouds. The Leandre instrument is a dual-polarization lidar system, emitting at 532 nm, which allows for the determination of the type of clouds observed, according to the usual classification of polar stratospheric clouds. More than 60 hours of flight were performed in Dec. 1991, and Jan. and Feb. 1992 in Kiruna, Sweden. The operation of the Leandre instrument has led to the observation of the short scale variability of the Pinatubo volcanic cloud in the high latitude regions and to several episodes of polar stratospheric clouds. Preliminary analysis of the data is presented.

Haner, D.; Godin, S.; Megie, G.; David, C.; Mitev, V.

1992-01-01

314

Arctic house  

E-print Network

Currently available housing in the Arctic is limited to solutions that have been adapted from designs for less severe climates. This thesis has developed a new manner of residential construction designed specifically for ...

Turkel, Joel A. (Joel Abram), 1969-

1999-01-01

315

Flicker vortex structures in multiferroic materials  

NASA Astrophysics Data System (ADS)

Computer simulation of ferroelastic materials reveals dynamic polar vortex structures related to flexo-electricity between cation and anion lattices. At finite temperatures, the vortices are found to flicker in time and space. Widely spaced ferroelastic twin boundaries nucleate vortices while dense twin boundaries suppress them. The time averaged number of vortices at any site decays exponentially, indicating the highly mobile dynamics of the vortex lattice. Applied electric fields break the rotational symmetry of vortices and finally destroy them. The total number density of vortices follows a field and temperature dependence as N(E)=N0/[1+A exp(E/k(T-TVF))] with TVF < 0. The observed vortex structures are akin to those observed in magnetic and superconducting disordered vortex lattices.

Zhao, Z.; Ding, X.; Salje, E. K. H.

2014-09-01

316

Vortex Flow Aerodynamics, volume 1  

SciTech Connect

Vortex modeling techniques and experimental studies of research configurations utilizing vortex flows are discussed. Also discussed are vortex flap investigations using generic and airplane research models and vortex flap theoretical analysis and design studies.

Campbell, J.F.; Osborn, R.F.; Foughner, J.T. Jr.

1986-07-01

317

Polarization of 'water-skies' above arctic open waters: how polynyas in the ice-cover can be visually detected from a distance  

Microsoft Academic Search

The foggy sky above a white ice-cover and a dark water surface (permanent polynya or temporary lead) is white and dark gray, phenomena called the 'ice-sky' and the 'water-sky,' respectively. Captains of icebreaker ships used to search for not-directly-visible open waters remotely on the basis of the water sky. Animals depending on open waters in the Arctic region may also

Ramón Hegedüs; Susanne Åkesson; Gábor Horváth

2007-01-01

318

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

Microsoft Academic Search

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires and anthropogenic sources in East Asia embedded in their associated air masses, creating an excellent opportunity to use satellite

H. Sodemann; M. Pommier; S. R. Arnold; S. A. Monks; K. Stebel; J. F. Burkhart; J. W. Hair; G. S. Diskin; C. Clerbaux; P.-F. Coheur; D. Hurtmans; H. Schlager; A.-M. Blechschmidt; J. E. Kristjánsson; A. Stohl

2011-01-01

319

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

Microsoft Academic Search

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the

A. Stohl; H. Sodemann; M. Pommier; S. R. Arnold; S. A. Monks; K. Stebel; J. F. Burkhart; J. W. Hair; G. S. Diskin; C. Clerbaux; P. Coheur; D. Hurtmans; H. Schlager; A. Blechschmidt; J. E. Kristjansson

2010-01-01

320

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

Microsoft Academic Search

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport

H. Sodemann; M. Pommier; S. R. Arnold; S. A. Monks; K. Stebel; J. F. Burkhart; J. W. Hair; G. S. Diskin; C. Clerbaux; P.-F. Coheur; D. Hurtmans; H. Schlager; A.-M. Blechschmidt; J. E. Kristjánsson; A. Stohl

2010-01-01

321

Study Of The Fundamental Physical Principles in Atmospheric Modeling Based On Identification Of Atmosphere - Climate Control Factors: Bromine Explosion At The Polar Arctic Sunrise  

E-print Network

We attempt is to provide accumulated evidence and qualitative understanding of the associated atmospheric phenomena of the Arctic bromine explosion and their role in the functioning of the biotic Earth. We rationalize the empirical expression of the bromine influx into atmospheric boundary layer and calculate total amounts of the tropospheric BrO and Bry of the Arctic origin. Based on the quantities and partitioning of the reactive bromine species, we estimate the biogeochemical parametric constraint on the surface ozone field of the springtime NH. The constraint expresses strong relationship between atmosphere-climate control factors of the Earth's life and of external energy source. Physical atmosphere can be seen as a complex network of maximum complexity. Henceforth, we analyze the network context of the Arctic bromine pollution. We suggest that demonstrated attitudinal approach to the distributed surface flux would be successfully used in the innovative atmospheric modeling. The analysis is illustrated by GEM model results which stay in a good agreement with the observational data and support the original idea of the global NH effect of bromine chemistry.

M. Iudin

2007-12-17

322

An Assessment of the Ozone Loss During the 1999-2000 SOLVE Arctic Campaign  

NASA Technical Reports Server (NTRS)

Ozone observations from ozonesondes, the lidars aboard the DC-8, in situ ozone measurements from the ER-2, and satellite ozone measurements from Polar Ozone and Aerosol Measurement III (POAM) were used to assess ozone loss during the Sage III Ozone Loss and Validation Experiment (SOLVE) 1999-2000 Arctic campaign. Two methods of analysis were used. In the first method a simple regression analysis is performed on the ozonesonde and POAM measurements within the vortex. In the second method, the ozone measurements from all available ozone data were injected into a free running diabatic trajectory model and carried forward in time from December 1 to March 15. Vortex ozone loss was then estimated by comparing the ozone values of those parcels initiated early in the campaign with those parcels injected later in the campaign. Despite the variety of observational techniques used during SOLVE, the measurements provide a fairly consistent picture. Over the whole vortex, the largest ozone loss occurs between 550 and 400 K potential temperatures (approximately 23-16 km) with over 1.5 ppmv lost by March 15, the end of the SOLVE mission period. An ozone loss rate of 0.04-0.05 ppmv/day was computed for March 15. Ozonesondes launched after March 15 suggest that an additional 0.5 ppmv or more ozone was lost between March 15 and April 1. The small disagreement between ozonesonde and POAM analysis of January ozone loss is found to be due to biases in vortex sampling. POAM makes most of its solar occultation measurements at the vortex edge during January 2000 which bias samples toward air parcels that have been exposed to sunlight and likely do experience ozone loss. Ozonesonde measurements and the trajectory technique use observations that are more distributed within the interior of the vortex. Thus the regression analysis of the POAM measurements tends to overestimate mid-winter vortex ozone loss. Finally, our loss calculations are broadly consistent with other loss computations using ER-2 tracer data and MLS satellite data, but we find no evidence for the 1992 high mid-January loss reported using the Match technique.

Schoeberl, Mark R.; Newman, Paul A.; Lait, Leslie R.; McGee, Thomas J.; Burris, John F.; Browell, Edward V.; Grant, William B.; Richard, Eric; VonderGathen, Peter; Bevilacqua, Richard; Einaudi, Franco (Technical Monitor)

2001-01-01

323

Chemical ozone loss and ozone mini-hole event during the Arctic winter 2010/2011 as observed by SCIAMACHY and GOME-2  

NASA Astrophysics Data System (ADS)

Record breaking loss of ozone (O3) in the Arctic stratosphere has been reported in winter-spring 2010/2011. We examine in detail the composition and transformations occurring in the Arctic polar vortex using total column and vertical profile data products for O3, bromine oxide (BrO), nitrogen dioxide (NO2), chlorine dioxide (OClO), and polar stratospheric clouds (PSC) retrieved from measurements made by SCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric CHartography) on-board Envisat (Environmental Satellite), as well as total column ozone amount, retrieved from the measurements of GOME-2 (Global Ozone Monitoring Experiment) on MetOp-A (Meteorological Experimental Satellite). Similarly we use the retrieved data from DOAS (Differential Optical Absorption Spectroscopy) measurements made in Ny-Ålesund (78.55° N, 11.55° E). A chemical transport model (CTM) has been used to relate and compare Arctic winter-spring conditions in 2011 with those in the previous year. In late winter-spring 2010/2011 the chemical ozone loss in the polar vortex derived from SCIAMACHY observations confirms findings reported elsewhere. More than 70% of O3 was depleted by halogen catalytic cycles between the 425 and 525 K isentropic surfaces, i.e. in the altitude range ~16-20 km. In contrast, during the same period in the previous winter 2009/2010, a typical warm Arctic winter, only slightly more than 20% depletion occurred below 20 km, while 40% of O3 was removed above the 575 K isentrope (~23 km). This loss above 575 K is explained by the catalytic destruction by NOx descending from the mesosphere. In both Arctic winters 2009/2010 and 2010/2011, calculated O3 losses from the CTM are in good agreement to our observations and other model studies. The mid-winter 2011 conditions, prior to the catalytic cycles being fully effective, are also investigated. Surprisingly, a significant loss of O3 around 60%, previously not discussed in detail, is observed in mid-January 2011 below 500 K (~19 km) and sustained for approximately 1 week. The low O3 region had an exceptionally large spatial extent. The situation was caused by two independently evolving tropopause elevations over the Asian continent. Induced adiabatic cooling of the stratosphere favoured the formation of PSC, increased the amount of active chlorine for a short time, and potentially contributed to higher polar ozone loss later in spring.

Hommel, R.; Eichmann, K.-U.; Aschmann, J.; Bramstedt, K.; Weber, M.; von Savigny, C.; Richter, A.; Rozanov, A.; Wittrock, F.; Khosrawi, F.; Bauer, R.; Burrows, J. P.

2014-04-01

324

Modeling the Frozen-In Anticyclone in the 2005 Arctic Summer Stratosphere  

NASA Technical Reports Server (NTRS)

Immediately following the breakup of the 2005 Arctic spring stratospheric vortex, a tropical air mass, characterized by low potential vorticity (PV) and high nitrous oxide (N2O), was advected poleward and became trapped in the easterly summer polar vortex. This feature, known as a "Frozen-In Anticyclone (FrIAC)", was observed in Earth Observing System (EOS) Aura Microwave Limb Sounder (MLS) data to span the potential temperature range from approximately 580 to 1100 K (approximately 25 to 40 km altitude) and to persist from late March to late August 2005. This study compares MLS N2O observations with simulations from the Global Modeling Initiative (GMI) chemistry and transport model, the GEOS-5/MERRA Replay model, and the VanLeer Icosahedral Triangular Advection isentropic transport model to elucidate the processes involved in the lifecycle of the FrIAC which is here divided into three distinct phases. During the "spin-up phase" (March to early April), strong poleward flow resulted in a tight isolated anticyclonic vortex at approximately 70-90 deg N, marked with elevated N2O. GMI, Replay, and VITA all reliably simulted the spin-up of the FrIAC, although the GMI and Replay peak N2O values were too low. The FrIAC became trapped in the developing summer easterly flow and circulated around the polar region during the "anticyclonic phase" (early April to the end of May). During this phase, the FrIAC crossed directly over the pole between the 7th and 14th of April. The VITA and Replay simulations transported the N2O anomaly intact during this crossing, in agreement with MLS, but unrealistic dispersion of the anomaly occurred in the GMI simulation due to excessive numerical mixing of the polar cap. The vortex associated with the FrIAC was apparently resistant to the weak vertical hear during the anticyclonic phase, and it thereby protected the embedded N20 anomaly from stretching. The vortex decayed in late May due to diabatic processes, leaving the N2O anomaly exposed to horizontal and vertical wind shears during the "shearing phase" (June to August). The observed lifetime of the FrIAC during this phase is consistent with time-scales calculated from the ambient horizontal and vertical wind shear. Replay maintained the horizontal structure of the N2O anomaly similar to NILS well into August. The VITA simulation also captured the horizontal structure of the FrIAC during this phase, but VITA eventually developed fine-scale N2O structure not observed in MLS data.

Allen, D. R.; Douglass, A. R.; Manney, G. L.; Strahan, S. E.; Krosschell, J. C.; Trueblood, J.

2010-01-01

325

Propagation of a vortex Airy beam in chiral medium  

NASA Astrophysics Data System (ADS)

The analytical expression for the propagation of a vortex Airy beam through ABCD optical systems is derived. As an example, the propagation of the beam in chiral medium is discussed. It is shown that the vortex will destroy the center lobe of the Airy beam at a critical position which is different for the left circularly polarized (LCP) and the right circularly polarized (RCP) vortex Airy beam. The intensity distribution exhibits novel features due to the existence of the vortex. In addition, the intensity distributions of the LCP beam and the RCP beam are more sensitive to the chirality parameter in far-zone than that in near-zone. The transverse shift of the center lobe of a vortex Airy beam during propagation is affected by the chiral parameter.

Liu, Xiayin; Zhao, Daomu

2014-06-01

326

Arctic Refraction Catalogue  

NSDL National Science Digital Library

The Geological Survey of Canada provides this site containing abundant data on seismic refraction surveys from the Arctic Ocean. The data available include maps, velocity-depth profiles, and text on cruise information, depths and velocities, source and receiver locales, and experiment descriptions. The seismic data come from the following areas: Alaska, Amerasian Basin, Baffin Bay, Barents-Kara Sea, Bering Sea, Canadian Polar Margin, Eurasian Basin, Laptev Sea, Lomonosov Ridge, and Norway. A clickable index map of the seismic profiles serves as a gateway to the data sets. Contributions to the data catalog come from numerous countries including Norway, Germany, Russia,, and the US.

327

Arctic National Wildlife Refuge  

NSDL National Science Digital Library

This is the homepage of the Arctic National Wildlife Refuge (ANWR). Materials available here include information for visitors, refuge history and culture, information on the refuge's oil and gas resources. There is also extensive information on wild lands and wildlife, including caribou, bears, moose, wolves, and muskoxen, among others. Caribou calving maps, caribou movements, polar bear and muskox locations, snow geese fall use areas, and fish locations are available on maps. Habitat details are described, including a section on ice wedges and other permafrost features.

328

INTRODUCTIOn* Arctic air pollution, commonly observedas Arctic  

E-print Network

Pergamon INTRODUCTIOn* Arctic air pollution, commonly observedas Arctic haze, is now a wellAsia(Eurasia) to the Arctic on winds that favor transport to the north in winter over that in summer. Hence. the suspendedparticulate matter and acidic gasesmeas- ured in the Arctic region undergo strong seasonal variationsin

Short, Daniel

329

Arctic Net  

NSDL National Science Digital Library

This network of Canadian agencies brings together scientists and managers in the natural, human health and social sciences with their partners in Inuit organizations, northern communities, federal and provincial agencies and the private sector to study the impacts of climate change in the coastal Canadian Arctic. Over 90 ArcticNet researchers from 23 Canadian universities and 5 Federal departments collaborate with research teams in the USA, Japan, Denmark, Sweden, Norway, Poland, the United Kingdom, Spain, Russia, Greenland and France. The site contains information about the background and structure of the organization as well as news and events and information about research, education and training, media and publications, and the Canadian Coast Guard Ship Amundsen, which is a combination research vessel and ice breaker. Shortcut links lead to a photograph gallery and information about Schools on Board, an outreach program to interest Canadian secondary school children in Arctic studies.

330

Arctic Meltdown  

NSDL National Science Digital Library

In 1996, US entrepreneur and explorer Gary Comer took his small boat through the Northwest Passage in 19 days, a route that had once been ice, but was now easily navigated open water. This radio broadcast weighs up the extent and implications of the imminent Arctic ice breakup. The broadcast discusses the Historical Limit line in Greenland, which denotes glacier recession; Inuit observations of climate changes that are challenging their culture; the acceleration of global warming on Arctic sea ice; the problems increased Arctic shipping and melting permafrost are creating for infrastructure; the long-term outlook for global sea levels; and the possibility for the complete melting of Greenland. The broadcast is 28 minutes and 11 seconds in length and is available in real audio format.

2011-11-29

331

Episodes of Cross-Polar Transport in the Arctic Troposphere During July 2008 as Seen from Models, Satellite, and Aircraft Observations  

NASA Technical Reports Server (NTRS)

During the POLARCAT summer campaign in 2008, two episodes (2 5 July and 7 10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires and anthropogenic sources in East Asia embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART and the Eulerian chemical transport model TOMCAT with retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite. The main aspect of the comparison is how realistic horizontal and vertical structures are represented in the model simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the model simulations. However, finer-scale structures are too quickly diffused in the Eulerian model. Applying the IASI averaging kernels to the model data is essential for a meaningful comparison. Using aircraft data as a reference suggests that the satellite data are biased high, while TOMCAT is biased low. FLEXPART fits the aircraft data rather well, but due to added background concentrations the simulation is not independent from observations. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. In addition to the very good agreement between simulated and observed total column CO fields, the results also highlight the difficulty to identify a data set that most realistically represents the actual pollution state of the Arctic atmosphere.

Sodemann, H.; Pommier, M.; Arnold, S. R.; Monks, S. A.; Stebel, K.; Burkhart, J. F.; Hair, J. W.; Diskin, G. S.; Clerbaux, C.; Coheur, P.-F.; Hurtmans, D.; Schlager, H.; Blechschmidt, A.-M.; Kristjansson, J. E.; Stohl, A.

2011-01-01

332

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

NASA Astrophysics Data System (ADS)

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires and anthropogenic sources in East Asia embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART and the Eulerian chemical transport model TOMCAT with retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite. The main aspect of the comparison is how realistic horizontal and vertical structures are represented in the model simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the model simulations. However, finer-scale structures are too quickly diffused in the Eulerian model. Applying the IASI averaging kernels to the model data is essential for a meaningful comparison. Using aircraft data as a reference suggests that the satellite data are biased high, while TOMCAT is biased low. FLEXPART fits the aircraft data rather well, but due to added background concentrations the simulation is not independent from observations. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. In addition to the very good agreement between simulated and observed total column CO fields, the results also highlight the difficulty to identify a data set that most realistically represents the actual pollution state of the Arctic atmosphere.

Sodemann, H.; Pommier, M.; Arnold, S. R.; Monks, S. A.; Stebel, K.; Burkhart, J. F.; Hair, J. W.; Diskin, G. S.; Clerbaux, C.; Coheur, P.-F.; Hurtmans, D.; Schlager, H.; Blechschmidt, A.-M.; Kristjánsson, J. E.; Stohl, A.

2011-04-01

333

Climatology of large-scale isentropic mixing in the Arctic winter stratosphere from analyzed winds  

NASA Astrophysics Data System (ADS)

Dynamic isolation of the winter Arctic circumpolar vortex is studied using analyzed winds derived from geopotential height fields. Isentropic trajectories are calculated for assemblages of particles initialized on uniform latitude-longitude grids. Transport across isolines of Ertel potential vorticity (PV) is used to characterize the mixing processes of ejection of vortex air and entrainment of midlatitude air into the vortex. During January and February a barrier to mixing, where exchange of air is inhibited, typically forms near the vortex boundary. At 450 K, transport across the barrier is predominantly in the form of thin filaments of particles ejected from the vortex. These filaments tend to wrap around the vortex, creating a layered structure of vortex and midlatitude air at the vortex edge. Near or total splits of the vortex into two or more distinct vortex fragments are quite common based on these trajectory calculations. Significant entrainment deep into the vortex is rare and results from only a limited number of the splitting events. During December and March the mixing barrier is less evident due to nonconservative factors during the spin-up and breakdown of the vortex, respectively. In December both ejection and entrainment are only weakly inhibited by the mixing barrier. Exchange in March is dominated by ejection of air from the vortex.

Dahlberg, Steven P.; Bowman, Kenneth P.

1994-10-01

334

Unprecedented Arctic ozone loss in 2011.  

PubMed

Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18-20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded. PMID:21964337

Manney, Gloria L; Santee, Michelle L; Rex, Markus; Livesey, Nathaniel J; Pitts, Michael C; Veefkind, Pepijn; Nash, Eric R; Wohltmann, Ingo; Lehmann, Ralph; Froidevaux, Lucien; Poole, Lamont R; Schoeberl, Mark R; Haffner, David P; Davies, Jonathan; Dorokhov, Valery; Gernandt, Hartwig; Johnson, Bryan; Kivi, Rigel; Kyrö, Esko; Larsen, Niels; Levelt, Pieternel F; Makshtas, Alexander; McElroy, C Thomas; Nakajima, Hideaki; Parrondo, Maria Concepción; Tarasick, David W; von der Gathen, Peter; Walker, Kaley A; Zinoviev, Nikita S

2011-10-27

335

Where Does the Arctic Begin? End?  

NSDL National Science Digital Library

This article points out that there is no one official definition for the Arctic. Then the author identifies definitions ranging from geography to climate to culture and more. Maps and other visuals illustrate the definitions. The author suggests that defining the Arctic can be an example for K-Grade 5 students of the nature and challenges of classification systems. The article appears in the free, online magazine Beyond Penguins and Polar Bears.

Fries-Gaither, Jessica

2011-01-01

336

Decadal Time Scale change in terrestrial plant communities in North American arctic and alpine tundra: A contribution to the International Polar Year Back to the Future Project (Invited)  

Microsoft Academic Search

The International Polar Year-Back to the Future (IPY-BTF) is an endorsed International Polar Year project (IPY project #214). The overarching goal of this program is to determine how key structural and functional characteristics of high latitude\\/altitude terrestrial ecosystems have changed over the past 25 or more years and assess if such trajectories of change are likely to continue in the

C. E. Tweedie; D. Ebert-May; R. D. Hollister; D. R. Johnson; M. J. Lara; S. Villarreal; M. Spasojevic; P. Webber

2010-01-01

337

Controlling the chirality and polarity of vortices in magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

Static and dynamic control of the chirality and polarity of a magnetic vortex confined in a magnetic tunnel junction is demonstrated. The modes associated with the four chirality/polarity vortex configurations are first explored by resonant excitation with a low power rf current. When the rf power is increased, both the chirality and polarity of the vortex can be resonantly switched, which—as shown by micromagnetic simulations—involves vortex expulsion and renucleation. This tunable resonant switching of the vortex parameters are an exciting step forward for the viability of magnetic vortex-based applications.

Jenkins, A. S.; Grimaldi, E.; Bortolotti, P.; Lebrun, R.; Kubota, H.; Yakushiji, K.; Fukushima, A.; de Loubens, G.; Klein, O.; Yuasa, S.; Cros, V.

2014-10-01

338

Aura's Microwave Limb Sounder Estimates of Ozone Loss, 2004/2005 Arctic Winter  

NASA Technical Reports Server (NTRS)

These data maps from Aura's Microwave Limb Sounder depict levels of hydrogen chloride (top), chlorine monoxide (center), and ozone (bottom) at an altitude of approximately 19 kilometers (490,000 feet) on selected days during the 2004-05 Arctic winter. White contours demark the boundary of the winter polar vortex.

The maps from December 23, 2004, illustrate vortex conditions shortly before significant chemical ozone destruction began. By January 23, 2005, chlorine is substantially converted from the 'safe' form of hydrogen chloride, which is depleted throughout the vortex, to the 'unsafe' form of chlorine monoxide, which is enhanced in the portions of the region that receive sunlight at that time of year. Ozone increased over the month as a result of dynamical effects, and chemical ozone destruction is just beginning at this time. A brief period of intense cold a few days later promotes further chlorine activation and consequent changes in hydrogen chloride and chlorine monoxide levels on January 27, 2005. Peak chlorine monoxide enhancement occurs in early February.

By February 24, 2005, chlorine deactivation is well underway, with chlorine monoxide abundances dropping and hydrogen chloride abundances rising. Almost all chlorine monoxide has been quenched by March 10, 2005. The fact that hydrogen chloride has not fully rebounded to December abundances suggests that some of that chemical was recovered into another chlorine reservoir species.

Ozone maps for January 27, 2005, through March 10, 2005, show indications of mixing of air from outside the polar vortex into it. Such occurrences throughout this winter, especially in late February and early March, complicate analyses, and detailed calculations are required to rigorously disentangle chemical and dynamical effects and accurately diagnose chemical ozone destruction.

Based on various analyses of Microwave Limb Sounder data, we estimate that maximum local ozone loss of approximately 2 parts per million by volume (approximately 60 percent) has taken place at this level during the period from January 23, 2005, to March 10, 2005, with vortex-averaged loss of approximately 1.5 parts per million by volume.

2005-01-01

339

Atmospheric Environment 38 (2004) 805820 Arctic haze, mercury and the chemical composition of snow  

E-print Network

Atmospheric Environment 38 (2004) 805­820 Arctic haze, mercury and the chemical composition of snow in atmospheric aerosol loading (arctic haze) that develops as the Arctic polar front expands southward in March and April. Haze contaminant concentrations in the snow pack were as high south of the Brooks Range

Douglas, Thomas A.

340

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

NASA Astrophysics Data System (ADS)

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART, the Eulerian chemical transport model TOMCAT, and for numerical aspects the limited-area chemical transport model WRF-Chem. Retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite are used as a total column CO reference for the two simulations. Main aspect of the comparison is how realistic horizontal and vertical structures are represented in the model simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the model simulations. However, finer-scale structures are too quickly diffused in the Eulerian models. Aircraft data suggest that the satellite data are biased high, while TOMCAT and WRF-Chem are biased low. FLEXPART fits the aircraft data rather well, but due to added background concentrations the simulation is not independent from observations. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. In addition to the very good agreement between simulated and observed total column CO fields, the results also highlight the difficulty to identify a data set that most realistically represents the actual state of the atmosphere.

Sodemann, H.; Pommier, M.; Arnold, S. R.; Monks, S. A.; Stebel, K.; Burkhart, J. F.; Hair, J. W.; Diskin, G. S.; Clerbaux, C.; Coheur, P.-F.; Hurtmans, D.; Schlager, H.; Blechschmidt, A.-M.; Kristjánsson, J. E.; Stohl, A.

2010-11-01

341

Episodes of cross-polar transport in the Arctic troposphere during July 2008 as seen from models, satellite, and aircraft observations  

NASA Astrophysics Data System (ADS)

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART, the Eulerian chemical transport model TOMCAT, and the limited-area chemical transport model WRF-Chem. Retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite are used as a total column CO reference for the two simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the two model simulations. Thereby, finer-scale structures are too quickly diffused in the Eulerian model. In absolute numbers the total CO fields is highest in the satellite observations, followed by the FLEXPART and the TOMCAT model. Aircraft data suggest that the satellite data are biased high. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. Results indicate very good agreement between simulated and observed total column CO fields, but also highlight the difficulty to identify a data set that most realistically represents the actual state of the atmosphere.

Stohl, A.; Sodemann, H.; Pommier, M.; Arnold, S. R.; Monks, S. A.; Stebel, K.; Burkhart, J. F.; Hair, J. W.; Diskin, G. S.; Clerbaux, C.; Coheur, P.; Hurtmans, D.; Schlager, H.; Blechschmidt, A.; Kristjansson, J. E.

2010-12-01

342

Canada's Polar Environments: Marine Waters  

NSDL National Science Digital Library

This site contains information about the three ecozones in the marine waters of polar Canada: The Arctic Archipelago Marine Ecozone, the Arctic Basin, and the Northwest Atlantic Ecozone. The features section describes the physical characteristics of the deep Arctic Basin and shallow Continental Shelf water settings and the major currents responsible for water movement in the Arctic, as well as three features (leads, polynyas, tides) that have important effects on Arctic life. Information is also provided about icebergs, ice islands, ice shelves, sea ice, and the polar ice cap. Information about icebergs in the Davis Straight, frost flowers, iceblink, water sky, the Northwest Passage and open water at the North Pole is offered in the cool facts section.

343

Arctic Cooling  

NSDL National Science Digital Library

Most scientists agree that human activities are causing the global climate to heat up. However, in this radio broadcast, two scientists from Alaska explain how nature still has a big say in how much the Arctic heats up and that recent warming is part of a natural cycle, occurring over thousands of years. The clip from 2005 is 3 minutes and 54 seconds in length.

344

Propeller tip vortex interactions  

NASA Technical Reports Server (NTRS)

Propeller wakes interacting with aircraft aerodynamic surfaces are a source of noise and vibration. For this reason, flow visualization work on the motion of the helical tip vortex over a wing and through the second stage of a counterrotation propeller (CRP) has been pursued. Initially, work was done on the motion of a propeller helix as it passes over the center of a 9.0 aspect ratio wing. The propeller tip vortex experiences significant spanwise displacements when passing across a lifting wing. A stationary propeller blade or stator was installed behind the rotating propeller to model the blade vortex interaction in a CRP. The resulting vortex interaction was found to depend on the relative vortex strengths and vortex sign.

Johnston, Robert T.; Sullivan, John P.

1990-01-01

345

Estimation of polar low characteristics for the Nordic Seas for 1995-2008 using satellite data  

NASA Astrophysics Data System (ADS)

In recent years the scientific research confirmed the fact of the global warming. The Arctic climate is warming even more rapidly. Powerful storm polar lows having wind speeds of about 25 m/c are known to be the cause of hazardous weather. Polar lows present themselves as the atmospheric phenomena the horizontal dimensions of which do not exceed 1,000 km, appear and which exist from 12 to 24 hours. The wave fall and low temperatures can lead to increased probability of vessel icing the intensity of which increases with the high wind speed and large wave height. Study of the mesoscale processes, such as polar lows in the Arctic has become especially relevant due to the sharp sea ice decreasing in the Arctic Ocean and Arctic seas in recent years. Only the use of satellite data allows obtaining regular and spacious information about the polar lows. Early detection and evaluation of the characteristics of the polar lows is an extremely important task to ensure the safety of navigation, fishing and oil industry in the Arctic region. With new open areas dangerous polar lows can arise over them. So early detection of the polar lows, studying their characteristics, tracking their movement and prediction presents one the most important problems of the modern science. The present-day meteorological observational network has severe limitations in detecting all, especially small mesoscale cyclones, so there is a strong need for new and/or improved methods to detect and monitor polar lows. Satellite remote sensing seems to be the most feasible tool for early detection and monitoring of the polar lows. Several remote sensing sensors are capable to detect a polar low but each of them suffers from various deficiencies. In the work, satellite passive microwave data have been intensively exploited aiming at obtaining the fields of geophysical parameters inside the polar lows. DMSP Special Sensor Microwave/Imager - SSM/I data were used in the research. The polar lows have been identified on satellite passive microwave imagery by fields of means of analysis of atmospheric water vapour fields using a new approach. This approach consists of two stages. During the first stage the total atmospheric water vapor fields are calculated from passive microwave measurements using precise retrieval Neural Network Algorithms (Bobylev et al., 2010). During the second stage the vortex structures are detected in these fields, and polar lows are identified and tracked. Based on this approach, were estimated polar low characteristics in the Nordic seas for the period of 1995 - 2008. All polar lows have been identified for this period on SSM/I imagery. Other satellite data, such as QuikSCAT SeaWinds, NOAA AVHRR were used as additional information for polar low parameter retrieval and analysis.

Smirnova, Julia; Chapron, Bertrand; Zabolotskikh, Elizaveta; Leonid Bobylev, Mr

346

On the Influence of North Pacific Sea Surface Temperature on the Arctic Winter Climate  

NASA Technical Reports Server (NTRS)

Differences between two ensembles of Goddard Earth Observing System Chemistry-Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High Low differences are consistent with a weakened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid- and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in late winter, affecting the April clear-sky UV index at Northern Hemisphere mid-latitudes.

Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.

2012-01-01

347

Clay Minerals in Response to the Mid-Pliocene Global Warmth in Polar Regions (ODP, Site 911, Yermak Plateau, Arctic Ocean and Site 1165, Prydz Bay, Antarctica)  

NASA Astrophysics Data System (ADS)

The Mid-Pliocene global warmth (MPGW), a period when the global average temperatures were significantly warmer than the present, was possibly caused by higher CO2 levels than today and significantly stronger ocean thermohaline circulation due to drastic climatic changes in the Southern Ocean. In the Northern Hemisphere, MPGW could have been one decisive trigger for the intensification of glaciation at 2.7 Ma. Some recent studies in the East Antarctica have shown that the East Antarctic Ice Sheet (EAIS) may have varied from a polythermal, dynamic condition to a predominantly cold stable state as recently as the Pliocene period, including MPGW. This presentation may illuminate the Mid-Pliocene climate conditions of the Arctic Ocean and the dynamics of the EAIS based on a clay mineral study. Research of this kind, integrated with other proxies, can provide some indication of how the Earth may respond to the future global warming The Ocean Drilling Program (ODP) Site 911 was drilled on the Yermak Plateau, Arctic Ocean to a depth of 505.8 meters below the seafloor (mbsf). It contained sediments from the Pliocene to Pleistocene ages. ODP Site 1165 was drilled on the Wild Drift on the Continental Rise off Prydz Bay, East Antarctica, to a total depth of 999.1 mbsf. Of special interest is the sediment column between 0 and 50 mbsf, which consists of a well-preserved section of Pliocene- to Pleistocene-age sediments. The Pliocene sediments at Site 911 have higher smectite content and lower kaolinite and chlorite contents compared to the Pleistocene samples. This may indicate more active sea-ice conditions for smectite transportation from the Kara and Laptev Seas during the Pliocene compared to the Pleistocene sea-ice transportation conditions. The Mid-Pliocene sediments at Site 1165 show increasing smectite contents and decreasing illite contents and suggest that the EAIS at that time may have been more dynamic than that during the Plio-Pleistocene transition, to which the results were compared.

Junttila, J.; Strand, K.

2005-12-01

348

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi-agency Study of Environmental Arctic Change (SEARCH) program, providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS’ central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include, among many others, the Witness the Arctic newsletter, the Arctic Visiting Speakers’ Series, the ArcticInfo listserve, the Internet Media Archive (IMA), and the annual Arctic Forum conference. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Fox, S. E.; Wiggins, H. V.; Creek, K. R.

2009-12-01

349

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi-agency Study of Environmental Arctic Change (SEARCH) program, providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS’ central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include, among many others, the Witness the Arctic newsletter, the Arctic Visiting Speakers’ Series, the ArcticInfo listserve, the Internet Media Archive (IMA), and the annual Arctic Forum conference. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Creek, K. R.; Fox, S. E.; Wiggins, H. V.

2010-12-01

350

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi- agency Study of Environmental Arctic Change (SEARCH) program, providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS" central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include, among many others, the Witness the Arctic newsletter, the Arctic Visiting Speakers" Series, the ArcticInfo listserve, the Internet Media Archive (IMA), and the annual Arctic Forum conference. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Wiggins, H. V.; Warnick, W. K.

2008-12-01

351

The Arctic Research Consortium of the United States  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broad science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of current ARCUS science planning activities include: serving as the project office for the multi-agency Study of Environmental Arctic Change (SEARCH) program and providing support to the related Bering Ecosystem Study (BEST), and serving as the Science Management Office for the National Science Foundation (NSF) Arctic System Science (ARCSS) Program. ARCUS' central educational activity is PolarTREC (Teachers and Researchers Exploring and Collaborating), an International Polar Year (IPY) program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. Additional science planning, educational, information, and outreach activities include the Witness the Arctic newsletter, the Arctic Visiting Speakers' Series, the ArcticInfo listserve, the Internet Media Archive (IMA), the annual Arctic Forum conference, and many others. More information about these and other ARCUS activities can be found at the ARCUS website at www.arcus.org.

Warnick, W. K.; Wiggins, H. V.

2007-12-01

352

Detection of the phase shift from a single Abrikosov vortex.  

PubMed

We probe a quantum mechanical phase rotation induced by a single Abrikosov vortex in a superconducting lead, using a Josephson junction, made at the edge of the lead, as a phase-sensitive detector. We observe that the vortex induces a Josephson phase shift equal to the polar angle of the vortex within the junction length. When the vortex is close to the junction it induces a ? step in the Josephson phase difference, leading to a controllable and reversible switching of the junction into the 0-? state. This in turn results in an unusual ?(0)/2 quantization of the flux in the junction. The vortex may hence act as a tunable "phase battery" for quantum electronics. PMID:20867200

Golod, T; Rydh, A; Krasnov, V M

2010-06-01

353

Arctic Social Sciences: Opportunities in Arctic Research.  

ERIC Educational Resources Information Center

The U.S. Congress passed the Arctic Research and Policy Act in 1984 and designated the National Science Foundation (NSF) the lead agency in implementing arctic research policy. In 1989, the parameters of arctic social science research were outlined, emphasizing three themes: human-environment interactions, community viability, and rapid social…

Arctic Research Consortium of the United States, Fairbanks, AK.

354

Arctic Energy Resources: Energy Research  

NASA Astrophysics Data System (ADS)

Arctic Energy Resources is a volume of 26 papers recording the proceedings of the Comite' Arctique International Conference, held at the Veritas Centre, Oslo, Norway, September 22-24, 1982. This was the fourth of a series of meetings on the Arctic organized by the Comite', an organization established in the Principality of Monaco with the active support of H.S.H. Prince Rainer III. The fourth Conference was opened by H.R.H. Crown Prins Harald of Norway, a noble beginning for a noble objective.The North Polar Region has drawn world attention recently because of several large hydrocarbon and other mineral discoveries and because of major political and environmental actions in the North American Arctic. Since 1923 when Naval Petroleum Reserve number 4 (NPR-4) was established, northern Alaska has been considered a major petroleum province. It was first explored systematically with modern techniques from 1943 to 1953. In 1958, Alaska became a state, and both federal and state lands in northern Alaska were available for private exploration. Building on the knowledge base provided by the Pet-4 program and its spinoff research laboratory at Barrow, industry explored the area east of NPR-4 and discovered the largest hydrocarbon accumulation (9.6 bbl crude oil and 26 Tcf (trillion cubic feet) gas) in North America at Prudhoe Bay. Concerns for environmental impacts, including oil spills, led to the passing of the National Environmental Policy Act in 1969. In 1970, over 9 million acres were set aside, now known as the Arctic National Wildlife Range, and in 1971 the Alaska Native Claims Settlement Act was passed by the U.S. Congress. The Arab oil embargo of 1973 heightened the energy crisis and changed the economic basis for further exploration in the Arctic. The convergence of these events dramatically changed the balance of power and the pace of activity in the North American Arctic.

Gryc, George

1984-04-01

355

Arctic Languages: An Awakening.  

ERIC Educational Resources Information Center

This work is a study of Arctic languages written in an interdisciplinary manner. Part of the Unesco Arctic project aimed at safeguarding the linguistic heritage of Arctic peoples, the book is the outcome of three Unesco meetings at which conceptual approaches to and practical plans for the study of Arctic cultures and languages were worked out.…

Collis, Dermid R. F., Ed.

356

Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations.  

PubMed

Polar bears (Ursus maritimus) have experienced substantial changes in the seasonal availability of sea ice habitat in parts of their range, including the Beaufort, Chukchi, and Bering Seas. In this study, we compared the body size, condition, and recruitment of polar bears captured in the Chukchi and Bering Seas (CS) between two periods (1986-1994 and 2008-2011) when declines in sea ice habitat occurred. In addition, we compared metrics for the CS population 2008-2011 with those of the adjacent southern Beaufort Sea (SB) population where loss in sea ice habitat has been associated with declines in body condition, size, recruitment, and survival. We evaluated how variation in body condition and recruitment were related to feeding ecology. Comparing habitat conditions between populations, there were twice as many reduced ice days over continental shelf waters per year during 2008-2011 in the SB than in the CS. CS polar bears were larger and in better condition, and appeared to have higher reproduction than SB bears. Although SB and CS bears had similar diets, twice as many bears were fasting in spring in the SB than in the CS. Between 1986-1994 and 2008-2011, body size, condition, and recruitment indices in the CS were not reduced despite a 44-day increase in the number of reduced ice days. Bears in the CS exhibited large body size, good body condition, and high indices of recruitment compared to most other populations measured to date. Higher biological productivity and prey availability in the CS relative to the SB, and a shorter recent history of reduced sea ice habitat, may explain the maintenance of condition and recruitment of CS bears. Geographic differences in the response of polar bears to climate change are relevant to range-wide forecasts for this and other ice-dependent species. PMID:23913506

Rode, Karyn D; Regehr, Eric V; Douglas, David C; Durner, George; Derocher, Andrew E; Thiemann, Gregory W; Budge, Suzanne M

2014-01-01

357

Vortex Coupler for Atomic Bose-Einstein Condensates  

SciTech Connect

A coherent coupler is proposed to spin a Bose-Einstein condensate composed of ultracold alkali atoms into a vortex state. The proposal is based on a Raman transition induced by two copropagating {sigma}{sup +} and {sigma}{sup {minus}} polarized Laguerre-Gaussian laser beams with different frequencies. We show that the transfer of angular momentum of photons to the condensed atoms through a Raman transition leads to a coherent coupling of the ground-state condensate to a rotating condensate in a vortex state. The detection of such a vortex state is discussed. {copyright} {ital 1997} {ital The American Physical Society}

Marzlin, K.; Zhang, W. [School of Mathematics, Physics, Computing and Electronics, Macquarie University, Sydney, NSW 2109 (Australia)] [School of Mathematics, Physics, Computing and Electronics, Macquarie University, Sydney, NSW 2109 (Australia); Wright, E.M. [Optical Sciences Center, University of Arizona, Tucson, Arizona 85721 (United States)] [Optical Sciences Center, University of Arizona, Tucson, Arizona 85721 (United States)

1997-12-01

358

Electrostatically Enhanced Vortex Separator  

NASA Technical Reports Server (NTRS)

Proposed device removes fine particles from high-pressure exhaust gas of chemical reactor. Negatively charged sectors on rotating disks in vortex generator attracts positively charged particles from main stream of exhaust gas. Electrostatic charge enhances particle-separating action of vortex. Gas without particles released to atmosphere.

Collins, Earl R.

1993-01-01

359

Vortex control: Further encounters  

NASA Technical Reports Server (NTRS)

The progress of continuing investigations on vortex control techniques is updated. The following topics are briefly discussed: (1) vortex flaps adapted for high-alpha control; (2) alleviation of leading edge extension (LEX) vortex induced twin-tail buffet; (3) controlled decoupling of interactive forebody chine and wing vortices; (4) forebody vortex manipulation by mechanical and pneumatic techniques; and (5) stall-departure alleviation of high aspect-ratio wings. Salient results of exploratory low speed wind tunned experiments are presented. The investigations, primarily aimed at concept validation, were performed on generic configurations utilizing flow visualizations and pressure and balance measurements. Selected results illustrate the efficacy and potential for development of specific vortex control concepts for improved high-alpha configuration aerodynamics.

Rao, Dhanvada M.

1991-01-01

360

Microscopic Investigation of Vortex-Vortex Interaction in Conventional Superconductors  

NASA Astrophysics Data System (ADS)

Quasi-particle structures around a pair of vortices and its effect on the vortex-vortex interaction are investigated. For this purpose, a new numerical method is developed. This method uses the elliptic coordinate and (modified) Mathieu functions. Using this method and solving the Bogoliubov-de Gennes equation, we analyse how quasi-particle structures change with the vortex-vortex distance.

Kato, Masaru; Niwa, Yuhei

2012-12-01

361

High Speed Vortex Flows  

NASA Technical Reports Server (NTRS)

A review of the research conducted at the National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) into high-speed vortex flows during the 1970s, 1980s, and 1990s is presented. The data reviewed is for flat plates, cavities, bodies, missiles, wings, and aircraft. These data are presented and discussed relative to the design of future vehicles. Also presented is a brief historical review of the extensive body of high-speed vortex flow research from the 1940s to the present in order to provide perspective of the NASA LaRC's high-speed research results. Data are presented which show the types of vortex structures which occur at supersonic speeds and the impact of these flow structures to vehicle performance and control is discussed. The data presented shows the presence of both small- and large scale vortex structures for a variety of vehicles, from missiles to transports. For cavities, the data show very complex multiple vortex structures exist at all combinations of cavity depth to length ratios and Mach number. The data for missiles show the existence of very strong interference effects between body and/or fin vortices and the downstream fins. It was shown that these vortex flow interference effects could be both positive and negative. Data are shown which highlights the effect that leading-edge sweep, leading-edge bluntness, wing thickness, location of maximum thickness, and camber has on the aerodynamics of and flow over delta wings. The observed flow fields for delta wings (i.e. separation bubble, classical vortex, vortex with shock, etc.) are discussed in the context of' aircraft design. And data have been shown that indicate that aerodynamic performance improvements are available by considering vortex flows as a primary design feature. Finally a discussing of a design approach for wings which utilize vortex flows for improved aerodynamic performance at supersonic speed is presented.

Wood, Richard M.; Wilcox, Floyd J., Jr.; Bauer, Steven X. S.; Allen, Jerry M.

2000-01-01

362

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions  

NASA Astrophysics Data System (ADS)

Significant reductions in stratospheric ozone occur inside the polar vortices each spring when chlorine radicals produced by heterogeneous reactions on cold particle surfaces in winter destroy ozone mainly in two catalytic cycles, the ClO dimer cycle and the ClO/BrO cycle. Chlorofluorocarbons (CFCs), which are responsible for most of the chlorine currently present in the stratosphere, have been banned by the Montreal Protocol and its amendments, and the ozone layer is predicted to recover to 1980 levels within the next few decades. During the same period, however, climate change is expected to alter the temperature, circulation patterns and chemical composition in the stratosphere, and possible geo-engineering ventures to mitigate climate change may lead to additional changes. To realistically predict the response of the ozone layer to such influences requires the correct representation of all relevant processes. The European project RECONCILE has comprehensively addressed remaining questions in the context of polar ozone depletion, with the objective to quantify the rates of some of the most relevant, yet still uncertain physical and chemical processes. To this end RECONCILE used a broad approach of laboratory experiments, two field missions in the Arctic winter 2009/10 employing the high altitude research aircraft M55-Geophysica and an extensive match ozone sonde campaign, as well as microphysical and chemical transport modelling and data assimilation. Some of the main outcomes of RECONCILE are as follows: (1) vortex meteorology: the 2009/10 Arctic winter was unusually cold at stratospheric levels during the six-week period from mid-December 2009 until the end of January 2010, with reduced transport and mixing across the polar vortex edge; polar vortex stability and how it is influenced by dynamic processes in the troposphere has led to unprecedented, synoptic-scale stratospheric regions with temperatures below the frost point; in these regions stratospheric ice clouds have been observed, extending over >106km2 during more than 3 weeks. (2) Particle microphysics: heterogeneous nucleation of nitric acid trihydrate (NAT) particles in the absence of ice has been unambiguously demonstrated; conversely, the synoptic scale ice clouds also appear to nucleate heterogeneously; a variety of possible heterogeneous nuclei has been characterised by chemical analysis of the non-volatile fraction of the background aerosol; substantial formation of solid particles and denitrification via their sedimentation has been observed and model parameterizations have been improved. (3) Chemistry: strong evidence has been found for significant chlorine activation not only on polar stratospheric clouds (PSCs) but also on cold binary aerosol; laboratory experiments and field data on the ClOOCl photolysis rate and other kinetic parameters have been shown to be consistent with an adequate degree of certainty; no evidence has been found that would support the existence of yet unknown chemical mechanisms making a significant contribution to polar ozone loss. (4) Global modelling: results from process studies have been implemented in a prognostic chemistry climate model (CCM); simulations with improved parameterisations of processes relevant for polar ozone depletion are evaluated against satellite data and other long term records using data assimilation and detrended fluctuation analysis. Finally, measurements and process studies within RECONCILE were also applied to the winter 2010/11, when special meteorological conditions led to the highest chemical ozone loss ever observed in the Arctic. In addition to quantifying the 2010/11 ozone loss and to understand its causes including possible connections to climate change, its impacts were addressed, such as changes in surface ultraviolet (UV) radiation in the densely populated northern mid-latitudes.

von Hobe, M.; Bekki, S.; Borrmann, S.; Cairo, F.; D'Amato, F.; Di Donfrancesco, G.; Dörnbrack, A.; Ebersoldt, A.; Ebert, M.; Emde, C.; Engel, I.; Ern, M.; Frey, W.; Griessbach, S.; Grooß, J.-U.; Gulde, T.; Günther, G.; Hösen, E.; Hoffmann, L.; Homonnai, V.; Hoyle, C. R.; Isaksen, I. S. A.; Jackson, D. R.; Jánosi, I. M.; Kandler, K.; Kalicinsky, C.; Keil, A.; Khaykin, S. M.; Khosrawi, F.; Kivi, R.; Kuttippurath, J.; Laube, J. C.; Lefèvre, F.; Lehmann, R.; Ludmann, S.; Luo, B. P.; Marchand, M.; Meyer, J.; Mitev, V.; Molleker, S.; Müller, R.; Oelhaf, H.; Olschewski, F.; Orsolini, Y.; Peter, T.; Pfeilsticker, K.; Piesch, C.; Pitts, M. C.; Poole, L. R.; Pope, F. D.; Ravegnani, F.; Rex, M.; Riese, M.; Röckmann, T.; Rognerud, B.; Roiger, A.; Rolf, C.; Santee, M. L.; Scheibe, M.; Schiller, C.; Schlager, H.; Siciliani de Cumis, M.; Sitnikov, N.; Søvde, O. A.; Spang, R.; Spelten, N.; Stordal, F.; Sumi?ska-Ebersoldt, O.; Viciani, S.; Volk, C. M.; vom Scheidt, M.; Ulanovski, A.; von der Gathen, P.; Walker, K.; Wegner, T.; Weigel, R.; Weinbuch, S.; Wetzel, G.; Wienhold, F. G.; Wintel, J.; Wohltmann, I.; Woiwode, W.; Young, I. A. K.; Yushkov, V.; Zobrist, B.; Stroh, F.

2012-11-01

363

Model simulation of chemical depletion of Arctic ozone during the winter of 1989  

NASA Astrophysics Data System (ADS)

Ozone depletion in the Arctic vortex has become an important issue. As part of a Canadian research program designed to study the effect of polar stratospheric clouds on the chemistry of the Arctic ozone layer, project CANOZE (Canadian Arctic Northern OZone Experiment) 4, a series of ozonesondes were flown during January and February 1989 from Alert at 82.5 deg N. This time series of ozone profiles indicated a decrease of ozone during this period. A simple chemical model is used to estimate the possible ozone depletions that could have occurred during this period. The results suggest a chemical depletion of about 4 percent per week is possible, in approximate agreement with the observed depletion rate at 20 km of 5 percent per week. The major features of the analysis confirm earlier suggestions that thermal dissociation of Cl2O2 could limit the amount of O3 destruction. For the simulation conditions of largely unperturbed O3 densities the ClO + O reaction is a major loss process for O3 above 19 km, while Cl2O2 photolysis is the major loss process below 19 km, with the BrO + ClO reaction contributing about 14 percent of the loss in both cases. The branch of the BrO + ClO reaction that results in the formation of BrCl also acts to limit the nighttime O3 destruction via BrO + ClO since BrO is rapidly converted to BrCl at twilight. The photolytic release of NO and NO2 from HNO3 at the latitudes encountered by the air parcels driving these late winter/early spring conditions is sufficiently slow that it has no major impact on O3 destruction by Cl(x) and Br(x) on the time scale of about 1 month.

McConnell, John C.; Templeton, Edna M. J.; Evans, Wayne F. J.

1991-06-01

364

Arctic Summer Ice Processes  

NASA Technical Reports Server (NTRS)

The primary objective of this study is to estimate the flux of heat and freshwater resulting from sea ice melt in the polar seas. The approach taken is to examine the decay of sea ice in the summer months primarily through the use of spaceborne Synthetic Aperture Radar (SAR) imagery. The improved understanding of the dynamics of the melt process can be usefully combined with ice thermodynamic and upper ocean models to form more complete models of ice melt. Models indicate that more heat is absorbed in the upper ocean when the ice cover is composed of smaller rather than larger floes and when there is more open water. Over the course of the summer, floes disintegrate by physical forcing and heating, melting into smaller and smaller sizes. By measuring the change in distribution of floes together with open water over a summer period, we can make estimates of the amount of heating by region and time. In a climatic sense, these studies are intended to improve the understanding of the Arctic heat budget which can then be eventually incorporated into improved global climate models. This work has two focus areas. The first is examining the detailed effect of storms on floe size and open water. A strong Arctic low pressure storm has been shown to loosen up the pack ice, increase the open water concentration well into the pack ice, and change the distribution of floes toward fewer and smaller floes. This suggests episodic melting and the increased importance of horizontal (lateral) melt during storms. The second focus area is related to an extensive ship-based experiment that recently took place in the Arctic called Surface Heat Budget of the Arctic (SHEBA). An icebreaker was placed purposely into the older pack ice north of Alaska in September 1997. The ship served as the base for experimenters who deployed extensive instrumentation to measure the atmosphere, ocean, and ice during a one-year period. My experiment will be to derive similar measurements (floe size, open water, temporal change) using spaceborne SAR data obtained during the summer of 1998, and compare these results with an ocean and ice model of summer melt. Additional information is contained in the original.

Holt, Benjamin

1999-01-01

365

Anisotropic and long-range vortex interactions in two-dimensional dipolar Bose gases.  

PubMed

We perform a theoretical study into how dipole-dipole interactions modify the properties of superfluid vortices within the context of a two-dimensional atomic Bose gas of co-oriented dipoles. The reduced density at a vortex acts like a giant antidipole, changing the density profile and generating an effective dipolar potential centred at the vortex core whose most slowly decaying terms go as 1/?(2) and ln(?)/?(3). These effects modify the vortex-vortex interaction which, in particular, becomes anisotropic for dipoles polarized in the plane. Striking modifications to vortex-vortex dynamics are demonstrated, i.e., anisotropic corotation dynamics and the suppression of vortex annihilation. PMID:24206463

Mulkerin, B C; van Bijnen, R M W; O'Dell, D H J; Martin, A M; Parker, N G

2013-10-25

366

The Age of the Arctic.  

ERIC Educational Resources Information Center

Examines trends related to exploration in the Arctic by considering: (1) technology and military strategies; (2) foreign policy and the Arctic; (3) Arctic industrialization; (4) the Arctic policy agenda; and (5) recent United States initiatives in this region. (JN)

Young, Oran R.

1986-01-01

367

Arctic and Antarctic Birds: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Arctic and Antarctic Birds issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Fries-Gaither, Jessica; Shiverdecker, Terry

368

Arctic Warming - a Perspective from Svalbard  

Microsoft Academic Search

During the International Polar Year many projects connected to IGBP science will be implemented, mostly within the Arctic and Antarctic areas. This glaciology project is connected to the IPY via the projects IPY-GLACIODYN and IPY-KINNVIKA, and has been carried out since 1997 on the Lomosovfonna ice field on central Spitsbergen in the Svalbard archipelago, and, in this respect, has a

V. Pohjola

2007-01-01

369

Peoples of the Arctic: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Peoples of the Arctic issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Fries-Gaither, Jessica

370

The University of the Arctic and Canada.  

ERIC Educational Resources Information Center

Reports on ongoing development of the University of the Arctic--a network of institutions of higher education in eight polar countries--in the context of the changing nature of distance education in Canada. Discusses Canadian access to telelearning, institutions of virtual education, related research and supportive organizations, and course…

Adams, Peter

1999-01-01

371

Proceedings of the Symposium on the Arctic Heat Budget and Atmospheric Circulation, 31 January Through 4 February 1966, Lake Arrowhead, California.  

National Technical Information Service (NTIS)

Contents: Polar ice and climate; The Arctic heat budget and atmospheric circulation; Stochastic models of air--sea interaction and climatic fluctuation; Heat regime of the Soviet Arctic related to the main atmospheric circulation patterns and their many v...

J. O. Fletcher

1966-01-01

372

Expanded record of Quaternary oceanographic change: Amerasian Arctic Ocean  

USGS Publications Warehouse

Four sediment cores collected from the Northwind and Mendeleyev ridges, Arctic Ocean, from 1089 m to 1909 m water depth, provide an oceanographic record extending back into the Matuyama reversed polarity chron. Benthic foraminiferal analyses show four prominent assemblage zones: Bolivina arctica, Cassidulina teretis, Bulimina aculeata, and Oridorsalis tener from the upper Matuyama reversed polarity chronozone through the Brunhes normal polarity chronozone. These assemblage zones represent depth-dependent benthic foraminiferal biofacies changes associated with oceanographic events that occurred in the Amerasian basin at ??? 780 and 300 ka, and indicate oceanographic influence from the North Atlantic. Recognition of these benthic assemblage zones in Arctic cores from the Alpha Ridge indicates that the benthic foraminiferal zonations in intermediate to deep water (>1000 m) Arctic cores may be more useful than preexisting lithostratigraphic zonations and should provide important information pertaining to the Quaternary paleoceanographic evolution of the Arctic Ocean.

Ishman, S. E.; Polyak, L. V.; Poore, R. Z.

1996-01-01

373

Arctic Asteroid!  

NSDL National Science Digital Library

The National Aeronautics and Space Administration's (NASA) news service provides this report on the composition of the meteor that put on a brilliant sky show before landing in Western Canada this January. The fragments of the meteorite fell into a frozen lake, so they were not recovered for study until the lake began to thaw this April. Analyses of the pieces that were recovered suggest that the fallen object had a relatively rare composition and was "...about seven meters across and 200 to 250 metric tons. This wasn't your average meteoroid -- it was basically a C-class asteroid detonating in the atmosphere over the Arctic!" says Dr. Peter Brown of the University of Western Ontario. Visit the site for the full report.

374

http://psc.apl.washington.edu/ArcticChange09.html Ocean 506B/497B -3 credit graduate course  

E-print Network

http://psc.apl.washington.edu/ArcticChange09.html #12;Ocean 506B/497B - 3 credit graduate course The Changing Arctic Ocean: an interdisciplinary perspective after IPY (International Polar Year 2007­2009) · Recent years show unprecedented change in the ice-covered Arctic Ocean. · What is currently known about

Washington at Seattle, University of

375

Size distribution time series of a polar stratospheric cloud observed above Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) (69°N) and analyzed from multiwavelength lidar measurements during winter 2005  

NASA Astrophysics Data System (ADS)

A case study of a polar stratospheric cloud (PSC) is described using multiwavelength (355, 532, and 1064 nm) lidar measurements performed at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) on 6 December 2005. Rotational Raman signals at 529 and 530 nm are used to derive a temperature field within the cloud using the rotational Raman technique (RRT). The PSC size distributions are retrieved between 1500 and 2000 UTC through a combination of statistical filtering and best match approaches. Several PSC types were detected between 22 and 26 km during the measurement session. Liquid ternary aerosols are identified before about 1600 and after 1900 UTC typically; their averaged retrieved size distribution parameters and associated errors at the backscatter peak are: No ? 1-10 cm-3 (50%), rm ? 0.15 ?m (20%), and ? ? 1.2 (15%). A mode of much larger particles is detected between 1600 and 1900 UTC (No ? 0.04 cm-3 (30%), rm ? 1.50 ?m (15%), and ? ? 1.37 (10%). The different PSC types are also identified using standard semiempirical classifications, based on lidar backscatter, temperature, and depolarization. Overall, the characteristics of the retrieved size distributions are consistent with these classifications. They all suggest that these very large particles are certainly nitric acid trihydrate that could have been generated by the strong gravity wave activity visible in the temperature profiles. The results demonstrate that multiwavelength lidar data coupled to both RRT temperatures and our size distribution retrieval can provide useful additional information for identification of PSC types and for direct comparisons with microphysical model simulations.

Jumelet, Julien; Bekki, Slimane; David, Christine; Keckhut, Philippe; Baumgarten, Gerd

2009-01-01

376

Q. J. R. Meteorol. Soc. (2003), 129, pp. 11911215 doi: 10.1256/qj.01.181 The in uence of PV inversion on polar-vortex dynamics and passive-tracer  

E-print Network

. Finite amplitude wave-mean ow theory is used to diagnose a zonally symmetric background state and wave. The largest amplitude lateral disturbances to the stratospheric vortex have a strong zonal wave-number-1 or wave-number-2 component and are called stratospheric warmings. The lateral disturbances

Hoskins, Brian

377

Airborne investigation of Arctic tropospheric ozone depletions  

NASA Astrophysics Data System (ADS)

After polar sunrise, tropospheric ozone experiences episodic depletions for a few months, down to sub-ppb levels, before stabilizing into the summer. These ozone depletion episodes (ODEs), first discovered in the early 1980s, have been studied extensively from observatories on the shores of the Arctic Ocean, and are now understood to be due to bromine chemistry. However, it is still unclear where and how the bromine enters the atmosphere from the oceanic interface. This is due to the fact that the Arctic Ocean remains very difficult and expensive to access for in-situ measurements, and that satellite-based methods cannot resolve the trace gases of interest, on the required time scales, with the exception of bromine oxide. The PAM-ARCMIP ("Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project"), a multi-year program to improve our understanding of physical processes in the inner Arctic, provides an opportunity to investigate the location, spatial extent and vertical characteristics of ozone depletions over the Arctic Ocean. Over 5 weeks in the spring of 2011, 32 research flights were conducted spanning the Arctic from Barrow, Alaska, over the Canadian Archipelago and Greenland to Longyearbyen, Spitsbergen. In-situ ozone measurements in the lower troposphere over the Arctic Ocean, with frequent vertical profiling, were performed with a UV photometric analyzer. The first 8 research flights also had on board a LIDAR for nadir profiles of the ozone concentration. An analysis of ozone in relation to aerosol particles, hydrometeors, boundary layer and ice cover characteristics will be presented.

Staebler, R. M.; Liu, P. S.; Strapp, W.; Whiteway, J. A.; Haas, C.; Herber, A.; Neuber, R.

2011-12-01

378

The Holographic Superconductor Vortex  

E-print Network

A gravity dual of a superconductor at finite temperature has been recently proposed. We present the vortex configuration of this model and study its properties. In particular, we calculate the free energy as a function of an external magnetic field, the magnetization and the superconducting density. We also find the two critical magnetic fields that define the region in which the vortex configurations are energetically favorable.

Marc Montull; Alex Pomarol; Pedro J. Silva

2009-06-12

379

Behavior of Vortex Systems  

NASA Technical Reports Server (NTRS)

Progressive application of the Kutta-Joukowsky theorem to the relationship between airfoil lift and circulation affords a number of formulas concerning the conduct of vortex systems. The application of this line of reasoning to several problems of airfoil theory yields an insight into many hitherto little observed relations. This report is confined to plane flow, hence all vortex filaments are straight and mutually parallel (perpendicular to the plane of flow).

Betz, A

1933-01-01

380

Changing Arctic Landscape  

NSDL National Science Digital Library

In this video adapted from the Arctic Athabaskan Council, learn how warmer temperatures in the Arctic are transforming the landscape, triggering a host of effects such as permafrost thawing and insect infestations.

Foundation, Wgbh E.

2008-01-17

381

Arctic Rabies - A Review  

PubMed Central

Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, is the only part of the Arctic where rabies has not been diagnosed in recent time. The arctic fox is the main host, and the same arctic virus variant seems to infect the arctic fox throughout the range of this species. The epidemiology of rabies seems to have certain common characteristics in arctic regions, but main questions such as the maintenance and spread of the disease remains largely unknown. The virus has spread and initiated new epidemics also in other species such as the red fox and the racoon dog. Large land areas and cold climate complicate the control of the disease, but experimental oral vaccination of arctic foxes has been successful. This article summarises the current knowledge and the typical characteristics of arctic rabies including its distribution and epidemiology. PMID:15535081

M?rk, Torill; Prestrud, Pal

2004-01-01

382

Polar Oceans - Issue 14, May 2009  

NSDL National Science Digital Library

This issue of the free online magazine, Beyond Penguins and Polar Bears, explores the characteristics and living systems of the Arctic and Southern Oceans. Instructional resources include ocean-related lessons and informational text about blue whales.

University, The O.

383

Canada's Polar Environments: Images  

NSDL National Science Digital Library

These images of the polar region of Canada include ground level photographs, satellite images, and videos. Weather videos show a blizzard, the wind, and an arctic sunset. Arctic Ocean videos are of a glacier in the water, a melting ice pack, a rocky streambed, ice floes and leads, an icy bay and even some footage under the ice. Both the ground and satellite image sections provide interactive maps. Each location on the map will produce several thumbnails from which to choose. Clicking on a thumbnail will produce a full size photograph with an explanation.

384

Canadian Arctic vegetation mapping  

Microsoft Academic Search

During the next few decades the Arctic is expected to experience unprecedented changes in climate and resource development. All of these will potentially aVect land use and vegetation cover. There is a need for a comprehens- ive and consistent circumpolar map of arctic vegetation that will be useful for modelling vegetation change in the circumpolar region. The Canadian arctic vegetation

W. A. Gould; S. Edlund; S. Zoltai; M. Raynolds; D. A. Walker; H. Maier

2002-01-01

385

Controlling vortex motion and vortex kinetic friction  

NASA Astrophysics Data System (ADS)

We summarize some recent results of vortex motion control and vortex kinetic friction. (1) We describe a device [J.E. Villegas, S. Savel’ev, F. Nori, E.M. Gonzalez, J.V. Anguita, R. Garcìa, J.L. Vicent, Science 302 (2003) 1188] that can easily control the motion of flux quanta in a Niobium superconducting film on an array of nanoscale triangular magnets. Even though the input ac current has zero average, the resulting net motion of the vortices can be directed along either one direction, the opposite direction, or producing zero net motion. We also consider layered strongly anisotropic superconductors, with no fixed spatial asymmetry, and show [S. Savel’ev, F. Nori, Nature Materials 1 (2002) 179] how, with asymmetric drives, the ac motion of Josephson and/or pancake vortices can provide a net dc vortex current. (2) In analogy with the standard macroscopic friction, we present [A. Maeda, Y. Inoue, H. Kitano, S. Savel’ev, S. Okayasu, I. Tsukada, F. Nori , Phys. Rev. Lett. 94 (2005) 077001] a comparative study of the friction force felt by vortices in superconductors and charge density waves.

Nori, Franco; Savel'ev, Sergey

2006-05-01

386

Vortex and anti-vortex compositions of exact elegant Laguerre-Gaussian vector beams  

NASA Astrophysics Data System (ADS)

Reformulation of conventional beam definitions into their bidirectional versions and use of Hertz potentials make beam fields exact vector solutions to Maxwell's equations. This procedure is applied to higher-order elegant Laguerre-Gaussian beams of transverse magnetic and transverse electric polarization. Their vortex and anti-vortex co-axial compositions of equal and opposite topological charges are given in a closed analytic form. Polarization components of the composed beams are specified by their radial and azimuthal indices. The longitudinal components are common for beam compositions of both types; meanwhile, their transverse components are different and comprise two—nonparaxial and paraxial—separate parts distinguished by a paraxial parameter and its inverse, respectively. The new solutions may appear useful in modeling and tailoring of arbitrary vector beams.

Nasalski, W.

2014-05-01

387

Vortex and anti-vortex compositions of exact elegant Laguerre-Gaussian vector beams  

E-print Network

Reformulation of conventional beam definitions into their bidirectional versions and use of Hertz potentials make beam fields exact vector solutions to Maxwell's equations. This procedure is applied to higher-order elegant Laguerre-Gaussian beams of TM and TE polarization. Their vortex and anti-vortex co-axial compositions of equal and opposite topological charges are given in a closed analytic form. Polarization components of the composed beams are specified by their radial and azimuthal indices. The longitudinal components are common for beam compositions of both types, meanwhile their transverse components are different and comprise two - nonparaxial and paraxial - separate parts distinguished by a paraxial parameter and its inverse, respectively. The new solutions may appear useful in modelling and tailoring of arbitrary vector beams.

Nasalski, Wojciech

2014-01-01

388