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1

Non-uniform PSC occurrence within the Arctic polar vortex  

Microsoft Academic Search

A multi-year dataset of lidar measurements of polar stratospheric clouds (PSCs) from two sites in the Arctic (Sodankylä, 67°N, 27°E. and Ny-Ålesund, 79°N, 12°E) has been analyzed with respect to the existence temperature of different PSC types. Due to the location of the measurement sites relative to the polar vortex, their observations are most of the time representative of vortex

Marion Müller; Roland Neuber; Georg Beyerle; E. Kyrö; R. Kivi; L. Wöste

2001-01-01

2

Synoptic scale study of the Arctic polar vortex's influence on the middle atmosphere, 1, Observations  

E-print Network

Synoptic scale study of the Arctic polar vortex's influence on the middle atmosphere, 1 a period of days to weeks that can be attributed to movement and interaction of the polar vortex of the polar vortex and Aleutian High. All of these synoptic scale measurements indicate a change in the local

Duck, Thomas J.

3

A method for estimating the extent of denitrification of arctic polar vortex air from tracer-tracer scatter plots  

E-print Network

A method for estimating the extent of denitrification of arctic polar vortex air from tracer for estimating the extent of denitrification of Arctic polar vortex air is proposed. Previous estimates in Arctic polar vortex air exhibits large interannual variability, which is due to the strong temperature

Esler, Gavin

4

Ozone loss in the Arctic polar vortex inferred from high-altitude aircraft measurements  

Microsoft Academic Search

The Arctic polar vortex in winter is known to be chemically primed for ozone depletion, yet it does not exhibit the large seasonal ozone decrease that characterizes its southern counterpart. This difference may be due in part to a net flux of ozone-rich air through the Arctic vortex, which can mask ozone loss. But by using a chemically con-served tracer

M. H. Proffitt; J. J. Margitan; K. K. Kelly; M. Loewenstein; J. R. Podolske; K. R. Chan

1990-01-01

5

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

6

Ozone depletion at the edge of the Arctic polar vortex 1996\\/1997  

Microsoft Academic Search

In winter 1996\\/1997 the Arctic polar stratospheric vortex was extremely long-lived. During most of its lifetime the vortex was centered at the pole, and its edge was almost permanently located over Northern Scandinavia. The ozone lidar at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) was operated from mid-December 1996 until mid-May 1997 when the final breakup of the

Georg Hansen; Martyn P. Chipperfield

1999-01-01

7

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

8

MLS ClO observations and arctic polar vortex temperatures  

SciTech Connect

Analysis of 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. 14 refs., 5 figs.

Schoeberl, M.R.; Stolarski, R.S.; Douglass, A.R.; Newman, P.A.; Lait, L. R. (NASA Goddard Space Flight Center, Greenbelt, MD (United States)); Waters, J.W.; Froidevaux, L.; Ready, W.G. (Jet Propulsion Lab., Pasadena, CA (United States))

1993-12-23

9

Weakening of the Stratospheric Polar Vortex by Arctic Sea-Ice Loss  

SciTech Connect

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, enhance 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

2014-09-02

10

Stratospheric Meteorological Conditions in the Arctic Polar Vortex, 1991 to 1992  

Microsoft Academic Search

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

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

1993-01-01

11

Ozone loss in the Arctic polar vortex inferred from high-altitude aircraft measurements  

NASA Technical Reports Server (NTRS)

The Arctic polar vortex in winter is known to be chemically primed for ozone depletion, yet it does not exhibit the large seasonal ozone decrease that characterizes its southern counterpart. This difference may be due in part to a net flux of ozone-rich air through the Arctic vortex, which can mask ozone loss. But by using a chemically conserved tracer as a reference, significant ozone loss can be identified. This loss is found to be correlated with high levels of chlorine monoxide, suggesting that much of the decrease in ozone is caused by anthropogenic emissions of chlorofluorocarbons.

Proffitt, M. H.; Margitan, J. J.; Kelly, K. K.; Loewenstein, M.; Podolske, J. R.

1990-01-01

12

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

13

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

14

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

15

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

16

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

17

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

18

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

19

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

20

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

21

Arctic Vortex  

Atmospheric Science Data Center

... of the obstacle. These turbulence patterns are known as von Karman vortex streets. In these images from NASA's Multi-angle Imaging ... placed over your left eye. Fluid dynamicist Theodore von Karman was the first to derive the conditions under which these turbulence ...

2013-06-26

22

Stratospheric water vapour in the vicinity of the Arctic polar vortex  

NASA Astrophysics Data System (ADS)

The stratospheric water vapour mixing ratio inside, outside, and at the edge of the polar vortex has been accurately measured by the FLASH-B Lyman-Alpha hygrometer during the LAUTLOS campaign in Sodankylä, Finland, in January and February 2004. The retrieved H2O profiles reveal a detailed view on the Arctic lower stratospheric water vapour distribution, and provide a valuable dataset for the validation of model and satellite data. Analysing the measurements with the semi-lagrangian advection model MIMOSA, water vapour profiles typical for the polar vortex' interior and exterior have been identified, and laminae in the observed profiles have been correlated to filamentary structures in the potential vorticity field. Applying the validated MIMOSA transport scheme to specific humidity fields from operational ECMWF analyses, large discrepancies from the observed profiles arise. Although MIMOSA is able to reproduce weak water vapour filaments and improves the shape of the profiles compared to operational ECMWF analyses, both models reveal a dry bias of about 1 ppmv in the lower stratosphere above 400 K, accounting for a relative difference from the measurements in the order of 20%. The large dry bias in the analysis representation of stratospheric water vapour in the Arctic implies the need for future regular measurements of water vapour in the polar stratosphere to allow the validation and improvement of climate models.

Maturilli, M.; Fierli, F.; Yushkov, V.; Lukyanov, A.; Khaykin, S.; Hauchecorne, A.

2006-07-01

23

Polar processing in a split vortex: early winter Arctic ozone loss in 2012/13  

NASA Astrophysics Data System (ADS)

A sudden stratospheric warming (SSW) in early January 2013 caused the polar vortex to split. After the lower stratospheric vortex split on 8 January, the two offspring vortices - one over Canada and the other over Siberia - remained intact, well-confined, and largely at latitudes that received sunlight until they reunited at the end of January. As the SSW began, temperatures abruptly rose above chlorine activation thresholds throughout the lower stratosphere. The vortex was very disturbed prior to the SSW, and was exposed to much more sunlight than usual in December 2012 and January 2013. Aura Microwave Limb Sounder (MLS) nitric acid (HNO3) data and observations from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) indicate extensive polar stratospheric cloud (PSC) activity, with evidence of PSCs containing solid nitric acid trihydrate particles during much of December 2012. Consistent with the sunlight exposure and PSC activity, MLS observations show that chlorine monoxide (ClO) became enhanced early in December. Despite the cessation of PSC activity with the onset of the SSW, enhanced vortex ClO persisted until mid-February, indicating lingering chlorine activation. The smaller Canadian offspring vortex had lower temperatures, lower HNO3, lower hydrogen chloride (HCl), and higher ClO in late January than the Siberian vortex. Chlorine deactivation began later in the Canadian than in the Siberian vortex. HNO3 remained depressed within the vortices after temperatures rose above the PSC existence threshold, and passive transport calculations indicate vortex-averaged denitrification of about 4 ppbv; the resulting low HNO3 values persisted until the vortex dissipated in mid-February. Consistent with the strong chlorine activation and exposure to sunlight, MLS measurements show rapid ozone loss commencing in mid-December and continuing through January. Lagrangian transport estimates suggest ~ 0.7-0.8 ppmv (parts per million by volume) vortex-averaged chemical ozone loss by late January near 500 K (~ 21 km), with substantial loss occurring from ~ 450 to 550 K. The surface area of PSCs in December 2012 was larger than that in any other December observed by CALIPSO. As a result of denitrification, HNO3 abundances in 2012/13 were among the lowest in the MLS record for the Arctic. ClO enhancement was much greater in December 2012 through mid-January 2013 than that at the corresponding time in any other Arctic winter observed by MLS. Furthermore, reformation of HCl appeared to play a greater role in chlorine deactivation than in more typical Arctic winters. Ozone loss in December 2012 and January 2013 was larger than any previously observed in those months. This pattern of exceptional early winter polar processing and ozone loss resulted from the unique combination of dynamical conditions associated with the early January 2013 SSW, namely unusually low temperatures in December 2012 and offspring vortices that remained well-confined and largely in sunlit regions for about a month after the vortex split.

Manney, G. L.; Lawrence, Z. D.; Santee, M. L.; Livesey, N. J.; Lambert, A.; Pitts, M. C.

2015-02-01

24

The anomalous arctic lower stratospheric polar vortex of 1992-1993  

Microsoft Academic Search

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 â¼3 months PV gradients were closer to typical Antarctic values than to most Arctic values. Air motion diagnostics computed for 3-dimensional air parcel trajectories confirm that the 1992-1993 Arctic lower stratospheric vortex

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

1994-01-01

25

Evidence of large scale ozone depletion within the arctic polar vortex 94\\/95 based on airborne LIDAR measurements  

Microsoft Academic Search

Measurements with an airborne lidar performed during the Arctic winter 1994\\/95 show, that the ozone mixing ratio declined by about 50% throughout the polar vortex in the period from the beginning of February to mid of March in a sharp defined altitude band from 420 K to 520 K potential temperature. The simultaneous detection of the stratospheric aerosol density provides

M. Wirth; W. Renger

1996-01-01

26

A Possible Explanation on the Dynamical Linkage between Arctic Sea-ice Loss and Stratospheric Polar Vortex  

NASA Astrophysics Data System (ADS)

The abrupt retreat of Arctic sea-ice in recent several decades and associated atmospheric circulation changes are debating issue. In particular, what brings a lagged connection between sea-ice and atmospheric circulation remains unclear. In this study, we propose that Arctic sea-ice loss in autumn (October-December) has likely affected stratospheric polar vortex and temperature in winter (January-March). During recent two decades a large-scale wave pattern has emerged in mid-troposphere in autumn, which is characterized by anomalous high centered over Eastern Europe and elongated low along the wave-guide of polar jet. At the same time, stratospheric polar vortex in subsequent winter has weakened substantially. Statistical analysis shows that both of these trends are significantly correlated with the Arctic sea-ice melting in autumn. With a simple linear model experiment, it is shown that the enhanced diabatic heating due to the sea-ice melting can generate a similar large-scale wave as observed. Furthermore, this wave pattern highly projects onto the climatological wave-number 1 stationary wave, driving stronger planetary-scale wave propagation from the troposphere to the stratosphere through constructive wave interference. The resulting stratospheric change might contribute to the weakening of stratospheric polar vortex during last two decades. Although more quantitative investigations are needed, this result suggests that Arctic sea-ice change might play a broader role in global climate change than what is currently thought of.

Kim, B.; Min, S.; Son, S.; Jeong, J.; Kim, S.

2012-12-01

27

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

28

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

29

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

30

Polar vortex conditions during the 1995–96 Arctic Winter: MLS CLO and HNO 3  

Microsoft Academic Search

Microwave Limb Sounder (MLS) measure- ments of lower stratospheric C10 and HNOa during the 1995-96 Arctic winter are presented. The 1995-96 Arc- tic winter was both colder and more persistently cold than usual, leading to an enhancement in lower strato- spheric C10 of greater magnitude, vertical extent, and duration than previously observed in the Arctic. Vortex concentrations of HNOa in

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

1996-01-01

31

Subsidence Mixing and Denitrification of Arctic Polar Vortex Air Measured During POLARIS  

Microsoft Academic Search

Abstract. A new technique is presented to determine,the degree of denitrification that occured during the 1996\\/97 Arctic winter, based on balloon and aircraft borne measurements of NO,, N2O and CH4. The NO, \\/ N20 relation can undergo significant change due to isentropic mixing of subsided vortex air masses,with extra-vortex air due to the high non-linearity of the relation. In this

M. Rex; R. J. Salawitch; G. C. Toon; B. Sen; J. J. Margitan; G. B. Osterman; J. f. Blavier; R. S. Gao; S. Donnelly; E. Keim; J. Neuman; D. W. Fahey; W. Irion; A. Y. Chang; C. P. Rinsland; T. P. Bui; M. R. Gunson; F. W. Irion

1998-01-01

32

Measurements of condensation nuclei in the Airborne Arctic Stratospheric Expedition: Observations of particle production in the polar vortex  

SciTech Connect

The ER-2 Condensation Nucleus Counter (ER-2 CNC) was operated in the Airborne Arctic Stratospheric Expedition (AASE) in January and February 1989. The ER-2 CNC measures the mixing ratio of particles, CN, with diameters from approximately 0.02 {mu}m to approximately 1 {mu}m. The spatial distribution of CN in the Arctic polar vortex was found to resemble that measured in the Antarctic in the Spring of 1987. The vertical profile of CN in the vortex was lowered by subsidence. At altitudes above the minimum in the CN mixing ratio profile, CN mixing ratios correlated negatively with that of N{sub 2}O, demonstrating new particle production. CN serve as nuclei in the formation of Polar Stratospheric Clouds (PSC's) and the concentration of CN can affect PSC properties.

Wilson, J.C.; Stolzenburg, M.R. (Univ. of Denver, CO (USA)); Clark, W.E. (California Polytechnic State Univ., San Luis Obispo (USA)); Loewenstein, M.; Ferry, G.V.; Chan, K.R. (NASA Ames Research Center, Moffett Field, CA (USA))

1990-03-01

33

Measurements of condensation nuclei in the Airborne Arctic Stratospheric Expedition - Observations of particle production in the polar vortex  

NASA Technical Reports Server (NTRS)

The ER-2 Condensation Nucleus Counter (ER-2 CNC) was operated in the Airborne Arctic Stratospheric Expedition (AASE) in January and February 1989. The ER-2 CNC measures the mixing ratio of particles, CN, with diameters from approximately 0.02 to approximately 1 micron. The spatial distribution of CN in the Arctic polar vortex was found to resemble that measured in the Antarctic in the Spring of 1987. The vertical profile of CN in the vortex was lowered by subsidence. At altitudes above the minimum in the CN mixing ratio profile, CN mixing ratios correlated negatively with that of N2O, demonstrating new particle production. CN serve as nuclei in the formation of Polar Stratospheric Clouds (PSCs) and the concentration of CN can affect PSC properties.

Wilson, J. C.; Stolzenburg, M. R.; Clark, W. E.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.

1990-01-01

34

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 four-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 initializing a transport of refractory aerosol into the lower stratosphere (? < 500 K). 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 potential temperatures ? ? 450 K around 11 submicron particles per cm3 were generally detected. Up to 8 of these 11 particles per cm3 were found to contain thermo-stable (at 250 °C) residuals with diameters of 10 nm to about 1 ?m. Particle mixing ratios (150 mg-1) and fractions of non-volatile particles (75% of totally detected particles) exhibited highest values in air masses having the lowest content of nitrous oxide (70 nmol mol-1 of N2O). This indicates that refractory aerosol originates from the upper stratosphere or the mesosphere. Derived from the mixing ratio of the simultaneously measured long-lived tracer N2O, an empirical index serves to differentiate probed air masses according to their origin: inside the vortex, the vortex edge region, or 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. However, measurements under perturbed vortex conditions in 2010 and during early winter in December 2011 revealed similarly high values. Thus, the abundance of refractory aerosol in the lower stratosphere within the Arctic vortices appears to be a regular feature rather than the exception. 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 in March. The correlations of refractory aerosol with N2O suggest that, apart from mean subsidence, diabatic dispersion inside the vortex significantly contributes to the transport of particles to the Arctic lower stratosphere. 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) by a factor of 4.5 between early and late winter, we estimate the total mass of mesospheric particles deposited over the winter 2009/2010 in the entire Arctic vortex to range between 77 × 103 and 375 × 106 kg. This estimate is compared with 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 this article. Nevertheless, the results enable placing constraints on the shape of the so far unknown size distribution of refractory aerosol within the vortex.

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

2014-11-01

35

Subsidence, mixing, and denitrification of Arctic polar vortex air measured during POLARIS  

Microsoft Academic Search

We determine the degree of denitrification that occurred during the 1996-1997 Arctic winter using a technique that is based on balloon and aircraft borne measurements of NOy, N2O, and CH4. The NOy\\/N2O relation can undergo significant change due to isentropic mixing of subsided vortex air masses with extravortex air due to the high nonlinearity of the relation. These transport related

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

1999-01-01

36

Polar stratospheric cloud threshold temperatures in the 1995-1996 arctic vortex  

Microsoft Academic Search

Balloon-borne backscattersondes have been used to study the relationship between particle scattering and ambient temperature near the vertical edge of arctic polar stratospheric clouds (PSCs) as well as to delineate the cloud type occurrence probability as a function of temperature. The observed typical threshold temperatures as a function of altitude are about 1°K warmer than the temperature TSTS expected for

James M. Rosen; Norman T. Kjome; Niels Larsen; Bjørn M. Knudsen; Esko Kyrö; Rigel Kivi; Juha Karhu; Roland Neuber; Ingo Beninga

1997-01-01

37

Does the HoltonTan Mechanism Explain How the Quasi-Biennial Oscillation Modulates the Arctic Polar Vortex?  

E-print Network

) modulates the Northern Hemisphere wintertime stratospheric polar vortex. Overall, the effect of the critical to enhanced planetary wave convergence in the polar vortex region. These two effects are mechanistically stratospheric polar vortex, in agreement with previous studies, although not because of changes

Waugh, Darryn W.

38

Statistical characterization of arctic polar-night jet oscillation events  

E-print Network

of the Arctic stratospheric polar vortex over multiple decades. This visualization illustrates the ubiquity and reanalyses. The time scale for the recovery of the polar vortex following sudden warmings correlates strongly the polar vortex. They follow vortex splits more frequently than they do vortex displacements. They are also

Wirosoetisno, Djoko

39

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

40

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

Microsoft Academic Search

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

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

1993-01-01

41

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

42

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

NASA Technical Reports Server (NTRS)

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.

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.

1993-01-01

43

Chemical Loss of Ozone in the Arctic Polar Vortex in the Winter of 1991-1992  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

44

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

45

Tracer-based determination of vortex descent in the 1999/2000 Arctic winter  

E-print Network

, polar vortex, subsidence, descent, stratosphere Citation: Greenblatt, J. B., et al., TracerTracer-based determination of vortex descent in the 1999/2000 Arctic winter Jeffery B. Greenblatt1 vortex has been performed in order to quantify the temporal evolution of vortex descent. Differences

Chipperfield, Martyn

46

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

47

The Arctic Vortex in March 2011: A Dynamical Perspective  

NASA Technical Reports Server (NTRS)

Despite the record ozone loss observed in March 2011, dynamical conditions in the Arctic stratosphere were unusual but not unprecedented. Weak planetary wave driving in February preceded cold anomalies in t he polar lower stratosphere in March and a relatively late breakup of the Arctic vortex in April. La Nina conditions and the westerly phas e of the quasi-biennial oscillation (QBO) were observed in March 201 1. Though these conditions are generally associated with a stronger vortex in mid-winter, the respective cold anomalies do not persist t hrough March. Therefore, the La Nina and QBO-westerly conditions cannot explain the observed cold anomalies in March 2011. In contrast, po sitive sea surface temperature anomalies in the North Pacific may ha ve contributed to the unusually weak tropospheric wave driving and s trong Arctic vortex in late winter 2011.

Hurwitz, Margaret M.; Newman, Paul A.; Garfinkel,Chaim I.

2011-01-01

48

Polar vortex dynamics  

NASA Technical Reports Server (NTRS)

Recent work with high resolution, one-layer numerical models of fluid flows resembling those in the real stratosphere has suggested that: (1) the interiors of strong cyclonic vortices like the Antarctic polar vortex may be almost completely isolated laterally from their surroundings - perhaps even completely isolated, under some circumstances; (2) by contrast, material near the edge of such and isolated region can easily be eroded (or mixed one-sidedly) into the surrounding region; and (3) the erosion characteristically produces extremely steep gradients in isentropic distributions of potential vorticity (PV) and of other tracers, possibly down to horizontal length scales of a few kilometers only. Such length scales may occur both at the edge of the main polar vortex and in smaller features outside it, such as thin filamentary structures, produced by the erosion process.

Mcintyre, Michael

1988-01-01

49

Sub-Monthly Polar Vortex Variability and Stratosphere-Troposphere Coupling  

E-print Network

Sub-Monthly Polar Vortex Variability and Stratosphere-Troposphere Coupling in the Arctic Robert X in the boreal stratospheric polar vortex. Compared to previous studies, the current analysis examines daily zonal-mean variability within a limited spatial domain encompassing the stratospheric polar vortex

Black, Robert X.

50

A New Look at Stratospheric Sudden Warmings. Part III: Polar Vortex Evolution and Vertical Structure  

E-print Network

A New Look at Stratospheric Sudden Warmings. Part III: Polar Vortex Evolution and Vertical of the Arctic polar vortex during observed major midwinter stratospheric sudden warmings (SSWs) is investigated. The evolving vertical structure of the polar vortex during a typical SSW of each type is clearly illustrated

Esler, Gavin

51

A test of our understanding of the ozone chemistry in the Arctic polar vortex based on in situ measurements of ClO, BrO, and O3 in the 1994\\/1995 winter  

Microsoft Academic Search

We present an analysis of in situ measurements of ClO, BrO, O3, and long-lived tracers obtained on a balloon flight in the Arctic polar vortex launched from Kiruna, Sweden, 68°N, on February 3, 1995. Using the method of tracer correlations, we deduce that the air masses sampled at an altitude of 21 km (480 K potential temperature), where a layer

Thomas Woyke; Rolf Müller; Fred Stroh; Daniel S. McKenna; Andreas Engel; James J. Margitan; Markus Rex; Kenneth S. Carslaw

1999-01-01

52

Match observations in the Arctic winter 1996\\/97: High stratospheric ozone loss rates correlate with low temperatures deep inside the polar vortex  

Microsoft Academic Search

With the Match technique, which is based on the coordinated release of ozonesondes, chemical ozone loss rates in the Arctic stratospheric vortex in early 1997 have been quantified in a vertical region between 400 K and 550 K. Ozone destruction was observed from mid February to mid March in most of these levels, with maximum loss rates between 25 and

A. Schulz; M. Rex; J. Steger; N. R. P. Harris; G. O. Braathen; E. Reimer; R. Alfier; A. Beck; M. Alpers; J. Cisneros; H. Claude; H. De Backer; H. Dier; V. Dorokhov; H. Fast; S. Godin; G. Hansen; H. Kanzawa; B. Kois; Y. Kondo; E. Kosmidis; E. Kyrö; Z. Litynska; M. J. Molyneux; G. Murphy; H. Nakane; C. Parrondo; F. Ravegnani; C. Varotsos; C. Vialle; P. Viatte; V. Yushkov; C. Zerefos; P. von der Gathen

2000-01-01

53

Observation of an unusual mid-stratospheric aerosol layer in the Arctic: possible sources and implications for polar vortex dynamics  

Microsoft Academic Search

By the beginning of winter 2000\\/2001, a mysterious stratospheric aerosol layer had been detected by four different Arctic lidar stations. The aerosol layer was observed first on 16 November 2000, at an altitude of about 38 km near Søndre Strømfjord, Greenland (67° N, 51° W) and on 19 November 2000, near Andenes, Norway (69° N, 16° E). Subsequently, in early

M. Gerding; G. Baumgarten; U. Blum; J. P. Thayer; K.-H. Fricke; R. Neuber; J. Fiedler

2003-01-01

54

MLS observations of ClO and HNO 3 in the 1996–97 Arctic Polar Vortex  

Microsoft Academic Search

Microwave Limb Sounder (MLS) measurements of lower stratospheric ClO and gas-phase HNO3 are presented for the 1996{97 Arctic winter. The horizontal and vertical extent of enhanced ClO were smaller in 1997 than in 1996, as was the degree of enhancement. This is consistent with dierences in the evolution and vertical structure of temper- atures in the two years. Gas-phase HNO3

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

1997-01-01

55

MLS observations of ClO and HNO3 in the 1996–97 Arctic Polar Vortex  

Microsoft Academic Search

Microwave Limb Sounder (MLS) measurements of lower stratospheric ClO and gas-phase HNO3 are presented for the 1996–97 Arctic winter. The horizontal and vertical extent of enhanced ClO were smaller in 1997 than in 1996, as was the degree of enhancement. This is consistent with differences in the evolution and vertical structure of temperatures in the two years. Gas-phase HNO3 abundances,

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

1997-01-01

56

Chemical Observations of a Polar Vortex Intrusion  

NASA Technical Reports Server (NTRS)

An intrusion of vortex edge air in D the interior of the Arctic polar vortex was observed on the January 31,2005 flight of the NASA DC-8 aircraft. This intrusion was identified as anomalously high values of ozone by the AROTAL and DIAL lidars. Our analysis shows that this intrusion formed when a blocking feature near Iceland collapsed, allowing edge air to sweep into the vortex interior. along the DC-8 flight track also shows the intrusion in both ozone and HNO3. Polar Stratospheric Clouds (PSCs) were observed by the DIAL lidar on the DC-8. The spatial variability of the PSCs can be explained using MLS HNO3 and H2O observations and meteorological analysis temperatures. We also estimate vortex denitrification using the relationship between N2O and HNO3. Reverse domain fill back trajectory calculations are used to focus on the features in the MLS data. The trajectory results improve the agreement between lidar measured ozone and MLS ozone and also improve the agreement between the HNO3 measurements PSC locations. The back trajectory calculations allow us to compute the local denitrification rate and reduction of HCl within the filament. We estimate a denitrification rate of about lO%/day after exposure to below PSC formation temperature. Analysis of Aura MLS observations made

Schoeberl, M. R.; Kawa, S. R.; Douglass, A. R.; McGee, T. J.; Browell, E.; Waters, J.; Livesey, N.; Read, W.; Froidevaux, L.

2006-01-01

57

The potential for ozone depletion in the Arctic polar stratosphere  

SciTech Connect

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{sub 2}) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl{sub 2}O{sub 2} throughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO{sub 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.

Brune, W.H. (Pennsylvania State Univ., University Park (United States)); Anderson, J.G.; Toohey, D.W. (Harvard Univ., Cambridge, MA (United States)); Fahey, D.W.; Kawa, S.R. (National Oceanic and Atmospheric Administration, Boulder, CO (United States)); Jones, R.L. (Univ. of Cambridge (England)); McKenna, D.S. (United Kingdom Meteorological Office, Berkshire (England)); Poole, L.R. (NASA Langley Research Center, Hampton, VA (United States))

1991-05-31

58

The potential for ozone depletion in the Arctic polar stratosphere  

NASA Technical Reports Server (NTRS)

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 (CHl and ClONO2) was converted by reactions on polar stratospheric clouds to reactive ClO and Cl2O2 thoroughout the Arctic polar vortex before midwinter. Reactive nitrogen was converted to HNO3, and some, with spatial inhomogeneity, fell out of the stratosphere. These chemical changes ensured characteristic ozone losses of 10 to 15 percent at altitudes inside the polar vortex where polar stratospheric clouds had occurred. These local losses can translate into 5 to 8 percent losses in the vertical column abundance of ozone. As the amount of stratospheric chlorine inevitably increases by 50 percent over the next two decades, ozone losses recognizable as an ozone hole may well appear.

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

1991-01-01

59

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

60

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

61

Transport out of the lower stratospheric Arctic vortex by Rossby wave breaking  

NASA Technical Reports Server (NTRS)

The fine-scale structure in lower stratospheric tracer transport during the period of the two Arctic Airborne Stratospheric Expeditions (January and February 1989; December 1991 to March 1992) is investigated using contour advection with surgery calculations. These calculations show that Rossby wave breaking is an ongoing occurrence during these periods and that air is ejected from the polar vortex in the form of long filamentary structures. There is good qualitative agreement between these filaments and measurements of chemical tracers taken aboard the NASA ER-2 aircraft. The ejected air generally remains filamentary and is stretched and mixed with midlatitude air as it is wrapped around the vortex. This process transfers vortex air into midlatitudes and also produces a narrow region of fine-scale filaments surrounding the polar vortex. Among other things, this makes it difficult to define a vortex edge. The calculations also show that strong stirring can occur inside as well as outside the vortex.

Waugh, D. W.; Plumb, R. A.; Atkinson, R. J.; Schoeberl, M. R.; Lait, L. R.; Newman, P. A.; Loewenstein, M.; Toohey, D. W.; Avallone, L. M.; Webster, C. R.

1994-01-01

62

The structure of the polar vortex  

NASA Technical Reports Server (NTRS)

The paper develops a comparative picture of the 1987 Southern Hemisphere and 1989 Northern Hemisphere lower stratospheric, polar vortex circulation and constituent distributions as observed by the Airborne Antarctic Ozone Experiment, August 17-September 22, 1987, and Airborne Arctic Stratospheric Expedition, January 3-February 19, 1989 aircraft campaigns. Overall, both polar vortices define a region of highly isolated air, where the exchange of trace gases occurs principally at the vortex edge through erosional wave activity. Aircraft measurement showed that between 50 and 100 mbar, horizontally stratified long-lived tracers such as N2O are displaced downward 2-3 km on the cyclonic (poleward) side of the jet with the meridional tracer gradient sharpest at the jet core. Eddy mixing rates, computed using parcel ensemble statistics, are an order of magnitude or more lower on the cyclonic side of the jet compared to those on the anticyclonic side. Poleward zonal mean meridional flow on the anticyclonic side of the jet terminates in a descent zone at the jet core.

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

1992-01-01

63

Transport out of the lower stratospheric Arctic vortex by Rossby wave breaking  

Microsoft Academic Search

The fine-scale structure in lower stratospheric tracer transport during the period of the two Arctic Airborne Stratospheric Expeditions (January and February 1989; December 1991 to March 1992) is investigated using contour advection with surgery calculations. These calculations show that Rossby wave breaking is an ongoing occurrence during these periods and that air is ejected from the polar vortex in the

D. W. Waugh; R. A. Plumb; R. J. Atkinson; R. J; M. R. Schoeberl; L. R. Lait; P. A; M. Loewenstein; D. W. Toohey; L. M. Avallone; C. R. Webster; R. D. May

1994-01-01

64

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

65

N2O as a dynamical tracer in the Arctic vortex  

NASA Technical Reports Server (NTRS)

This paper reports N2O measurements obtained by the Airborne Tunable Laser Absorption Spectrometer from 14 flights of the NASA ER-2 aircraft during the 1989 Airborne Arctic Stratospheric Expedition field campaign. In the altitude range expected for ozone loss, N2O has a long photochemical lifetime, making it an excellent tracer of lower stratospheric air motions. As in the southern hemisphere, the zonal wind speed maximum and large gradients of potential vorticity and N2O identify the vortex edge. The N2O profiles inside the vortex indicate net descent relative to outside the vortex and to the summer polar lower stratosphere. The descent of the N2O profile during the Arctic night relative to the summer profile is comparable to the downward shift in the vertical profile observed in the 1987 Antarctic winter vortex. Winter profiles at the poles are very similar above the 435 K potential temperature surface, but divergent below.

Loewenstein, M.; Podolske, J. R.; Chan, K. R.; Strahan, S. E.

1990-01-01

66

Vortex polarity switching by a spin-polarized current.  

PubMed

The spin-transfer effect is investigated for the vortex state of a magnetic nanodot. A spin current is shown to act similarly to an effective magnetic field perpendicular to the nanodot. Then a vortex with magnetization (polarity) parallel to the current polarization is energetically favorable. Following a simple energy analysis and using direct spin-lattice simulations, we predict the polarity switching of a vortex. For magnetic storage devices, an electric current is more effective to switch the polarity of a vortex in a nanodot than the magnetic field. PMID:17358881

Caputo, Jean-Guy; Gaididei, Yuri; Mertens, Franz G; Sheka, Denis D

2007-02-01

67

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

68

The variability of ClONO{sub 2} and HNO{sub 3} in the Arctic polar vortex: Comparison of Transall Michelso interferometer for passive atmospheric sounding measurements and three-dimensional model results  

SciTech Connect

The authors compare aircraft based infrared measurements of column amounts of nitric acid and chlorine nitrate in the northern European stratosphere with a three-dimensional stratospheric model which incorporates detailed chemical reactions, including heterogeneous processing effects on polar stratospheric clouds. In particular the authors compare the model and measurements in the region of the polar vortex, where during late January the measurements showed a marked gradient of chlorine nitrate across the vortex. This is consistent with model results which indicate strong horizontal gradients. The model has fairly coarse resolution and could not well reproduce the variation through the vortex where observed gradient were quite large. In March, with the appearance of distortions in the polar vortex, the experiment showed high densities of chlorine nitrate at high altitudes at the northern latitudes, and as one moved south in the polar vortex, the densities increased at lower altitudes. This is consistent with model predictions when the vortex begins to distort.

Chipperfield, M.P.; Pyle, J.A. [Univ. of Cambridge (United Kingdom)] [Univ. of Cambridge (United Kingdom); Blom, C.E. [Universitaet Karlsruhe (Germany)] [and others] [Universitaet Karlsruhe (Germany); and others

1995-05-20

69

Venus's Southern Polar Vortex Reveals Precessing Circulation  

Microsoft Academic Search

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

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

2011-01-01

70

On the origin of polar vortex air  

Microsoft Academic Search

Forward and backward three-dimensional stratospheric polar vortex trajectory computations between fall and spring for each of the years 1992-1993 through 1999-2000 in the Northern Hemisphere and the years 1992-1999 in the Southern Hemisphere have been carried out. We find that the forward and backward trajectories give very different pictures of polar vortex descent. The backward trajectories show a complex distribution

Joan E. Rosenfield; Mark R. Schoeberl

2001-01-01

71

How permeable is the edge of the Arctic vortex: Model studies of winter 1999–2000  

Microsoft Academic Search

The edge of the Arctic vortex constitutes a strong barrier to transport; however, the extent of isolation of the vortex air as a function of altitude and season is relatively poorly quantified. In this study, by examining the transport of midlatitude air parcels across the vortex edge into the vortex, we analyze the permeability of the vortex edge. With the

Hildegard-Maria Steinhorst; Paul Konopka; Gebhard Günther; Rolf Müller

2005-01-01

72

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

73

Stratospheric polar vortex influence on Northern Hemisphere winter climate variability  

E-print Network

Stratospheric polar vortex influence on Northern Hemisphere winter climate variability H. Douville140 reanalyses north of 25°N in order to mimic a ``perfect'' polar vortex. The comparison and precipitation, especially over Europe. Citation: Douville, H. (2009), Stratospheric polar vortex influence

Ribes, Aurélien

74

The Stratospheric Polar Vortex in Winter  

Microsoft Academic Search

In winter the polar stratospheric air within the earth's shadow forms the core of an intense 'cold low' which extends from about 10 km to at least 50 km and possibly to the base of the ionosphere. Compared with the tropospheric general circulation, this vortex seems to be remarkably stable, particularly in the Southern Hemisphere. Recent research work in Canada

Clarence E. Palmer

1959-01-01

75

THE INTERNATIONAL POLAR YEAR PROJECT `KINNVIKA' ARCTIC WARMING AND IMPACT  

E-print Network

PREFACE: THE INTERNATIONAL POLAR YEAR PROJECT `KINNVIKA' ­ ARCTIC WARMING AND IMPACT RESEARCH AT 80., 2011. The International PolarYear Project `KINNVIKA'­ Arctic warming and impact research at 80° N of the polar systems. Furthermore, the significant role of the Arctic and Antarctic in climate change allowed

Moore, John

76

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

77

Penetration of Mt. Pinatubo aerosols into the north polar vortex  

Microsoft Academic Search

This paper reports results from measurements performed to study the cross polar vortex transport properties, using the aerosols injected by the Mt. Pinatubo eruption. The initial aerosol cloud arrived prior to the establishment of the polar vortex in 1992. However, using balloon borne backscattersondes, the authors were able to sample the aerosol densities in the vortex during the 1992 winter

James M. Rosen; Norman T. Kjome; Hans Fast; Vyacheslav U. Khattatov; Vladimir V. Rudakov

1992-01-01

78

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

79

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

80

Probing Titan's Polar Vortex With Chemical Tracers  

Microsoft Academic Search

Titan's winter polar vortex has profound effects on its atmospheric circulation and chemistry and is currently the most important dynamical feature of Titan's stratosphere and mesosphere. We use two years of limb observations from Cassini's composite infrared spectrometer (CIRS) to determine atmospheric cross sections of five independent chemical tracers (HCN, HC3N, C2H2, C3H4, and C4H2). The distribution of these tracers

Nicholas Teanby; R. de Kok; P. G. J. Irwin; S. Osprey; S. Vinatier; P. J. Gierasch; P. L. Read; F. M. Flasar; B. J. Conrath; R. K. Achterberg; B. Bezard; C. A. Nixon; S. B. Calcutt

2008-01-01

81

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

82

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

83

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.

Dethloff et al.

84

Vortex polarization dynamics in a square magnetic nanodot.  

PubMed

Langevin simulations at finite temperature of two-dimensional magnetic nanodots were performed using the Landau-Lifshitz equation with exchange and dipolar interactions. In a wide range of temperatures, the dynamics of square samples with one central vortex was studied, focusing on the out-of-plane magnetic component at the vortex-core. This vortex-core undergoes polarization sign reversals in a thermally activated process. In the intervals between polarization flips, the out-of-plane spin components at the vortex-core show oscillations with identifiable frequencies connected with certain eigenfrequencies of the system associated with polarity active modes. The vortex-core positions were also monitored. PMID:24134877

Depondt, Ph; Lévy, J-C S; Mamica, S

2013-11-20

85

Stability of Latitudinal Vortex Rings with Polar Vortices  

E-print Network

Stability of Latitudinal Vortex Rings with Polar Vortices Stefanella Boatto (a) and Carles Sim#19;o of the Hessian. 5) Particular cases. 5.1) One ring. 5.2) One ring with one polar vortex. 5.3) One ring with two polar vor- tices. Relative equilibrium con#12;gurations are so called because the motion vanishes

86

Volcanic aerosol and polar stratospheric clouds in the winter 1992/93 north polar vortex  

SciTech Connect

Backscatter profiles were measured at 940 and 490 nm in the winter north polar vortex using balloon borne backscattersondes. There was no mid-season breakdown of the vortex, and temperatures were sufficiently cold to expect the formation of polar stratospheric clouds (PSCs). The mass loading from the Mount Pinatubo aerosols inside the vortex was observed to be larger than that of the previous year and equivalent to about 20 megatonnes if spread uniformly over the earth. The positive identification of typical PSCs was made more difficult by the presence of considerable volcanic aerosol background. An unusual scattering layer that can probably be identified as some type of PSC was not associated with as much backscatter as observed in previous non-volcanic years with similar stratospheric temperatures. The layer apparently was composed of comparatively large particles with a relatively low, highly variable number concentration and was easily identified by the enhancement in fine structure of the scattering properties rather than an outstanding increase in average scattering values. The arctic volcanic aerosol layer was found to produce a small but significant depolarized backscattered signal. This preliminary results could be interpreted as indicating the presence of some non-spherical particles (perhaps due to freezing effects) and/or spherical particles containing inclusions of irregular shapes with differing refractive index. 9 refs., 5 figs.

Rosen, J.M.; Kjome, N.T. (Univ. of Wyoming, Laramine WY (United States)); Fast, H. (Atmospheric Environmental Service, Toronto (Canada)); Larsen, N. (Danish Meteorol. Inst., Copenhagen (Denmark))

1994-01-01

87

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

88

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

89

Ozone depletion in the Arctic vortex at Alert during February 1989  

SciTech Connect

Evidence for an apparent chemical depletion of ozone was observed in the Arctic polar vortex during February 1989 in the form of a depleted layer in the ozone mixing ratio altitude profile. The measurements of the distribution of ozone partial pressure in the polar vortex were conducted with ECC ozonesondes which covered the altitude range from 1 to 30 km. These balloon measurements demonstrated a depleted layer in the profile at altitudes from 18 to 24 km. The meteorological ozonesonde balloon ascents took place from January 24 to February 22, 1989 from Alert, Canada at 82.5 N. A comparison of the late February ozone profiles with the late January ozone profiles indicates that the depletion was due to a process which may have occurred while the polar air was partially in sunlight. The depleted layer was similar to that observed from the South Pole base in the Antarctic inside the ozone hole in mid-September. The depletion may have commenced at high altitudes above 22 km and moved downwards during February in a manner similar to the process in September in the Antarctic. Polar stratospheric clouds were previously observed in mid-January over the altitude regime from 16 to 24 km.

Evans, W.F.J. (Atmospheric Environment Service, Downsview, Ontario (Canada))

1990-02-01

90

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

E-print Network

The Effect of Tropospheric Jet Latitude on Coupling between the Stratospheric Polar Vortex coupling between the stratospheric polar vortex and the extratropical tropospheric circulation depends flux, appear to explain this effect. The dependence of coupling between the stratospheric polar vortex

Waugh, Darryn W.

91

Evolution of the 1991-1992 Arctic vortex and comparison with the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model  

SciTech Connect

Nitrous oxide (N2O) measured on board the ER-2 aircraft during the Airborne Arctic Stratospheric Expedition 2 (AASE 2) has been used to monitor descent of air inside the Arctic vortex between October 1991 and March 1992. Monthly mean N2O fields are calculated from the flight data and then compared with mean fields calculated from the high-resolution Geophysical Fluid Dynamics Laboratory general circulation model SKYHI in order to evaluate the model`s simulation of the polar vortex. From late fall through winter the model vortex evolves in much the same way as the 1991-1992 vortex, with N2O gradients at the edge becoming progressively steeper. The October to March trends in N2O profiles inside the vortex are used to verify daily net heating rates in the vortex that were computed from clear sky radiative heating rates and National Meteorological Center temperature observations. The computed heating rates successfully estimate the descent of vortex air from December through February but suggest that before December, air at high latitudes may not be isolated from the midlatitudes. SKYHI heating rates are in good agreement with the computed rates but tend to be slightly higher (i.e., less cooling) due to meteorological differences between SKYHI and the 1991-1992 winter. Three ER-2 flights measured N2O just north of the subtropical jet. These low-midlatitude profiles show only slight differences from the high-midlatitude profiles (45 deg - 60 deg N), indicating strong meridional mixing in the midlatitude `surf zone.` Mean midwinter N2O profiles inside and outside the vortex calculated from AASE 2 data are shown to be nearly identical to 1989 AASE profiles, pointing to the N2O/potential temperature relationship as an excellent marker for vortex air.

Strahan, S.E.; Rosenfield, J.E.; Loewenstein, M.; Podolske, J.R.; Weaver, A. [Applied Research Corp., Landover, MD (United States)]|[NASA, Goddard Space Flight Center, Greenbelt, MD (United States)]|[NASA, Ames Research Center, Moffett Field, CA (United States)

1994-10-01

92

Evolution of the 1991-1992 Arctic vortex and comparison with the Geophysical Fluid Dynamics Laboratory SKYHI general circulation model  

NASA Technical Reports Server (NTRS)

Nitrous oxide (N2O) measured on board the ER-2 aircraft during the Airborne Arctic Stratospheric Expedition 2 (AASE 2) has been used to monitor descent of air inside the Arctic vortex between October 1991 and March 1992. Monthly mean N2O fields are calculated from the flight data and then compared with mean fields calculated from the high-resolution Geophysical Fluid Dynamics Laboratory general circulation model SKYHI in order to evaluate the model's simulation of the polar vortex. From late fall through winter the model vortex evolves in much the same way as the 1991-1992 vortex, with N2O gradients at the edge becoming progressively steeper. The October to March trends in N2O profiles inside the vortex are used to verify daily net heating rates in the vortex that were computed from clear sky radiative heating rates and National Meteorological Center temperature observations. The computed heating rates successfully estimate the descent of vortex air from December through February but suggest that before December, air at high latitudes may not be isolated from the midlatitudes. SKYHI heating rates are in good agreement with the computed rates but tend to be slightly higher (i.e., less cooling) due to meteorological differences between SKYHI and the 1991-1992 winter. Three ER-2 flights measured N2O just north of the subtropical jet. These low-midlatitude profiles show only slight differences from the high-midlatitude profiles (45 deg - 60 deg N), indicating strong meridional mixing in the midlatitude 'surf zone.' Mean midwinter N2O profiles inside and outside the vortex calculated from AASE 2 data are shown to be nearly identical to 1989 AASE profiles, pointing to the N2O/potential temperature relationship as an excellent marker for vortex air.

Strahan, S. E.; Rosenfield, J. E.; Loewenstein, M.; Podolske, J. R.; Weaver, A.

1994-01-01

93

Arctic polar stratospheric cloud observations by airborne lidar  

SciTech Connect

Lidar observations obtained from January 24 to February 2, 1989, during the Airborne Arctic Stratospheric Expedition (AASE) mission further support the existence of two distinct classes (Types 1 and 2) of polar stratospheric clouds (PSCs). Most of the Type 1 PSCs observed were formed by rapid adiabatic cooling and exhibited very low depolarization ratios and low-to-intermediate scattering ratios. Type 2 PSCs were observed in regions of lowest temperature and showed much larger depolarization and scattering ratios, as would be expected from larger ice crystals. PSCs with low scattering ratios but moderate depolarization ratios were observed near the center of the vortex on one flight. These may have been either sparse Type 2 PSCs or Type 1 PSCs formed by less rapid cooling.

McCormick, M.P.; Poole, L.R. (NASA Langley Research Center, Hampton, VA (USA)); Kent, G.S. (Science and Technology Corporation, Hampton, VA (USA)); Hunt, W.H. (Wyle Laboratories, Hampton, VA (USA)); Osborn, M.T.; Pitts, M.C. (ST Systems Corporation, Hampton, VA (USA))

1990-03-01

94

Arctic polar stratospheric cloud observations by airborne lidar  

NASA Technical Reports Server (NTRS)

Lidar observations obtained from January 24 to February 2, 1989, during the Airborne Arctic Stratospheric expedition (AASE) mission further support the existence of two distinct classes (Types 1 and 2) of polar stratospheric clouds (PSCs). Most of the Type 1 PSCs observed were formed by rapid adiabatic cooling and exhibited very low depolarization ratios and low-to-intermediate scattering ratios. Type 2 PSCs were observed in regions of lowest temperature and showed much larger depolarization and scattering ratios, as would be expected from larger ice crystals. PSCs with low scattering ratios but moderate depolarization ratios were observed near the center of the vortex on one flight. These may have been either sparse Type 2 PSCs or Type 1 PSCs formed by less rapid cooling.

Mccormick, M. P.; Poole, L. R.; Kent, G. S.; Hunt, W. H.; Osborn, M. T.

1990-01-01

95

Model calculations of ozone depletion in the Artic polar vortex for 1991\\/92 to 1994\\/95  

Microsoft Academic Search

The authors use a 3D chemical transport code to model the ozone depletion over the Arctic polar vortex during the winters of 1991 thru 1994. They find that the meteorological conditions of the winter of 1994\\/1995 provided the largest depletion in this period. At altitudes near 18 km they predicted 30 to 50% depletions in the January to March time

M. P. Chipperfield; A. M. Lee; J. A. Pyle

1996-01-01

96

Model calculations of ozone depletion in the Artic polar vortex for 1991/92 to 1994/95  

SciTech Connect

The authors use a 3D chemical transport code to model the ozone depletion over the Arctic polar vortex during the winters of 1991 thru 1994. They find that the meteorological conditions of the winter of 1994/1995 provided the largest depletion in this period. At altitudes near 18 km they predicted 30 to 50% depletions in the January to March time frames.

Chipperfield, M.P.; Lee, A.M.; Pyle, J.A. [Univ. of Cambridge (United Kingdom)] [Univ. of Cambridge (United Kingdom)

1996-03-01

97

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

98

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

99

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

100

Control of the polarity of magnetization vortex by torsion  

NASA Astrophysics Data System (ADS)

The switching behavior of vortex polarity in a circular ferromagnetic nanodot subjected to torsion is investigated by using a real space phase field model, which explicitly includes the coupling between magnetization and mechanical strain. It is found that the vortex polarity of the nanodot can be switched by torsion when the sign of the torsion is opposite to that of vortex chirality whereas switching does not take place if the sign of torsion is the same as that of vortex chirality. The magneto-elastic coupling and demagnetization field play a decisive role in the polarity switching, which involves an intriguing interplay of magnetization, strain, and demagnetization. The results suggest another way to control vortex polarity by mechanical torsion other than magnetic field and electric current.

Wang, Jie; Li, Gui-Ping; Shimada, Takahiro; Fang, Hui; Kitamura, Takayuki

2013-12-01

101

Penetration of Mt. Pinatubo aerosols into the north polar vortex  

SciTech Connect

This paper reports results from measurements performed to study the cross polar vortex transport properties, using the aerosols injected by the Mt. Pinatubo eruption. The initial aerosol cloud arrived prior to the establishment of the polar vortex in 1992. However, using balloon borne backscattersondes, the authors were able to sample the aerosol densities in the vortex during the 1992 winter season. At altitudes below 20 km, the density rose dramatically following a mid January disturbance of the vortex. By comparison, at altitudes above 20 km there was no significant increase observed through mid March.

Rosen, J.M.; Kjome, N.T. (Univ. of Wyoming, Laramie, WY (United States)); Fast, H. (Atmospheric Environment Service, Toronto (Canada)); Khattatov, V.U.; Rudakov, V.V. (Central Aerological Observatory, Moscow (Russian Federation))

1992-09-04

102

The Yearly Variation in Fall-Winter Arctic Winter Vortex Descent  

NASA Technical Reports Server (NTRS)

Using the change in HALOE methane profiles from early September to late March, we have estimated the minimum amount of diabatic descent within the polar which takes place during Arctic winter. The year to year variations are a result in the year to year variations in stratospheric wave activity which (1) modify the temperature of the vortex and thus the cooling rate; (2) reduce the apparent descent by mixing high amounts of methane into the vortex. The peak descent amounts from HALOE methane vary from l0km -14km near the arrival altitude of 25 km. Using a diabatic trajectory calculation, we compare forward and backward trajectories over the course of the winter using UKMO assimilated stratospheric data. The forward calculation agrees fairly well with the observed descent. The backward calculation appears to be unable to produce the observed amount of descent, but this is only an apparent effect due to the density decrease in parcels with altitude. Finally we show the results for unmixed descent experiments - where the parcels are fixed in latitude and longitude and allowed to descend based on the local cooling rate. Unmixed descent is found to always exceed mixed descent, because when normal parcel motion is included, the path average cooling is always less than the cooling at a fixed polar point.

Schoeberl, Mark R.; Newman, Paul A.

1999-01-01

103

The Role of Stratospheric Polar Vortex Breakdown in Southern Hemisphere Climate Trends  

E-print Network

The Role of Stratospheric Polar Vortex Breakdown in Southern Hemisphere Climate Trends LANTAO SUN the delay in the final breakdown of the stratospheric polar vortex, the stratospheric final warming (SFW). This cooling trend results in a stronger polar vortex, and it delays the final breakdown of the polar vortex

Chen, Gang

104

Investigation of Ch4 and Cfc-11 Vertical Profiles In The Arctic Vortex During The Solve/theseo 2000 Campaign.  

NASA Astrophysics Data System (ADS)

Simultaneous balloon-borne measurements of ozone and long-lived tracers were made in Esrange, Sweden (68N, 22E), during the 1999/2000 winter as part of the SOLVE/THESEO 2000 campaign. Here we present the data from two lightweight instruments. A near-infrared tunable diode laser absorption spectrometer (TDLAS) making high spatial resolution in situ measurements of methane and the DIRAC in situ gas chromatograph measuring CFCs. We compare our tracer vertical profiles with a number of instruments on board of balloon and aircraft platforms and calculate the ozone loss inside the Arctic vortex between late January and early March using the relation between long-lived tracers and O3. In order for the 3-D Chemical Transport Models to quantify the rate of chemically induced ozone loss as a function of time both inside the Arctic vortex and at mid- latitudes, the models must correctly describe atmospheric transport. Results from the REPROBUS and the SLIMCAT 3D CTMs are tested using the tracers measurements made by the TDLAS and the DIRAC instruments and the high-resolution PV advec- tion contour MIMOSA model. The analysis shows that measurements are in good agreement with the 3D models inside the polar vortex but there are differences when measurements where performed near the edge of the vortex.

Garcelon, S.; Gardiner, T. D.; Hansford, G. M.; Harris, N. R. P.; Howieson, I. H.; Jones, R. L.; McIntyre, J. D.; Pyle, J. A.; Robinson, A. D.; Swann, N. R.; Woods, P. T.

105

N2O as an indicator of Arctic vortex dynamics: Correlations with O3 over Thule, Greenland in February and March, 1992  

NASA Technical Reports Server (NTRS)

We have recovered vertical profiles of stratospheric N2O from spectra observed using a ground-based mm-wave spectrometer during the Arctic spring. The measurements were made from Thule, Greenland (76.3 deg N, 68.4 deg W) on nine occasions from late February to late March, 1992 as part of the Upper Atmosphere Research Satellite (UARS) Correlative Measurements Program and the European Arctic Stratospheric Ozone Experiment (EASOE). During late February Thule was under inside edge of the Arctic vortex and mixing ratio profiles measured in that period are substantially reduced from typical high-latitude summer values. By late March the polar vortex had moved well away from Thule and N2O mixing ratios were greatly increased, coinciding with a basic change in circulation that brought in air from the Aleutian high. The motion of the vortex is also illustrated in the change in potential vorticity above Thule. A correlation with ozone balloonsonde data from Thule is made and compared to similar analyses of the Airborne Arctic Stratospheric Expedition (AASE) measurements. Within the sensitivity of our analysis, the correlation of N2O and O3 shows no evidence of ozone depletion within the vortex during this period; however, there is a distinct difference in the correlation inside and outside the vortex.

Emmons, L. K.; Reeves, J. M.; Shindell, D. T.; De Zafra, R. L.

1994-01-01

106

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

107

Experimental verification on tightly focused radially polarized vortex beams  

NASA Astrophysics Data System (ADS)

The theoretical and experimental results of tightly focused radially polarized vortex beams are demonstrated. An auto-focus technology is introduced into the measurement system in order to enhance the measurement precision, and the radially polarized vortex beams are generated by a liquid-crystal polarization converter and a vortex phase plate. The focused fields of radially polarized vortex beams with different topological charges at numerical apertures (NAs) of 0.65 and 0.85 are measured respectively, and the results indicate that the total intensity distribution at focus is dependent not only on the NA of the focusing objective lens and polarization pattern of the beam but also on the topological charge l of the beam. Some unique focusing properties of radially polarized vortex beams with fractional topological charges are presented based on numerical calculations. The experimental verification paves the way for some practical applications of radially polarized vortex beams, such as in optical trapping, near-field microscopy, and material processing.

Du, Fu-Rong; Zhou, Zhe-Hai; Tan, Qiao-Feng; Yang, Chang-Xi; Zhang, Xiao-Qing; Zhu, Lian-Qing

2013-06-01

108

Modified Black Hole with Polar Jet and Vortex  

E-print Network

There are many models relating an accretion disk of Black Hole to jet outflow. The herein heuristic model describes the continuation of an external accretion disk to an internal accretion disk for less than Black Hole horizon, and subsequent polar jet outflow along polar axis out of polar vortex wherein the event horizon is no longer descriptive.

T. Tmmalm

2001-12-06

109

Intensity and polarization properties of elliptically polarized vortex beams in turbulent atmosphere  

NASA Astrophysics Data System (ADS)

Based on the extended Huygens-Fresnel principle, the propagation of elliptically polarized vortex beams in a turbulent atmosphere is investigated. The analytical expressions for the average intensity and degree of polarization of the elliptically polarized vortex beams are derived in a turbulent atmosphere, respectively. The influences of polarization ellipticity, topological charge, beam width, and structure constant of the atmospheric turbulence on average intensity and degree of polarization are numerically demonstrated and analyzed in detail.

Ou, Jun; Jiang, Yuesong; He, Yuntao

2015-04-01

110

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

111

Titan's South Polar Vortex in Motion - Duration: 11 seconds.  

NASA Video Gallery

This movie captured by NASA'S Cassini spacecraft shows a south polar vortex, or a swirling mass of gas around the pole in the atmosphere, at Saturnâ??s moon Titan. The swirling mass appears to exec...

112

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

113

GoosHnchen and ImbertFedorov shifts of polarized vortex beams  

E-print Network

Goos­Hänchen and Imbert­Fedorov shifts of polarized vortex beams Konstantin Y. Bliokh,1,2, * Ilya V and transmission of an arbitrarily polarized vortex beam on an interface separating two dielectric media and derive case of an arbitrarily polarized vortex beam. We un- veil a direct relation between the vortex

114

Occurrence of ozone laminae near the boundary of the stratospheric polar vortex  

SciTech Connect

The authors report on observations of laminae in ozone distributions observed at high northern latitudes near the polar vortex. Regions of enhanced and depleted ozone density are observed. Data from ozonesonde collections and lidar measurements during the Airborne Arctic Stratosphere Expedition (AASE) are analyzed, and compared with earlier work. The ozonesonde archives of the World Meteorological Organization are also examined in this analysis. The laminae are observed to distribute differently as a function of season, and with the potential temperature. Transport of ozone equatorward is also found with a class of these laminae.

Reid, S.J.; Vaughan, G. (Univ. of Wales, Aberystwyth (Finland)); Kyro, E. (FMI, Sodankyla (Finland))

1993-05-20

115

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

NASA Technical Reports Server (NTRS)

Polar stratospheric cloud (PSC) distributions in the wintertime Arctic stratosphere and their optical characteristics were measured with a multiwavelength 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 where the temperatures were less than 195 K. Two types of aerosols with different optical characteristics (Types 1a and 1b) were observed in PSCs thought to be composed of nitric acid trihydrate. Water ice PSCs (Type 2) were observed to have high scattering ratios (greater than 10) and high aerosol depolarizations (greater than 10 percent) at temperatures less than 190 K.

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

1990-01-01

116

ACE-FTS measurements across the edge of the winter 2004 Arctic Ray Nassar,1  

E-print Network

at the poles. When a strong polar vortex is present, it can act as a barrier isolating air within by a steep gradient in potential vorticity (PV) coincident with the polar-night jet. When the vortex is weak the Arctic polar vortex and use these to estimate descent rates in the vortex. 2. ACE-FTS Retrievals [5

Nassar, Ray

117

Vortex polarization instabilities in PbTiO3 nanowires  

NASA Astrophysics Data System (ADS)

The possibility of circular, toroidal or vortex-like ordering (closure domains) of magnetic spin vectors have been considered, and their existence versified, in the past. Recent experimental and computational (based on effective Hamiltonian simulations) work have contributed to the mounting evidence for the presence of such vortex-like domains of electric polarization vectors in ferroelectric nanostructures. Here, for the first time using parameter-free ab initio density functional theory (DFT) based computations, we show the existence of such a vortex polarization state in PbTiO3 [001] nanowires. Our computations involved relaxed and axially strained free-standing PbTiO3 [001] nanowires with varying sidewall terminations and diameters. While stress-free nanowires with their sidewalls terminated by PbO surfaces displayed purely axial rectilinear polarization at all sizes, the TiO2-terminated nanowires, at a critical diameter of 16 å, display a vortex polarization transverse to the nanowire axis. Moreover, we predict the existence of novel stress-induced phase transitions between the vortex and the rectilinear polarization states in both the PbO- and TiO2-terminated nanowires. Normal mode vibrational frequency analysis of these nanowires further confirms these results.

Pilania, Ghanshyam; Ramprasad, R.

2010-03-01

118

A vortex model for transport in the polar stratosphere  

NASA Technical Reports Server (NTRS)

A semi-empirical model based on a Gaussian vorticity distribution was developed for determining eddy diffusivity and wind transport distributions in the polar stratosphere. The model uses as input data pressure surface heights measured at periods of the year when the stratospheric polar vortex exhibits nearly circular patterns around the pole. The components of the polar wind velocities that result from a Prandtl eddy viscosity distribution are found to be in general agreement with those obtained by other investigators.

Eberstein, I. J.; Yap, F. Y.; Veirs, V.

1978-01-01

119

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

120

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

121

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

122

Rapid descent of mesospheric air into the stratospheric polar vortex  

SciTech Connect

This paper describes simulations carried out to calculate the Lagrangian trajectories of greater than 40,000 air parcels in the middle atmospheric region of the southern polar vortex. The purpose was to see if model calculations would support recent observations which indicate that there is rapid vertical transport of air masses downward from the mesosphere into the stratospheric polar vortex. This conclusion was drawn from looking at the spatial distribution of long lived trace gases such as methane in the middle atmosphere. Looking at the Lagrangian fields provides a graphic picture of any mass motion, and does so in a fairly averaged manner.

Fisher, M.; O'Neill, A.; Sutton, R.

1993-06-18

123

Modelling the stratospheric polar vortex and its changes for GHGs increase and ozone depletion.  

E-print Network

Modelling the stratospheric polar vortex and its changes for GHGs increase and ozone depletion and possible feedback of the stratospheric polar vortex to changes in GHGs and ozone, as simulated by general of the stratospheric polar vortex and its possible impacts on the troposphere? #12;Models · MAECHAM4: middle atmosphere

Greatbatch, Richard

124

Visualization of Vortex Bound States in Polarized Fermi Gases at Unitarity Xia-Ji Liu,2  

E-print Network

Visualization of Vortex Bound States in Polarized Fermi Gases at Unitarity Hui Hu,1,2 Xia-Ji Liu,2 a single vortex in a spin polarized 3D trapped atomic Fermi gas near a broad Feshbach resonance. Above with a vortex may help to resolve the issue of the nature of polarized fermion pairing. It is natural to ask how

Queensland, University of

125

Final warming of the Southern Hemisphere polar vortex in high-and low-  

E-print Network

Final warming of the Southern Hemisphere polar vortex in high- and low- top CMIP5 models 1234567 89­2546, doi:10.1002/jgrd.50254, 2013 Final warming of the Southern Hemisphere polar vortex in high- and low; accepted 06 February 2013; published 25 March 2013. [1] The final warming date of the polar vortex is a key

Wirosoetisno, Djoko

126

Different ENSO teleconnections and their effects on the stratospheric polar vortex  

E-print Network

Different ENSO teleconnections and their effects on the stratospheric polar vortex C. I. Garfinkel1 ENSO does not show a PNA response in the observational record. Consequently, the polar vortex does. Hartmann (2008), Different ENSO teleconnections and their effects on the stratospheric polar vortex, J

Hartmann, Dennis

127

Correction to ``Wave breaking along the stratospheric polar vortex as seen in ERA-40 data''  

E-print Network

Correction to ``Wave breaking along the stratospheric polar vortex as seen in ERA-40 data'' John T., and G. Magnusdottir (2007), Correction to ``Wave breaking along the stratospheric polar vortex as seen breaking along the stratospheric polar vortex as seen in ERA-40 data'' by John T. Abatzoglou and Gudrun

Magnusdottir, Gudrun

128

On the Lagrangian Dynamics of Atmospheric Zonal Jets and the Permeability of the Stratospheric Polar Vortex  

E-print Network

Polar Vortex I. I. RYPINA, M. G. BROWN, AND F. J. BERON-VERA Rosenstiel School of Marine and Atmospheric at the perimeter of the stratospheric polar vortex in the austral spring. 1. Introduction It is now generally accepted that during the austral winter and spring the Southern Hemisphere strato- spheric polar vortex

Olascoaga, Maria Josefina

129

Optimally coherent sets in geophysical flows: A new approach to delimiting the stratospheric polar vortex  

E-print Network

" of the Antarctic polar vortex is known to behave as a barrier to the meridional (pole- ward) transport of ozone during the austral winter. This chemical isolation of the polar vortex from the middle and low latitudes existing methods of estimation. It is common meteorological practice to diagnose the polar vortex edge

Monahan, Adam Hugh

130

Downward Wave Propagation on the Polar Vortex R. K. SCOTT* AND D. G. DRITSCHEL  

E-print Network

Downward Wave Propagation on the Polar Vortex R. K. SCOTT* AND D. G. DRITSCHEL School of a stratospheric polar vortex, represented by a three-dimensional patch of uniform potential vorticity propagation on the edge of the winter stratospheric polar vortex. The subject of wave propa- gation and wave

Cambridge, University of

131

Response of the northern stratospheric polar vortex to the seasonal alignment of  

E-print Network

Response of the northern stratospheric polar vortex to the seasonal alignment of QBO phase and the strength of the stratospheric polar vortex is optimized for subsets of the 44-year record that are chosen effective at influencing the interannual variability of the polar vortex, and that an early (late) winter

Wirosoetisno, Djoko

132

Final warming of the Southern Hemisphere polar vortex in high-and low-  

E-print Network

Final warming of the Southern Hemisphere polar vortex in high- and low- top CMIP5 models 1234567 warming of the Southern Hemisphere polar1 vortex in high- and low-top CMIP5 models2 L. J. Wilcox and A. JBB, UK5 Abstract6 The final warming date of the polar vortex is a key component of7 Southern

Wirosoetisno, Djoko

133

Transport out of the Antarctic polar vortex from a three-dimensional transport model  

E-print Network

Transport out of the Antarctic polar vortex from a three-dimensional transport model Shuhua Li,1-dimensional chemical transport model is utilized to study the transport out of the Antarctic polar vortex during: Middle atmosphere--energy deposition; KEYWORDS: transport, polar vortex, mass flux, dilution effect 1

Cordero, Eugene

134

Hyperbolic lines and the stratospheric polar vortex Tieh-Yong Koha)  

E-print Network

Hyperbolic lines and the stratospheric polar vortex Tieh-Yong Koha) and Bernard Legrasb 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

Legras, Bernard

135

Stratosphere-troposphere evolution during polar vortex intensification Varavut Limpasuvan,1  

E-print Network

Stratosphere-troposphere evolution during polar vortex intensification Varavut Limpasuvan,1 Dennis-troposphere evolution associated with polar vortex intensification (VI) events is examined during the Northern (2005), Stratosphere-troposphere evolution during polar vortex intensification, J. Geophys. Res., 110, D

136

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

137

Measurements of polar vortex air in the midlatitudes  

Microsoft Academic Search

The Stratospheric Photochemistry, Aerosols, and Dynamics Expedition (SPADE) was conducted in the spring of 1993 from Moffett Field, California (NASA Ames Research Center), utilizing the NASA high-altitude ER-2 aircraft. These northern midlatitude aircraft flights showed laminae containing high ozone concentrations, traceable to the April 1993 polar vortex breakup and corroborated by laminae of other trace gases such as CFCs, CH4,

Paul A. Newman; L. R. Lait; M. R. Schoeberl; M. Seablom; L. Coy; R. Rood; R. Swinbank; M. Proffitt; M. Loewenstien; J. R. Podolske; J. W. Elkins; C. R. Webster; R. D. May; D. W. Fahey; G. S. Dutton; K. R. Chan

1996-01-01

138

Rapid descent of mesospheric air into the stratospheric polar vortex  

Microsoft Academic Search

Wind fields from a numerical simulation are used to give a detailed Lagrangian picture of air flow in the middle atmosphere of the southern hemisphere in winter and early spring 1991. Trajectories for many thousands of air particles exhibit rapid descent of mesospheric air into the stratospheric polar vortex, revealing its organizing and structure-preserving properties. Results are used to account

Michael Fisher; Alan O'Neill; Rowan Sutton

1993-01-01

139

Climatology of the stratospheric polar vortex and planetary wave breaking  

NASA Technical Reports Server (NTRS)

The distribution of Ertel's potential vorticity (PV) on the 850 K isentropic surface is used to establish a climatology for the transient evolution of the planetary scale circulation in the Northern Hemisphere winter midstratosphere. PV distributions are computed from gridded NMC daily temperature and height maps for the 10 and 30 mb levels, and show that a very good approximation for 850 K PV can be derived from 10 mb heights and temperatures alone. It is assumed that reversals of the latitudinal gradient of PV, localized in longitude and latitude may be regarded as signatures of planetary wave breaking. Wave breaking identified by such signatures tends to occur mainly in the vicinity of the Aleutian anticyclone, with a secondary maximum over Europe. The area of the polar vortex, defined as the area enclosed by PV contours greater than a certain critical value, is strongly influenced by wave breaking. Erosion of the polar vortex due to transport and mixing of PV leads to a preconditioned state, when defined in terms of vortex area, that always occurs prior to major stratospheric warmings. During winters with little PV transport or mixing, the vortex area evolves rather uniformly in response to radiative forcing. During winters with major sudden warmings, the wave breaking signature as defined here first appears at low values of PV, then rapidly moves toward higher values as the vortex area is reduced and the 'surf-zone' structure becomes well defined.

Baldwin, Mark P.; Holton, James R.

1988-01-01

140

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

141

The structure and maintenance of tropopause polar vortices over the Arctic  

NASA Astrophysics Data System (ADS)

Tropopause polar vortices (TPVs) are coherent vortices based the tropopause in polar regions, where they are isolated from the wind shear associated with the midlatitude jet stream. Cyclonic TPVs are a common feature of the Arctic, have radii up to 1500 km, and can have lifetimes of over one month. The Arctic is a particularly favorable region for these features due to the isolation from the jet stream, an environment conducive for vortex longevity. Further, TPVs can have an impact on surface weather since they provide more favorable conditions for surface cyclogenesis. The intensification of cyclonic TPVs is examined using an Ertel Potential Vorticity (EPV) framework to test the hypothesis that diabatic effects are able to intensify the vortices due to a dominance of radiative cooling within the vortices that can be seen in high latitudes. This thesis first generalizes the diabatic intensification mechanisms by applying the EPV framework methods to a large sample of cyclones in the Canadian Arctic, and shows that there is a net tendency to create EPV in the vortex, and hence intensify cyclones from radiative processes. While the effects of latent heating are considerable, they are smaller in magnitude. The physical mechanisms leading to these observations are then examined in idealized numerical experiments, where it is shown that longwave radiative cooling is the most important mechanism for intensification. Dry air from the downward intrusion of stratospheric air in the vortex strengthens the vertical gradient of water vapor near the tropopause, and weakens the vertical gradient of water vapor in the lower stratosphere. This results in relatively high radiative cooling near the tropopause, and relatively low radiative cooling in the lower stratosphere with respect to the background environment in the vortex core, enhancing EPV generation in the vortex core. The impact of radiative processes to the climatology of cyclonic TPVs is then examined by comparing a numerically simulated control mesoscale climatology with full physics to one without radiative forcings. The two simulated climatologies exhibit substantially different evolutions, and emphasize the important role of radiation in intensifying and maintaining cyclonic TPVs.

Cavallo, Steven M.

2009-12-01

142

Determination of the polarization states of an arbitrary polarized terahertz beam: Vectorial vortex analysis.  

PubMed

Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1-1.6?THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of ? = 163° and are made of polytetrafluorethylene. Polarized THz beams are converted into THz vectorial vortex beams with no spatial or wavelength dispersion, and the unknown polarization states of the incident THz beams are reconstructed. The polarization determination is also demonstrated at frequencies of 0.16 and 0.36?THz. The results obtained by solving the inverse source problem agree with the values used in the experiments. This vectorial vortex analysis enables a determination of the polarization states of the incident THz beam from the THz image. The polarization states of the beams are estimated after they pass through the TAS plates. The results validate this new approach to polarization detection for intense THz sources. It could find application in such cutting edge areas of physics as nonlinear THz photonics and plasmon excitation, because TAS plates not only instantaneously elucidate the polarization of an enclosed THz beam but can also passively control THz vectorial vortex beams. PMID:25799965

Wakayama, Toshitaka; Higashiguchi, Takeshi; Oikawa, Hiroki; Sakaue, Kazuyuki; Washio, Masakazu; Yonemura, Motoki; Yoshizawa, Toru; Tyo, J Scott; Otani, Yukitoshi

2015-01-01

143

Determination of the polarization states of an arbitrary polarized terahertz beam: Vectorial vortex analysis  

PubMed Central

Vectorial vortex analysis is used to determine the polarization states of an arbitrarily polarized terahertz (0.1–1.6?THz) beam using THz achromatic axially symmetric wave (TAS) plates, which have a phase retardance of ? = 163° and are made of polytetrafluorethylene. Polarized THz beams are converted into THz vectorial vortex beams with no spatial or wavelength dispersion, and the unknown polarization states of the incident THz beams are reconstructed. The polarization determination is also demonstrated at frequencies of 0.16 and 0.36?THz. The results obtained by solving the inverse source problem agree with the values used in the experiments. This vectorial vortex analysis enables a determination of the polarization states of the incident THz beam from the THz image. The polarization states of the beams are estimated after they pass through the TAS plates. The results validate this new approach to polarization detection for intense THz sources. It could find application in such cutting edge areas of physics as nonlinear THz photonics and plasmon excitation, because TAS plates not only instantaneously elucidate the polarization of an enclosed THz beam but can also passively control THz vectorial vortex beams. PMID:25799965

Wakayama, Toshitaka; Higashiguchi, Takeshi; Oikawa, Hiroki; Sakaue, Kazuyuki; Washio, Masakazu; Yonemura, Motoki; Yoshizawa, Toru; Tyo, J. Scott; Otani, Yukitoshi

2015-01-01

144

Transport into the south polar vortex in early spring  

NASA Technical Reports Server (NTRS)

Estimates of the mean circulation and diffusive transport of ozone and other species into the Antarctic polar vortex during the spring of 1987 are made using data from the Airborne Antarctic Ozone Experiment. Measurements of long-lived tracers of tropospheric origin remained relatively constant at the levels of the maximum rate of decline of ozone during September. At lower levels in the stratosphere some evidence exists to support intrusions of tropospheric or low latitude air. Given the distribution in latitude and height of these tracers measured from the ER-2 aircraft, it can be inferred that the Lagrangian or diabatic mean circulation was zero or downward over Antarctica during the period of the ozone decline. The observation of a decline in ozone therefore requires a photochemical sink for ozone. The magnitude of the required photochemical sink must be sufficient to offset the transport of ozone into the polar region and produce the observed decline. Quasi-isentropic mixing and downward motion are coupled and are difficult to estimate from a single tracer. The full suite of measured tracers and auxiliary information are brought together to provide an estimate of the rate at which air is cycled through the polar vortex during spring. Estimates of large scale transport of potential vorticity and ozone from previous years are generally consistent with the data from the airborne experiment in suggesting a relatively slow rate of mass flow through the polar vortex in the lower stratosphere during September.

Hartmann, D.; Heidt, L. E.; Loewenstein, M.; Podolske, J.; Starr, Walter L.; Vedder, James F.

1988-01-01

145

Wave breaking along the stratospheric polar vortex as seen in ERA-40 John T. Abatzoglou1  

E-print Network

Wave breaking along the stratospheric polar vortex as seen in ERA-40 data John T. Abatzoglou1), Wave breaking along the stratospheric polar vortex as seen in ERA-40 data, Geophys. Res. Lett., 34, L is observed in daily ERA-40 reanalysis data. Strong wave breaking along the vortex edge is objectively

Magnusdottir, Gudrun

146

Spatial changes in the stratospheric aerosol associated with the north polar vortex  

NASA Technical Reports Server (NTRS)

In late January and early February 1983, observations made by the Stratospheric Aerosol Measurement (SAM II) satellite system showed that aerosol extinction profiles measured within the northern polar vortex differed significantly above 18 km from those measured outside the vortex. Values of the calculated optical depths above 18 km for February 1, 1983, are lower by approximately one order of magnitude within the polar vortex than those outside. Similar differences were found in the aerosol back-scattering profiles obtained using an airborne lidar system when crossing the polar vortex. Since potential vorticity at a constant altitude is not conserved across the polar vortex, horizontal adiabatic transport does not occur.

Mccormick, M. P.; Trepte, C. R.; Kent, G. S.

1983-01-01

147

Optical backscatter characteristics of Arctic polar stratospheric clouds  

NASA Technical Reports Server (NTRS)

Airborne lidar measurements have been made of polar stratospheric clouds (PSCs) during the Airborne Arctic Stratospheric Expedition in January-February 1989. These show the existence of a systematic relationship between the backscatter depolarization ratio and the (aerosol + molecular)/molecular backscatter ratio. The data are consistent with a two population PSC particle model.

Kent, G. S.; Schaffner, S. K.; Poole, L. R.; Mccormick, M. P.; Hunt, W. H.

1990-01-01

148

Stratospheric trace gas concentrations in the Arctic polar night derived by FTIR-spectroscopy with the moon as ir light source  

Microsoft Academic Search

In winter 1992\\/93 we have performed ground-based FTIR measurements in the Arctic (79°N, 12°E) to derive column densities of stratospheric trace gases within the polar vortex. Due to the polar night the moon had to serve as infrared light source instead of the sun. It was possible to perform FTIR-measurements for about a week around full moon. Column densities of

J. Notholt; R. Neuber; O. Schrems; T. v. Clarmann

1993-01-01

149

7) Stratospheric Sudden Warmings and the Arctic Oscillation a) Observations  

E-print Network

data This is the Arctic Polar vortex Note how its deformation occurs over very large scales Note how never disappear The air masses in the polar stratosphere stays isolated since the vortex never break the polar cap warms, and the polar jet can even reverse At the beginning, there are essentially waves

Spiga, Aymeric

150

Denitrification and formation of polar stratospheric clouds during the Arctic winter 2009/2010  

NASA Astrophysics Data System (ADS)

The sedimentation of HNO3 containing Polar Stratospheric Cloud (PSC) particles leads to an irreversible removal of HNO3 and thus a denitrification in the stratosphere which plays an im-portant role in stratospheric ozone depletion. The polar vortex in the Arctic winter 2009/2010 was very cold and stable between end of December and end of January. Strong denitrifica-tion was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR). Thereby, atmospheric gaseous HNO3 was depleted completely north of Scandi-navia. During the time period the vortex was very stable and cold PSCs were observed quite frequently. Lidar measurements of PSCs were performed in the area of Kiruna, Northern Swe-den (69° N 21° E) from 3 January to 24 January 2010 with the IRF lidar and from 17 to 30 January 2010 with the Esrange lidar. The measurements show during the entire time period the presence of PSCs over the area of Kiruna. The composition of this cloud changes from NAT to ice in mid January and then back to STS/NAT/mix towards the end of January. The formation of PSCs during the Arctic winter 2009/2010 is investigated using a microphysical box model. Box model simulations are performed along air parcel trajectories calculated six days backward according to the PSC measurements with the ground-based lidar in the Kiruna area. Using the box model simulations along backward trajectories together with the observations of Odin/SMR and the ground-based lidar we investigate how and by which type of PSC particles the denitrification was caused.

Khosrawi, Farahnaz; Urban, Joachim; Achtert, Peggy; Khaplanov, Mikhail; Voelger, Peter; Murtagh, Donal P.; Fricke, K.-H.

151

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.

Ivanka Stajner

152

Titan's winter polar vortex structure revealed by chemical tracers  

Microsoft Academic Search

The winter polar vortex on Saturn's largest moon Titan has profound effects on atmospheric circulation and chemistry and for the current northern midwinter season is the major dynamical feature of Titan's stratosphere and mesosphere. We use 2 years of observations from Cassini's composite infrared spectrometer to determine cross sections of five independent chemical tracers (HCN, HC3N, C2H2, C3H4, and C4H2),

N. A. Teanby; R. de Kok; P. G. J. Irwin; S. Osprey; S. Vinatier; P. J. Gierasch; P. L. Read; F. M. Flasar; B. J. Conrath; R. K. Achterberg; B. Bézard; C. A. Nixon; S. B. Calcutt

2008-01-01

153

Transport into the south polar vortex in early spring  

Microsoft Academic Search

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

D. L. Hartmann; L. E. Heidt; M. Loewenstein; J. R. Podolske; J. Vedder; W. L. Starr; S. E. Strahan

1989-01-01

154

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

155

Contour surgery simulations of a forced polar vortex  

Microsoft Academic Search

High-resolution simulations of a polar vortex disturbed by quasi-topographic forcing are performed using the method of [open quotes]contour surgery,[close quotes] a numerical method for inviscid flows wherein arbitrarily steep vorticity gradients can be formed and wherein scales of motion can vary over an extensive range. Simulations are performed of inviscid, incompressible, barotropic motion on the hemisphere, the sphere, and the

Darryn W. Waugh

1993-01-01

156

Polar Stratospheric Cloud occurrence during the Arctic winter 2008/2009 as observed by CALIPSO  

NASA Astrophysics Data System (ADS)

Although the Arctic winter 2008/2009 was a rather warm winter in the climatological sense, the stratospheric circulation was undisturbed until 8 January 2009 leading to a strong cyclonic vortex during this time period. Temperatures within the vortex cooled sufficiently down to allow the formation of Polar Stratospheric Clouds (PSCs). A major stratospheric warming in January 2009 ended the winter much earlier than usual. This major stratospheric warming was the strongest and most prolonged on record. In this study, we analyse PSC occurrence during the Arctic winter 2008/2009 applying space-borne lidar observations from the CALIOP instrument on board the CALIPSO satellite. PSCs were observed by CALIOP during a period of approximately one month, from 15 December 2008 to 16 January 2009. The highest frequency of PSCs was found at the end of December/begin of January. During that time period temperatures became also sufficiently cold to allow the formation of ice PSCs. Backward trajectories were calculated with the HYSPLIT model to investigate the air parcels history and thus the formation conditions for the different PSC types.

Khosrawi, Farahnaz; Lundberg, Angelica; Achtert, Peggy; Pitts, Michael C.

2013-04-01

157

Pipeline under the arctic ice: the Polar Gas Project  

SciTech Connect

The Polar Gas Project was established in 1972 to determine the best means of moving frontier natural gas from Canada's high arctic to southern markets. Pipeline was found to be most feasible. Several pipeline routings from two major supply areas--the MacKenzie Delta/Beaufort Sea region, and the Sverdrup Basin of the Arctic Islands--have been considered. Field programs to determine the type and ice content of soils along the route have been undertaken. The most challenging engineering aspect will be two marine crossings in arctic waters at either end of Victoria Island, at Dolphin and Union Strait, and at McClure's strait. The ''Ice Hole Bottom Pull'' technique has been recommended, and is illustrated in detail. The planned pipeline demonstration would significantly enhance the current state-of-the-art for deepwater pipelining worldwide.

Kaustinen, O.M.

1982-06-01

158

Polarization pattern of vector vortex beams generated by q-plates with different topological charges  

E-print Network

Polarization pattern of vector vortex beams generated by q-plates with different topological angular momentum (OAM) [5]. Among vector vortex beams, radially or azimuthally polarized vec- tor beams; posted 3 January 2012 (Doc. ID 159438); published 5 March 2012 We describe the polarization topology

Marrucci, Lorenzo

159

Magnetic vortex oscillator driven by d.c. spin-polarized current  

E-print Network

ARTICLES Magnetic vortex oscillator driven by d.c. spin-polarized current V. S. PRIBIAG, I. N been demonstrated that the vortex-core polarization can be efficiently switched by short radiofrequency momentum from a spin-polarized current to a ferromagnet provides an efficient means to control

Loss, Daniel

160

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

161

On the Identification of the Downward Propagation of Arctic Stratospheric Climate Change over Recent Decades*  

E-print Network

by a strengthening of the Arctic polar vortex over the past 30 years. The associated declines in stratospheric and early spring. In sharp contrast to the Antarctic, the strengthening of the Arctic stratospheric vortex are considered in the analysis. 1. Introduction The apparent propagation of some polar circula- tion anomalies

162

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

163

The tropospheric-stratospheric polar vortex breakdown of January 1977  

NASA Technical Reports Server (NTRS)

An extraordinary warming of the stratosphere in December-January 1976-77 was followed by tropospheric warming in the polar region and cooling in middle latitudes. During January 10-20, the associated polar anticyclone extended from the surface to 10 mb. Antecedents of the polar vortex breakdown are reviewed with the aid of results of zonal-harmonic analyses of planetary waves, for heights of the pressure surfaces (700-10 mb), temperature, and mean stratospheric temperature (the latter determined from satellite radiation measurements). Wave 1 in height and temperature played a dominant role in the stratosphere, attaining amplitudes of 1600 gpm and 25 C, respectively, at 10 mb. On the other hand, superposition of retrogressing wave 1 and quasi-stationary wave 2 in the height of the 300-mb surface, with individual amplitudes exceeding 300 gpm, is judged to have been an important factor in the overall development.

Quiroz, R. S.

1977-01-01

164

Stratospheric water vapour as tracer for Vortex filamentation in the Arctic winter 2002/2003  

NASA Astrophysics Data System (ADS)

Balloon-borne frost point hygrometers measured three high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen during winter 2002/2003. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. The water vapour sounding on 11 February 2003 was obtained within the vortex edge region of the lower stratosphere. Here, a significant reduction of water vapour mixing ratio was observed between 16 and 19 km. The stratospheric temperatures indicate that this dehydration was not caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. Ozone observations on this day indicate a large scale movement of the polar vortex and show laminae in the same altitude range as the water vapour profile. The link between the observed water vapour reduction and filaments in the vortex edge region is indicated in the results of the semi-lagrangian advection model MIMOSA, which show that adjacent filaments of polar and mid latitude air can be identified above the Spitsbergen region. A vertical cross-section produced by the MIMOSA model reveals that the water vapour sonde flew through polar air in the lowest part of the stratosphere below 425 K, then passed through filaments of mid latitude air with lower water vapour concentrations, before it finally entered the polar vortex above 450 K. These results indicate that on 11 February 2003 the frost point hygrometer measured different water vapour concentrations as the sonde detected air with different origins. Instead of being linked to dehydration due to PSC particle sedimentation, the local reduction in the stratospheric water vapour profile was in this case caused by dynamical processes in the polar stratosphere.

Müller, M.; Neuber, R.; Fierli, F.; Hauchecorne, A.; Vömel, H.; Oltmans, S. J.

2003-11-01

165

An objective determination of the polar vortex using Erte's potential vorticity  

Microsoft Academic Search

We have developed objective criteria for choosing the location of the northern hemisphere polar vortex boundary region and the onset and breakup dates of the vortex. By determining the distribution of Ertel's potential vorticity (Epv) on equivalent latitudes, we define the vortex edge as the location of maximum gradient of Epv constrained by the location of the maximum wind jet

Eric R. Nash; Paul A. Newman; Joan E. Rosenfield; Mark R. Schoeberl

1996-01-01

166

Ozone Loss Inside the Northern Polar Vortex During the 1991-1992 Winter  

Microsoft Academic Search

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

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

1993-01-01

167

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

SciTech Connect

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 where the temperatures were {le}195 K. Two types of aerosols with different optical characteristics (Types 1a and 1b) were observed in PSCs thought to be composed of nitric acid trihydrate. Type 1a PSCs typically exhibited low scattering ratios (1.2-1.5) and high aerosol depolarizations (30-50%) at 603 nm, while Type 1b PSCs had higher scattering ratios (3-8) and lower aerosol depolarizations (0.5-2.5%). Water ice PSCs (Type 2) were observed to have high scattering ratios (>10) and high aerosol depolarizations (>10%) at temperatures {le}190 K.

Browell, E.V.; Ismail, S.; Carter, A.F.; Higdon, N.S. (NASA Langley Research Center, Hampton, VA (USA)); Butler, C.F.; Robinette, P.A. (ST Systems Corporation, Hampton, VA (USA)); Toon, O.B. (NASA Ames Research Center, Moffett Field, CA (USA)); Schoeberl, M.R. (NASA Goddard Space Flight Center, Greenbelt, MD (USA)); Tuck, A.F. (NOAA Aeronomy Laboratory, Boulder, CO (USA))

1990-03-01

168

The variability of ClONO2 and HNO3 in the Arctic polar vortex: Comparison of Transall Michelson interferometer for passive atmospheric sounding measurements and three-dimensional model results  

Microsoft Academic Search

A three-dimensional radiative-dynamical-chemical model has been used to investigate measurements of column ClONO2 and HNO3 made by the airborne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument. MIPAS made measurements from the Transall aircraft in the northern hemisphere lower stratosphere from December 1992 to March 1993. The three-dimensional model has a detailed stratospheric chemistry scheme including heterogeneous reactions on polar

M. P. Chipperfield; J. A. Pyle; C. E. Blom; N. Glatthor; M. Höpfner; T. Gulde; C. Piesch; P. Simon

1995-01-01

169

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

170

Chlorine chemistry on polar stratospheric cloud particles in the Arctic winter  

NASA Technical Reports Server (NTRS)

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 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 HCl mixing ratios equal to 1/2(ClO+ 2Cl2O2). These data indicate that the heterogeneous reaction HCl + ClONO2 - Cl2 + HNO3 on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO2, not HCl.

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.

1993-01-01

171

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

172

Stratospheric water vapour as tracer for vortex filamentation in the Arctic winter 2002/2003  

NASA Astrophysics Data System (ADS)

During winter 2002/2003, three balloon-borne frost point hygrometers measured high-resolution profiles of stratospheric water vapour above Ny-Ålesund, Spitsbergen. All measurements reveal a high H2O mixing ratio of about 7 ppmv above 24 km, thus differing significantly from the 5 ppmv that are commonly assumed for the calculation of polar stratospheric cloud existence temperatures. The profiles obtained on 12 December 2002 and on 17 January 2003 provide an insight into the vertical distribution of water vapour in the core of the polar vortex. Unlike the earlier profiles, the water vapour sounding on 11 February 2003 detected the vortex edge region in the lower part of the stratosphere. Here, a striking diminuition in H2O mixing ratio stands out between 16 and 19 km. The according stratospheric temperatures clarify that this dehydration can not be caused by the presence of polar stratospheric clouds or earlier PSC particle sedimentation. On the same day, ozone observations by lidar indicate a large scale movement of the polar vortex, while an ozone sonde measurement even shows laminae in the same altitude range as in the water vapour profile. Tracer lamination in the vortex edge region is caused by filamentation of the vortex. The link between the observed water vapour diminuition and filaments in the vortex edge region is highlighted by results of the MIMOSA contour advection model. In the altitude of interest, adjoined filaments of polar and mid-latitudinal air can be identified above the Spitsbergen region. A vertical cross-section reveals that the water vapour sonde has flown through polar air in the lowest part of the stratosphere. Where the low water vapour mixing ratio was detected, the balloon passed through air from a mid-latitudinal filament from about 425 to 445 K, before it finally entered the polar vortex above 450 K. The MIMOSA model results elucidate the correlation that on 11 February 2003 the frost point hygrometer measured strongly variable water vapour concentrations as the sonde detected air with different origins, respectively. Instead of being linked to dehydration due to PSC particle sedimentation, the local diminuition in the stratospheric water vapour profile of 11 February 2003 has been found to be caused by dynamical processes in the polar stratosphere.

Müller, M.; Neuber, R.; Fierli, F.; Hauchecorne, A.; Vömel, H.; Oltmans, S. J.

2003-08-01

173

Polarization radiation of vortex electrons with large orbital angular momentum  

NASA Astrophysics Data System (ADS)

Vortex electrons—freely propagating electrons whose wave functions have helical wave fronts—could become a novel tool in the physics of electromagnetic radiation. They carry a nonzero intrinsic orbital angular momentum (OAM) ? with respect to the propagation axis and, for ??1, a large OAM-induced magnetic moment ????B (?B is the Bohr magneton), which influences the radiation of electromagnetic waves. Here, we consider in detail the OAM-induced effects caused by such electrons in two forms of polarization radiation, namely, in Cherenkov radiation and transition radiation. Thanks to the large ?, we can neglect quantum or spin-induced effects, which are of the order of ??/Ee?1, but retain the magnetic moment contribution ???/Ee?1, which makes the quasiclassical approach to polarization radiation applicable. We discuss the magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on the kinematical parameters and the medium permittivity. In particular, it is shown that this contribution can, in principle, be detected in azimuthally nonsymmetrical problems, for example when vortex electrons obliquely cross a metallic screen (transition radiation) or move near it (diffraction radiation). We predict a left-right angular asymmetry of the transition radiation (in the plane where the charge radiation distributions would stay symmetric), which appears due to an effective interference between the charge radiation field and the magnetic moment contribution. Numerical values of this asymmetry for vortex electrons with Ee=300 keV and ?=100-1000 are 0.1%-1%, and we argue that this effect could be detected with existing technology. The finite conductivity of the target and frequency dispersion play crucial roles in these predictions.

Ivanov, Igor P.; Karlovets, Dmitry V.

2013-10-01

174

Polarization radiation of vortex electrons with large orbital angular momentum  

E-print Network

Vortex electrons, - freely propagating electrons whose wavefunction has helical wavefronts, - could become a novel tool in the physics of electromagnetic radiation. They carry a non-zero intrinsic orbital angular momentum (OAM) $\\ell$ with respect to the propagation axis and, for \\ell \\gg 1, a large OAM-induced magnetic moment, \\mu ~ \\ell \\mu_B (\\mu_B is the Bohr magneton), which influences the radiation of electromagnetic waves. Here, we consider in detail the OAM-induced effects by such electrons in two forms of polarization radiation, namely in Cherenkov radiation and transition radiation. Thanks to the large \\ell, we can neglect quantum or spin-induced effects, which are of the order of \\hbar \\omega/E_e \\ll 1, but retain the magnetic moment contribution \\ell \\hbar \\omega/E_e \\lesssim 1, which makes the quasiclassical approach to polarization radiation applicable. We discuss the magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on the kinematical parameters and the medium permittivity. In particular, it is shown that this contribution can, in principle, be detected in azimuthally non-symmetrical problems, for example when vortex electrons obliquely cross a metallic screen (transition radiation) or move nearby it (diffraction radiation). We predict a left-right angular asymmetry of the transition radiation (in the plane where the charge radiation distributions would stay symmetric), which appears due to an effective interference between the charge radiation field and the magnetic moment one. Numerical values of this asymmetry for vortex electrons with E_e = 300keV and \\ell = O(100-1000) are O(0.1-1%), and we argue that this effect could be detected with existing technology. The finite conductivity of the target and frequency dispersion play the crucial roles in these predictions.

Igor P. Ivanov; Dmitry V. Karlovets

2013-07-20

175

Polar Gateways Arctic Circle Sunrise 2008 Conference at the Top of the World  

Microsoft Academic Search

The Polar Gateways conference was hosted during January 23-29, 2008, the first week of polar sunrise at Barrow, Alaska, at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium (BASC). The dawn week of polar day, the highly variable low temperatures, and the ice-covered shore tundra and adjacent sea ice conditions provided an appropriate locale for a

J. F. Cooper; K. Kauristie; A. T. Weatherwax; G. W. Sheehan; R. W. Smith; T. D. Cline; E. M. Lewis; G. Haines-Stiles

2008-01-01

176

Optimally coherent sets in geophysical flows: A new approach to delimiting the stratospheric polar vortex  

E-print Network

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 letter, we obtain objective estimates of the structure of the polar vortex by introducing a new technique based on transfer operators that aims to find regions with minimal external transport. Applying this new 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 novel computational approach has wide potential application in detecting and analysing mixin...

Santitissadeekorn, Naratip; Monahan, Adam

2010-01-01

177

Active ClOx species and ClONO2 as measured by MIPAS-B inside the Arctic vortex in winters 2001 and 2003  

NASA Astrophysics Data System (ADS)

Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Under this aspect, arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been analyzed with regard to the chlorine reservoir species ClONO2 and the active species ClO and ClOOCl (Cl2O2). High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of up to 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter arctic vortex on 20 March 2003. No significant ClOx amounts are visible on this date. Calculations with the 3-dimensional Karlsruhe Simulation model of the Middle Atmosphere (KASIMA) show less chlorine activation compared to the measurements in January 2001. The model generally underestimates ClONO2 mixing ratios in favour of HCl.

Wetzel, G.; Oelhaf, H.; Ruhnke, R.; Friedl-Vallon, F.; Kleinert, A.; Maucher, G.; Birk, M.; Wagner, G.

2009-04-01

178

Dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions  

Microsoft Academic Search

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

M. R. Schoeberl; D. L. Hartmann

1991-01-01

179

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

180

Diel vertical migration of Arctic zooplankton during the polar night.  

PubMed

High-latitude environments show extreme seasonal variation in physical and biological variables. The classic paradigm of Arctic marine ecosystems holds that most biological processes slow down or cease during the polar night. One key process that is generally assumed to cease during winter is diel vertical migration (DVM) of zooplankton. DVM constitutes the largest synchronized movement of biomass on the planet, and is of paramount importance for marine ecosystem function and carbon cycling. Here we present acoustic data that demonstrate a synchronized DVM behaviour of zooplankton that continues throughout the Arctic winter, in both open and ice-covered waters. We argue that even during the polar night, DVM is regulated by diel variations in solar and lunar illumination, which are at intensities far below the threshold of human perception. We also demonstrate that winter DVM is stronger in open waters compared with ice-covered waters. This suggests that the biologically mediated vertical flux of carbon will increase if there is a continued retreat of the Arctic winter sea ice cover. PMID:18948249

Berge, Jørgen; Cottier, Finlo; Last, Kim S; Varpe, Øystein; Leu, Eva; Søreide, Janne; Eiane, Ketil; Falk-Petersen, Stig; Willis, Kate; Nygård, Henrik; Vogedes, Daniel; Griffiths, Colin; Johnsen, Geir; Lorentzen, Dag; Brierley, Andrew S

2009-02-23

181

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, Ólafur

182

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

183

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 31, MARCH 2014, 492503 Quantifying the Response Strength of the Southern Stratospheric Polar Vortex to  

E-print Network

of the Southern Stratospheric Polar Vortex to Indian Ocean Warming in Austral Summer LI Shuanglin1,3 and CHEN: southern hemispheric polar vortex, SST, atmospheric general circulation models, ozone depletion Citation polar vortex to Indian Ocean warming in austral summer. Adv. Atmos. Sci., 31(2), 492­503, doi: 10.1007/s

184

Routes of Transport across the Antarctic Polar Vortex in the Southern Spring ALVARO DE LA CA MARA  

E-print Network

Routes of Transport across the Antarctic Polar Vortex in the Southern Spring ALVARO DE LA CA´ MARA the Antarctic polar vortex. 1. Introduction During the last two decades, much attention has been paid to the study of large-scale horizontal transport and stirring in the stratospheric polar night vortex (SPV

Ide, Kayo

185

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 3, 2010, 469482 A Comparison of Polar Vortex Response to  

E-print Network

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 3, 2010, 469­482 A Comparison of Polar Vortex words: tropical Indo-Pacific Ocean warming, northern and southern polar vortex, atmospheric general circulation model, transient eddy, stationary wave Citation: Li, S. L., 2010: A comparison of polar vortex

186

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

E-print Network

the stratospheric polar vortex Naratip Santitissadeekorn,1 Gary Froyland,1 and Adam Monahan2 1 School of Mathematics winter. This chemical isolation of the polar vortex from the middle and low latitudes produces an ozone of research. In this paper, we obtain objective estimates of the structure of the polar vortex by introducing

Froyland, Gary

187

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

188

Lidar measurements of polar stratospheric clouds during the 1989 airborne Arctic stratospheric expedition  

NASA Technical Reports Server (NTRS)

The Airborne Arctic Stratospheric Expedition (AASE) was conducted during January to February 1989 from the Sola Air Station, Norway. As part of this expedition, the NASA Langley Research Center's multiwavelength airborne lidar system was flown on the NASA Ames Research Center's DC-8 aircraft to measure ozone (O3) and aerosol profiles in the region of the polar vortex. The lidar system simultaneously transmitted laser beams at 1064, 603, 311, and 301.5 nm to measure atmospheric scattering, polarization and O3 profiles. Long range flights were made between Stavanger, Norway, and the North Pole, and between 40 deg W and 20 deg E meridians. Eleven flights were made, each flight lasting an average of 10 hours covering about 8000 km. Atmospheric scattering ratios, aerosol polarizations, and aerosol scattering ratio wavelength dependences were derived from the lidar measurements to altitudes above 27 km. The details of the aerosol scattering properties of lidar observations in the IR, VIS, and UV regions are presented along with correlations with the national meteorological Center's temperature profiles.

Ismail, Syed; Browell, Edward V.

1991-01-01

189

Lidar measurements of polar stratospheric clouds during the 1989 airborne Arctic stratospheric expedition  

NASA Astrophysics Data System (ADS)

The Airborne Arctic Stratospheric Expedition (AASE) was conducted during January to February 1989 from the Sola Air Station, Norway. As part of this expedition, the NASA Langley Research Center's multiwavelength airborne lidar system was flown on the NASA Ames Research Center's DC-8 aircraft to measure ozone (O3) and aerosol profiles in the region of the polar vortex. The lidar system simultaneously transmitted laser beams at 1064, 603, 311, and 301.5 nm to measure atmospheric scattering, polarization and O3 profiles. Long range flights were made between Stavanger, Norway, and the North Pole, and between 40 deg W and 20 deg E meridians. Eleven flights were made, each flight lasting an average of 10 hours covering about 8000 km. Atmospheric scattering ratios, aerosol polarizations, and aerosol scattering ratio wavelength dependences were derived from the lidar measurements to altitudes above 27 km. The details of the aerosol scattering properties of lidar observations in the IR, VIS, and UV regions are presented along with correlations with the national meteorological Center's temperature profiles.

Ismail, Syed; Browell, Edward V.

190

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

191

Polarization radiation of vortex electrons with large orbital angular momentum  

E-print Network

Vortex electrons, i.e. freely propagating electrons whose wavefunction has helical wavefronts, could emerge as a novel tool for the physics of electromagnetic (EM) radiation. They carry non-zero intrinsic orbital angular momentum (OAM) $\\ell$ and, for $\\ell \\gg 1$, a large OAM-induced magnetic moment, $\\mu \\approx \\ell \\mu_B$ ($\\mu_B$ is the Bohr magneton), which affects the radiation of EM waves. Here, we consider in detail its influence on two forms of polarization radiation, namely on Cherenkov and transition radiation. Due to large $\\ell$, we can neglect quantum or spin-induced effects, which are of order $\\hbar \\omega/E_e \\ll 1$, but retain the magnetic moment contribution $\\ell \\hbar \\omega/E_e \\lesssim 1$, which makes the quasiclassical approach to polarization radiation applicable. We discuss magnetic moment contribution to polarization radiation, which has never been experimentally observed, and study how its visibility depends on kinematical parameters and permittivity of the medium. In particular, ...

Ivanov, Igor P

2013-01-01

192

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

193

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

194

Three-dimensional Thermal Structure of the South Polar Vortex of Venus  

NASA Astrophysics Data System (ADS)

Our current knowledge of Venus' south polar vortex is based mainly on its cloud morphology and motions. In order to interpret its dynamical nature, it is critical to characterize the thermal structure of the vortex, which remains poorly constrained. We have obtained high resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes for three different dynamical configurations of the polar vortex using VIRTIS-M-IR data. From the temperature maps, we also studied the vertical stability of different atmospheric layers.

Garate-Lopez, I.; Garcia Muñoz, A.; Hueso, R.; Sanchez-Lavega, A.

2014-04-01

195

Determining the topological charge of stochastic electromagnetic vortex beams with the degree of cross-polarization.  

PubMed

By analysis of the degree of cross-polarization of a stochastic electromagnetic vortex beam, we find that the number of bright ring dislocations is equal to the topological charge of the vortex beam. Based on this property, we suggest a method to access the measurement of the orbital angular momentum of vector vortex beams, which holds true for cases of high coherence or low coherence. PMID:25166076

Luo, Meilan; Zhao, Daomu

2014-09-01

196

Angular momentum density of a linearly polarized Lorentz-Gauss vortex beam  

NASA Astrophysics Data System (ADS)

Based on the vectorial Rayleigh-Sommerfeld integral formulae, the analytical propagation equation of a linearly polarized Lorentz-Gauss vortex beam is derived in free space. By taking curl of the electric field, the propagating magnetic field of the linearly polarized Lorentz-Gauss vortex beam is also presented. By using the analytical propagation equation of the Lorentz-Gauss vortex beam beyond the paraxial approximation, the analytical expression of the angular momentum density of a Lorentz-Gauss vortex beam is obtained. The effects of the linearly polarized angle and the beam parameters on the three components of the angular momentum density of a Lorentz-Gauss vortex beam are analyzed in detail. The two transversal components of the angular momentum of a Lorentz-Gauss vortex beam beyond the paraxial approximation must be zero in an arbitrary reference plane. The longitudinal component of the angular momentum is determined by the linearly polarized angle and the beam parameters. The distributions of the angular momentum densities of the Lorentz-Gauss vortex beam are also compared with those of the Gaussian vortex beam. This research is very useful to the optical trapping, the optical guiding, and the optical manipulation of microscopic particles using the single mode diode laser beams.

Zhou, Guoquan; Ru, Guoyun

2014-02-01

197

The Dependence of Rossby Wave Breaking on the Vertical Structure of the Polar Vortex  

Microsoft Academic Search

The three-dimensional structure of wave propagation and breaking on the edge of polar vortices is examined using a multilayer quasigeostrophic model, with piecewise constant potential vorticity (PV) in each layer. The linear propagation of waves up the edge of a vortex is found to be sensitive to vertical variations in the vortex structure, with reduced propagation if the PV or

Darryn W. Waugh; David G. Dritschel

1999-01-01

198

PUBLISHED ONLINE: 31 OCTOBER 2010 | DOI: 10.1038/NPHYS1810 Optimal control of vortex-core polarity by  

E-print Network

. This distortion increases with the linear velocity of the vortex core and opposes the core polarity, until constant) is reached and the vortex-core polarity is reversed9 . In zero magnetic field, dynamical controlLETTERS PUBLISHED ONLINE: 31 OCTOBER 2010 | DOI: 10.1038/NPHYS1810 Optimal control of vortex

Loss, Daniel

199

Optimal control of vortex core polarity by resonant microwave pulses Benjamin Pigeau,1  

E-print Network

polarity8 . Control of polarity switching can also be achieved by precise timing of non resonant magnetic, 2011) Abstract In a vortex-state magnetic nano-disk1­3, the static magnetization is curling possible stable states of opposite core polarity p. Dynamical reversal of p by large amplitude motion

Boyer, Edmond

200

Dielectric Meta-Reflectarray for Broadband Linear Polarization Conversion and Optical Vortex Generation  

E-print Network

: Metamaterial, dielectric antenna, polarization conversion, vortex beam Achieving full control over light and Computer Science, Vanderbilt University, Nashville, Tennessee 37212, United States § Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States Department

Simaan, Nabil

201

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

NASA Technical Reports Server (NTRS)

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

1993-01-01

202

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

203

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

204

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

205

Dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions  

SciTech Connect

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. 5 figs., 43 refs.

Schoeberl, M.R. (Goddard Space Flight Center, Greenbelt, MD (USA)); Hartmann, D.L. (Univ. of Washington, Seattle (USA))

1991-01-01

206

Optical backscatter characteristics of Arctic polar stratospheric clouds  

SciTech Connect

Airborne lidar measurements have been made of polar stratospheric clouds (PSCs) during the Airborne Arctic Stratospheric Expedition in January-February 1989. These show the existence of a systematic relationship between the backscatter depolarization ratio, {delta}, and the (aerosol + molecular)/molecular backscatter ratio, R. The data are consistent with a two population PSC particle model. The first population consists of particles with low values for {delta} ({le} 0.02) and low to intermediate values for R ({le} 6). The second population is characterized by higher values for {delta} (up to 0.60) and R (up to 40 or greater). The relationship between {delta} and R, observed within a limited range of altitudes and latitudes, corresponds to a mixture of the two populations with variable concentrations but constant optical properties.

Kent, G.S.; Schaffner, S.K. (Science and Technology Corporation, Hampton, VA (USA)); Poole, L.R.; McCormick, M.P. (NASA Langley Research Center, Hampton, VA (USA)); Hunt, W.H. (Wyle Laboratories, Hampton, VA (USA)); Osborn, M.T. (ST Systems Corporation, Hampton, VA (USA))

1990-03-01

207

Frequency generation by a magnetic vortex-antivortex dipole in spin-polarized current  

E-print Network

A vortex-antivortex (VA) dipole may be generated due to a spin-polarized current flowing through a nano-aperture in a magnetic element. We study the vortex dipole dynamics using the Landau-Lifshitz equation in the presence of an in-plane applied magnetic field and a Slonczewski spin-torque term with in-plane polarization. We establish that the vortex dipole is set in steady state rotational motion. The frequency of rotation is due to two independent forces: the interaction between the two vortices and the external magnetic field. The nonzero skyrmion number of the dipole is responsible for both forces giving rise to rotational dynamics. The spin-torque acts to stabilize the vortex dipole motion at a definite vortex-antivortex separation distance. We give analytical and numerical results for the angular frequency of rotation and VA dipole features as functions of the parameters.

Komineas, Stavros

2012-01-01

208

Frequency generation by a magnetic vortex-antivortex dipole in spin-polarized current  

E-print Network

A vortex-antivortex (VA) dipole may be generated due to a spin-polarized current flowing through a nano-aperture in a magnetic element. We study the vortex dipole dynamics using the Landau-Lifshitz equation in the presence of an in-plane applied magnetic field and a Slonczewski spin-torque term with in-plane polarization. We establish that the vortex dipole is set in steady state rotational motion. The frequency of rotation is due to two independent forces: the interaction between the two vortices and the external magnetic field. The nonzero skyrmion number of the dipole is responsible for both forces giving rise to rotational dynamics. The spin-torque acts to stabilize the vortex dipole motion at a definite vortex-antivortex separation distance. We give analytical and numerical results for the angular frequency of rotation and VA dipole features as functions of the parameters.

Stavros Komineas

2012-03-05

209

Profile observations of long-lived trace gases in the Arctic vortex  

SciTech Connect

Five sets of vertical profiles of long-lived trace gases were measured in the stratosphere at high northern latitudes (68{degree}N) during three field campaigns of the CHEOPS-Project. Large whole air samples were collected by means of balloon-borne cryogenic samplers analyzed for their content of N{sub 2}O, CH{sub 4}, CFCl{sub 3}, CF{sub 2}Cl{sub 2}, C{sub 2}F{sub 3}Cl{sub 3}, CCl{sub 4}, CH{sub 3}Cl and CH{sub 3}CCl{sub 3}. The measured polar profiles well be compared with mean vertical distributions derived from a series of observations at midlatitudes (44{degree}N). The difference indicates a pronounced effect of subsidence in the Arctic winter stratosphere with a net downward shift of the Arctic vertical profile by about 7 km over the time period from November until February. Owing to this efficient downward transport, the abundance of chlorine in the form of reservoir and reactive species, is increased in the lower Arctic stratosphere to about twice that observed at mid-latitudes.

Schmidt, U.; Bauer, R.; Khedim, A.; Klein, E.; Kulessa, G.; Schiller, C. (Forschungszentrum Juelich (West Germany))

1991-04-01

210

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

211

Infrared Measurements Throughout Polar Night using Two AERIs in the Arctic  

E-print Network

Infrared Measurements Throughout Polar Night using Two AERIs in the Arctic Z. Mariani*1 , K. Strong-range Atmospheric Emitted Radiance Interferometer (E-AERI) is a moderate resolution (1 cm-1 ) Fourier transform of the Arctic. The E-AERI provides information about radiative balance, trace gases, and cloud properties

Strong, Kimberly

212

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

213

The Sensitivity of Arctic Ozone Loss to Polar Stratospheric Cloud Volume and Chlorine and Bromine Loading in a Chemistry and Transport Model  

NASA Technical Reports Server (NTRS)

The sensitivity of Arctic ozone loss to polar stratospheric cloud volume (V(sub PSC)) and chlorine and bromine loading is explored using chemistry and transport models (CTMs). A simulation using multi-decadal output from a general circulation model (GCM) in the Goddard Space Flight Center (GSFC) CTM complements one recycling a single year s GCM output in the Global Modeling Initiative (GMI) CTM. Winter polar ozone loss in the GSFC CTM depends on equivalent effective stratospheric chlorine (EESC) and polar vortex characteristics (temperatures, descent, isolation, polar stratospheric cloud amount). Polar ozone loss in the GMI CTM depends only on changes in EESC as the dynamics repeat annually. The GSFC CTM simulation reproduces a linear relationship between ozone loss and Vpsc derived from observations for 1992 - 2003 which holds for EESC within approx.85% of its maximum (approx.1990 - 2020). The GMI simulation shows that ozone loss varies linearly with EESC for constant, high V(sub PSC).

Douglass, A. R.; Stolarski, R. S.; Strahan, S. E.; Polansky, B. C.

2006-01-01

214

Saturn's south polar vortex compared to other large vortices in the Solar System  

NASA Astrophysics Data System (ADS)

Observations made by the Imaging Science Subsystem (ISS), Visible and Infrared Mapping Spectrometer (VIMS) and the long-wavelength Composite Infrared Spectrometer (CIRS) aboard the Cassini spacecraft reveal that the large, long-lived cyclonic vortex at Saturn's south pole has a 4200-km-diameter cloud-free nearly circular region. This region has a 4 K warm core extending from the troposphere into the stratosphere, concentric cloud walls extending 20-70 km above the internal clouds, and numerous external clouds whose anticyclonic vorticity suggests a convective origin. The rotation speeds of the vortex reach 150±20 ms. The Saturn polar vortex has features in common with terrestrial hurricanes and with the Venus polar vortex. Neptune and other giant planets may also have strong polar vortices.

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

2009-07-01

215

Summertime total ozone variations over middle and polar latitudes  

E-print Network

by this mechanism. [3] Low temperatures and the isolation of stratospheric air in the polar vortex in winter, and in some years in the Arctic. After the breakup of the vortex, ozone-depleted polar air is mixedSummertime total ozone variations over middle and polar latitudes 1234567 89A64BC7DEF72B4 4673

Wirosoetisno, Djoko

216

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

217

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

218

In-situ measurements of changes in stratospheric aerosol and the N[sub 2]O-aerosol relationship inside and outside of the polar vortex  

SciTech Connect

Two optical particle counters on the ER-2, together covering a particle size diameter range from 0.1 [mu]m to 23 [mu]m, 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. 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 II (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 N[sub 2]O 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. 13 refs., 5 figs., 1 tab.

Borrmann, S.; Dye, J.E.; Baumgardner, D.; Barr, K.S. (National Center for Atmospheric Research, Boulder, CO (United States)); Wilson, J.C.; Jonsson, H.H.; Brock, C.A. (Univ. of Denver, CO (United States)); Loewenstein, M.; Podolske, J.R.; Ferry, G.V. (NASA Ames Research Center, Moffett Field, CA (United States))

1993-11-19

219

Optimally coherent sets in geophysical flows: A new approach to delimiting the stratospheric polar vortex  

E-print Network

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 letter, we obtain objective estimates of the structure of the polar vortex by introducing a new technique based on transfer operators that aims to find regions with minimal external transport. Applying this new 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 novel computational approach has wide potential application in detecting and analysing mixing structures in a variety of atmospheric, oceanographic, and general fluid dynamical settings.

Naratip Santitissadeekorn; Gary Froyland; Adam Monahan

2010-04-20

220

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

221

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

222

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

SciTech Connect

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 ({approximately}24 {mu}m diameter); and are shown to contain too large a volume to be primarily NAT. Based on measured vertical temperature profiles, the authors conclude 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. (NCAR, Boulder, CO (USA)); Ferry, G.V.; Loewenstein, M.; Chan, K.R. (NASA Ames, Moffett Field, CA (USA)); Sanford, L. (Univ. of Washington, Seattle, WA (USA)); Gary, B. (Jet Propulsion Laboratory, Pasadena, CA (USA)); Kelly, K. (NOAA Aeronomy Laboratory, Boulder, CO (USA))

1990-03-01

223

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

224

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.

225

The evolution of ozone observed by UARS MLS in the 1992 late winter southern polar vortex  

Microsoft Academic Search

This paper presents initial data analysis of ozone distributions in the southern polar vortex region during the winter of 1992. The data comes from the microwave limb sounder on the upper atmosphere research satellite. The data provides never before available coverage of the polar stratosphere, and reveals the development of an ozone hole from column ozone data, changes in ozone

G. L. Manney; L. Froidevaux; J. W. Waters; L. S. Elson; E. F. Fishbein; R. W. Zurek; R. S. Harwood; W. A. Lahoz

1993-01-01

226

The evolution of ozone observed by UARS MLS in the 1992 late winter southern polar vortex  

SciTech Connect

This paper presents initial data analysis of ozone distributions in the southern polar vortex region during the winter of 1992. The data comes from the microwave limb sounder on the upper atmosphere research satellite. The data provides never before available coverage of the polar stratosphere, and reveals the development of an ozone hole from column ozone data, changes in ozone mixing ratios in the lower stratosphere consistent with ozone destruction processes in the stratosphere, and evidence to support the transport of ozone toward the pole by tidal wave activity in the stratosphere. The ozone measurements are compared with the development of the polar vortex derived from national meteorological center data.

Manney, G.L.; Froidevaux, L.; Waters, J.W.; Elson, L.S.; Fishbein, E.F.; Zurek, R.W. (California Institute of Technology, Pasadena (United States)); Harwood, R.S.; Lahoz, W.A. (Edinburgh Univ. (United Kingdom))

1993-06-18

227

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.

228

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

229

Vortex-antivortex dynamics and field-polarity-dependent flux creep in hybrid superconductor/ferromagnet nanostructures  

E-print Network

Vortex-antivortex dynamics and field-polarity-dependent flux creep in hybrid superconductor Leuven, Belgium Received 15 April 2005; published 22 August 2005 Vortex-antivortex arrays VAA field, and current-voltage characteristics show different regimes of vortex motion even in zero

Moshchalkov, Victor V.

230

Possible Effects of Climate Warming on Selected Populations of Polar Bears (Ursus maritimus) in the Canadian Arctic  

Microsoft Academic Search

Polar bears depend on sea ice for survival. Climate warming in the Arctic has caused significant declines in total cover and thickness of sea ice in the polar basin and progressively earlier breakup in some areas. Inuit hunters in the areas of four polar bear populations in the eastern Canadian Arctic (including Western Hudson Bay) have reported seeing more bears

IAN STIRLING; CLAIRE L. PARKINSON

2006-01-01

231

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

232

Development of a Regional Arctic Climate System model: Performance of Polar WRF for regional pan-Arctic atmospheric simulations  

NASA Astrophysics Data System (ADS)

Efforts are currently underway to develop a regional Arctic climate system model (RACM), which will include atmosphere, ocean, sea ice, and land components. The atmospheric component of RACM is a version of Weather Research and Forecasting (WRF) model optimized for use in polar regions, known as Polar WRF. Extensive work has been completed to evaluate the performance of Polar WRF in the Arctic, with an emphasis on evaluating a variety of WRF's physical parameterizations and representation of ice covered surfaces. Using a pan-Arctic model domain, the sensitivity of atmospheric circulation, temperature, moisture, and precipitation is examined as a response to model physics options in boundary layer schemes, microphysics schemes, and longwave and shortwave radiation schemes. In addition, lower boundary land use properties (albedo, emissivity) for ice covered surfaces and fractional sea ice forcing options are examined. For each experiment, a three-member ensemble of January, April, July, and October one month simulations is used and compared with the NCEP/DOE Reanalysis II, with an emphasis on comparison with the broad features of the Arctic climate. Simulations with and without data assimilation will be presented. Significant biases in the circulation over the North Pacific are found for all model configurations that do not use data assimilation.

Higgins, Matthew; Cassano, John

2010-05-01

233

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

NASA Technical Reports Server (NTRS)

Recent aircraft observations have determined the structure of polar vortices during winter and their relationship to polar ozone depletions, based on high dynamical isolation and the extremely low temperatures required for stratospheric cloud formation. The aircraft data reveal large gradients of potential vorticity and concentrations of conservative trace species at the transition from high-latitude to polar air, implying 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. It is therefore the overall polar vortex which limits the annual polar ozone depletions' maximum area-coverage.

Schoeberl, Mark R.; Hartmann, Dennis L.

1991-01-01

234

Polarization singularities in near-field of Gaussian vortex beam diffracted by a circular aperture  

Microsoft Academic Search

Polarization singularities in the near-field of Gaussian vortex beams diffracted by a circular aperture are studied by a rigorous electromagnetic theory. It is shown that there exist C-points and L-lines, which depend on off-axis displacement parameters along the x and y directions, waist width, wavelength, and topological charge of the diffracted Gaussian vortex beam, as well as on propagation distance.

Jian-Long Li

2010-01-01

235

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

Microsoft Academic Search

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

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

1995-01-01

236

The polar mesospheric cloud mass in the Arctic summer  

NASA Astrophysics Data System (ADS)

We infer the polar mesospheric cloud (PMC) mass throughout the Arctic summer using results from two sets of satellite observations and a microphysical model. Solar backscatter ultraviolet (SBUV) PMC observations in July 1999 indicate a burst of activity persisting for ˜8 days after a space shuttle launch and averaging 262 ± 52 t near 4.7 local time. This mass is consistent with the propellant mass available from the shuttle's main engines and accounts for 22% of the total SBUV PMC mass over the season between 65° and 75°N. This is the first evidence that PMCs formed by space shuttle water exhaust can contribute significantly to both the number of observed PMCs and the total PMC mass in a season. In another approach, 11 years of observations by the Halogen Occultation Experiment (HALOE) indicate that on average 90 ± 12 t of water ice is present near local midnight between 65° and 75°N. Using simultaneous HALOE water vapor observations, we find that a one-dimensional microphysical model reproduces the start and end of the PMC season but overpredicts the ice mass by about a factor of 1.8 when compared with the observations. This overprediction is within the time-dependent variability of ice formation and the uncertainties of temperature, water vapor, and vertical winds used to initialize the model.

Stevens, Michael H.; Englert, Christoph R.; Deland, Matthew T.; Hervig, Mark

2005-02-01

237

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

238

Polar stratospheric clouds over Finland in the 2012/2013 Arctic winter measured by two Raman lidars  

NASA Astrophysics Data System (ADS)

Already in December 2012, the Arctic stratospheric vortex reached temperatures sufficiently low for polar stratospheric cloud (PSC) formation over wide areas of Northern Europe and whole Finland. Within Finland, stratospheric aerosol lidar measurements have been and are performed with two Raman lidar systems, the PollyXT, owned by the Finnish Meteorological Institute (FMI) and situated well below the Arctic circle close to Kuopio (63 N, 27 E) and the MARL lidar owned by the Alfred-Wegener-Institute for Polar and Marine Research (AWI), and situated at the FMI Arctic Research Centre in Sodankylä (67 N, 26 E). The PollyXT has been designed as an autonomous tropospheric lidar system, but it has proven to be able to detect aerosol backscatter and depolarization at least as high up as 25 km. Measurements are ongoing as far as low clouds allow for stratospheric analysis with both lidars until the end of PSC season in February. For the winter 2012/2013, PSC occurrence frequency, types and characteristics will be determined. Comparative analysis with Calipso lidar profiles covering Finland will be performed. Preliminary results from December 17-24 show PSCs detected in Kuopio during seven days with the PollyXT lidar. The altitude of the clouds varied in the range of 17-25 km. In Sodankylä the measurements were running on one day during the period and PSCs were observed between altitudes 17-25 km. For the same time period (December 17-24, 2012) CALIPSO has observed stratospheric layers at all overpasses over Finland (9 tracks on five days). The clouds were observed between 18.5 and 26 km, with varying geometric and optical thickness.

Hoffmann, Anne; Giannakaki, Eleni; Kivi, Rigel; Schrems, Otto; Immler, Franz; Komppula, Mika

2013-04-01

239

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

240

Spatial, temporal, and vertical variability of polar stratospheric ozone loss in the Arctic winters 2004/05-2009/10  

NASA Astrophysics Data System (ADS)

The stratospheric ozone loss during the Arctic winters 2004/05-2009/10 is investigated by using high resolution simulations from the chemical transport model Mimosa-Chim and observations from Microwave Limb Sounder (MLS) on Aura by the passive tracer technique. The winter 2004/05 was the coldest of the series with strongest chlorine activation. The ozone loss diagnosed from both model and measurements inside the polar vortex at 475 K ranges from ~1-0.7 ppmv in the warm winter 2005/06 to 1.7 ppmv in the cold winter 2004/05. Halogenated (chlorine and bromine) catalytic cycles contribute to 75-90% of the accumulated ozone loss at this level. At 675 K the lowest loss of ~0.4 ppmv is computed in 2008/09 from both simulations and observations and, the highest loss is estimated in 2006/07 by the model (1.3 ppmv) and in 2004/05 by MLS (1.5 ppmv). Most of the ozone loss (60-75%) at this level results from cycles catalysed by nitrogen oxides (NO and NO2) rather than halogens. At both 475 and 675 K levels the simulated ozone evolution inside the polar vortex is in reasonably good agreement with the observations. The ozone total column loss deduced from the model calculations at the MLS sampling locations inside the vortex ranges between 40 DU in 2005/06 and 94 DU in 2004/05, while that derived from observations ranges between 37 DU and 111 DU in the same winters. These estimates from both Mimosa-Chim and MLS are in general good agreement with those from the ground-based UV-VIS (ultra violet-visible) ozone loss analyses for the respective winters.

Kuttippurath, J.; Godin-Beekmann, S.; Lefèvre, F.; Goutail, F.

2010-06-01

241

Interhemispheric comparison of the development of the stratospheric polar vortex during fall: A 3-dimensional perspective for 1991-1992  

Microsoft Academic Search

The authors present the results of detailed studies of the northern and southern polar vortex development during 1991\\/1992, recreated from National Meteorological Center data. In general the data shows that in the southern hemisphere, the polar vortex developed with less short term variations, deepened very rapidly, and continued to grow well into the winter. Temperatures in the southern hemisphere would

Gloria L. Manney; Richard W. Zurek

1993-01-01

242

CRISTA2 observations of the south polar vortex in winter 1997: A new dataset for polar process studies  

Microsoft Academic Search

During the second mission of the Cryogenic Spectrometers and Telescopes for the Atmosphere (CRISTA) in August 1997 considerable and highly variable cloud cover in the stratosphere was seen over Antarctica. Two large areas of polar stratospheric clouds (PSC) could be observed. One region of PSCs near the vortex edge was caused by a meteorological situation as it is typical for

Reinhold Spang; Martin Riese; Dirk Offermann

2001-01-01

243

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

244

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

245

Computations of diabatic descent in the stratospheric polar vortex  

Microsoft Academic Search

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

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

1994-01-01

246

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

247

Sustained Arctic Observations: A Legacy of the Polar Year  

NASA Astrophysics Data System (ADS)

Is the Arctic a vast, beautiful, wild, and unsullied natural refuge, or is it small, fragile, and vulnerable, suffering the brunt of global warming? In the late nineteenth century, as U.S. admiral Robert E. Peary and his competitors engaged in their mad scramble to be the first humans to set foot on the North Pole, ``fragile'' was unlikely to be an adjective that sprang to mind when they described their surroundings. Quite the opposite, exploring the Arctic exposed the fragility of man. But the Arctic Ocean and mankind's relationships to it are changing fast.

Alverson, Keith

2008-09-01

248

Polar bear and walrus response to the rapid decline in Arctic sea ice  

USGS Publications Warehouse

The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus rosmarus divergens) are dependent on sea ice over the continental shelves of the Arctic Ocean's marginal seas. The continental shelves are shallow regions with high biological productivity, supporting abundant marine life within the water column and on the sea floor. Polar bears use sea ice as a platform for hunting ice seals; walruses use sea ice as a resting platform between dives to forage for clams and other bottom-dwelling invertebrates. How have sea ice changes affected polar bears and walruses? How will anticipated changes affect them in the future?

Oakley, K.; Whalen, M.; Douglas, D.; Udevitz, M.; Atwood, T.; Jay, C.

2012-01-01

249

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

E-print Network

, Arctic, belowground, climate change, polar regions, precipitation, soil fauna, warming. Ecology Letters 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

Wall, Diana

250

Observations of backscatter, particle concentration and frost point in north polar vortex stratospheric clouds  

SciTech Connect

Near-simultaneous soundings of backscatter, particle size distribution and frost point were obtained in north polar stratospheric clouds (PSCs) near the center of the vortex. The measured particle sizes and concentration in type I PSCs tend to confirm earlier predictions based on remotely sensed properties.

Rosen, J.M.; Kjome, N.T. (Univ. of Wyoming, Laramie (USA)); Oltmans, S.J. (NOAA CMDL, Boulder, CO (USA))

1990-08-01

251

Potential Vorticity and Mixing in the South Polar Vortex During Spring  

Microsoft Academic Search

A central part of the explanation of the Antarctic ozone hole is the dynamical isolation provided by the intense vortex present over the south polar region until late in the spring. In this paper some fluid dynamical aspects of the Antarctic ozone hole phenomena are investigated, using data collected by the ER-2 aircraft during the Airborne Antarctic Ozone Experiment (AAOE).

D. L. Hartmann; K. R. Chan; B. L. Gary; M. R. Schoeberl; P. A. Newman; R. L. Martin; M. Loewenstein; J. R. Podolske; S. E. Strahan

1989-01-01

252

Occurrence of ozone laminae near the boundary of the stratospheric polar vortex  

Microsoft Academic Search

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

S. J. Reid; G. Vaughan; E. Kyro

1993-01-01

253

Observations of backscatter, particle concentration and frost point in north polar vortex stratospheric clouds  

Microsoft Academic Search

Near-simultaneous soundings of backscatter, particle size distribution and frost point were obtained in north polar stratospheric clouds (PSCs) near the center of the vortex. The measured particle sizes and concentration in type I PSCs tend to confirm earlier predictions based on remotely sensed properties.

James M. Rosen; Norman T. Kjome; Samuel J. Oltmans

1990-01-01

254

Relation between Kinematic Boundaries, Stirring, and Barriers for the Antarctic Polar Vortex  

Microsoft Academic Search

Maximum stretching lines in the lower stratosphere around the Antarctic polar vortex are diagnosed using a method based on finite-size Lyapunov exponents. By analogy with the mathematical results known for simple dynamical systems, these curves are identified as stable and unstable manifolds of the underlying hyperbolic structure of the flow. For the first time, the exchange mechanism associated with lobe

Binson Joseph; Bernard Legras

2002-01-01

255

Large-Scale Isentropic Mixing Properties of the Antarctic Polar Vortex From Analyzed Winds  

Microsoft Academic Search

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

Kenneth P. Bowman

1993-01-01

256

Instantaneous three-dimensional thermal structure of the South Polar Vortex of Venus  

NASA Astrophysics Data System (ADS)

The Venus thermal radiation spectrum exhibits the signature of CO2 absorption bands. By means of inversion techniques, those bands enable the retrieval of atmospheric temperature profiles. We have analyzed VIRTIS-M-IR night-side data obtaining high-resolution thermal maps of the Venus south polar region between 55 and 85 km altitudes. This analysis is specific to three Venus Express orbits where the vortex presents different dynamical configurations. The cold collar is clearly distinguishable centered at ?62 km (?100 mbar) altitude level. On average, the cold collar is more than 15 K colder than the pole, but its specific temperature varies with time. In the three orbits under investigation the South Polar Vortex appears as a vertically extended hot region close to the pole and squeezed by the cold collar between altitudes 55 and 67 km but spreading equatorwards at about 74 km. Both the instantaneous temperature maps and their zonal averages show that the top altitude limit of the thermal signature from the vortex is at ?80 km altitude, at least on the night-side of the planet. The upper part of the atmosphere (67-85 km) is more homogeneous and has long-scale horizontal temperature differences of about 25 K over horizontal distances of ?2000 km. The lower part (55-67 km) shows more fine-scale structure, creating the vortex morphology, with thermal differences of up to about 50 K over the same altitude range and ?500 km horizontal distances. This lower part of the atmosphere is highly affected by the upper cloud deck, leading to stronger local temperature variations and larger uncertainties in the retrieval. From the temperature maps, we also study the vertical stability of different atmospheric layers for the three vortex configurations. The static stability is always positive (ST > 0) in the considered altitude range (55-85 km) and in the whole polar vortex. The cold collar is the most vertically stable structure at polar latitudes, while the vortex and sub-polar latitudes show lower stability values. Furthermore, the hot filaments present within the vortex exhibit lower stability values than their surroundings. The layer between 62 and 67 km resulted to be the most stable. These results are in good agreement with conclusions from previous radio occultation analyses.

Garate-Lopez, I.; García Muñoz, A.; Hueso, R.; Sánchez-Lavega, A.

2015-01-01

257

Spatial, temporal, and vertical variability of polar stratospheric ozone loss in the Arctic winters 2004/2005-2009/2010  

NASA Astrophysics Data System (ADS)

The polar stratospheric ozone loss during the Arctic winters 2004/2005-2009/2010 is investigated by using high resolution simulations from the chemical transport model Mimosa-Chim and observations from Aura Microwave Limb Sounder (MLS), by applying the passive tracer technique. The winter 2004/2005 shows the coldest temperatures, highest area of polar stratospheric clouds and strongest chlorine activation in 2004/2005-2009/2010. The ozone loss diagnosed from both simulations and measurements inside the polar vortex at 475 K ranges from 0.7 ppmv in the warm winter 2005/2006 to 1.5-1.7 ppmv in the cold winter 2004/2005. Halogenated (chlorine and bromine) catalytic cycles contribute to 75-90% of the ozone loss at this level. At 675 K the lowest loss of 0.3-0.5 ppmv is computed in 2008/2009, and the highest loss of 1.3 ppmv is estimated in 2006/2007 by the model and in 2004/2005 by MLS. Most of the ozone loss (60-75%) at this level results from nitrogen catalytic cycles rather than halogen cycles. At both 475 and 675 K levels the simulated ozone and ozone loss evolution inside the vortex is in reasonably good agreement with the MLS observations. The ozone partial column loss in 350-850 K deduced from the model calculations at the MLS sampling locations inside the polar vortex ranges between 43 DU in 2005/2006 and 109 DU in 2004/2005, while those derived from the MLS observations range between 26 DU and 115 DU for the same winters. The partial column ozone depletion derived in that vertical range is larger than that estimated in 350-550 K by 19±7 DU on average, mainly due to NOx chemistry. The column ozone loss estimates from both Mimosa-Chim and MLS in 350-850 K are generally in good agreement with those derived from ground-based ultraviolet-visible spectrometer total ozone observations for the respective winters, except in 2010.

Kuttippurath, J.; Godin-Beekmann, S.; Lefèvre, F.; Goutail, F.

2010-10-01

258

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, Steven C.; Ambrosius, K.J.

2006-01-01

259

Stereographical Tomography of Polarization State using Weak Measurement with Optical Vortex Beam  

E-print Network

We propose a state-tomographic 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 Poincare sphere. We experimentally perform single-setup weak measurement to validate the stereographical relationship between the polarization state on the Poincare sphere and the location of the zero-intensity point.

Kobayashi, Hirokazu; Shikano, Yutaka

2013-01-01

260

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

E-print Network

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 Poincar\\'{e} sphere. We experimentally perform single-setup weak measurement to validate the stereographical relationship between the polarization state on the Poincar\\'{e} sphere and the location of the zero-intensity point.

Hirokazu Kobayashi; Koji Nonaka; Yutaka Shikano

2014-05-13

261

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

SciTech Connect

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.

Manney, G.L.; Froidevaux, L.; Waters, J.W.; Zurek, R.W. [Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA (United States)] [Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA (United States)

1995-02-01

262

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

PubMed

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. PMID:25147490

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

2014-01-01

263

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

PubMed Central

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. PMID:25147490

2014-01-01

264

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.

David Tenenbaum

265

Observations of polar stratospheric clouds in the Arctic winter 1989 at 79 N  

SciTech Connect

Throughout January 1989 polar stratospheric clouds were frequently observed over Ny-Alesund/Svalbard by means of a lidar instrument. The aerosol layer was located between 17 and 24 km altitude and showed signs of a downward movement. The presence of PSC's suggests that the same chemical processes, that lead to the springtime ozone depletion in the southern hemisphere may go on during the Arctic polar night.

Krueger, B.C. (Universitaet Bremen (West Germany))

1990-03-01

266

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

267

The final warming and polar vortex disappearance during the Southern Hemisphere spring  

NASA Technical Reports Server (NTRS)

Seven years (1979-1985) of NMC data are used to analyze Southern Hemisphere middle stratosphere winter-to-summer circulation transitions. These transitions are classified into two extreme categories: (1) a mid-October final warming accompanied by a major mid-October wave event (1979 and 1982), and (2) a mid-November final warming with no strong October wave event (1980 and 1981). After the final warming a wave event in late November-early December results in the disappearance of the polar vortex. All of these wave events in conjunction with zonal mean mass motions act to reduce zonal mean gradients of potential vorticity and ozone through horizontal mixing, and hence they act to destroy the vortex and fill the ozone hole. Additionally, it is noted that the final warming and the vortex breakdown are two distinct events separated by 15-40 days. Finally, past studies show that the time of these events has not radically changed.

Newman, Paul A.

1986-01-01

268

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

SciTech Connect

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.; Rache Salles, B.; Jenkins, A. S.; Bortolotti, P.; Grollier, J.; Cros, V.; Fert, A. [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); Grimaldi, E., E-mail: eva.grimaldi@thalesgroup.com [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); CNES, 1 Avenue Edouard Belin, 31400 Toulouse (France); Khvalkovskiy, A. V. [Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); A.M. Prokhorov General Physics Institute of RAS, Vavilova Str. 38, 119991 Moscow (Russian Federation); Kubota, H.; Fukushima, A.; Yakushiji, K.; Yuasa, S. [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba (Japan)

2014-07-14

269

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

NASA Technical Reports Server (NTRS)

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. 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 O3 loss rates could be larger than deduced here because of underestimates of total O3 by TOMS near the terminator.

Yung, Yuk L.; Allen, Mark; Crisp, David; Zurek, Richard W.; Sander, Stanley P.

1990-01-01

270

CO as a marker and probe of polar vortex structure in the upper stratosphere and mesosphere  

Microsoft Academic Search

We present new ground-based measurements of polar stratospheric and mesospheric CO showing that it serves as an excellent tracer of vortex position, size, and descent at an altitude range where other information may be sparse or unreliable. Observations were made with a mm-wave spectrometer at Thule, Greenland (76.5o N, 68.7o W), and involved almost-daily measurements between January 17 and March

R. L. de Zafra; G. Muscari

2003-01-01

271

Mixing of polar vortex air into middle latitudes as revealed by tracer-tracer scatterplots  

Microsoft Academic Search

The occurrence of mixing of polar vortex air with midlatitude air is investigated by examining the scatterplots of insitu measurements of long-lived tracers from the NASA ER-2 aircraft during the Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE, April, May 1993; northern hemisphere) and the Airborne Southern Hemisphere Ozone Experiment\\/Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE\\/MAESA, March-October 1994; southern

D. W. Waugh; R. A. Plumb; J. W. Elkins; D. W. Fahey; K. A. Boering; G. S. Dutton; C. M. Volk; E. Keim; R.-S. Gao; B. C. Daube; S. C. Wofsy; M. Loewenstein; J. R. Podolske; K. R. Chan; M. H. Proffitt; K. K. Kelly; P. A. Newman; L. R. Lait

1997-01-01

272

Lidar measurements of ozone and aerosol distributions during the 1992 airborne Arctic stratospheric expedition  

NASA Technical Reports Server (NTRS)

The NASA Langley airborne differential absorption lidar system was operated from the NASA Ames DC-8 aircraft during the 1992 Airborne Arctic Stratospheric Expedition to investigate the distribution of stratospheric aerosols and ozone (O3) across the Arctic vortex from January to March 1992. Aerosols from the Mt. Pinatubo eruption were found outside and inside the Arctic vortex with distinctly different scattering characteristics and spatial distributions in the two regions. The aerosol and O3 distributions clearly identified the edge of the vortex and provided additional information on vortex dynamics and transport processes. Few polar stratospheric clouds were observed during the AASE-2; however, those that were found had enhanced scattering and depolarization over the background Pinatubo aerosols. The distribution of aerosols inside the vortex exhibited relatively minor changes during the AASE-2. Ozone depletion inside the vortex as limited to less than or equal to 20 percent in the altitude region from 15-20 km.

Browell, Edward V.; Butler, Carolyn F.; Fenn, Marta A.; Grant, William B.; Ismail, Syed; Carter, Arlen F.

1994-01-01

273

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

274

Observations of deformation and mixing of the total ozone field in the Antarctic polar vortex  

NASA Technical Reports Server (NTRS)

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. Occaisional 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 occurs in midlatitiudes even when wave amplitudes are not exceptionally large. 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 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 or false-color images.

Bowman, Kenneth P.; Mangus, Nicholas J.

1993-01-01

275

Using FTIR measurements of stratospheric composition to identify midlatitude polar vortex intrusions over Toronto  

NASA Astrophysics Data System (ADS)

Using 11 years of trace gas measurements made at the University of Toronto Atmospheric Observatory (43.66°N, 79.40°W) and Environment Canada's Centre for Atmospheric Research Experiments (44.23°N, 79.78°W), along with derived meteorological products, we identify a number of polar intrusion events, which are excursions of the polar vortex or filaments from the polar vortex extending down to midlatitudes. These events are characterized by enhanced stratospheric columns (12-50 km) of hydrogen fluoride (HF), by diminished stratospheric columns of nitrous oxide (N2O), and by a scaled potential vorticity above 1.2 × 10-4s-1. The events comprise 16%of winter/spring (November to April inclusive) Fourier transform infrared (FTIR) spectroscopic measurements from January 2002 to March 2013, and we find at least two events per year. The events are corroborated by Modèle Isentrope du transport Méso-échelle de l'Ozone Stratosphérique par Advection, Modern-Era Retrospective Analysis for Research and Applications potential vorticity maps, and Global Modeling Initiative N2O maps. During polar intrusion events, the stratospheric ozone (O3) columns over Toronto are usually greater than when there is no event. Our O3 measurements agree with the Optical Spectrograph and Infrared Imaging System satellite instrument and are further verified with the Earth Probe Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument satellite observations. We find six cases out of 53 for which chemical O3depletion within the polar vortex led to a reduction in stratospheric O3 columns over Toronto. We have thus identified a dynamical cause for most of the winter/spring variability of stratospheric trace gas columns observed at our midlatitude site. While there have been a number of prior polar intrusion studies, this is the first study to report in the context of 11 years of ground-based FTIR column measurements, providing insight into the frequency of midlatitude polar vortex intrusions and observations of upper stratospheric (25-50 km) intrusions. It is also the first to present HF measurements during multiple polar intrusions, which provided an excellent tracer for their identification.

Whaley, C.; Strong, K.; Adams, C.; Bourassa, A. E.; Daffer, W. H.; Degenstein, D. A.; Fast, H.; Fogal, P. F.; Manney, G. L.; Mittermeier, R. L.; Pavlovic, B.; Wiacek, A.

2013-11-01

276

Full vector measurements of converging terahertz beams with linear, circular, and cylindrical vortex polarization.  

PubMed

The complete vector information of converging terahertz (THz) beams with linear, circular, and cylindrical vortex polarization are precisely measured by using a THz digital holographic imaging system. The transverse (Ex, Ey) and longitudinal (Ez) polarization components of the THz fields around the focal point are separately obtained utilizing the detection crystals with different crystalline orientations. The measured results are in good agreement with the theoretical expectations. This imaging technique provides an effective way for revealing the vector diffraction properties of the THz electro-magnetic waves. PMID:25322037

Wang, Xinke; Wang, Sen; Xie, Zhenwei; Sun, Wenfeng; Feng, Shengfei; Cui, Ye; Ye, Jiasheng; Zhang, Yan

2014-10-01

277

Gouy phase and phase singularities of tightly focused, circularly polarized vortex beams  

NASA Astrophysics Data System (ADS)

An investigation is made of the phase properties, especially the Gouy phase of the tightly focused, circularly polarized vortex beams. First two groups of symmetry relations of the focused field are derived, from which the effect of the topological charge on the field can be found easily. By decomposing the electric field into three specific components, the corresponding Gouy phases are defined and their properties are examined in detail. Our result shows that not only the polarization of the incident field or the numerical aperture influence the phase behavior, but also the topological charge gives much contribution to the phase structure near the focus.

Pang, Xiaoyan

2015-03-01

278

The evolution of ozone observed by UARS MLS in the 1992 late winter southern polar vortex  

NASA Technical Reports Server (NTRS)

The evolution of ozone (O3) observed by the Microwave Limb Sounder on board the Upper Atmosphere Research Satellite is described for 14 Aug through 20 Sep 1992, in relation to the polar vortex. The development of an ozone hole is observed in column O3, and a corresponding decrease is seen in O3 mixing ratio in the polar lower stratosphere, consistent with chemical destruction. The observations also suggest that poleward transport associated with episodes of strong planetary wave activity is important in increasing O3 in the mid-stratosphere.

Manney, G. L.; Froidevaux, L.; Waters, J. W.; Elson, L. S.; Fishbein, E. F.; Zurek, R. W.; Harwood, R. S.; Lahoz, W. A.

1993-01-01

279

Stratospheric sulfate aerosol in and near the Northern Hemisphere polar vortex - The morphology of the sulfate layer, multimodal size distributions, and the effect of denitrification  

NASA Technical Reports Server (NTRS)

Measurements were made of stratospheric sulfate aerosols using a passive cavity aerosol spectrometer and a condensation nucleus counter on a NASA ER-2 aircraft in the Airborne Arctic Stratospheric Experiment of 1989. The problems of representative and accurate sampling and particle evaporation were explicitly addressed in the design of the inlets and reduction of the data. The measurements suggest that the sulfate aerosol is bimodal in the polar vortex above the mass mixing ratio maximum in the sulfate layer. It appears that a nuclei mode of small, newly formed particles exists in this region. A stronger case is made for a nuclei mode in the upper few kilometers of the troposphere and in the lower few kilometers of the stratosphere. This mode is probably a global phenomenon occurring in all seasons. Comparison of denitrified and nondenitrified air suggests that denitrification removes some of the larger sulfate particles.

Wilson, J. G.; Stolzenburg, M. R.; Clark, W. E.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Kelly, K. K.

1992-01-01

280

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

281

Projected Polar Bear Sea Ice Habitat in the Canadian Arctic Archipelago  

PubMed Central

Background Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 – 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. Principal Findings Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2–5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands. Conclusions/Significance Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100. PMID:25426720

Hamilton, Stephen G.; Castro de la Guardia, Laura; Derocher, Andrew E.; Sahanatien, Vicki; Tremblay, Bruno; Huard, David

2014-01-01

282

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

283

Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow, Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in The Solar System  

Microsoft Academic Search

Polar, heliophysical, and planetary science topics related to the International Heliophysical and Polar Years 2007-2009 were addressed during this circumpolar video conference hosted January 23-29, 2008 at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium in Barrow, Alaska. This conference was planned as an IHY-IPY event science outreach event bringing together scientists and educational specialists for

John F. Cooper; K. Kauristie; A. T. Weatherwax; G. W. Sheehan; R. W. Smith; I. Sandahl; N. Østgaard; S. Chernouss; M. H. Moore; L. M. Peticolas; D. A. Senske; B. J. Thompson; L. K. Tamppari; E. M. Lewis

2008-01-01

284

Vortex  

NSDL National Science Digital Library

In this activity, learners create a tornado in a bottle to observe a spiraling, funnel-shaped vortex. A simple connector device allows water to drain from a 2-liter bottle into a second bottle. Learners can observe the whirling water and then repeat the process by inverting the bottle. Use this activity to talk about surface tension, pressure, gravity, friction, angular momentum, and centripetal force.

2012-06-26

285

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

286

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

287

Interhemispheric Differences in Dentifrication and Related Processes Affecting Polar Ozone  

NASA Technical Reports Server (NTRS)

The severe depletion of stratospheric ozone over Antarctica in late winter and early spring is caused by enhanced CLO abundances arising from heterogeneous reactions on polar stratospheric clouds (PSCs). CLO abundances comparable to those over Antarctica have also been observed throughout the Arctic Vortex, but the accompanying loss of Arctic ozone has been much less severe.

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.

1994-01-01

288

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

289

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

290

Atmospheric aspects of Arctic change  

NASA Astrophysics Data System (ADS)

Three important features of recent Arctic change are the rather uniform pattern of Arctic temperature amplification in response to greenhouse gas forcing, the modification of atmospheric temperature and wind patterns over newly sea-ice-free regions, and the possible increased linkage between Arctic climate and sub-arctic weather. An important argument for anthropogenic forcing of recent Arctic change is the model predicted rather uniform increases in Arctic temperatures, in contrast to more regional temperature maximums associated with intrinsic climate variability patterns such as those which occurred during the 1930s Arctic warming. Sea-ice-free areas at the end of summer are allowing: added heat and moisture transport into the troposphere as documented during the recent Japanese vessel Mirai cruises, decreased boundary layer stratification, and modification of wind flow through thermal wind processes. Winter 2009-2010 and December 2010 showed a unique connectivity between the Arctic and more southern weather when the typical polar vortex was replaced by high geopotential heights over the central Arctic and low heights over mid-latitudes that resulted in record snow and low temperatures, a Warm Arctic-Cold Continents pattern. A major challenge of Arctic meteorology is to understand the interaction of forced changes such as loss of sea ice and land impacts with intrinsic climate patterns such as the North Atlantic Oscillation and Pacific North American climate patterns. Could persistent shifts in Arctic climate be triggered by a combination of a gradual upward trend in temperature, an extreme event e.g. fortuitous timing in the natural variability of the atmospheric or ocean general circulation, and Arctic specific feedbacks? Scientific progress on both issues requires sustained decadal observations.

Overland, J. E.

2011-12-01

291

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

292

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

293

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

NASA Technical Reports Server (NTRS)

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.

Browell, Edward V.; Buller, Carolyn F.; Fenn, Marta A.; Grant, William B.; Ismail, Syed; Schoeberl, Mark R.; Toon, Owen B.; Loewenstein, Max; Podolske, James R.

1993-01-01

294

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

295

Ozone and aerosol changes during the 1991-1992 Airborne Arctic Stratospheric Expedition  

SciTech Connect

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.

Browell, E.V.; Grant, W.B.; Ismail, S. (NASA Langley Research Center, Hampton, VA (United States)); Butler, C.F.; Fenn, M.A. (Science Applications International Corp., Hampton, VA (United States)); Schoeberl, M.R. (NASA Goddard Space Flight Center, Greenbelt, MD (United States)); Toon, O.B.; Loewenstein, M.; Podolske, J.R. (NASA Ames Research Center, Moffett Field, CA (United States))

1993-08-27

296

United States Naval Academy Polar Science Program's Visual Arctic Observing Buoys; The IceGoat  

NASA Astrophysics Data System (ADS)

The U.S. Naval Academy Oceanography Department currently has a curriculum based Polar Science Program (USNA PSP). Within the PSP there is an Arctic Buoy Program (ABP) student research component that will include the design, build, testing and deployment of Arctic Buoys. Establishing an active, field-research program in Polar Science will greatly enhance Midshipman education and research, as well as introduce future Naval Officers to the Arctic environment. The Oceanography Department has engaged the USNA Ocean Engineering, Systems Engineering, Aerospace Engineering, and Computer Science Departments and developed a USNA Visual Arctic Observing Buoy, IceGoat1, which was designed, built, and deployed by midshipmen. The experience gained through Polar field studies and data derived from these buoys will be used to enhance course materials and laboratories and will also be used directly in Midshipman independent research projects. The USNA PSP successfully deployed IceGoat1 during the BROMEX 2012 field campaign out of Barrow, AK in March 2012. This buoy reports near real-time observation of Air Temperature, Sea Temperature, Atmospheric Pressure, Position and Images from 2 mounted webcams. The importance of this unique type of buoy being inserted into the U.S. Interagency Arctic Buoy Program and the International Arctic Buoy Programme (USIABP/IABP) array is cross validating satellite observations of sea ice cover in the Arctic with the buoys webcams. We also propose to develop multiple sensor packages for the IceGoat to include a more robust weather suite, and a passive acoustic hydrophone. Remote cameras on buoys have provided crucial qualitative information that complements the quantitative measurements of geophysical parameters. For example, the mechanical anemometers on the IABP Polar Arctic Weather Station at the North Pole Environmental Observatory (NPEO) have at times reported zero winds speeds, and inspection of the images from the NPEO cameras have showed frosting on the camera during these same periods indicating that the anemometer has temporarily frozen up. Later when the camera lens clears, the anemometers resume providing reasonable wind speeds. The cameras have also provided confirmation of the onset of melt and freeze, and indications of cloudy and clear skies. USNA PSP will monitor meteorological and oceanographic parameters of the Arctic environment remotely via its own buoys. Web cameras will provide near real time visual observations of the buoys current positions, allowing for instant validation of other remotes sensors and modeled data. Each buoy will be developed with at a minimum a meteorological sensor package in accordance with IABP protocol (2m Air Temp, SLP). Platforms will also be developed with new sensor packages to possibly include, wind speed, ice temperature, sea ice thickness, underwater acoustics, and new communications suites (Iridium, Radio). The uniqueness of the IceGoat is that it is based on the new AXIB buoy designed by LBI, Inc. that has a proven record of being able to survive in the harsh marginal ice zone environment. IceGoat1 will be deployed in the High Arctic during the USCGC HEALY cruise in late August 2012.

Woods, J. E.; Clemente-Colon, P.; Nghiem, S. V.; Rigor, I.; Valentic, T. A.

2012-12-01

297

Arctic Ozone Depletion from UARS MLS Measurements  

NASA Technical Reports Server (NTRS)

Microwave Limb Sounder (MLS) measurements of ozone during four Arctic winters are compared. The evolution of ozone in the lower stratosphere is related to temperature, chlorine monoxide (also measured by MLS), and the evolution of the polar vortex. Lagrangian transport calculations using winds from the United Kingdom Meteorological Office's Stratosphere-Troposphere Data Assimilation system are used to estimate to what extent the evolution of lower stratospheric ozone is controlled by dynamics. Observations, along with calculations of the expected dynamical behavior, show evidence for chemical ozone depletion throughout most of the Arctic lower stratospheric vortex during the 1992-93 middle and late winter, and during all of the 1994-95 winter that was observed by MLS. Both of these winters were unusually cold and had unusually cold and had unusually strong Arctic polar vortices compared to meteorological data over the past 17 years.

Manney, G. L.

1995-01-01

298

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

299

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

300

Quantification of the transport of chemical constituents from the polar vortex to midlatitudes in the lower stratosphere using the high-resolution advection model MIMOSA and effective diffusivity  

NASA Astrophysics Data System (ADS)

The observed decrease of ozone in the northern midlatitude lower stratosphere is only partially reproduced by chemical models. The transport of ozone-depleted air from the polar vortex is one of the proposed mechanisms to explain the discrepancy. Here we present a study on the quantification of the air mass transported from the polar vortex to midlatitude during the four winters 1996-1997 to 1999-2000, in relation with vortex filamentation and break up, using the high-resolution advection model MIMOSA on isentropic surfaces. Sensitivity tests show that the advection model is able to predict the location of polar filaments with accuracy better than 100 km, limited by uncertainties in meteorological advecting wind fields. The effective diffusivity diagnostic is used to evaluate the intensity of the vortex edge barrier and to quantify the transport of air from the polar vortex to midlatitude. The intensity of the polar barrier is increasing with height from 400 to 550 K and is nearly constant above. During periods with a cold and undisturbed vortex, favorable to chlorine activation, the transport is very weak. This suggests that the midwinter vortex filamentation plays a minor role in the midlatitude ozone decline. In the opposite limit, during a stratospheric warming up to 30% of the polar vortex air is transported to midlatitudes. The cumulative transport from early January to end of April across the polar edge varies from almost 5% of the polar vortex air at 675 K in 1997 to 50% at 435 K in 1999.

Hauchecorne, Alain; Godin, Sophie; Marchand, Marion; Heese, Birgit; Souprayen, Claude

2002-10-01

301

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

302

Ozone profile measurements within, at the edge of, and outside the Antarctic polar vortex in the spring of 1988  

SciTech Connect

Ozone and temperature were measured during 38 balloon soundings at McMurdo Station, Antarctica (78{degree}S), in the spring of 1988. Because of the motion of the Antarctic polar vortex, measurements were obtained within, at the edge of, and outside the vortex. Although the polar vortex did not remain over McMurdo as it did in 1986 and 1987, it was overhead long enough to establish that ozone depletion was less extensive and ended earlier than in either 1986 or 1987. In the vortex the ozone mixing ratio at 18 km decayed with an exponential half-life of 29 days compared to 25 and 12 days in 1986 and 1987. While ozone partial pressure in the 16-18 km layer decayed to values as low as 10 nbar in 1986 and 3 nbar in 1987, ozone partial pressure dropped to only 60-70 nbar in 1988 in the depleted region, a reduction of 30 to 50%. Even with these differences in degree of ozone depletion there were similarities to previous measurements. Ozone depletion was caused by a sink between 12 and 20 km, and primary depletion was episodic, occurring in periods of <10 days. Measurements at the edge of the vortex displayed the ozone layering observed in 1986 and 1987 and suggest the exchange of ozone rich and poor air across the vortex wall in the 12-20 km layer. Outside the vortex, vertical profiles displayed a region of high ozone and constant temperature above 20 km.

Deshler, T.; Hofmann, D.J.; Hereford, J.V. (Univ. of Wyoming, Laramie (USA))

1990-06-20

303

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

304

Vulnerability of Polar Oceans to Anthropogenic Acidification: Comparison of Arctic and Antarctic Seasonal Cycles  

PubMed Central

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

305

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

306

Anthropogenic Impacts on Polar Bear Biology and the Arctic Ecosystem.  

E-print Network

differences in diet, food chain structure, and area of home range (Verreault et al., 2005). Bears in off-coast habitats bioaccumulate higher levels of PCBs for instance, than do bears in smaller coastal or near-coastal habitats. This occurs because bears... in off-coast habitats have larger territories which require traveling longer distances, thus requiring the consumption of more prey, resulting in more contaminant intake (Willerroider, 2003). For many POPs, concentrations in polar bear tissue increase...

Jordan, John E.

2013-12-16

307

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

308

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, Ólafur

2006-01-01

309

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

2014-12-01

310

Characterizing the polarization and cross-polarization of electromagnetic vortex pulses in the space-time and space-frequency domain.  

PubMed

The dynamics of the degree of polarization and the degree of cross-polarization for electromagnetic pulsed vortex beams in dispersive media are explored both in the space-time and space-frequency domains. It is shown that the impacts, arising from the second-order dispersion coefficient and the temporal coherence length, on the variations of the temporal degree of polarization are distinctly different from those on the spectral degree of polarization. Besides, we also suggest a method to access the measurement of the orbital angular momentum of pulsed vortex beams through the mapping relationship between the distribution of the temporal degree of cross-polarization and the number of topological charge. PMID:25836453

Luo, Meilan; Zhao, Daomu

2015-02-23

311

Quantification of the transport of chemical constituents from the polar vortex to midlatitudes in the lower stratosphere using the high-resolution advection model MIMOSA and effective diffusivity  

Microsoft Academic Search

The observed decrease of ozone in the northern midlatitude lower stratosphere is only partially reproduced by chemical models. The transport of ozone-depleted air from the polar vortex is one of the proposed mechanisms to explain the discrepancy. Here we present a study on the quantification of the air mass transported from the polar vortex to midlatitude during the four winters

Alain Hauchecorne; Sophie Godin; Marion Marchand; Birgit Heese; Claude Souprayen

2002-01-01

312

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

inversion on polar-vortex dynamics and passive-tracer simulations in atmosphere-like regimes By JOHN METHVEN polar-vortex edge and the midlatitude tropopause are characterized by strong potential vorticity (PV to investigate regimes under which a polar vortex with a sharp PV gradient and persistent wave activity can

Hoskins, Brian

313

Airborne lidar observations of Arctic polar stratospheric clouds - Indications of two distinct growth stages  

NASA Technical Reports Server (NTRS)

Airborne lidar observations of Arctic polar stratospheric clouds (PSCs) during January 1984 and January 1986 show contrast suggestive of two distinct PSC growth stages delineated by the frost-point temperature. Results obtained at temperatures 2-6 K above the frost point indicate a stage of significant, but limited, particle growth such as proposed in recent models of PSC formation by co-deposition of HNO3 and H2O vapors. Results obtained at a temperature near the frost point indicate the formation of somewhat larger crystalline particles.

Poole, Lamont R; Mccormick, M. Patrick

1988-01-01

314

First remote sensing measurements of ClOOCl along with ClO and ClONO2 in activated and deactivated Arctic vortex conditions using new ClOOCl IR absorption cross sections  

NASA Astrophysics Data System (ADS)

Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of the ClO dimer cycle was challenged by the release of new laboratory absorption cross sections (Pope et al., 2007) yielding significant model underestimates of observed ClO and ozone loss (von Hobe et al., 2007). Under this aspect, nocturnal Arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been reanalyzed with regard to the chlorine reservoir species ClONO2 and the active species, ClO and ClOOCl (Cl2O2). New laboratory measurements of IR absorption cross sections of ClOOCl for various temperatures and pressures allowed for the first time the retrieval of ClOOCl mixing ratios from remote sensing measurements. High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the cold mid-winter Arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of nearly 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter Arctic vortex on 20 March 2003. No significant ClOx amounts are detectable on this date since most of the active chlorine has already recovered to its main reservoir species ClONO2. The observed values of ClOx and ClONO2 are in line with the established polar chlorine chemistry. The thermal equilibrium constants between the dimer formation and its dissociation, as derived from the balloon measurements, are on the lower side of reported data and in good agreement with values recommended by von Hobe et al. (2007). Calculations with the ECHAM/MESSy Atmospheric Chemistry model (EMAC) using established kinetics show similar chlorine activation and deactivation, compared to the measurements in January 2001 and March 2003, respectively.

Wetzel, G.; Oelhaf, H.; Kirner, O.; Ruhnke, R.; Friedl-Vallon, F.; Kleinert, A.; Maucher, G.; Fischer, H.; Birk, M.; Wagner, G.; Engel, A.

2010-02-01

315

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, Stanislav; Boltunov, Andrei N.; Derocher, A.E.; Garner, G.W.; Wiig, O.; Skaare, J.U.

2003-01-01

316

Interhemispheric comparison of the development of the stratospheric polar vortex during fall: A 3-dimensional perspective for 1991-1992  

SciTech Connect

The authors present the results of detailed studies of the northern and southern polar vortex development during 1991/1992, recreated from National Meteorological Center data. In general the data shows that in the southern hemisphere, the polar vortex developed with less short term variations, deepened very rapidly, and continued to grow well into the winter. Temperatures in the southern hemisphere would support the formation of polar stratospheric clouds for greater periods of time, and over larger areas than in the north. These results are compared to observations of ClO from the microwave limb sounder on the upper atmosphere research satellite. They lend support to the hemispherical differences observed in ClO by this probe, under the present model of reactive chlorine formation on polar stratospheric cloud particles.

Manney, G.L.; Zurek, R.W. (California Institute of Technology, Pasadena (United States))

1993-06-18

317

Storm tracks in Arctic System Reanalysis - new view of polar cyclone activity  

NASA Astrophysics Data System (ADS)

We present the analysis of cyclone activity over the 10-yr period (2000-2010) based on storm tracks derived from the recently released Arctic System Reanalysis (ASR), Interim version. Storm tracking was performed for ASR high resolution 3-hourly SLP fields using numerical tracking algorithm of IORAS. Results provide a novel vision of cyclone activity in the Northern Hemisphere polar regions with much more detailed structure of the storm tracks compared to global reanalyses. Compared to the modern era global reanalyses ASR exhibits considerably higher number of cyclones in high latitudes with short lived and relatively shallow transients primarily contributing to the difference. The major differences amounting to several tens of percent were identified in summer season. Besides differences in cyclone life cycle characteristics (cyclone depth, propagation velocity, deepening rates), we also considered frequencies of cyclone generation and found local generation regions which are not captured by global reanalyses. Special consideration is given to the small cyclone of mesoscale nature identified in the North European basin. These short-lived mesoscale transients are hardly detectable in global reanalyses, however ASR is capable of identifying them. Short-term interannual variability in regional patterns of cyclone activity over the Arctic were considered in a view of their comparability with those implied by the alternative products and of their potential links to the variations in the Arctic sea ice cover and associated changes in surface diabatic heating of the atmosphere.

Tilinina, N.; Gulev, S.; Bromwich, D. H.

2013-12-01

318

Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic  

USGS Publications Warehouse

Although sea ice loss is the primary threat to polar bears (Ursus maritimus), little can be done to mitigate its effects without global efforts to reduce greenhouse gas emissions. Other factors, however, could exacerbate the impacts of sea ice loss on polar bears, such as exposure to increased industrial activity. The Arctic Ocean has enormous oil and gas potential, and its development is expected to increase in the coming decades. Estimates of polar bear resource selection will inform managers how bears use areas slated for oil development and to help guide conservation planning. We estimated temporally-varying resource selection patterns for non-denning adult female polar bears in the Chukchi Sea population (2008–2012) at two scales (i.e., home range and weekly steps) to identify factors predictive of polar bear use throughout the year, before any offshore development. From the best models at each scale, we estimated scale-integrated resource selection functions to predict polar bear space use across the population's range and determined when bears were most likely to use the region where offshore oil and gas development in the United States is slated to occur. Polar bears exhibited significant intra-annual variation in selection patterns at both scales but the strength and annual patterns of selection differed between scales for most variables. Bears were most likely to use the offshore oil and gas planning area during ice retreat and growth with the highest predicted use occurring in the southern portion of the planning area. The average proportion of predicted high-value habitat in the planning area was >15% of the total high-value habitat for the population during sea ice retreat and growth and reached a high of 50% during November 2010. Our results provide a baseline on which to judge future changes to non-denning adult female polar bear resource selection in the Chukchi Sea and help guide offshore development in the region. Lastly, our study provides a framework for assessing potential impacts of offshore oil and gas development to other polar bear populations around the Arctic.

Wilson, Ryan R.; Horne, Jon S.; Rode, Karyn D.; Regehr, Eric V.; Durner, George M.

2014-01-01

319

Arctic ozone and circulation changes during boreal spring  

NASA Astrophysics Data System (ADS)

The interannual variations of the Arctic total column ozone in spring from 1979 to 2011 are analyzed using measurements of the Total Ozone Unit (TOU) onboard the second generation polar orbiting meteorological satellite of China, Fengyun-3 (FY3/TOU) and other satellites. It is found that the interannual variations are very distinct and are connected with the stratospheric temperatures (with a correlation coefficient of 0.75). The daily and monthly variability of Arctic ozone are extremely different in the anomalous year. The chemical impact is pronounced in the strongest ozone loss years (1997 and 2011), but not obvious in the weakest ozone loss years (1999 and 2010). The daily variations in the weak ozone loss years could be regulated by the weather system process. The Arctic ozone variations are modulated by the atmospheric circulation, accounting for change of AO, polar vortex and stratospheric temperature. When AO index is positive and the polar vortex is stronger with colder stratosphere, the Arctic ozone loss is larger. When AO index is negative and polar vortex is weaker with warmer stratosphere, the Arctic ozone loss is smaller.

Zhang, Yan; Wang, Weihe

2014-11-01

320

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 simulated 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 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. Both observation-based forcing sets result in insignificant changes in vortex strength. For the model-based forcing sets, the vortex response is found to be sensitive to the structure of the forcing, with one forcing set leading to significant strengthening of the polar vortex in rough agreement with observation-based expectations. Differences in the dynamical response to the forcing sets 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.

2014-12-01

321

ECMWF Analyses and Forecasts of Stratospheric Winter Polar Vortex Breakup: September 2002 in the Southern Hemisphere and Related Events  

Microsoft Academic Search

Breakup of the polar stratospheric vortex in the Northern Hemisphere is an event that is known to be predictable for up to a week or so ahead. This is illustrated using data from the 45-yr ECMWF Re-Analysis (ERA-40) for the sudden warmings of January 1958 and February 1979 and operational ECMWF data for February 2003. It is then shown that

Adrian Simmons; Mariano Hortal; Graeme Kelly; Anthony McNally; Agathe Untch; Sakari Uppala

2005-01-01

322

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

323

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

324

Polar Gateways Arctic Circle Sunrise 2008 Conference at the Top of the World  

NASA Technical Reports Server (NTRS)

The Polar Gateways conference was hosted during January 23-29, 2008, the first week of polar sunrise at Barrow, Alaska, at the new Barrow Arctic Research Center of the Barrow Arctic Science consortium (BASC). The dawn week of polar day, the highly variable low temperatures, and the ice-covered shore tundra and adjacent sea ice conditions provided an appropriate locale for a conference dedicated in the spirit of the International Polar and Heliophysical Years 2007-2009 to the educational exploration of polar and icy world science of Earth and the solar system. The many scientific, educational, and cultural interactions with the local community of four thousand residents, sixty percent native Inupiat Eskimo, further provided an unforgettable experience of what life might be someday be like on other remote polar and icy worlds to be explored and eventually inhabited. Over one hundred active participants, more than half participating remotely, contributed science presentations and educational activities during this unique circumpolar and very "green" conference. Most remote contributions came via videoconference from the Swedish Institute of Space Physics (IRF) at Kisuna, Sweden, the EISCAT Svalbard Radar Facility at Spitzbergen, Norway, the University of Alaska at Fairbanks, NASA Goddard Space Flight Center and the Jet Propulsion Laboratory, the University of California at Berkeley, and the University of Arizona. A few contributors participated via teleconference, including one from the Polar Geophysical Institute at Apatity in Russia. These active contributions spanned up to thirteen time zones (Alaska to Russia) at various tirnes during the conference. Primary videoconferencing support between Barrow and other sites was ably provided by the University of Alaska at Fairbanks, and local operators at each remote site collectively made this conference possible. 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. Barrow participants experienced look and feel of icy worlds like Europa by going "on the ice" during snowmobile expeditions to the near-shore sea ice and Point Barrow. Extensive educational outreach activities were conducted with the local Barrow township and North Slope Borough communities, partly through several interviews with local host Earl Finkler on Barrow's KBRW Radio, and through the NASA Digital Learning Network (DLN) "live from the top of the world" at Barrow. The Goddard robotic rover "Nunuq of the North" became a local celebrity. The complete science program and photo library, eventually also including video recordings of all main presentations, will be available at the new polargateways2008.gsfc.nasa.gov web site (old version: polargateways2008.org) with links to educational materials from the conference already accessible at sunearthday.nasa.gov/polarsunrise.

Cooper, John F.; Kauristie, Kirsti; Weatherwax, Allan T.; Sandahl, Ingrid; Ostgaard, Nikolai; Sheehan, Glenn W.; Smith, Roger W.; Lewis, Elaine M.; Cline, Troy D.; Haines-Stiles, Geoff

2008-01-01

325

Polar Gateways Arctic Circle Sunrise 2008 Conference at the Top of the World  

NASA Astrophysics Data System (ADS)

The Polar Gateways conference was hosted during January 23-29, 2008, the first week of polar sunrise at Barrow, Alaska, at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium (BASC). The dawn week of polar day, the highly variable low temperatures, and the ice-covered shore tundra and adjacent sea ice conditions provided an appropriate locale for a conference dedicated in the spirit of the International Polar and Heliophysical Years 2007-2009 to the educational exploration of polar and icy world science of Earth and the solar system. The many scientific, educational, and cultural interactions with the local community of four thousand residents, sixty percent native Inupiat Eskimo, further provided an unforgettable experience of what life might be someday be like on other remote polar and icy worlds to be explored and eventually inhabited. Over one hundred active participants, more than half participating remotely, contributed science presentations and educational activities during this unique circumpolar and very "green" conference. Most remote contributions came via videoconference from the Swedish Institute of Space Physics (IRF) at Kiruna, Sweden, the EISCAT Svalbard Radar Facility at Spitzbergen, Norway, the University of Alaska at Fairbanks, NASA Goddard Space Flight Center and the Jet Propulsion Laboratory, the University of California at Berkeley, and the University of Arizona. A few contributors participated via teleconference, including one from the Polar Geophysical Institute at Apatity in Russia. These active contributions spanned up to thirteen time zones (Alaska to Russia) at various times during the conference. Primary videoconferencing support between Barrow and other sites was ably provided by the University of Alaska at Fairbanks, and local operators at each remote site collectively made this conference possible. 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. Barrow participants experienced look and feel of icy worlds like Europa by going "on the ice" during snowmobile expeditions to the near-shore sea ice and Point Barrow. Extensive educational outreach activities were conducted with the local Barrow township and North Slope Borough communities, partly through several interviews with local host Earl Finkler on Barrow's KBRW Radio, and through the NASA Digital Learning Network (DLN) "live from the top of the world" at Barrow. The Goddard robotic rover "Nanuq of the North" became a local celebrity. The complete science program and photo library, eventually also including video recordings of all main presentations, will be available at the new polargateways2008.gsfc.nasa.gov web site (old version: polargateways2008.org) with links to educational materials from the conference already accessible at sunearthday.nasa.gov/polarsunrise.

Cooper, J. F.; Kauristie, K.; Weatherwax, A. T.; Sheehan, G. W.; Smith, R. W.; Cline, T. D.; Lewis, E. M.; Haines-Stiles, G.

2008-12-01

326

Polar bears from space: assessing satellite imagery as a tool to track Arctic wildlife  

USGS Publications Warehouse

Development of efficient techniques for monitoring wildlife is a priority in the Arctic, where the impacts of climate change are acute and remoteness and logistical constraints hinder access. We evaluated high resolution satellite imagery as a tool to track the distribution and abundance of polar bears. We examined satellite images of a small island in Foxe Basin, Canada, occupied by a high density of bears during the summer ice-free season. Bears were distinguished from other light-colored spots by comparing images collected on different dates. A sample of ground-truthed points demonstrated that we accurately classified bears. Independent observers reviewed images and a population estimate was obtained using mark- recapture models. This estimate (N: 94; 95% Confidence Interval: 92-105) was remarkably similar to an abundance estimate derived from a line transect aerial survey conducted a few days earlier (N: 102; 95% CI: 69-152). Our findings suggest that satellite imagery is a promising tool for monitoring polar bears on land, with implications for use with other Arctic wildlife. Large scale applications may require development of automated detection processes to expedite review and analysis. Future research should assess the utility of multi-spectral imagery and examine sites with different environmental characteristics.

Stapleton, Seth P.; LaRue, Michelle A.; Lecomte, Nicolas; Atkinson, Stephen N.; Garshelis, David L.; Porter, Claire; Atwood, Todd C.

2014-01-01

327

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

SciTech Connect

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 identified for the first time as an environmental contaminant. S-PCB and S-CHLOR accounted for >80% of the total organochlorines in adipose tissue. Six PCB congeners constituted approximately 93% of S-PCB in polar bears. Levels of most OCs were lowest in the high Arctic, intermediate in Baffin Bay, and highest in Hudson Bay. Levels of ..cap alpha..-HCH were evaluated in zones influenced by surface runoff. Levels of S-CHLOR were four times higher and levels of the other OCs were two times higher in adipose tissue of bears from Hudson Bay and Baffin Bay in 1984 than in adipose tissue archived since 1969 from these areas; levels of S-DDT did not change.

Norstrom, R.J.; Simon, M.; Muir, D.C.G.; Schweinsburg, R.E.

1988-09-01

328

Arctic microbial ecosystems and impacts of extreme warming during the International Polar Year  

NASA Astrophysics Data System (ADS)

As a contribution to the International Polar Year program MERGE (Microbiological and Ecological Responses to Global Environmental change in polar regions), studies were conducted on the terrestrial and aquatic microbial ecosystems of northern Canada (details at: http://www.cen.ulaval.ca/merge/). The habitats included permafrost soils, saline coldwater springs, supraglacial lakes on ice shelves, epishelf lakes in fjords, deep meromictic lakes, and shallow lakes, ponds and streams. Microbiological samples from each habitat were analysed by HPLC pigment assays, light and fluorescence microscopy, and DNA sequencing. The results show a remarkably diverse microflora of viruses, Archaea (including ammonium oxidisers and methanotrophs), Bacteria (including filamentous sulfur-oxidisers in a saline spring and benthic mats of Cyanobacteria in many waterbodies), and protists (including microbial eukaryotes in snowbanks and ciliates in ice-dammed lakes). In summer 2008, we recorded extreme warming at Ward Hunt Island and vicinity, the northern limit of the Canadian high Arctic, with air temperatures up to 20.5 °C. This was accompanied by pronounced changes in microbial habitats: deepening of the permafrost active layer; loss of perennial lake ice and sea ice; loss of ice-dammed freshwater lakes; and 23% loss of total ice shelf area, including complete break-up and loss of the Markham Ice Shelf cryo-ecosystem. These observations underscore the vulnerability of Arctic microbial ecosystems to ongoing climate change.

Vincent, Warwick F.; Whyte, Lyle G.; Lovejoy, Connie; Greer, Charles W.; Laurion, Isabelle; Suttle, Curtis A.; Corbeil, Jacques; Mueller, Derek R.

2009-11-01

329

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

330

Interhemispheric comparison of the development of the stratospheric polar vortex during fall - A 3-dimensional perspective for 1991-1992  

NASA Technical Reports Server (NTRS)

The development of the stratospheric polar vortex during fall and early winter in the Northern Hemisphere (NH) during 1991-1992, and the Southern Hemisphere (SH) during 1992 is examined using National Meteorological Center data. Compared to the NH, the polar vortex in the SH developed with less variability on short time scales, deepened more rapidly and continued to expand well into winter. Daily minimum temperatures in the lower stratosphere were lowest at equivalent seasonal dates in both hemispheres, but values below the condensation temperatures of polar stratospheric clouds occurred earlier, persisted much longer, and occupied a larger volume of air in the SH. These interhemispheric meteorological differences can account for some of the key features of the chlorine monoxide distributions observed by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite.

Manney, Gloria L.; Zurek, Richard W.

1993-01-01

331

Steady vortex gyrotropic motion driven by an out-of-plane spin-polarized current in a confined nanocontact structure  

NASA Astrophysics Data System (ADS)

We studied the steady vortex gyrotropic motion in a Permalloy nanodot driven by an out-of-plane spin-polarized current which is injected through a nanocontact. First, we calculated the current density range in which the vortex steady motion can exist. It is found that both the nanocontact dimensions and dot aspect ratios have influence on it. Then the orbital radius and oscillation frequency of the steady motion in the plane of current density and nanocontact radius were diagramed. It indicated that smaller nanocontact corresponds to wider frequency range.

Liu, Yan; Li, Huanan; Hu, Yong; Du, An

2015-01-01

332

Probing the spin polarization of current by soft x-ray imaging of current-induced magnetic vortex dynamics  

SciTech Connect

Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micron-sized Permalloy disk. The high spatial resolution better than 25 nm enables us to observe the resonant motion of the vortex core. The result also provides the spin polarization of the current to be 0.67 {+-} 0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.

Kasai, Shinya; Fischer, Peter; Im, Mi-Young; Yamada, Keisuke; Nakatani, Yoshinobu; Kobayashi, Kensuke; Kohno, Hiroshi; Ono, Teruo

2008-12-09

333

Fungal hyphal length in litter of Dryas octopetala in a high-Arctic polar semi-desert, Svalbard  

Microsoft Academic Search

Mean fungal hyphal length was estimated in the surface horizons of a lithosol underDryas octopetala in a polar semi-desert ecosystem at Ny-lesund, Svalbard (7856?N, 1150?E). This site is the most northerly from which such\\u000a values have been collected and provides the only record from polar semi-desert sites in the Eurasian high Arctic. Although\\u000a mean ( SE) fungal hyphal length was

C. H. Robinson; O. B. Borisova; T. V. Callaghan; J. A. Lee

1996-01-01

334

Fungal hyphal length in litter of Dryas octopetala in a high-Arctic polar semi-desert, Svalbard  

Microsoft Academic Search

Mean fungal hyphal length was estimated in the surface horizons of a lithosol underDryas octopetala in a polar semi-desert ecosystem at Ny-Ålesund, Svalbard (78°56'N, 11°50'E). This site is the most northerly from which such values have been collected and provides the only record from polar semi-desert sites in the Eurasian high Arctic. Although mean (+SE) fungal hyphal length was the

C. H. Robinson; O. B. Borisova; T. V. Callaghan; J. A. Lee

1996-01-01

335

Observations of Boundary Layer air over Western Arctic Sea Ice During the April 2009 Polar5 Airborne Campaign  

Microsoft Academic Search

During April 2009 the Polar-5, a refurbished DC-3 aircraft owned by the Alfred Wegener Institute in Bremerhaven Germany, undertook several low level flights over the Arctic Ocean, from Longyearbyen (Svalbard, Norway), Alert and Eureka (NU, Canada), Sachs Harbor (NWT, Canada), and Barrow (AK, USA), reaching latitudes as far north as 87.80 by landing on the Russian North Pole drifting station

C. T. McElroy; J. W. Bottenheim; C. Banic; J. Narayan; P. Liu; W. Strapp; C. Haas; R. S. Stone; A. Herber; M. Maturilli; K. Dethloff; V. Y. Sokolov; A. Makshtas; R. Brauner

2009-01-01

336

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

337

First remote sensing measurements of ClOOCl along with ClO and ClONO2 in activated and deactivated Arctic vortex conditions using new ClOOCl IR absorption cross sections  

NASA Astrophysics Data System (ADS)

Active chlorine species play a dominant role in the catalytic destruction of stratospheric ozone in the polar vortices during the late winter and early spring seasons. Recently, the correct understanding of the ClO dimer cycle was challenged by the release of new laboratory absorption cross sections (Pope et al., 2007) yielding significant model underestimates of observed ClO and ozone loss (von Hobe et al., 2007). Under this aspect, Arctic stratospheric limb emission measurements carried out by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 11 January 2001 and 20/21 March 2003 have been reanalyzed with regard to the chlorine reservoir species ClONO2 and the active species, ClO and ClOOCl (Cl2O2). New laboratory measurements of IR absorption cross sections of ClOOCl for various temperatures and pressures allowed for the first time the retrieval of ClOOCl mixing ratios from remote sensing measurements. High values of active chlorine (ClOx) of roughly 2.3 ppbv at 20 km were observed by MIPAS-B in the cold mid-winter Arctic vortex on 11 January 2001. While nighttime ClOOCl shows enhanced values of nearly 1.1 ppbv at 20 km, ClONO2 mixing ratios are less than 0.1 ppbv at this altitude. In contrast, high ClONO2 mixing ratios of nearly 2.4 ppbv at 20 km have been observed in the late winter Arctic vortex on 20 March 2003. No significant ClOx amounts are detectable on this date since most of the active chlorine has already recovered to its main reservoir species ClONO2. The observed values of ClOx and ClONO2 are in line with the established chlorine chemistry. The thermal equilibrium constants between the dimer formation and its dissociation, as derived from the balloon measurements, are on the lower side of reported data and in good agreement with values recommended by von Hobe et al. (2007). Calculations with the ECHAM/MESSy Atmospheric Chemistry model (EMAC) using established kinetics show similar chlorine activation and deactivation, compared to the measurements in January 2001 and March 2003, respectively.

Wetzel, G.; Oelhaf, H.; Kirner, O.; Ruhnke, R.; Friedl-Vallon, F.; Kleinert, A.; Maucher, G.; Fischer, H.; Birk, M.; Wagner, G.; Engel, A.

2009-09-01

338

Self-adjointness of the two-dimensional massless Dirac Hamiltonian and vacuum polarization effects in the background of a singular magnetic vortex  

E-print Network

A massless spinor field is quantized in the background of a singular static magnetic vortex in 2+1-dimensional space-time. The method of self-adjoint extensions is employed to define the most general set of physically acceptable boundary conditions at the location of the vortex. Under these conditions, all effects of polarization of the massless fermionic vacuum in the vortex background are determined. Absence of anomaly is demonstrated, and patterns of both parity and chiral symmetry breaking are discussed.

Yurii A. Sitenko

2001-01-03

339

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

340

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

341

Evidence of large scale ozone depletion within the arctic polar cortex 94/95 based on airborne LIDAR measurements  

SciTech Connect

The authors discuss aircraft measurements in the northern polar vortex which show that in the winter of 1994/95 that the ozone levels showed a 50 percent decline in the February to March period. This observation was correlated with simultaneous observations of stratospheric aerosols which support the argument that this density depletion was not the result of a purely dynamic process.

Wirth, M.; Renger, W. [Insitut fur Physik der Atmosphaere, Oberpfaffenhofen (Germany)] [Insitut fur Physik der Atmosphaere, Oberpfaffenhofen (Germany)

1996-04-15

342

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

343

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

344

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

345

Dynamical response of the Arctic atmospheric boundary layer to sea ice in Polar WRF model  

NASA Astrophysics Data System (ADS)

Impact of sea ice concentration (SIC) on the Arctic atmospheric boundary layer (ABL) is investigated using a Polar-optimized version of the Weather Research and Forecasting (Polar WRF) model. A detailed comparison of the simulations forced with various SIC datasets to historical ship and ice station based data are presented demonstrating the reasonable representation of the observed ABL evolution by the Polar WRF. Further, two dynamically distinctive effects of sea ice on the surface wind were found, which act on different spatial scales. Reduced SIC lowers ABL stability, thereby increasing surface wind (W10) speeds. The spatial scale of this response is comparable to the basin-scale of the SIC difference. In contrast, near-surface geostrophic wind (Wg) shows a strong response in the MIZ, where, a good spatial correspondence exists among the Laplacian of the sea level pressure (SLP), the surface wind convergence, and the vertical motion within the ABL. This indicates that SIC affects Wg through variation in SLP but on a much narrower scale. Larger-amplitude and broader-scale response in W10 implies that surface wind stress derived from Wg to drive ice-ocean models may not fully reflect the effect of SIC changes.

Seo, Hyodae; Yang, Jiayan

2014-05-01

346

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

347

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

PubMed

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

Jamieson, Kathleen Hall; Hardy, Bruce W

2014-09-16

348

Particle size distributions in Arctic polar stratospheric clouds, growth and freezing of sulfuric acid droplets, and implications for cloud formation  

NASA Technical Reports Server (NTRS)

The paper uses particle size and volume measurements obtained with the forward scattering spectrometer probe model 300 during January and February 1989 in the Airborne Arctic Stratospheric Experiment to investigate processes important in the formation and growth of polar stratospheric cloud (PSC) particles. It is suggested on the basis of comparisons of the observations with expected sulfuric acid droplet deliquescence that in the Arctic a major fraction of the sulfuric acid droplets remain liquid until temperatures at least as low as 193 K. It is proposed that homogeneous freezing of the sulfuric acid droplets might occur near 190 K and might play a role in the formation of PSCs.

Dye, James E.; Baumgardner, D.; Gandrud, B. W.; Kawa, S. R.; Kelly, K. K.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Gary, B. L.

1992-01-01

349

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

350

Analysis of UARS data in the southern polar vortex in September 1992 using a chemical transport model  

Microsoft Academic Search

We have used a new, isentropic-coordinate three-dimensional chemical transport model to investigate the decay of C10 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. (this issue). The model is initialized using the available data from the

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

1996-01-01

351

Observational evidence for chemical ozone depletion over the Arctic in winter 1991-92  

Microsoft Academic Search

LONG-TERM depletion of ozone has been observed since the early 1980s in the Antarctic polar vortex, and more recently at mid-latitudes in both hemispheres, with most of the ozone loss occurring in the lower stratosphere1. Insufficient measurements of ozone exist, however, to determine decadal trends in ozone concentration in the Arctic winter. Several studies of ozone concentrations in the Arctic

Peter von der Gathen; Markus Rex; Neil R. P. Harris; Diana Lucic; Bjørn M. Knudsen; Geir O. Braathen; Hugo de Backer; Rolf Fabian; Hans Fast; Manuel Gil; Esko Kyrö; Ib Steen Mikkelsen; Markku Rummukainen; Johannes Stähelin; Costas Varotsos

1995-01-01

352

Lunar tide in the thermosphere and weakening of the northern polar vortex  

NASA Astrophysics Data System (ADS)

The lunar tide and its variability are beginning to be realized as elements of ionosphere-thermosphere weather. Herein we demonstrate that an enhancement in M2 amplitude at 110 km in the dynamo region is related to the timing and intensity of stratospheric polar vortex weakening (PVW). Timing of the PVW, which typically occurs during January-February, changes on the order of 4-7 d/yr between 2002 and 2013 and the M2 enhancement changes with it, with a time delay of order 2.8 days. The M2 temperature amplitude at 110 km as determined from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) measurements on the Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) spacecraft increases linearly from about 20 K to 29 K as the westward zonal mean zonal wind increases from about 10 m s-1 to 80 m s-1 at 70°N and 48 km altitude in accord with PVW events from year to year according to Modern-Era Retrospective Analysis for Research and Applications (MERRA) data. These relationships point to a level of predictability regarding impacts of the lunar tide on thermosphere and ionosphere densities, winds, and plasma drifts.

Zhang, Xiaoli; Forbes, Jeffrey M.

2014-12-01

353

The variation of available chlorine, Cly, in the Arctic polar vortex during EASOE  

Microsoft Academic Search

Whole air samplers were flown on large balloons that were launched from Kiruna (67.9°N, 21.1°E) in the period from 30 November 1991 until 20 March 1992 during EASOE. Thirteen vertical profiles of the CCl2F2 mixing ratio were obtained from the analyses of stratospheric air samples that were collected at altitudes between about 10 and 31 km. An empirical correlation function

Ulrich Schmidt; Reimar Bauer; Andreas Engel; Reinhard Borchers; Julia Lee

1994-01-01

354

Dynamics of Venus' Southern hemisphere and South Polar Vortex from VIRTIS data obtained during the Venus Expres Mission  

NASA Astrophysics Data System (ADS)

The VIRTIS instrument onboard Venus Express observes Venus in two channels (visible and infrared) obtaining spectra and multi-wavelength images of the planet. The images have been used to trace the motions of the atmosphere at different layers of clouds [1-3]. We review the VIRTIS cloud image data and wind results obtained by different groups [1-3] and we present new results concerning the morphology and evolution of the South Polar Vortex at the upper and lower cloud levels with data covering the first 900 days of the mission. We present wind measurements of the South hemisphere obtained by cloud tracking individual cloud features and higher-resolution wind results of the polar region covering the evolution of the South polar vortex. The later were obtained by an image correlation algorithm run under human supervision to validate the data. We present day-side data of the upper clouds obtained at 380 and 980 nm sensitive to altitudes of 66-70 km, night-side data in the near infrared at 1.74 microns of the lower cloud (45-50 km) and day and night-side data obtained in the thermal infrared (wavelengths of 3.8 and 5.1 microns) which covers the dynamical evolution of Venus South Polar vortex at the cloud tops (66-70 km). We explore the different dynamics associated to the varying morphology of the vortex, its dynamical structure at different altitudes, the variability of the global wind data of the southern hemisphere and the interrelation of the polar vortex dynamics with the wind dynamics at subpolar and mid-latitudes. Acknowledgements: Work funded by Spanish MICIIN AYA2009-10701 with FEDER support and Grupos Gobierno Vasco IT-464-07. References [1] A. Sánchez-Lavega et al., Geophys. Res. Lett. 35, L13204, (2008). [2] D. Luz et al., Science, 332, 577-580 (2011). [3] R. Hueso, et al., Icarus doi:10.1016/j.icarus.2011.04.020 (2011)

Hueso, R.; Garate-Lopez, I.; Sanchez-Lavega, A.

2011-12-01

355

Quantifying the role of orographic gravity waves on polar stratospheric cloud occurrence in the Antarctic and the Arctic  

NASA Astrophysics Data System (ADS)

The proportion of polar stratospheric clouds due to orographic gravity wave (OGW) forcing is quantified during four Antarctic (2007-2010) and four Arctic (2006/2007 to 2009/2010) winter seasons. OGW?active days are defined as those days above major polar mountain ranges which have wave?ice polar stratospheric clouds (PSCs), tropospheric wind conditions appropriate for orographic wave generation and propagation, and stratospheric temperatures below the frost point: 37% of Antarctic days and 12% of Arctic days are OGW?active. Regions downstream of these mountain ranges are defined using a forward?trajectory model which follows particle movement from ridge lines for 24 h periods. In both hemispheres in these mountain regions, more than 75% of H2O ice PSCs and around 50% of a high number density liquid?nitric acid trihydrate mixture class (Mix 2?enh) are attributed to OGW activity, with the balances due to non?orographic formation. For the whole Arctic (equatorward of 82°), 25% of Mix 2?enh and 54% of H2O ice PSCs are attributed to OGWs, while for the whole Antarctic, 7% of Mix 2?enh and 13% of H2O ice PSCs are attributed to OGWs. For all types of PSC, 5% in the whole Antarctic and 12% in the whole Arctic are attributed to OGW forcing. While gravity waves play a role in PSC formation in the Antarctic, overall it is minor compared with other forcing sources. However, in the synoptically warmer Arctic, much larger proportions of PSCs are due to OGW activity.

Alexander, S. P.; Klekociuk, A. R.; McDonald, A. J.; Pitts, M. C.

2013-10-01

356

Nitric oxide measurements in the Arctic winter stratosphere  

NASA Technical Reports Server (NTRS)

Measurements of NO from five flights of the NASA ER-2 aircraft during the Airborne Arctic Stratospheric Expedition are presented. The NO values and vertical gradient near 60 deg N latitude are similar to previous measurements near 50 deg N in winter (Ridley et al., 1984, 1987). The NO latitudinal gradient is distinctly negative outside of the polar vortex, approaching zero at the boundary of the vortex, and remaining below the 20 pptv detection limit inside the vortex. Steady state NO2 and NO(x) (NO + NO2) are calculated from measured NO, O3, and ClO, and modeled photodissociation rates. NO(x) outside the vortex shows a negative dependence on latitude and solar zenith angle. Low NO(x) and NO(x)/NO(y), inside and near the vortex boundary may be indications of heterogeneous removal of ClONO2 and N2O5.

Fahey, D. W.; Kawa, S. R.; Chan, K. R.

1990-01-01

357

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

358

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.

Lori Perkins

2004-12-13

359

Integrating Access to Arctic Environmental Change and Human Health Research for the International Polar Year and Beyond  

NASA Astrophysics Data System (ADS)

Each day, people in the communities of the Arctic face challenges to their health and well-being from changing climatic and environmental conditions and increasing levels of pollution to emerging infectious diseases. For this reason, it is critical that Arctic researchers and residents have access to timely, accurate, and relevant information addressing their unique concerns. To meet this need, the National Library of Medicine (NLM) and the University of Alaska Anchorage (UAA) have developed the Arctic Health website, www.arctichealth.org. The website provides an easy-to-use one-stop shop for information on the diverse health-related aspects of the Arctic region. It is organized around relevant topics, including climate change and environmental health, traditional healing and telehealth/telemedicine. The Arctic Health website provides links to the most reliable resources available from local, state, and international agencies, universities, and professional organizations. Two major goals of the site are to create a comprehensive, accessible repository for various media and a listing of research projects, past and present that relate to climate change and human health in the Arctic. To increase the site's relevance, the project has established and continues to create collaborations with researchers, communities, and other organizations to supply publications not available elsewhere, including gray literature, streaming video of traditional healers, and oral histories. These collaborations will also help ensure a database with a comprehensive list of research projects being done in the Arctic, from the international to the local level. Finding ways to negotiate the legal, cultural and national concerns of data sharing are a continuing job for the management team. All of this helps to create a system that will eventually track and ensure that data and reports from the research database translate to the publications database. As part of these efforts, the site is hosting the Arctic Human Health Initiative (AHHI), the human health focus of the International Polar Year activities. AHHI will coordinate research in the areas of infectious disease; the effects of anthropogenic pollution, UV radiation, and climate variability on human health; and telehealth innovations. A major goal of AHHI is the better integration of the findings of Arctic health research through outreach programs and public education.

Garrett, C. L.

2006-12-01

360

Simultaneous measurements of HDO, H2O, and CH4 with MIPAS-B: Hydrogen budget and indication of dehydration inside the polar vortex  

Microsoft Academic Search

For the first time, vertical profiles of HDO inside the Arctic vortex along with CH4 and H2O were retrieved from nighttime infrared limb emission spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding, Balloonborne instrument (MIPAS-B) from Kiruna (Sweden, 68°N) on February 11, 1995 and March 24, 1997. The deuterium to hydrogen ratio (D\\/H) of water vapor shows a

M. Stowasser; H. Oelhaf; G. Wetzel; F. Friedl-Vallon; G. Maucher; M. Seefeldner; O. Trieschmann; T. v. Clarmann; H. Fischer

1999-01-01

361

Three-Dimensional, Spin-Resolved Structure of Magnetic Vortex and Antivortex States in Patterned Co Films Using Scanning Ion Microscopy with Polarization Analysis  

E-print Network

Three-Dimensional, Spin-Resolved Structure of Magnetic Vortex and Antivortex States in Patterned Co Films Using Scanning Ion Microscopy with Polarization Analysis Jian Li and Carl Rau Department with polarization analysis is utilized for three-dimensional spin mapping of the surface magnetization (SM

Rau, Carl

362

Evolution of the Antarctic polar vortex in spring: Response of a GCM to a prescribed Antarctic ozone hole  

NASA Technical Reports Server (NTRS)

The possible effect of the Antartic ozone hole on the evolution of the polar vortex during late winter and spring using a general circulation model (GCM) is examined. The GCM is a version of the NCAR Community Climate Model whose domain extends from the surface to the mesosphere and is similar to that described on Boville and Randel (1986). Ozone is not a predicted variable in the model. A zonally averaged ozone distribution is specified as a function of latitude, pressure and month for the radiation parameterization. Rather that explicitly address reasons for the formation of the ozone hole, researchers postulate its existence and ask what effect it has on the subsequent evolution of the vortex. The evolution of the model when an ozone hole is imposed is then discussed.

Boville, B. A.; Kiehl, J. T.; Briegleb, B. P.

1988-01-01

363

Temporal trends and transport within and around the Antarctic polar vortex during the formation of the 1987 Antarctic ozone hole  

NASA Technical Reports Server (NTRS)

During AAOE in 1987 an ER-2 high altitude aircraft made twelve flights out of Punta Arenas, Chile (53 S, 71 W) into the Antarctic polar vortex. The aircraft was fitted with fast response instruments for in situ measurements of many trace species including O3, ClO, BrO, NO sub y, NO, H2O, and N2O. Grab samples of long-lived tracers were also taken and a scanning microwave radiometer measured temperatures above and below the aircraft. Temperature, pressure, and wind measurements were also made on the flight tracks. Most of these flights were flown to 72 S, at a constant potential temperature, followed by a dip to a lower altitude and again assuming a sometimes different potential temperature for the return leg. The potential temperature chosen was 425 K (17 to 18 km) on 12 of the flight legs, and 5 of the flight legs were flown at 450 K (18 to 19 km). The remaining 7 legs of the 12 flights were not flown on constant potential temperature surfaces. Tracer data have been analyzed for temporal trends. Data from the ascents out of Punta Arenas, the constant potential temperature flight legs, and the dips within the vortex are used to compare tracer values inside and outside the vortex, both with respect to constant potential temperature and constant N2O. The time trend during the one-month period of August 23 through September 22, 1987, shows that ozone decreased by 50 percent or more at altitudes form 15 to 19 km. This trend is evident whether analyzed with respect to constant potential temperature or constant N2O. The trend analysis for ozone outside the vortex shows no downward trend during this period. The analysis for N2O at a constant potential temperature indicates no significant trend either inside or outside the vortex; however, a decrease in N2O with an increase in latitude is evident.

Proffitt, M. H.; Powell, J. A.; Tuck, A. F.; Fahey, D. W.; Kelly, K. K.; Loewenstein, M.; Podolske, J. R.; Chan, K. Roland

1988-01-01

364

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

365

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

366

Examining diapirs as a nutrient source for plants in a High Arctic polar desert.  

NASA Astrophysics Data System (ADS)

Polar deserts cover a quarter of ice-free land in the Canadian Arctic, yet little is known about the key ecological processes that take place. This understudied ecosystem is becoming increasingly vulnerable to climate change and growth of the natural resource industry. In polar deserts, below ground soil masses called diapirs occur in some patterned ground features such as frost boils. Diapirs are formed above permafrost soil where increases in moisture and temperature stimulate biological activity when thawing occurs to create an organic rich, Bhy horizon. Vascular plants are scarce (< 5% cover) and nutrients for survival are likely supplied by diapirs but this interaction is poorly understood. To determine if diapirs are an important nutrient source, nitrogen and phosphorous were traced from the diapir Bhy to vascular plants using ?15N and ?18O stable isotope signatures. Recent developments have shown that the oxygen isotopes of orthophosphate (18OP) can be used to trace plant-available phosphorous. At a polar desert site at Alexandra Fjord, Canada, diapir (n=12) and non-diapir (n=12) frost boils were identified in 12 blocks with a field-portable vis-NIR (visible and near infrared spectrometer) device. Soil cores and Salix arctica plant tissue were collected from each frost boil for stable isotope analysis. The ?15N of Salix arctica plant tissue (n=144) shows a significant relationship between block location and diapir presence (p=0.003). There was a consistent pattern in average ?15N in plant tissue parts with increasing concentration from leaf, stem to root in all frost boils. There was no significant difference in total plant ?15N between diapir and non-diapir frost boils but ?15N in soil cores will be measured to determine if these signatures are attributed to the Bhy horizon or biological nitrogen fixation. These results highlight the potential for stable isotopes to be used as a nutrient tracer in polar desert ecosystems and further analysis of phosphorous stable isotopes will provide a clearer picture of the role of diapirs as a nutrient source.

Hardy, Sarah; Siciliano, Steven

2014-05-01

367

Airborne lidar observations in the wintertime Arctic stratosphere - Ozone  

NASA Technical Reports Server (NTRS)

Large-scale distributions of ozone (O3) were measured with an airborne lidar system as part of the 1989 Airborne Arctic Stratospheric Expedition. Measurements of O3 distributions were obtained between January 6 and February 15, 1989, on 15 long-range flights into the polar vortex from the Solar Air Station, Norway. The observed O3 distribution was found to clearly indicate the edge of the polar vortex and to be an effective tracer of dynamical processes in the lower stratosphere. On the last two flights of the expedition, large regions with reduced O3 levels were observed by the lidar inside the polar vortex. Ozone had decreased by as much as 17 percent in the center of these areas, and using the in situ measurements made on the ER-2 aircraft, it was concluded that this decline was due to chemical O3 destruction.

Browell, E. V.; Ismail, S.; Carter, A. F.; Butler, C. F.; Fenn, M. A.; Kooi, S. A.; Tuck, A. F.; Toon, O. B.; Loewenstein, M.; Schoeberl, M. R.

1990-01-01

368

Polar front associated variation in prokaryotic community structure in Arctic shelf seafloor  

PubMed Central

Spatial variations in composition of marine microbial communities and its causes have largely been disclosed in studies comprising rather large environmental and spatial differences. In the present study, we explored if a moderate but temporally permanent climatic division within a contiguous arctic shelf seafloor was traceable in the diversity patterns of its bacterial and archaeal communities. Soft bottom sediment samples were collected at 10 geographical locations, spanning spatial distances of up to 640 km, transecting the oceanic polar front in the Barents Sea. The northern sampling sites were generally colder, less saline, shallower, and showed higher concentrations of freshly sedimented phytopigments compared to the southern study locations. Sampling sites depicted low variation in relative abundances of taxa at class level, with persistent numerical dominance by lineages of Gamma- and Deltaproteobacteria (57–66% of bacterial sequence reads). The Archaea, which constituted 0.7–1.8% of 16S rRNA gene copy numbers in the sediment, were overwhelmingly (85.8%) affiliated with the Thaumarchaeota. Beta-diversity analyses showed the environmental variations throughout the sampling range to have a stronger impact on the structuring of both the bacterial and archaeal communities than spatial effects. While bacterial communities were significantly influenced by the combined effect of several weakly selective environmental differences, including temperature, archaeal communities appeared to be more uniquely structured by the level of freshly sedimented phytopigments. PMID:25667586

Nguyen, Tan T.; Landfald, Bjarne

2015-01-01

369

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

370

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

371

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

372

Connections Between the Spring Breakup of the Southern Hemisphere Polar Vortex, Stationary Waves, and Air-sea Roughness  

NASA Technical Reports Server (NTRS)

A robust connection between the drag on surface-layer winds and the stratospheric circulation is demonstrated in NASA's Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Specifically, an updated parameterization of roughness at the air-sea interface, in which surface roughness is increased for moderate wind speeds (4ms to 20ms), leads to a decrease in model biases in Southern Hemispheric ozone, polar cap temperature, stationary wave heat flux, and springtime vortex breakup. A dynamical mechanism is proposed whereby increased surface roughness leads to improved stationary waves. Increased surface roughness leads to anomalous eddy momentum flux convergence primarily in the Indian Ocean sector (where eddies are strongest climatologically) in September and October. The localization of the eddy momentum flux convergence anomaly in the Indian Ocean sector leads to a zonally asymmetric reduction in zonal wind and, by geostrophy, to a wavenumber-1 stationary wave pattern. This tropospheric stationary wave pattern leads to enhanced upwards wave activity entering the stratosphere. The net effect is an improved Southern Hemisphere vortex: the vortex breaks up earlier in spring (i.e., the spring late-breakup bias is partially ameliorated) yet is no weaker in mid-winter. More than half of the stratospheric biases appear to be related to the surface wind speed biases. As many other chemistry climate models use a similar scheme for their surface layer momentum exchange and have similar biases in the stratosphere, we expect that results from GEOSCCM may be relevant for other climate models.

Garfinkel, Chaim I.; Oman, Luke David; Barnes, Elizabeth A.; Waugh, Darryn W.; Hurwitz, Margaret H.; Molod, Andrea M.

2013-01-01

373

Mechanisms of Arctic Oscillation response to volcanic aerosols and ozone changes caused by the 1991 Mt. Pinatubo eruption  

Microsoft Academic Search

All strong equatorial volcanic eruptions during the period of instrumental observations have forced a positive phase of the Arctic Oscillation (AO) for one or two years following each eruption. The conventional view is that the volcanic effect on the AO is caused by aerosol heating in the tropical lower stratosphere that produces a stronger polar vortex that prevents the propagation

G. Stenchikov; A. Robock; M. D. Schwarzkopf; V. Ramaswamy; S. Ramachandran

2001-01-01

374

A 3D simulation of the early winter distribution of reactive chlorine in the north polar vortex  

SciTech Connect

This paper presents the results of 3D simulations of the formation of reactive chlorine on polar stratospheric clouds in the southern polar vortex. The purpose behind these simulations is to compare calculations with measurements of the microwave limb sounder (MLS) carried on the upper atmosphere research satellite (UARS), which showed regions of enhanced ClO in early December 1991, in regions south of areas where temperatures would support the formation of polar stratospheric clouds. The presently accepted model is that reactive chlorine is formed by rapid chemical reactions on the surfaces of particles in polar stratospheric clouds, from gases such as HCl and ClONO[sub 2]. It is then converted to ClO by photochemical processes. The simulations look at cyclonic and anticyclonic circulation patterns in the region of polar stratospheric cloud formation, and the impact this circulation has on the transport of reactive chlorine northward or southward from its creation to regions where it is converted to ClO.

Douglass, A.; Rood, R. (NASA/Goddard Space Flight Center, Greenbelt, MD (United States)); Waters, J.; Froidevaux, L.; Read, W.; Elson, L. (California Institute of Technology, Pasadena (United States)); Geller, M.; Chi, Y. (State Univ. of New York, Stony Brook (United States)); Cerniglia, M.; Steenrod, S.

1993-06-18

375

Reconstruction of the constituent distribution and trends in the Antarctic polar vortex from ER-2 flight observations  

NASA Technical Reports Server (NTRS)

The measurements of ozone, ClO, and N2O concentrations in the south polar region taken aboard the ER-2 aircraft during the Airborne Antarctic Ozone Experiment are analyzed using conservative coordinate transformations to potential temperature-N2O and potential temperature-potential vorticity space. The latter transformation is equivalent to interpreting trace species observations within the modified Lagrangian mean (MLM) coordinate system. The results show that the MLM transformed ozone concentration decreases at about 0.06 ppmv per day between 20- and 16-km altitude inside the polar vortex during the mid-August to mid-September period. These ozone changes are collocated with the region of high ClO concentration. Outside the chemically perturbed region, at the highest aircraft altitudes, ozone concentration systematically increases, suggesting a diabatic cooling of the order 0.3-0.6 K/day.

Schoeberl, Mark R.; Lait, Leslie R.; Newman, Paul A.; Martin, Russell L.; Proffitt, Michael H.; Hartmann, Dennis L.; Loewenstein, Max; Podolske, James; Strahan, Susan E.; Gary, Bruce

1989-01-01

376

Airborne lidar observations in the wintertime Arctic stratosphere - Ozone  

Microsoft Academic Search

Large-scale distributions of ozone (O3) were measured with an airborne lidar system as part of the 1989 Airborne Arctic Stratospheric Expedition. Measurements of O3 distributions were obtained between January 6 and February 15, 1989, on 15 long-range flights into the polar vortex from the Solar Air Station, Norway. The observed O3 distribution was found to clearly indicate the edge of

E. V. Browell; S. Ismail; A. F. Carter; C. F. Butler; M. A. Fenn; S. A. Kooi; A. F. Tuck; O. B. Toon; M. Loewenstein; M. R. Schoeberl; I. Isaksen; G. Braathen

1990-01-01

377

United States Naval Academy Polar Science Program's Visual Arctic Observing Platforms; IceGoat and IceKids  

NASA Astrophysics Data System (ADS)

The U.S. Naval Academy Oceanography Department currently has a curriculum based Polar Science Program (USNA PSP). Within the PSP there is an Arctic Buoy Program (ABP) student research component that will include the design, build, testing and deployment of Arctic Observing Platforms. Establishing an active, field-research program in Polar Science will greatly enhance Midshipman education and research, as well as introduce future Naval Officers to the Arctic environment. The Oceanography Department has engaged the USNA Engineering Departments, and in close collaboration with SRI International, developed the USNA Visual Arctic Observing Platforms. The experience gained through Polar field studies and data derived from these platforms will be used to enhance course materials and laboratories and will also be used directly in Midshipman independent research projects. The USNA PSP successfully deployed IceGoat1 (IG1) off the USCGC HEALY in September, 2012. IG1 suffered a malfunction to its solar powered webcam system upon deployment, but is still reporting via ARGOS SATCOM systems basic weather parameters of air temperature, pressure, and position. USNA PSP attempted to build a less robust, but more economical system integrating similar low power observing platforms housed in heavy duty coolers. This allowed for a streamlined process to get a complete system completed in one academic year. IceKids (IK) are similar observing platforms, just not designed to float once the sea ice melts. IK1 was deployed to Antarctica from October 2012 through January 2013 and captured over 11,000 web cam images in near real time of two remote environmental monitoring stations. IK2A and IK3T were built to be deployed at the Naval Academy Ice Experiment in Barrow, AK in March 2013. IK2A was unique in trying to collect and transmit underwater acoustic signals in near real time. The system integrated a passive hydrophone into the already developed low power data transport system. Unfortunately a malfunction occurred post deployment and only a few hours of data was collected while under the ice. IK3T integrated a Vaisala all in one weather station for very accurate Air Temperature, Pressure, and Wind measurements. IK3T is still operating in Barrow, AK as part of the University of Washington's Arctic Observing Experiment (AOX) where very precise temperature measurements are being collected for validation studies.

Woods, J. E.; Rigor, I. G.; Valentic, T. A.

2013-12-01

378

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

379

On the influence of polar stratospheric cloud formation on chemical composition during the 1988/89 Arctic winter  

SciTech Connect

The northern winter polar vortex is more disturbed dynamically and warmer than the Antarctic equivalent, and correspondingly fewer polar stratospheric clouds (PSCs) are observed to form. However, the rapid flow of stratospheric air through slow moving synoptically forced PSC regions can result in exposure of both vortical and extra vortical air to PSCs intermittently throughout the winter months. This periodic exposure to PSCs may be sufficient to perturb the chemical composition of large volumes of northern hemisphere air. The synoptic forcing also leads to marked meridional flow which has a profound effect on chemical composition, having major impacts on both short term ozone depletion and the longer term recovery to lower ClOx abundances. Accurate simulation of the air flow is thus essential for the reliable calculation of ozone loss in polar regions.

Jones, R.L.; McKenna, D.S. (United Kingdom Meteorological Office, Brackness (England)); Poole, L.R. (NASA Langley Research Center, Hampton, VA (USA)); Solomon, S. (NOAA Environmental Research Laboratory, Boulder, CO (USA))

1990-03-01

380

On the influence of polar stratospheric cloud formation on chemical composition during the 1988/89 Arctic winter  

NASA Technical Reports Server (NTRS)

The northern winter polar vortex is more disturbed dynamically and warmer than the Antarctic equivalent, and correspondingly fewer polar stratospheric clouds (PSCs) are observed to form. However, the rapid flow of stratospheric air through slow moving synoptically forced PSC regions can result in exposure of both vortical and extra vortical air to PSCs intermittently throughout the winter months. This periodic exposure to PSCs may be sufficient to perturb the chemical composition of large volumes of nothern hemisphere air. The synoptic forcing also leads to marked meridional flow which has a profound effect on chemical composition, having major impacts on both short term ozone depletion and the longer term recovery to lower ClOx abundances. Accurate simulation of the air flow is thus essential for the reliable calculation of ozone loss in polar regions.

Jones, R. L.; Mckenna, D. S.; Poole, L. R.; Solomon, S.

1990-01-01

381

Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow, Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in the Solar System  

NASA Technical Reports Server (NTRS)

Polar, heliophysical, and planetary science topics related to the International Heliophysical and Polar Years 2007-2009 were addressed during this circumpolar video conference hosted January 23-29, 2808 at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium in Barrow, Alaska. This conference was planned as an IHY-IPY event science outreach event bringing together scientists and educational specialists for the first week of sunrise at subzero Arctic temperatures in Barrow. Science presentations spanned the solar system from the polar Sun to Earth, Moon, Mars, Jupiter, Saturn, and the Kuiper Belt. On-site participants experienced look and feel of icy worlds like Europa and Titan by being in the Barrow tundra and sea ice environment and by going "on the ice" during snowmobile expeditions to the near-shore sea ice environment and to Point Barrow, closest geographic point in the U.S. to the North Pole. Many 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. 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 Sun- Earth Day team from Goddard, and a videographer from the Passport to Knowledge project, carried out extensive educational interviews with many participants and native Inupiaq Eskimo residents of Barrow. Video and podcast recordings of selected interviews are available at http://sunearthday.nasa.gov/2008/multimedidpodcasts.php. Excerpts from these and other interviews will be included in a new high definition video documentary called "From the Sun to the Stars: The New Science of Heliophysics" from Passport to Knowledge that will later broadcast on NASA TV and other educational networks. Full conference proceedings are accessible at http://polargateways2008.org/.

Cooper, John F.; Kauristie, Kirsti; Weatherwax, Allan T.; Sheehan, Glenn W.; Smith, Roger W.; Sandahl, Ingrid; Ostgaard, Nikolai; Chernouss, Sergey; Thompson, Barbara J.; Peticolas, Laura; Moore, Marla H.; Senske, David A.; Tamppari, Leslie K.; Lewis, Elaine M.

2008-01-01

382

Polar Gateways Arctic Circle Sunrise Conference 2008, Barrow, Alaska: IHY-IPY Outreach on Exploration of Polar and Icy Worlds in The Solar System  

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 circumpolar video conference hosted January 23-29, 2008 at the new Barrow Arctic Research Center of the Barrow Arctic Science Consortium in Barrow, Alaska. This conference was planned as an IHY-IPY event science outreach event bringing together scientists and educational specialists for the first week of sunrise at subzero Arctic temperatures in Barrow. Science presentations spanned the solar system from the polar Sun to Earth, Moon, Mars, Jupiter, Saturn, and the Kuiper Belt. On-site participants experienced look and feel of icy worlds like Europa and Titan by being in the Barrow tundra and sea ice environment and by going "on the ice" during snowmobile expeditions to the near-shore sea ice environment and to Point Barrow, closest geographic point in the U.S. to the North Pole. Many 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. 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 Sun-Earth Day team from Goddard, and a videographer from the Passport to Knowledge project, carried out extensive educational interviews with many participants and native Inupiaq Eskimo residents of Barrow. Video and podcast recordings of selected interviews are available at http://sunearthday.nasa.gov/2008/multimedia/podcasts.php. Excerpts from these and other interviews will be included in a new high definition video documentary called "From the Sun to the Stars: The New Science of Heliophysics" from Passport to Knowledge that will later broadcast on NASA TV and other educational networks. Full conference proceedings are accessible at http://polargateways2008.org/.

Cooper, John F.; Kauristie, K.; Weatherwax, A. T.; Sheehan, G. W.; Smith, R. W.; Sandahl, I.; Østgaard, N.; Chernouss, S.; Moore, M. H.; Peticolas, L. M.; Senske, D. A.; Thompson, B. J.; Tamppari, L. K.; Lewis, E. M.

2008-09-01

383

Effects of Boson-Vacuum Polarization by a Singular Magnetic Vortex  

E-print Network

In a space of arbitrary dimensions, the effect of an external magnetic field on the vacuum of a quantized charged scalar field is studied for the field configuration in the form of a singular vortex. The zeta-function technique is used to regularize ultraviolet divergences. The expression for the effective action is derived. It is shown that the energy density and current induced in the vacuum decrease exponentially at large distances from the vortex. The analytic properties of vacuum features as functions of the complex-valued space dimension are discussed.

Yu. A. Sitenko; A. Yu. Babansky

1998-12-28

384

2, 24892506, 2002 Impact of vortex  

E-print Network

of mid-latitude intrusions into the polar vortex on ozone loss estimates J.-U. GrooÃ? and R. M-latitude air into the polar vortex on these ozone5 loss estimates. This study focuses on the winter 1991 descent to derive chemical ozone loss estimates for the polar vortex. Briefly, the vortex average approach

Paris-Sud XI, Université de

385

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

386

Observations of Boundary Layer air over Western Arctic Sea Ice During the April 2009 Polar-5 Airborne Campaign  

NASA Astrophysics Data System (ADS)

During April 2009 the Polar-5, a refurbished DC-3 aircraft owned by the Alfred Wegener Institute in Bremerhaven Germany, undertook several low level flights over the Arctic Ocean, from Longyearbyen (Svalbard, Norway), Alert and Eureka (NU, Canada), Sachs Harbor (NWT, Canada), and Barrow (AK, USA), reaching latitudes as far north as 87.80 by landing on the Russian North Pole drifting station NP 36, as part of the PAM-ARCMIP program (Pan-Arctic Measurements and Interpretation by regional climate models). Air, extensively depleted of ozone and mercury, was frequently observed at levels below 100 m ASL with a boundary layer height of less than 200 m. Higher altitude (500-1000 m) depletions were also occasionally recorded. There was no clear indication that ambient temperatures played a role, with depleted air observed at temperatures between -25 to -15 0C. Aerosol Optical Depth observations showed relatively high concentrations of Arctic haze within the surface-based temperature inversion. The concentration of bromine monoxide (BrO) was measured photometrically during several of the flights. Conditions of the underlying ice were also recorded, including the ice thickness, albedo, and surface temperature. Connections between these and other variables will be explored in this presentation.

McElroy, C. T.; Bottenheim, J. W.; Banic, C.; Narayan, J.; Liu, P.; Strapp, W.; Haas, C.; Stone, R. S.; Herber, A.; Maturilli, M.; Dethloff, K.; Sokolov, V. Y.; Makshtas, A.; Brauner, R.

2009-12-01

387

Polarization pattern of vector vortex beams generated by $q$-plates with different topological charges  

E-print Network

We describe the polarization topology of the vector beams emerging from a patterned birefringent liquid crystal plate with a topological charge $q$ at its center ($q$-plate). The polarization topological structures for different $q$-plates and different input polarization states have been studied experimentally by measuring the Stokes parameters point-by-point in the beam transverse plane. Furthermore, we used a tuned $q=1/2$-plate to generate cylindrical vector beams with radial or azimuthal polarizations, with the possibility of switching dynamically between these two cases by simply changing the linear polarization of the input beam.

Cardano, Filippo; Slussarenko, Sergei; Marrucci, Lorenzo; de Lisio, Corrado; Santamato, Enrico

2012-01-01

388

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

389

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

390

Correlation of N2O and ozone in the southern polar vortex during the Airborne Antarctic Ozone Experiment  

NASA Technical Reports Server (NTRS)

The correlation of N2O and ozone in the Antarctic stratosphere during the late austral winter was investigated using measurements of N2O mixing ratios obtained by an airborne laser spectrometer and in situ measurements of ozone for latitudes between 53 and 72 deg S. In addition, airborne N2O and O3 measurements taken between 13 and 20 km in the mid-latitudes (37 deg N and 53 deg S) were correlated. It was found that, while the mid-latitude ozone-N2O corelation was negative, poleward of 53 deg S, the N2O and O3 mixing ratios often showed a strong positive correlation, which approximately coincided with the edge of the polar vortex as defined by the wind-speed maximum. Inside the vortex, in lower wind speed regions, the N2O-O3 correlation became negative again, with the lowest ozone mixing ratios usually found near the boundary with the positively correlated region.

Strahan, S. E.; Loewenstein, M.; Podolske, J. R.; Starr, W. L.; Chan, K. R.

1989-01-01

391

Airborne measurements of stratospheric constituents over the Arctic in the winter of 1989  

SciTech Connect

The authors have used a Fourier transform spectrometer aboard the NASA DC-8 aircraft during the Airborne Arctic Stratospheric Expedition (AASE) to record infrared absorption spectra of the polar stratosphere. From these high resolution spectra the authors have derived vertical column amounts above flight altitude of O{sub 3}, CH{sub 4}, N{sub 2}O, HCl, HF, NO, NO{sub 2}, ClONO{sub 2}, and HNO{sub 3} for eleven flights poleward of 60{degree}N. The authors report here measurements on the flight of 26 January 1989 when the flight path during the observations crossed from outside the polar vortex to inside. This allowed a clear comparison of the conditions of the air within the vortex with that outside. Observations of passive tracers such as CH{sub 4} and HF indicate that air of a certain composition within the polar vortex occurs at lower altitude than air outside. Within the vortex, they observed markedly reduced columns of HCl and NO{sub 2}. The ratio of HCl to HF column dropped from its typical midlatitude value of 4.5 to as low as 1.7 within the vortex, implying that the HCl had been chemically or physically removed from the air in the vortex. NO{sub 2} values within the vortex were near 3.0{times}10{sup 14} molecules-cm{sup {minus}2}, about a factor of two less than columns outside. In contrast to the Antarctic observations, HNO{sub 3} values were elevated within the vortex. HNO{sub 3} columns inside the vortex reached values of 30{times}10{sup 15} molecules-cm{sup {minus}2}. The ClONO{sub 2} column was largest within the vortex, peaking at 4{times}10{sup 15} molecules-cm{sup {minus}2} near the boundary of the vortex, and decreasing farther into the vortex.

Mankin, W.G.; Coffey, M.T.; Goldman, A. (National Center for Atmospheric Research, Boulder, CO (USA)); Schoeberl, M.R.; Lait, L.R.; Newman, P.A. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

1990-03-01

392

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

393

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

NASA Astrophysics Data System (ADS)

January 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

394

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

395

High bacterial diversity of biological soil crusts in water tracks over permafrost in the high arctic polar desert.  

PubMed

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

396

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

397

Environmental constraints on the growth, photosynthesis and reproductive development of Dryas octopetala at a high Arctic polar semi-desert, Svalbard  

Microsoft Academic Search

Opportunities exist in high Arctic polar semidesert communities for colonisation of unvegetated ground by long-lived clonal plants such as Dryas octopetala. This can be achieved by lateral spread of vegetative ramets, or by sexual reproduction and seedling recruitment. The objectives of this study were (1) to determine whether these two means of proliferation show differential sensitivity to contrasting components of

P. A. Wookey; C. H. Robinson; A. N. Parsons; J. M. Welker; T. V. Callaghan; J. A. Lee

1995-01-01

398

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

399

Arctic region Antarctica What are the differences between the two polar regions?  

E-print Network

phytoplankton get light 6.) Huge bloom of phytoplankton http://www.free-people-world.com/4/animals-world/wild #12;http://animals.nationalgeographic.com Arctic fox #12;Big mammals feed on small mammals... photo://www.windows.ucar.edu/tourlink=earthpolararctic_marine_life.jpg cod copepod microscopic algae (Pictures not to scale!) Which in turn feed on smaller animals... which

400

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

401

Stratospheric trace gas concentrations in the Arctic Polar night derived by FTIR-spectroscopy with the moon as IR light source  

SciTech Connect

This article reports measurements of column densities of trace gas concentrations within the polar vortex by means of an FTIR instrument using moon light as a light source. N[sub 2]O, CH[sub 4], HF, HCl, O[sub 3], NO[sub 2], HNO[sub 3], and ClONO[sub 2] were measured, and correlated with the observation of polar stratospheric clouds, which appeared at several times during the observation period.

Notholt, J.; Neuber, R.; Schrems, O.; Clarmann, T.V.

1993-10-08

402

Energetic particle induced inter-annual variability of ozone inside the Antarctic polar vortex observed in satellite data  

NASA Astrophysics Data System (ADS)

Measurements from 2002-2011 by three independent satellite instruments, namely MIPAS, SABER, and SMR on board the ENVISAT, TIMED, and Odin satellites are used to investigate the inter-annual variability of stratospheric and mesospheric O3 volume mixing ratio (vmr) inside the Antarctic polar vortex due to solar and geomagnetic activity. In this study, we individually analysed the relative O3 vmr variations between maximum and minimum conditions of a number of solar and geomagnetic indices (F10.7 cm solar radio flux, Ap index, ? 2 MeV electron flux). The indices are 26 day averages centred at 1 April, 1 May, and 1 June while O3 is based on 26 day running means from 1 April-1 November at altitudes from 20-70 km. During solar quiet time from 2005-2010, the composite of all three instruments reveals an apparent negative O3 feedback associated to the geomagnetic activity (Ap index) around 1 April, on average reaching amplitudes between -5 and -10% of the respective O3 background. The O3 response exceeds the significance level of 95% and propagates downwards throughout the polar winter from the stratopause down to ∼ 25 km. These observed results are in good qualitative agreement with the O3 vmr pattern simulated with a three-dimensional chemistry-transport model, which includes particle impact ionisation.

Fytterer, T.; Mlynczak, M. G.; Nieder, H.; Pérot, K.; Sinnhuber, M.; Stiller, G.; Urban, J.

2014-12-01

403

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.

Project Activities for Conceptualizing Climate and Climate Change

404

Heterogeneous formation of polar stratospheric clouds-nucleation of nitric acid trihydrate (NAT) in the arctic stratosphere  

NASA Astrophysics Data System (ADS)

Satellite based observations during the Arctic winter of 2009/2010 provide firm evidence that, in contrast to the current theory, the nucleation of nitric acid trihydrate (NAT) in the polar stratosphere does not only occur on preexisting ice particles. In order to explain the NAT clouds observed over the Arctic in mid December 2009, a heterogeneous nucleation mechanism is required, occurring on the surface of dust or meteoritic particles. For the first time, a detailed microphysical modelling of this NAT formation pathway has been carried out. Heterogeneous NAT formation was calculated along tens of thousands of trajectories, ending at Cloud Aerosol Lidar with Orthogonal Polarisation (CALIOP) observation points. Comparing the optical properties of the modelled NAT PSCs with these observations enables the thorough validation of a newly developed NAT nucleation parameterisation, which has been built into the Zurich Optical and Microphysical box Model (ZOMM). The parameterisation is based on active site theory and is simple to implement in models. It is shown that the new method is capable of reproducing observed PSCs very well, despite the varied conditions experienced by air parcels travelling along the different trajectories.

Hoyle, C. R.; Engel, I.; Luo, B. P.; Pitts, M. C.; Poole, L. R.; Grooß, J.-U.; Peter, T.

2013-05-01

405

Future Arctic temperature and ozone: The role of stratospheric composition changes  

NASA Astrophysics Data System (ADS)

Using multidecadal simulations with the European Centre/Hamburg-Modular Earth Submodel System Atmospheric Chemistry (EMAC) model, the role of changing concentrations of ozone-depleting substances (ODSs) and greenhouse gases (GHGs) on Arctic springtime ozone was examined. The focus is on potential changes in the meteorological conditions relevant for Arctic ozone depletion. It is found that with rising GHG levels the lower Arctic stratosphere will cool significantly in early winter, while no significant temperature signal is identified later in winter or spring. A seasonal shift of the lowest polar minimum temperatures from late to early winter in the second part of the 21st century occurs. However, Arctic lower stratosphere temperatures do not seem to decline to new record minima. The future Arctic lower stratosphere vortex will have a longer lifetime, as a result of an earlier formation in autumn. No extended vortex persistence is found in spring due to enhanced dynamical warming by tropospheric wave forcing. Because of the dominant early winter cooling, largest accumulated polar stratospheric cloud (PSC) areas (APSC) are projected for the middle of the 21st century. A further increase of APSC toward the end of the 21st century is prevented by increased dynamical polar warming. EMAC suggests that in the near future, there is a chance of low Arctic springtime ozone in individual years; however, there is no indication of a formation of regular Arctic ozone holes. Toward the end of the 21st century, when ODSs will be close to the 1960 levels, further rising GHG levels will cause increased Arctic springtime ozone.

Langematz, Ulrike; Meul, Stefanie; Grunow, Katja; Romanowsky, Erik; Oberländer, Sophie; Abalichin, Janna; Kubin, Anne

2014-03-01

406

Radiative effects of polar stratospheric clouds during the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition  

NASA Technical Reports Server (NTRS)

Results are presented of a study of the radiative effects of polar stratospheric clouds during the Airborne Antarctic Ozone Experiment (AAOE) and the Airborne Arctic Stratospheric Expedition (AASE) in which daily 3D Type I nitric acid trihydrate (NAT) and Type II water ice polar stratospheric clouds (PSCs) were generated in the polar regions during AAOE and the AASE aircraft missions. Mission data on particular composition and size, together with NMC-analyzed temperatures, are used. For AAOE, both Type I and Type II clouds were formed for the time period August 23 to September 17, after which only Type I clouds formed. During AASE, while Type I clouds were formed for each day between January 3 and February 10, Type II clouds formed on only two days, January 24 and 31. Mie theory and a radiative transfer model are used to compute the radiative heating rates during the mission periods, for clear and cloudy lower sky cases. Only the Type II water ice clouds have a significant radiative effect, with the Type I NATO PSCs generating a net heating or cooling of 0.1 K/d or less.

Rosenfield, Joan E.

1992-01-01

407

Lidar observations of Arctic polar stratospheric clouds, 1988 - Signature of small, solid particles above the frost point  

NASA Technical Reports Server (NTRS)

The paper presents recent (January 1988) Arctic airborne lidar data which suggest that Type I polar stratospheric clouds (PSCs) are composed of small solid particles with radii on the order of 0.5 micron. PSCs were observed remotely in the 21-24 km altitude range north of Greenland during a round-trip flight from Andenes, Norway on January 29, 1988, aboard the NASA Wallops Flight Facility P-3 Orion aircraft. Synoptic analyses at the 30-mb level show local temperatures of 191-193 K, which are well above the estimated frost point temperature of 185 K; this suggests that the PSCs were probably of the binary HNO3-H2O (Type I) class.

Poole, L. R.; Osborn, M. T.; Hunt, W. H.

1988-01-01

408

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

409

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

410

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

411

Cassini ISS Observations Of The Early Stages Of The Formation Of Titan's South Polar Hood And Vortex In 2012  

NASA Astrophysics Data System (ADS)

Northern spring equinox on Titan occurred on August 11, 2009. In March of 2012 the Imaging Science Subsystem (ISS) on the Cassini spacecraft saw the first evidence for the formation of a polar hood in the atmosphere above Titan’s south pole. Views of the limb showed an optical thickening primarily at about 360 km altitude across a few degrees of latitude centered on the pole. Images of Titan in front of Saturn provide a nearly direct measure of the line-of-sight optical depth as a function of latitude and altitude from about 250 km and higher. Two or more distinct layers are seen, both near the pole and at other latitudes. The highest of these, near 360 km altitude, hosts the embryonic polar hood. On June 27, 2012 ISS observed the pole from high latitude. These images show a distinct and unusual cloudy patch, elongated and not centered on the pole and with an elevated perimeter. The morphology and color indicate an unfamiliar (for Titan) composition and dynamical regime. The interior of the feature consists of concentrations of cloud/haze organized on spatial scales of tens of kilometers. Its morphology is reminiscent of the open cellular convection sometimes seen in the atmospheric boundary layer over Earth’s oceans under conditions of large-scale subsidence. Unlike Earth, where such convection is forced by large surface heat fluxes or the onset of drizzle, convection at 360 km on Titan is more likely to be driven from above by radiative cooling. During the 9 hours we observed Titan, this feature completed a little over one rotation around the pole, providing direct evidence for a polar vortex rotating at a rate roughly consistent with angular-momentum-conserving flow for air displaced from the equator. Part of this work was performed by the Jet Propulsion Laboratory, California Institute of Technology.

West, Robert A.; Del Genio, A.; Perry, J.; Ingersoll, A. P.; Turtle, E. P.; Porco, C.; Ovanessian, A.

2012-10-01

412

The Martian polar vortex - Theory of seasonal variation and observations of eolian features  

NASA Technical Reports Server (NTRS)

Observations of eolian features in the south polar region of Mars show strikingly axisymmetric patterns. The paper presents an explanation for the patterns in terms of the simplest dynamical model possible. Piraglia's (1975) model is simplified by neglecting compressibility and by assuming a cylindrical rather than spherical geometry, but this model is extended by including the nonlinear transport terms (of order Rossby number) and the seasonal mass transfer terms. The proposed model is therefore focused on determining the surface stress in polar regions rather than the atmospheric structure. The model is described, the parameter values are discussed, and the solutions are compared with observations. It is shown that the model predicts seasonal behavior which can be divided into four periods: formation of the south polar cap, its maximum extent, sublimation, and absence.

French, R. G.; Gierasch, P. J.

1979-01-01

413

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

414

The Arctic Coastal Plain, Alaska  

NSDL National Science Digital Library

This tutorial is about the Arctic tundra biome; the plants and animals found there; and the amount of sunlight, temperatures, seasons and permafrost. Examples of Arctic ecosystem interactions, food chains, and biological adaptations to the Arctic Coastal Plain are given. There are photographs of wolves, caribou, arctic hares, minks, lemmings, arctic foxes, polar bears, seals, walruses, ptarmigans, hawks, and owls. Definitions of ecosystem terms can be found by clicking on the term within the tutorial.

415

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

416

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

PubMed

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%. PMID:17164851

Hegedüs, Ramón; Akesson, Susanne; Horváth, Gábor

2007-01-01

417

Balloon borne observations of PSCs, Frost Point, ozone and nitric acid in the north polar vortex  

Microsoft Academic Search

A new balloon borne instrument called a backscattersonde has been used to study Polar Stratospheric Clouds (PSCs) at Alert, NWT (82°N, 61.5°W) during January and February of 1989. These measurements were supplemented with frost point, ozone and nitric acid vapor soundings. Type I PSCs were observed at temperatures and pressures generally consistent with present vapor pressure models of HNOâ\\/HâO condensate,

James M. Rosen; S. J. Oltmans; W. F. Evans

1989-01-01

418

The polar bear in the room: diseases of poverty in the Arctic.  

PubMed

In the face of global warming, budgetary austerity and impoverished Arctic residents, the nations of the circumpolar region are presented with a number of difficult choices regarding the provision of health care to the far-flung and isolated regions of their northernmost provinces. Complicating that picture is the reality of neglected tropical diseases in areas far from their perceived normal equatorial range as well as endemic food-borne diseases, including protozoan and helminth parasites, respiratory and gastrointestinal diseases and vaccine-preventable illnesses. This paper discusses the problems of caring for the health and well-being of indigenous populations suffering from extreme poverty, isolation and discrimination in the circumpolar region. After presenting difficulties as supported by the extant literature, the paper continues by suggesting solutions that include novel telenursing applications, targeted distance-educational programs and local community-based health care assistant (HCA) vocational training. These programs will provide cost-effective care that increases life-spans, improves quality of life and provides opportunities to distressed populations in isolated rural communities of the Far North. The toolkit presented in the paper is intended to spur discussion on community health programs that could be adopted to provide proper and humane care for marginalized Arctic populations in an extreme and rapidly changing environment. PMID:23984296

Nelson, Chris

2013-01-01

419

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

2010-07-09

420

The polar bear in the room: diseases of poverty in the Arctic  

PubMed Central

In the face of global warming, budgetary austerity and impoverished Arctic residents, the nations of the circumpolar region are presented with a number of difficult choices regarding the provision of health care to the far-flung and isolated regions of their northernmost provinces. Complicating that picture is the reality of neglected tropical diseases in areas far from their perceived normal equatorial range as well as endemic food-borne diseases, including protozoan and helminth parasites, respiratory and gastrointestinal diseases and vaccine-preventable illnesses. This paper discusses the problems of caring for the health and well-being of indigenous populations suffering from extreme poverty, isolation and discrimination in the circumpolar region. After presenting difficulties as supported by the extant literature, the paper continues by suggesting solutions that include novel telenursing applications, targeted distance-educational programs and local community-based health care assistant (HCA) vocational training. These programs will provide cost-effective care that increases life-spans, improves quality of life and provides opportunities to distressed populations in isolated rural communities of the Far North. The toolkit presented in the paper is intended to spur discussion on community health programs that could be adopted to provide proper and humane care for marginalized Arctic populations in an extreme and rapidly changing environment. PMID:23984296

Nelson, Chris

2013-01-01

421

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 intracellul