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1

Warming Arctic, weakening polar vortex and winter cooling  

NASA Astrophysics Data System (ADS)

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

Alexeev, Vladimir; Esau, Igor; Outten, Stephen

2014-05-01

2

Arctic Vortex  

... about 650 kilometers northeast of Iceland in the north Atlantic Ocean. Jan Mayen's Beerenberg volcano rises about 2.2 kilometers above ... Arctic Vortex location:  Arctic Ocean Atlantic Ocean thumbnail:  ...

2013-06-26

3

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

4

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

5

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

6

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

7

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

8

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

9

Model calculations of ozone depletion in the Arctic Polar Vortex for 1991/92 to 1994/95  

NASA Astrophysics Data System (ADS)

We have used a 3D chemical transport model to investigate the potential for chemical ozone depletion in the Arctic polar vortex for the past 4 winters. By using the same chemical initial conditions for each winter we have isolated the effects of meteorological variability on polar ozone loss. These calculations show that during 1994/95 conditions in the Arctic polar vortex were the most conducive to ozone depletion in recent years. Our numerical experiments show that at 475 K (around 18 km) in the lower stratosphere the chemical ozone destruction between late December and mid March was greater than 30% over a large area of the polar vortex. Larger percentage losses, reaching 50%, occur at slightly lower altitudes. The average model depletion in the entire region poleward of 60°N over the same period was around 22% at 475 K. Similar calculations for the preceding three Arctic winters show less depletion. The large depletion for 1994/95 is a consequence of the extreme meteorological conditions during this winter.

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

10

Model studies of chlorine deactivation and formation of ClONO 2 collar in the Arctic polar vortex  

Microsoft Academic Search

We have investigated the processes which lead to the deactivation of active chlorine (C10 + 2C1202) and the formation of C1ONO2 in and around the Arctic polar vortex. By using a range of three-dimensional and trajectory models, forced by meteorological analyses for the 1991\\/1992 winger, we have been able to separate processes associated with the model formulation and resolution, from

M. P. Chipperfield; E. R. Lutman; J. A. Kettleborough; J. A. Pyle; A. E. Roche

1997-01-01

11

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

12

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

13

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

14

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

15

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

16

Observation of O3, HCl, ClO, and HOCl by ISS/JEM/SMILES inside and outside Arctic Polar Vortex during 2009-2010 Winter  

NASA Astrophysics Data System (ADS)

JEM/SMILES instrument has been in operation from Oct. 12, 2009 to Apr. 21, 2010 on the International Space Station. SMILES observed limb emission in the frequency region 625 and 650 GHz with 0.8 MHz sampling, and it can provide vertical profiles of O3, HCl, ClO, HOCl, HO2, BrO, HNO3, CH3CN and O3 isotopes. SMILES use 4K cooled SIS mixer which has very low noise (Tsys ~ 340 K), and SMILES L2 products should have significantly smaller random error for species such as ClO and HOCl compared to the previous measurements. This paper reports interpretation of chemistry at inside and outside Arctic polar vortex during 2009-2010 winter season based upon O3, HCl, ClO, and HOCl observation by SMILES.

Suzuki, M.; Mitsuda, C.; Manago, N.; Imai, K.; Naito, Y.; Hayashi, H.; Takahashi, K.; Shiotani, M.

2011-12-01

17

Polar cap mesopause dynamics during a calm polar vortex season  

NASA Astrophysics Data System (ADS)

Measurements of mesopause region winds are reported using a ground based Michelson interferometer stationed under the Arctic polar cap. Time series of the measurements are analyzed during a relatively calm polar vortex season, in the absence of major stratospheric warming events. Variability of winds is analyzed for tidal, planetary and gravity wave signatures, and compared to the state of the stratospheric vortex derived from assimilated data. The results are interpreted in terms of degree of vertical coupling of the upper stratosphere and the mesopause.

Bhattacharya, Y.; Gerrard, A.

2008-12-01

18

Ozone depletion in the Arctic vortex at Alert during February 1989  

Microsoft Academic Search

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.

W. F. J. Evans; W. F. J

1990-01-01

19

Four Fourier transform spectrometers and the Arctic polar vortex: instrument intercomparison and ACE-FTS validation at Eureka during the IPY springs of 2007 and 2008  

NASA Astrophysics Data System (ADS)

The Canadian Arctic Atmospheric Chemistry Experiment Validation Campaigns have been carried out at Eureka, Nunavut (80.05° N, 86.42° W) during the polar sunrise period since 2004. During the International Polar Year (IPY) springs of 2007 and 2008, three ground-based Fourier transform infrared (FTIR) spectrometers were operated simultaneously. This paper presents a comparison of trace gas measurements of stratospherically important species involved in ozone depletion, namely O3, HCl, ClONO2, HNO3 and HF, recorded with these three spectrometers. Total column densities of the gases measured with the new Canadian Network for the Detection of Atmospheric Change (CANDAC) Bruker 125HR are shown to agree to within 3.5% with the existing Environment Canada Bomem DA8 measurements. After smoothing both of these sets of measurements to account for the lower spectral resolution of the University of Waterloo Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the measurements were likewise shown to agree with PARIS-IR to within 7%. Concurrent measurements of these gases were also made with the satellite-based Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) during overpasses of Eureka during these time periods. While one of the mandates of the ACE satellite mission is to study ozone depletion in the polar spring, previous validation exercises have identified the highly variable polar vortex conditions of the spring period to be a challenge for validation efforts. In this work, comparisons between the CANDAC Bruker 125HR and ACE-FTS have been used to develop strict criteria that allow the ground- and satellite-based instruments to be confidently compared. When these criteria are taken into consideration, there is shown to be no significant bias between the ACE-FTS and ground-based FTIR spectrometer for any of these gases.

Batchelor, R. L.; Kolonjari, F.; Lindenmaier, R.; Mittermeier, R. L.; Daffer, W.; Fast, H.; Manney, G.; Strong, K.; Walker, K. A.

2009-11-01

20

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

21

Low-N2O Air Masses after the Breakdown of the Arctic Polar Vortex in 1997 Simulated by the CCSR\\/NIES Nudging CTM  

Microsoft Academic Search

Low-concentration N2O regions in high latitudes of the lower stratosphere were observed by the Improved Limb Atmospheric Spectrometer (ILAS) for one and half months after the Arctic vortex breakdown in May 1997. A new Chemical Transport Model (CTM), referred to as the CCSR\\/NIES nudging CTM, has been developed, and used to simulate these low-N2O air masses. The simulation shows that

Hideharu AKIYOSHI; Seiji SUGATA; Takafumi SUGITA; Hideaki NAKAJIMA; Hiroo HAYASHI; Jun-ichi KUROKAWA; Masaaki TAKAHASHI

2002-01-01

22

Four Fourier transform spectrometers and the Arctic polar vortex: instrument intercomparison and ACE-FTS validation at Eureka during the IPY springs of 2007 and 2008  

NASA Astrophysics Data System (ADS)

The Canadian Arctic Atmospheric Chemistry Experiment Validation Campaigns have been carried out at Eureka, Nunavut (80.05° N, 86.42° W) during the polar sunrise period since 2004. During the International Polar Year (IPY) springs of 2007 and 2008, three ground-based Fourier transform infrared (FTIR) spectrometers were operated simultaneously. This paper presents a comparison of trace gas measurements of stratospherically important species involved in ozone depletion, namely O3, HCl, ClONO2, HNO3 and HF, recorded with these three spectrometers. Total column densities of the gases measured with the new Canadian Network for the Detection of Atmospheric Change (CANDAC) Bruker 125HR are shown to agree to within 3.5% with the existing Environment Canada Bomem DA8 measurements. After smoothing both of these sets of measurements to account for the lower spectral resolution of the University of Waterloo Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the measurements were likewise shown to agree with PARIS-IR to within 7%. Concurrent measurements of these gases were also made with the satellite-based Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) during overpasses of Eureka during these time periods. While one of the mandates of the ACE satellite mission is to study ozone depletion in the polar spring, previous validation exercises have identified the highly variable polar vortex conditions of the spring period to be a challenge for validation efforts. In this work, comparisons between the CANDAC Bruker 125HR and ACE-FTS have been used to develop strict criteria that allow the ground- and satellite-based instruments to be confidently compared. When these criteria are taken into consideration, the observed biases between the ACE-FTS and ground-based FTIR spectrometer are not persistent for both years and are generally insignificant, though small positive biases of ~5%, comparable in magnitude to those seen in previous validation exercises, are observed for HCl and HF in 2007, and negative biases of -15.3%, -4.8% and -1.5% are seen for ClONO2, HNO3 and O3 in 2008.

Batchelor, R. L.; Kolonjari, F.; Lindenmaier, R.; Mittermeier, R. L.; Daffer, W.; Fast, H.; Manney, G.; Strong, K.; Walker, K. A.

2010-01-01

23

Quantifying Subsidence in the 1999-2000 Arctic Winter Vortex  

NASA Technical Reports Server (NTRS)

Quantifying the subsidence of the polar winter stratospheric vortex is essential to the analysis of ozone depletion, as chemical destruction often occurs against a large, altitude-dependent background ozone concentration. Using N2O measurements made during SOLVE on a variety of platforms (ER-2, in-situ balloon and remote balloon), the 1999-2000 Arctic winter subsidence is determined from N2O-potential temperature correlations along several N2O isopleths. The subsidence rates are compared to those determined in other winters, and comparison is also made with results from the SLIMCAT stratospheric chemical transport model.

Greenblatt, Jeffery B.; Jost, Hans-juerg; Loewenstein, Max; Podolske, James R.; Bui, T. Paul; Elkins, James W.; Moore, Fred L.; Ray, Eric A.; Sen, Bhaswar; Margitan, James J.; Hipskind, R. Stephen (Technical Monitor)

2000-01-01

24

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

25

Titan's South Polar Vortex in Motion  

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...

26

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

27

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

28

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

29

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

NASA Astrophysics Data System (ADS)

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 result 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.

Rosen, James M.; Kjome, N. T.; Fast, H.; Larsen, N.

1994-01-01

30

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

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

31

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

32

Middle-high latitude N2O distributions related to the arctic vortex breakup  

NASA Astrophysics Data System (ADS)

The relationship of N2O distributions with the Arctic vortex breakup is first analyzed with a probability distribution function (PDF) analysis. The N2O concentration shows different distributions between the early and late vortex breakup years. In the early breakup years, the N2O concentration shows low values and large dispersions after the vortex breakup, which is related to the inhomogeneity in the vertical advection in the middle and high latitude lower stratosphere. The horizontal diffusion coefficient (K,,) shows a larger value accordingly. In the late breakup years, the N2O concentration shows high values and more uniform distributions than in the early years after the vortex breakup, with a smaller vertical advection and K,, after the vortex breakup. It is found that the N2O distributions are largely affected by the Arctic vortex breakup time but the dynamically defined vortex breakup time is not the only factor.

Zhou, L. B.; Zou, H.; Gao, Y. Q.

2006-03-01

33

Venus Lightning Characteristics and Polar Vortex Correlation  

NASA Astrophysics Data System (ADS)

Venus Express started taking magnetic field measurements at periapsis in 2006. Since then it has consistently detected whistler-mode signals attributed to lightning. Most, if not all, of these are thought to be intercloud, intracloud, or upward-going lightning; the cloud deck on Venus is at an altitude of about 60 km and thus cloud-to-ground strikes are extremely unlikely. These bursts have peak-to-peak amplitudes of up to1.5 nT in the frequency range 42-60 Hz. They are transverse and right-hand circularly polarized with respect to the background magnetic field. When this field is close to 0 nT, the occurrence rate is very low; it rises sharply at 15-20 nT, then gradually dies off as the field strength further increases. There are very few bursts observed below 200 km; the occurrence rate peaks sharply around 215 km then slowly decreases with increasing altitudes. Burst amplitude distributions and averages are also in agreement with these findings. Between 80 and 90 degrees north latitude, the burst rate with respect to local time maximizes over the terminators. It has been suggested that a burst rate local maximum around 83 degrees north latitude can be attributed to the approximate edge of the polar vortex. We further examine this possibility within this study.

Daniels, J. T. M.; Russell, C. T.; Strangeway, R. J.; Zhang, T. L.

2011-10-01

34

Investigation of dynamical processes in the polar stratospheric vortex during the unusually cold winter 2004\\/2005  

Microsoft Academic Search

The 2004\\/2005 Arctic winter was unusually cold with high potential for Polar Stratospheric Clouds formation. We use O3 and N2O assimilated fields from Aura\\/MLS in order to describe the dynamical processes inside the polar vortex during this winter. The evolution of N2O assimilated field shows that subsidence was the dominant dynamical process between early December and late January. The mixing

L. El Amraoui; N. Semane; V.-H. Peuch; M. L. Santee

2008-01-01

35

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

36

Dynamical connection between tropospheric blockings and stratospheric polar vortex  

NASA Astrophysics Data System (ADS)

The dynamical connection between Northern Hemisphere blocking events and the variability of the stratospheric polar vortex strength is studied. The analysis is based on the composite time evolution of the energy of baroclinic planetary waves during regional blocking occurrence. During Euro-Atlantic blocking events, an in phase forcing of stationary zonal wavenumber 1 occurs. The enhanced wave amplitude is associated with a stratospheric polar vortex deceleration, which may result, at times, in Sudden Stratospheric Warming (SSW) events of displacement type. Pacific blocking composites reveal an in phase forcing of stationary zonal wavenumber 2. In most cases, the amplification of the wavenumber 2 does not reduce the vortex strength, being even accompanied by a mean vortex acceleration. However, if the amplification of wavenumber 2 is preceded by an amplification of wavenumber 1, the initial vortex deceleration forced by wavenumber 1 may be continued by wavenumber 2, and a SSW event of splitting type may occur.

Castanheira, J. M.; Barriopedro, D.

2010-07-01

37

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.

38

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

39

Chemical ozone loss in Arctic and Antarctic polar vortices derived from SCIAMACHY limb-scattered solar radiation  

NASA Astrophysics Data System (ADS)

Stratospheric ozone profiles are retrieved for the period 2002 -2009 from SCIAMACHY mea-surements of limb-scattered solar radiation in the Hartley and Chappuis absorption bands of ozone. This data set is used to determine the chemical ozone loss in both placeArctic and Antarctic polar vortices using the vortex average method. The chemical ozone loss at the 450 -600 K isentropic levels is derived from the difference between observed ozone abundances and the ozone modeled considering diabatic cooling, but no chemical ozone loss. At the 475 K isentropic level, the results show accumulated chemical ozone losses of up to 20 -40% be-tween the beginning of January and the end of March inside the Arctic polar vortex. Strong inter-annual variability of the Arctic ozone loss is observed, with the cold winters 2004/2005 and 2006/2007 showing the largest chemical ozone losses. The Antarctic vortex averaged ozone loss does not vary much from year to year. The ozone losses of 70 -80% between mid-August and mid-November are observed every year inside the vortex, also in the anomalous year 2002. However, because the variations in the size of the polar vortex lead to inter-annual changes in total ozone mass loss, the polar vortex size is determined and the total mass of ozone chemically lost inside the polar vortex is estimated. Comparisons of the vertical variation of ozone loss derived from SCIAMACHY observations with several independent techniques for the northern hemisphere winter 2004/2005 show very good agreement.

Sonkaew, Thiranan; von Savigny, Christian; Eichmann, Kai-Uwe; Weber, Mark; Rozanov, Alexei; Bovensmann, Heinrich; Burrows, John P.

40

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

41

Nighttime OClO in the Winter Arctic Vortex  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

42

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

43

Penetration of Mt. Pinatubo aerosols into the north polar vortex  

NASA Astrophysics Data System (ADS)

Observations of the Mount Pinatubo cloud as it moved northward and into the winter polar vortex were made with a balloon borne two-wavelength backscatter sonde. Some volcanic debris had arrived at far northerly latitudes below 20 km by October and was apparently incorporated into the initial vortex. Subsequent measurements did not show a significant increase in the central vortex aerosol until after a mid-January disturbance, at which time the backscatter profiles began to increase. Above 20 km and near the center of the vortex there was no significant increase in aerosol through mid-March. The column stratospheric aerosol mass loading as calculated from individual soundings at the wall of the vortex during March 1992 ranged from 18 to 24 megatonnes per unit area where the unit of area is that of the earth. This indicates that a significant amount of material was transported northward by the end of the winter.

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

1992-09-01

44

Investigation of dynamical processes in the polar stratospheric vortex during the unusually cold winter 2004/2005  

NASA Astrophysics Data System (ADS)

The 2004/2005 Arctic winter was unusually cold with high potential for Polar Stratospheric Clouds formation. We use O3 and N2O assimilated fields from Aura/MLS in order to describe the dynamical processes inside the polar vortex during this winter. The evolution of N2O assimilated field shows that subsidence was the dominant dynamical process between early December and late January. The mixing effect between the polar vortex and midlatitudes has been diagnosed using the effective diffusivity parameter. It shows that from early February to the end of March, mixing was dominant compared to diabatic descent. The vortex-averaged ozone loss profile from O3 assimilated field shows a maximum of ~1.5 ppmv at 425 K, which is less pronounced compared to other winters of similar meteorological conditions (e.g., 1999/2000). This is due to the importance of the mixing processes between the polar vortex and midlatitudes which bring in ozone-rich air to the vortex.

El Amraoui, L.; Semane, N.; Peuch, V.-H.; Santee, M. L.

2008-02-01

45

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

46

The 2009-2010 Arctic polar stratospheric cloud season: a CALIPSO perspective  

NASA Astrophysics Data System (ADS)

Spaceborne lidar measurements from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) are used to provide a vortex-wide perspective of the 2009-2010 Arctic polar stratospheric cloud (PSC) season to complement more focused measurements from the European Union RECONCILE (reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) field campaign. The 2009-2010 Arctic winter was unusually cold at stratospheric levels, especially from mid-December 2009 until the end of January 2010, and was one of only a few winters from the past 52 years with synoptic-scale regions of temperatures below the frost point. More PSCs were observed by CALIPSO during the 2009-2010 Arctic winter than in the previous three Arctic seasons combined. In particular, there were significantly more observations of high number density nitric acid trihydrate (NAT) mixtures (referred to as Mix 2-enh) and ice PSCs. We found that the 2009-2010 season could roughly be divided into four periods with distinctly different PSC optical characteristics. The early season (15-30 December 2009) was characterized by patchy, tenuous PSCs, primarily low number density liquid/NAT mixtures. The second phase of the season (31 December 2009-14 January 2010) was characterized by frequent mountain wave ice clouds that nucleated widespread NAT particles throughout the vortex, including Mix 2-enh. The third phase of the season (15-21 January 2010) was characterized by synoptic-scale temperatures below the frost point which led to a rare outbreak of widespread ice clouds. The fourth phase of the season (22-28 January) was characterized by a major stratospheric warming that distorted the vortex, displacing the cold pool from the vortex center. This final phase was dominated by supercooled ternary solution (STS) PSCs, although NAT particles may have been present in low number densities, but were masked by the more abundant STS droplets at colder temperatures. We also found distinct variations in the relative proportion of PSCs in each composition class with altitude over the course of the 2009-2010 Arctic season. Lower number density liquid/NAT mixtures were most frequently observed in the lower altitude regions of the clouds (below ∼18-20 km), which is consistent with CALIPSO observations in the Antarctic. Higher number density liquid/NAT mixtures, especially Mix 2-enh, were most frequently observed at altitudes above 18-20 km, primarily downstream of wave ice clouds. This pattern is consistent with the conceptual model whereby low number density, large NAT particles are precipitated from higher number density NAT clouds (i.e. mother clouds) that are nucleated downstream of mountain wave ice clouds.

Pitts, M. C.; Poole, L. R.; Dörnbrack, A.; Thomason, L. W.

2010-10-01

47

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

48

Tight focusing of axially symmetric polarized vortex beams  

NASA Astrophysics Data System (ADS)

Tight focusing of axially symmetric polarized vortex beams is studied numerically based on vector diffraction theory. The mathematical expressions for the focused fields are derived. Simulation results show that the focused fields and phase distributions at focus are largely influenced by both the polarization order and topological charge of the incident beams. Moreover, focal spots with flat-topped or tightly-focused patterns can be flexibly achieved by carefully choosing the polarization order and the topological charge, which confirms the potential of such beams in wide applications, such as optical tweezers, laser printing, lithography, and material processing.

Zhou, Zhe-Hai; Guo, Yang-Kuan; Zhu, Lian-Qing

2014-04-01

49

MIPAS-B observations inside a weak Arctic vortex in late winter 2009 compared to EMAC simulations  

Microsoft Academic Search

According to statistical relationships involving the Quasi-Biennual Oscillation and the sunspot cycle the winter 2008\\/2009 should have been characterized by a cold and stable Arctic stratospheric vortex. In contrast, a major midwinter warming with record-breaking temperatures developed in January and February. Subsequently, the vortex did only recover to weak strength in March and April. Arctic stratospheric limb emission spectra were

Gerald Wetzel; Hermann Oelhaf; Oliver Kirner; Roland Ruhnke; Felix Friedl-Vallon; Anne Kleinert; Guido Maucher; Hans Nordmeyer

2010-01-01

50

Polar Vortex Variability in the CMIP5 Models  

NASA Astrophysics Data System (ADS)

Variability in the wintertime stratospheric polar vortex is dominated by annular modes that have important influence on tropospheric climate and surface weather patterns. This variability is dominated by variations in the strength of the polar vortex and is represented by the stratospheric Northern Annular Mode (SNAM). The second mode, designated the Polar Annular Mode (PAM), represents variability in the North-South location of the vortex. The ability of state-of-the-art climate models to accurately represent these modes is crucial in accurately simulating variability in the stratosphere and stratosphere-troposphere interactions. To assess the veracity of stratospheric simulations in current models, a suite of runs from different members of the CMIP5 experiment are analyzed. The climatological winter stratosphere for each model is calculated and the strength and location of the polar vortex are compared with observations. Principal component analyses of daily stratospheric zonally averaged zonal winds from the historical scenario are then employed with the first principal component characterizing the SNAM and the second representing the PAM. For each model, the latitudinal structure of the spatial pattern and the relative variance explained for each mode are calculated and compared to observations. In addition, long-term trends in the principal component timeseries and preferred timescales of each mode and model are examined. Finally, models are binned into "high-top" and "low-top" categories based on the degree of resolution of the stratosphere. High-top and low-top averages are calculated to test for biases in the ability to accurately simulate observed stratospheric variability among models with different vertical resolutions.

McDaniel, B.

2012-12-01

51

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

52

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

NASA Astrophysics Data System (ADS)

The sedimentation of HNO3 containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO3 and thus to a denitrification of the stratosphere, an effect which plays an important 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 denitrification was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR) which was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001-2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet för Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. 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. From the temperature history of the trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below Tice. Using the box model simulations along backward trajectories together with the observations of Odin/SMR, CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible mechanism that caused denitrification during the Arctic winter 2009/2010.

Khosrawi, F.; Urban, J.; Pitts, M. C.; Voelger, P.; Achtert, P.; Kaphlanov, M.; Murtagh, D.; Fricke, K.-H.

2011-04-01

53

Influence of Arctic polar ozone depletion on lower stratospheric ozone amounts at Haute-Provence Observatory (43.92°N, 5.71°E)  

NASA Astrophysics Data System (ADS)

Lidar and ozone sonde measurements performed at Haute-Provence Observatory are used together with a high-resolution potential vorticity (PV) transport model to study the influence of Arctic polar vortex ozone depletion on ozone amounts at this location prior to vortex dilution. The study focuses on four Arctic winters from 1996 to 2000. The transport model is used to investigate the presence of polar air masses above the station. These air masses, which are characterized by high PV values, can extend toward midlatitude regions during winter. Polar air masses are detected using a daily threshold value defined from the PV fields. The monthly average fraction of polar air generally increases with altitude from a few percent in the lower stratosphere to 10% or more above 500 K. The source of presence of polar air is largely dominated by filament events in the lower stratosphere and is equally divided between filaments and vortex excursions above the station in the middle stratosphere. The presence of polar air above the station shows high interannual variability. In the winter of 1999/2000 the least amount of polar air was detected above the station. However, vortex excursions above the station from January to March 2000 led to a significant average ozone reduction, estimated to 1.6% in the 400-650 K potential temperature range using a chemical transport model (CTM) evaluation of ozone loss at the vortex edge. Cold vortex, such as observed in 1999/2000, results in less transport toward midlatitude, but strong ozone depletion within the vortex combined with transient excursions of polar air can have a significant impact on ozone amounts in the midlatitude regions.

Godin, S.; Marchand, M.; Hauchecorne, A.; LefèVre, F.

2002-10-01

54

Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B inside the January 2010 Arctic vortex  

NASA Astrophysics Data System (ADS)

The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx). In order to assess the capacities of state-of-the-art chemistry models to predict polar stratospheric chemistry, stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change quickly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to shadowing of the lower stratosphere by upper tropospheric and polar stratospheric clouds. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (close to zero) of its reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are fairly well reproduced by the model during photochemical equilibrium. However, since the model assumes cloudless illumination, simulated concentration changes around sunrise start earlier but less quickly compared to the observed variation of the species concentration.

Wetzel, G.; Oelhaf, H.; Friedl-Vallon, F.; Kirner, O.; Kleinert, A.; Maucher, G.; Nordmeyer, H.; Orphal, J.; Ruhnke, R.

2012-02-01

55

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.

56

Polar vortex oscillation viewed in an isentropic potential vorticity coordinate  

NASA Astrophysics Data System (ADS)

The stratospheric polar vortex oscillation (PVO) in the Northern Hemisphere is examined in a semi-Lagrangian ?-PVLAT coordinate constructed by using daily isentropic potential vorticity maps derived from NCEP/NCAR reanalysis II dataset covering the period from 1979 to 2003. In the semi-Lagrangian ?-PVLAT coordinate, the variability of the polar vortex is solely attributed to its intensity change because the changes in its location and shape would be naturally absent by following potential vorticity contours on isentropic surfaces. The EOF and regression analyses indicate that the PVO can be described by a pair of poleward and downward propagating modes. These two modes together account for about 82% variance of the daily potential vorticity anomalies over the entire Northern Hemisphere. The power spectral analysis reveals a dominant time scale of about 107 days in the time series of these two modes, representing a complete PVO cycle accompanied with poleward propagating heating anomalies of both positive and negative signs from the equator to the pole. The strong polar vortex corresponds to the arrival of cold anomalies over the polar circle and vice versa. Accompanied with the poleward propagation is a simultaneous downward propagation. The downward propagation time scale is about 20 days in high and low latitudes and about 30 days in mid-latitudes. The zonal wind anomalies lag the poleward and downward propagating temperature anomalies of the opposite sign by 10 days in low and high latitudes and by 20 days in mid-latitudes. The time series of the leading EOF modes also exhibit dominant time scales of 8.7, 16.9, and 33.8 months. They approximately follow a double-periodicity sequence and correspond to the 3-peak extratropical Quasi-Biennial Oscillation (QBO) signal.

Ren, Rongcai; Cai, Ming

2006-12-01

57

Highly mobile vortex structures inside polar twin boundaries in SrTiO3  

NASA Astrophysics Data System (ADS)

We present computer simulations of previously unknown polarization singularities (vortexes) inside polar SrTiO3 twin boundaries. Usually polarity in twin walls is ferri-electric, whereas vortex excitations lead to true ferroelectricity on a very local scale. As a result, in-plane electric fields can selectively stabilize one of the vortex polarization states and enhance the ability of the walls to move. This behavior can explain the well-known and uniquely high, mobility of twin boundaries in SrTiO3. For nanoscale ferroelectric memory devices, we envisage a precisely controllable device, where a desired domain wall pattern is manipulated by shifting the vortex position electrically.

Zykova-Timan, Tatyana; Salje, Ekhard K. H.

2014-02-01

58

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

59

Polarity-Dependent Vortex Pinning and Spontaneous Vortex-Antivortex Structures in Superconductor/Ferromagnet Hybrids  

NASA Astrophysics Data System (ADS)

Hybrid structures composed of superconducting films that are magnetically coupled to arrays of nanoscale ferromagnetic dots have attracted enormous interest in recent years. Broadly speaking, such systems fall into one of two distinct regimes. Ferromagnetic dots with weak moments pin free vortices, leading to enhanced superconducting critical currents, particularly when the conditions for commensurability are satisfied. Dots with strong moments spontaneously generate one or more vortex-antivortex (V-AV) pairs which lead to a rich variety of pinning, anti-pinning and annihilation phenomena. We describe high resolution Hall probe microscopy of flux structures in various hybrid samples composed of superconducting Pb films deposited on arrays of ferromagnetic Co or Co/Pt dots with both weak and strong moments. We show directly that dots with very weak perpendicular magnetic moments do not induce vortex-antivortex pairs, but still act as strong polarity-dependent vortex pinning centres for free vortices. In contrast, we have directly observed spontaneous V-AV pairs induced by large moment dots with both in-plane and perpendicular magnetic anisotropy, and studied the rich physical phenomena that arise when they interact with added "free" (anti)fluxons in an applied magnetic field. The interpretation of our imaging results is supported by bulk magnetometry measurements and state-of-the-art Ginzburg-Landau and London theory calculations.

Bending, Simon J.; Miloševi?, Milorad V.; Moshchalkov, Victor V.

60

The polarization effect in the optical vortex interferometer  

NASA Astrophysics Data System (ADS)

The optical vortices were intensively studied during last decade. In the literature there are papers presenting application of the optical vortices. The regular net of optical vortices generated by the three plane waves interference allows for the new kind of the interferometer - the Optical Vortex Interferometer (OVI). The precision of the OVI depends on the localization accuracy and the phase reconstruction. The localization methods give errors if we use beamsplitters with coatings changing the polarization state of the light. There are six beamsplitters used in this interferometer. In the setup we used non-polarizing coatings. We observed pleochroism effect, which occurs in these coatings. It is the cause of errors in the localization of optical vortices. In this paper we study the effect of pleochroism and we show the way to avoid errors in the localization of optical vortices in the OVI.

Fr?czek, Ewa; Wo?niak, W?adys?aw

2006-03-01

61

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

62

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

63

On the Role of the Arctic Ocean in Polar Amplification  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

64

A quantitative measure of polar vortex strength using the function M  

NASA Astrophysics Data System (ADS)

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

Smith, Madeleine L.; McDonald, Adrian J.

2014-05-01

65

The 2009-2010 Arctic polar stratospheric cloud season: a CALIPSO perspective  

NASA Astrophysics Data System (ADS)

Spaceborne lidar measurements from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) are used to provide a vortex-wide perspective of the 2009-2010 Arctic PSC (polar stratospheric cloud) season to complement more focused measurements from the European Union RECONCILE (reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions) field campaign. The 2009-2010 Arctic winter was unusually cold at stratospheric levels from mid-December 2009 until the end of January 2010, and was one of only a few winters from the past fifty-two years with synoptic-scale regions of temperatures below the frost point. More PSCs were observed by CALIPSO during the 2009-2010 Arctic winter than in the previous three Arctic seasons combined. In particular, there were significantly more observations of high number density NAT (nitric acid trihydrate) mixtures (referred to as Mix 2-enh) and ice PSCs. We found that the 2009-2010 season could roughly be divided into four periods with distinctly different PSC optical characteristics. The early season (15-30 December 2009) was characterized by patchy, tenuous PSCs, primarily low number density liquid/NAT mixtures. No ice clouds were observed by CALIPSO during this early phase, suggesting that these early season NAT clouds were formed through a non-ice nucleation mechanism. The second phase of the season (31 December 2009-14 January 2010) was characterized by frequent mountain wave ice clouds that nucleated widespread NAT particles throughout the vortex, including Mix 2-enh. The third phase of the season (15-21 January 2010) was characterized by synoptic-scale temperatures below the frost point which led to a rare outbreak of widespread ice clouds. The fourth phase of the season (22-28 January) was characterized by a major stratospheric warming that distorted the vortex, displacing the cold pool from the vortex center. This final phase was dominated by STS (supercooled ternary solution) PSCs, although NAT particles may have been present in low number densities, but were masked by the more abundant STS droplets at colder temperatures. We also found distinct variations in the relative proportion of PSCs in each composition class with altitude over the course of the 2009-2010 Arctic season. Lower number density liquid/NAT mixtures were most frequently observed in the lower altitude regions of the clouds (below ~18-20 km), which is consistent with CALIPSO observations in the Antarctic. Higher number density liquid/NAT mixtures, especially Mix 2-enh, were most frequently observed at altitudes above 18-20 km, primarily downstream of wave ice clouds. This pattern is consistent with the conceptual model whereby low number density, large NAT particles are precipitated from higher number density NAT clouds (i.e. mother clouds) that are nucleated downstream of mountain wave ice clouds.

Pitts, M. C.; Poole, L. R.; Dörnbrack, A.; Thomason, L. W.

2011-03-01

66

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

67

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

68

Diurnal variations of reactive chlorine and nitrogen oxides observed by MIPAS-B inside the January 2010 Arctic vortex  

NASA Astrophysics Data System (ADS)

The winter 2009/2010 was characterized by a strong Arctic vortex with extremely cold mid-winter temperatures in the lower stratosphere associated with an intense activation of reactive chlorine compounds (ClOx) from reservoir species. Stratospheric limb emission spectra were recorded during a flight of the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) from Kiruna (Sweden) on 24 January 2010 inside the Arctic vortex. Several fast limb sequences of spectra (in time steps of about 10 min) were measured from nighttime photochemical equilibrium to local noon allowing the retrieval of chlorine- and nitrogen-containing species which change rapidly their concentration around the terminator between night and day. Mixing ratios of species like ClO, NO2, and N2O5 show significant changes around sunrise, which are temporally delayed due to polar stratospheric clouds reducing the direct radiative flux from the sun. ClO variations were derived for the first time from MIPAS-B spectra. Daytime ClO values of up to 1.6 ppbv are visible in a broad chlorine activated layer below 26 km correlated with low values (below 0.1 ppbv) of the chlorine reservoir species ClONO2. Observations are compared and discussed with calculations performed with the 3-dimensional Chemistry Climate Model EMAC (ECHAM5/MESSy Atmospheric Chemistry). Mixing ratios of the species ClO, NO2, and N2O5 are well reproduced by the model during night and noon. However, the onset of ClO production and NO2 loss around the terminator in the model is not consistent with the measurements. The MIPAS-B observations along with Tropospheric Ultraviolet-Visible (TUV) radiation model calculations suggest that polar stratospheric clouds lead to a delayed start followed by a faster increase of the photodissoziation of ClOOCl and NO2 near the morning terminator since stratospheric clouds alter the direct and the diffuse flux of solar radiation. These effects are not considered in the EMAC model simulations which assume a cloudless atmosphere.

Wetzel, G.; Oelhaf, H.; Kirner, O.; Friedl-Vallon, F.; Ruhnke, R.; Ebersoldt, A.; Kleinert, A.; Maucher, G.; Nordmeyer, H.; Orphal, J.

2012-07-01

69

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

70

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

71

Interannual variability of the winter stratospheric polar vortex in the Northern Hemisphere and their relations to QBO and ENSO  

Microsoft Academic Search

We investigated the interannual variations of the winter stratospheric polar vortex in this paper. EOF analysis shows that\\u000a two modes of variability dominate the stratospheric polar vortex on interannual timescales. The leading mode (EOF1) reflects\\u000a the intensity variation of the polar vortex and is characterized by a geopotential height seesaw between the polar region\\u000a and the mid-latitudes. The second one

Wen Chen; Ke Wei

2009-01-01

72

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

NASA Astrophysics Data System (ADS)

The sedimentation of HNO3 containing Polar Stratospheric Cloud (PSC) particles leads to a permanent removal of HNO3 and thus to a denitrification of the stratosphere, an effect which plays an important 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 denitrification between 475 to 525 K was observed in the Arctic in mid of January by the Odin Sub Millimetre Radiometer (Odin/SMR). This was the strongest denitrification that had been observed in the entire Odin/SMR measuring period (2001-2010). Lidar measurements of PSCs were performed in the area of Kiruna, Northern Sweden with the IRF (Institutet för Rymdfysik) lidar and with the Esrange lidar in January 2010. The measurements show that PSCs were present over the area of Kiruna during the entire period of observations. 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. From the temperature history of the backward trajectories and the box model simulations we find two PSC regions, one over Kiruna according to the measurements made in Kiruna and one north of Scandinavia which is much colder, reaching also temperatures below Tice. Using the box model simulations along backward trajectories together with the observations of Odin/SMR, Aura/MLS (Microwave Limb Sounder), CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and the ground-based lidar we investigate how and by which type of PSC particles the denitrification that was observed during the Arctic winter 2009/2010 was caused. From our analysis we find that due to an unusually strong synoptic cooling event in mid January, ice particle formation on NAT may be a possible formation mechanism during that particular winter that may have caused the denitrification observed in mid January. In contrast, the denitrification that was observed in the beginning of January could have been caused by the sedimentation of NAT particles that formed on mountain wave ice clouds.

Khosrawi, F.; Urban, J.; Pitts, M. C.; Voelger, P.; Achtert, P.; Kaphlanov, M.; Santee, M. L.; Manney, G. L.; Murtagh, D.; Fricke, K.-H.

2011-08-01

73

OMAE 1996 -- Proceedings of the 15. international conference on offshore mechanics and arctic engineering. Volume 4: Arctic/polar technology  

SciTech Connect

Volume 4 contains papers on the following topics: arctic/polar technology and development; ice properties; ice engineering; applied ice mechanics; ice-structure interaction; arctic structures and operations; frozen soil properties; and Russian Arctic development. In addition to the regular topics covered in OMAE conferences, there has been a special workshop as part of this year`s conference. In keeping with issues of current interest, there is a workshop on development of oil resources in the Russian Arctic. Over two days, papers dealing with development of oil and gas resources in the Russian Arctic are presented. Volume 4 contains papers from this workshop. Some of the papers have been processed separately for inclusion on the data base.

Nixon, W.A. [ed.] [Univ. of Iowa, Iowa City, IA (United States). Iowa Inst. of Hydraulic Research; Sodhi, D.S. [ed.] [Army Cold Regions Research and Engineering Lab., Hanover, NH (United States); Kennedy, K.P. [ed.] [Canmar/Amoco Canada, Calgary, Alberta (Canada); Yamaguchi, H. [ed.] [Univ. of Tokyo (Japan); Bugno, W. [ed.] [Chevron, San Ramon, CA (United States)

1996-12-01

74

Arctic ozone loss in threshold conditions: Match observations in 1997\\/1998 and 1998\\/1999  

Microsoft Academic Search

Chemical ozone loss rates inside the Arctic polar vortex were determined in early 1998 and early 1999 by using the Match technique based on coordinated ozonesonde measurements. These two winters provide the only opportunities in recent years to investigate chemical ozone loss in a warm Arctic vortex under threshold conditions, i.e., where the preconditions for chlorine activation, and hence ozone

A. Schulz; M. Rex; N. R. P. Harris; G. O. Braathen; E. Reimer; R. Alfier; I. Kilbane-Dawe; S. Eckermann; M. Allaart; M. Alpers; B. Bojkov; J. Cisneros; H. Claude; E. Cuevas; J. Davies; H. De Backer; H. Dier; V. Dorokhov; H. Fast; S. Godin; B. Johnson; B. Kois; Y. Kondo; E. Kosmidis; E. Kyrö; Z. Litynska; I. S. Mikkelsen; M. J. Molyneux; G. Murphy; T. Nagai; H. Nakane; F. O'Connor; C. Parrondo; F. J. Schmidlin; P. Skrivankova; C. Varotsos; C. Vialle; P. Viatte; V. Yushkov; C. Zerefos; P. von der Gathen

2001-01-01

75

Spin-polarized current driven vortex-pair Switching in a magnetic ellipse.  

PubMed

Micromagnetic simulations are performed to study the mechanism of vortex core reversal in a Permalloy elliptical element that contains two vortices with opposite polarities. A short current pulse is applied in the film plane along the short axis of the ellipse. The trajectories of the two vortex cores move either clockwise or anticlockwise, depending on the core polarization. Their reversal mechanisms of the two cores are the same through a creation-annihilation process of vortex-antivortex pair. By analyzing the partial energies of the sample we find that the core reversal occurs once the maximum local energy density reaches the threshold value (e.g., approximately 3.0 x 10(6) J/m3 for Permalloy). Interestingly, this energy threshold is a universal constant, irrespective of the applied current strength, vortex polarity and the sample size. PMID:22629896

Zhang, Hong; Liu, Yaowen

2012-02-01

76

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

77

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 In- frared 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 an- ticyclonic vorticity suggests a convective origin. The rotation speeds of the vortex reach 150-190 m/s, and may strengthen with depth. 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, U. A.; Ingersoll, A. P.; Ewald, S. P.; Vasavada, A. R.; West, R. A.; Baines, K. H.; Momary, T. W.; Barbara, J. M.; Del Genio, A. D.; Porco, C. C.; Achterberg, R. K.; Flasar, F.; Simon-Miller, A. A.; Fletcher, L. N.

2008-12-01

78

Aircraft deployment, and airborne arctic stratospheric expedition  

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

79

The Arctic tropopause fold  

NASA Technical Reports Server (NTRS)

Analyses of research-aircraft observations, satellite total-columnar-ozone retrievals, and synoptic upper-air soundings are used to describe the structure of Arctic jetstreams and their associated frontal zones and tropopause folds. These analyses document the presence of major tropopause folding events within the Arctic that occur at the flanks of large-scale (about 2000 km) polar vortices. One example shows a solar vortex and its associated tropopause fold and Arctic front that migrated from the high Canadian Arctic southward into midlatitudes over central North America. Total columnar ozone measurements from the Total Ozone Mapping Spectrometer are shown to identify the location of polar vortices and the mesoscale (about 200 km) ozone gradients at the flanks of these vortices, which coincide with regions of Arctic tropopause folding and associated stratospheric-tropospheric exchange processes.

Shapiro, M. A.; Hampel, T.; Krueger, A. J.

1987-01-01

80

Arctic climate characteristics and recent trends revealed by the AVHRR Polar Pathfinder data set  

Microsoft Academic Search

The newly available Advanced Very High Resolution (AVHRR) Polar Pathfinder (APP) data set was used to retrieve cloud amount, cloud optical depth, cloud particle phase and size, cloud temperature, surface temperature, surface broadband albedo, radiation fluxes and cloud forcing in the Arctic for the period 1982-1999. The spatial and temporal distributions of those retrieved Arctic climate parameters together with an

Xuanji Wang; Jeffrey R. Key; Michael J. Pavolonis

2003-01-01

81

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

82

Pliocene warmth, polar amplification, and stepped Pleistocene cooling recorded in NE Arctic Russia.  

PubMed

Understanding the evolution of Arctic polar climate from the protracted warmth of the middle Pliocene into the earliest glacial cycles in the Northern Hemisphere has been hindered by the lack of continuous, highly resolved Arctic time series. Evidence from Lake El'gygytgyn, in northeast (NE) Arctic Russia, shows that 3.6 to 3.4 million years ago, summer temperatures were ~8°C warmer than today, when the partial pressure of CO2 was ~400 parts per million. Multiproxy evidence suggests extreme warmth and polar amplification during the middle Pliocene, sudden stepped cooling events during the Pliocene-Pleistocene transition, and warmer than present Arctic summers until ~2.2 million years ago, after the onset of Northern Hemispheric glaciation. Our data are consistent with sea-level records and other proxies indicating that Arctic cooling was insufficient to support large-scale ice sheets until the early Pleistocene. PMID:23661643

Brigham-Grette, Julie; Melles, Martin; Minyuk, Pavel; Andreev, Andrei; Tarasov, Pavel; DeConto, Robert; Koenig, Sebastian; Nowaczyk, Norbert; Wennrich, Volker; Rosén, Peter; Haltia, Eeva; Cook, Tim; Gebhardt, Catalina; Meyer-Jacob, Carsten; Snyder, Jeff; Herzschuh, Ulrike

2013-06-21

83

Observations of Hydration and Dehydration in the Winter 2000 Arctic Stratosphere  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

84

Large Nitric Acid Trihydrate Particles and Denitrification Caused by Mountain Waves in the Arctic Stratosphere.  

National Technical Information Service (NTIS)

The contribution of stratospheric mountain waves to the formation of large nitric acid trihydrate (NAT) particles and subsequent denitrification of the Arctic polar vortex is calculated for the 1999/2000 winter using a three- dimensional (3-D) model. The ...

G. W. Mann K. S. Carslaw M. P. Chipperfield S. Davies S. D. Eckermann

2005-01-01

85

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

86

The relationship between the polar vortex and ozone in the boreal stratosphere from ERA40 reanalysis  

Microsoft Academic Search

The relation between the ozone and the polar vortex in the stratosphere has an outstanding role in climate studios, and also a large repercussion in the improvement of the climate models. This importance is due to the combination of two reasons: the key role of the stratospheric ozone in the Earth climate due to its radiative properties, and that the

Beatriz González-Merino; Encarna Serrano

2010-01-01

87

Closing the loop – Approaches to monitoring the state of the Arctic Mediterranean during the International Polar Year 2007–2008  

Microsoft Academic Search

During the 4th International Polar Year 2007–2009 (IPY), it has become increasingly obvious that we need to prepare for a new era in the Arctic. IPY occurred during the time of the largest retreat of Arctic sea ice since satellite observations started in 1979. This minimum in September sea ice coverage was accompanied by other signs of a changing Arctic,

C. Mauritzen; E. Hansen; M. Andersson; B. Berx; A. Beszczynska-Möller; I. Burud; K. H. Christensen; J. Debernard; L. de Steur; P. Dodd; S. Gerland; Ø. Godøy; B. Hansen; S. Hudson; F. Høydalsvik; R. Ingvaldsen; P. E. Isachsen; Y. Kasajima; I. Koszalka; K. M. Kovacs; M. Køltzow; J. LaCasce; C. M. Lee; T. Lavergne; C. Lydersen; M. Nicolaus; F. Nilsen; O. A. Nøst; K. A. Orvik; M. Reigstad; H. Schyberg; L. Seuthe; Ø. Skagseth; J. Skarðhamar; R. Skogseth; A. Sperrevik; C. Svensen; H. Søiland; S. H. Teigen; V. Tverberg; C. Wexels Riser

2011-01-01

88

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

NASA Astrophysics Data System (ADS)

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

Kobayashi, Hirokazu; Nonaka, Koji; Shikano, Yutaka

2014-05-01

89

Observational Evidence Against Mountain Wave Generation of Ice Clouds Leading to the Formation of NAT Clouds in Early December 1999 Within the Arctic Vortex  

NASA Astrophysics Data System (ADS)

A number of recently published papers suggest that mountain wave (or lee wave) activity in the stratosphere, producing temperatures below the ice frost point, may be the primary source of large NAT particles. We use thermal infrared radiance 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 mountain wave cloud activity inside the Arctic vortex. Lidar observations from three DC-8 flights in early December 1999 show the presence of solid polar stratospheric cloud (PSC) Type Ia particles. By using back trajectories and superimposing the position maps on the AVHRR cloud imagery, we show that the observed solid Type Ia PSC particles could not have originated at locations of high mountain wave cloud activity. We also show that Mountain Wave Forecast Model 2.0 (MWFM-2) gridbox-averaged hemispheric hindcasts from the same time period are in agreement with the AVHRR data. Our results show that ice cloud formation in mountain wave clouds cannot explain how at least three large-scale solid HNO3 PSC structures were formed in the stratosphere in early December 1999.

Pagan, K. L.; Tabazadeh, A.; Drdla, K.; Hervig, M. E.; Eckermann, S. D.; Browell, E. V.; Legg, M. J.; Foschi, P. G.

2003-12-01

90

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

91

Polar Energy: Where Did Arctic People Get Metal?  

NSDL National Science Digital Library

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

Tenenbaum, David

92

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.

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

2013-01-01

93

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

NASA Astrophysics Data System (ADS)

Polar oceans are chemically sensitive to anthropogenic acidification due to their relatively low alkalinity and correspondingly weak carbonate buffering capacity. Here, we compare unique observations of the complete annual cycles of the CO2 system 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), and has lower alkalinity (2220 vs 2300 ?mol/kg), and lower summer pH (8.15 vs 8.5). 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 by lowering CO2 with 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.

Shadwick, Elizabeth; Trull, Thomas; Thomas, Helmuth; Gibson, John

2013-04-01

94

Polar vortex evolution during the 2002 Antarctic major warming as observed by the Odin satellite  

Microsoft Academic Search

In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming. During this event, the Odin satellite was able to measure both ozone (O3) and chlorine monoxide (ClO), a key constituent responsible for the so-called ``ozone hole'', together with nitrous oxide (N2O), a dynamical tracer, and nitric acid (HNO3) and nitrogen dioxide (NO2), tracers

P. Ricaud; F. Lefèvre; G. Berthet; D. Murtagh; E. J. Llewellyn; G. Mégie; E. Kyrölä; G. W. Leppelmeier; H. Auvinen; C. Boonne; S. Brohede; D. A. Degenstein; J. de La Noë; E. Dupuy; L. El Amraoui; P. Eriksson; W. F. J. Evans; U. Frisk; R. L. Gattinger; F. Girod; S. Hassinen; A. Hauchecorne; C. Jimenez; E. Kyrö; N. Lautié; E. Le Flochmoën; N. D. Lloyd; J. C. McConnell; I. C. McDade; L. Nordh; M. Olberg; A. Pazmino; S. V. Petelina; A. Sandqvist; A. Seppälä; C. E. Sioris; B. H. Solheim; J. Stegman; K. Strong; P. Taalas; J. Urban; C. von Savigny; F. von Scheele; G. Witt

2005-01-01

95

Polar vortex evolution during the 2002 Antarctic major warming as observed by the Odin satellite  

Microsoft Academic Search

In September 2002 the Antarctic polar vortex split in two under the influence of a sudden warming. During this event, the Odin satellite was able to measure both ozone (O3) and chlorine monoxide (ClO), a key constituent responsible for the so-called “ozone hole”, together with nitrous oxide (N2O), a dynamical tracer, and nitric acid (HNO3) and nitrogen dioxide (NO2), tracers

P. Ricaud; F. Lefèvre; G. Berthet; D. Murtagh; E. J. Llewellyn; G. Mégie; E. Kyrölä; G. W. Leppelmeier; H. Auvinen; C. Boonne; S. Brohede; D. A. Degenstein; J. de La Noë; E. Dupuy; L. El Amraoui; P. Eriksson; W. F. J. Evans; U. Frisk; R. L. Gattinger; F. Girod; C. S. Haley; S. Hassinen; A. Hauchecorne; C. Jimenez; E. Kyrö; N. Lautié; E. Le Flochmoën; N. D. Lloyd; J. C. McConnell; I. C. McDade; L. Nordh; M. Olberg; A. Pazmino; S. V. Petelina; A. Sandqvist; A. Seppälä; C. E. Sioris; B. H. Solheim; J. Stegman; K. Strong; P. Taalas; J. Urban; C. von Savigny; F. von Scheele; G. Witt

2005-01-01

96

Antarctic ozone variability inside the polar vortex estimated from balloon measurements  

NASA Astrophysics Data System (ADS)

Thirteen years of ozone soundings at the Antarctic Belgrano II station (78° S, 34.6° W) have been analysed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemical ozone depletion. Weekly periodic profiles provide a suitable database for seasonal characterization of the evolution of stratospheric ozone, especially valuable during wintertime, when satellites and ground-based instruments based on solar radiation are not available. The work is focused on ozone loss rate variability (August-October) and its recovery (November-December) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-linear ozone reduction, around day 220 (mid-August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59%) are reached in coldest years, while warm winters exhibit significantly lower ozone loss (20%). It has been found that about 11% of the total O3 loss, in the layer where maximum depletion occurs, takes place before sunlight has arrived, as a result of transport to Belgrano of air from a somewhat lower latitude, near the edge of the polar vortex, providing evidence of mixing inside the vortex. Spatial homogeneity of the vortex has been examined by comparing Belgrano results with those previously obtained for South Pole station (SPS) for the same altitude range and for 9 yr of overlapping data. Results show more than 25% higher ozone loss rate at SPS than at Belgrano. The behaviour can be explained taking into account (i) the transport to both stations of air from a somewhat lower latitude, near the edge of the polar vortex, where sunlight reappears sooner, resulting in earlier depletion of ozone, and (ii) the accumulated hours of sunlight, which become much greater at the South Pole after the spring equinox. According to the variability of the ozone hole recovery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12-24 km layer remained in November, when the vortex is more persistent, while in years when the final stratospheric warming took place "very early", mean integrated ozone rose by up to 160-180 DU.

Parrondo, M. C.; Gil, M.; Yela, M.; Johnson, B. J.; Ochoa, H. A.

2014-01-01

97

Polar vortex dynamics observed by means of stratospheric and mesospheric CO ground-based measurements carried out at Thule (76.5°N, 68.8°W), Greenland  

NASA Astrophysics Data System (ADS)

The distribution of carbon monoxide (CO) in the stratosphere and mesosphere is a useful tool to study middle atmospheric dynamical processes during polar winters. CO concentrations exhibit a strong latitudinal gradient (positive moving towards the winter pole) and a large vertical increase in the mesosphere and lower thermosphere. These large gradients, together with a long photochemical lifetime, make CO an excellent tracer for studying both the poleward transport of air masses from lower latitudes and the descent of air inside the polar vortex. The CO measurements used in this study have been obtained observing the 230 GHz transition by means of a Ground-Based Millimeter-wave Spectrometer (GBMS) with a pass band of 50 MHz and a spectral resolution of 65 kHz. The GBMS was designed and built at the State University of New York at Stony Brook in the early 90's to detect rotational emission spectra of middle atmospheric trace gases at frequencies between approximately 230 and 280 GHz. Since the shape of spectral lines at millimeter-wave frequencies strongly depends on the pressure line broadening, an implementation of the Optimal Estimation technique allows the retrieval of mixing ratio vertical profiles from emission spectra. The GBMS spectral coverage and resolution allows CO mixing ratio profiles to be retrieved between about 30 and 80 km, i.e., at an altitude range where other forms of data used in dynamical studies become increasingly sparse or absent. In January 2009, the GBMS was installed at the NDACC (Network for the Detection of Atmospheric Composition Change) Arctic station at Thule (76.5°N, 68.8°W), Greenland, to commence a long-term observation plan of the polar middle atmosphere. Three winter campaigns have been carried out since then (winters 2008/09, 2009/10, and 2010/11), and the 2011/2012 campaign has been funded and it is about to get started. In this contribution, 4 winters of GBMS CO observations will be presented. Owing to the time span of the GBMS data record and the high temporal resolution of its spectral measurements (15 minutes), the GBMS CO vertical profiles allow to capture both the interannual variability of subsidence rates of air masses inside the polar vortex as well as the short-term planetary wave activity observed near the edge of the polar vortex. Particular emphasis is given to the two record winters of 2008/09 and 2010/11, characterized by opposite extreme events: the most intense Sudden Stratospheric Warming (2008/09) and the most severe Arctic ozone depletion ever observed (2010/11).

Fiorucci, I.; Muscari, G.; Bertagnolio, P. P.; Di Biagio, C.; Eriksen, P.; de Zafra, R. L.

2012-04-01

98

Simulation of the Inward Breaking Vortex Event Observed During the Polar Aura Validation Experiment  

NASA Astrophysics Data System (ADS)

During the Polar Aura Validation Experiment, a vortex intrusion was observed by the AROTAL ozone lidar aboard the NASA DC-8 on January 31, 2004. This intrusion is associated with a rare inward breaking event similar to that observed during AASE II and discussed by Plumb et al. [1994]. This event was also seen by Aura's MLS in both ozone and N2O. This paper reports chemical transport model and RDF trajectory simulations of the event using various resolution models. The event provides a good test case of the quality of polar stratospheric chemical and dynamical assimilations.

Schoeberl, M.; Douglass, A.; Kawa, S.; McGee, T.; Froidevaux, L.; Livesey, N.

2005-12-01

99

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.

Exploratorium, The

2012-06-26

100

The relationship between the polar vortex and ozone in the boreal stratosphere from ERA-40 reanalysis  

NASA Astrophysics Data System (ADS)

The relation between the ozone and the polar vortex in the stratosphere has an outstanding role in climate studios, and also a large repercussion in the improvement of the climate models. This importance is due to the combination of two reasons: the key role of the stratospheric ozone in the Earth climate due to its radiative properties, and that the most important dynamic activity in the high-latitude stratosphere is associated with the polar vortex (present during the whole winter and part of the spring). This work focuses on the spring months, a transitional period in the stratospheric circulation between the winter westerlies (the stratospheric polar vortex, SPV, is completely developed) and summer easterlies (SPV has already disappeared). This breakdown of the SPV is known as the Stratospheric Final Warming, SFW. Using ERA-40 data, currently the longest-period reanalysis (1979-2002) with a sufficiently realistic representation of the stratosphere circulation, we analyze different aspects about the relation between the ozone concentration and the intensity of polar vortex in the boreal stratosphere during the springtime. Among other results, we see that the 24-yr mean evolution of the stratospheric ozone, averaged over the polar region (60°N-80°N), exhibits a slow increase along March followed by a progressive decrease during April and May. The interannual variability of the monthly mean of zonal wind and ozone mixing ratio at 50 hPa in the analyzed polar region decreases gradually along the season as well. When analyzing the springtime stratospheric preconditioning, we found that almost all the warm Februaries are not associated with low ozone content and strong SPV at the beginning of March; and that none cold February was followed by a weak SPV in the first third of March. Also, the stratospheric conditions around the SFW occurrence have been studied. It is seen that the 50-hPa ozone over the polar region is nearly constant prior to the SFW, while it gets lower progressively after the SPV breakdown. The 50-hPa zonal velocity of this region suffers a little recovery after de SFW, although the positive values, that is, the westerlies, are not observed again up to the next winter. Finally, it should be added that some years in the 1979-2002 period showed discrepancies with the 24-yr mean behavior, which is reasonable as other factors and processes also involved in the studied topic have not been included in the present work. However, the main results obtained can be considered robust and consistent coming from ERA-40 reanalysis.

González-Merino, Beatriz; Serrano, Encarna

2010-05-01

101

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

102

Evaluation of Polar WRF forecasts on the Arctic System Reanalysis Domain: 2. Atmospheric hydrologic cycle  

NASA Astrophysics Data System (ADS)

The forecast atmospheric hydrologic cycle of the Polar version 3.1.1 of the Weather Research and Forecasting model (WRF) is examined for December 2006 - November 2007. The domain is similar to the Arctic System Reanalysis (ASR), an assimilation of model fields and Arctic observations being conducted partly by the Byrd Polar Research Center. Simulations are performed in 48 h increments initialized daily at 0000 UTC, with the first 24 h discarded for model spin-up of the hydrologic cycle and boundary layer processes. Precipitation analysis reveals a negative annual mean bias (-9.4%) in the polar region, with particularly dry station biases reflected in the Canadian Archipelago. Annual mean bias for the midlatitudes is small and positive (4.6%), attributed to excessive precipitation during spring and summer when convective precipitation is dominant. An examination of precipitation within four major Arctic river basins shows large positive biases due to excessive convective precipitation in summer as well, but highlights the Arctic climate's strong dependence on midlatitude precipitation. Nudging the model's boundary layer moisture toward drier conditions decreases convective precipitation improving the prediction. Cloud fraction analysis shows too little cloud cover, supported by an excess in incident shortwave radiation and a deficit in downwelling longwave radiation throughout the domain. The longwave bias is present regardless of the amount of cloud water or cloud ice, demonstrating a need to improve cloud effects on radiation in Polar WRF. This examination provides a benchmark of the forecast atmospheric hydrological cycle of Polar WRF and its use as ASR's primary model.

Wilson, Aaron B.; Bromwich, David H.; Hines, Keith M.

2012-02-01

103

Modelling the effect of denitrification on polar ozone depletion for Arctic winter 2004/2005  

NASA Astrophysics Data System (ADS)

A three-dimensional (3-D) chemical transport model (CTM), SLIMCAT, has been used to quantify the effect of denitrification on ozone loss for the Arctic winter 2004/2005. The simulated HNO3 is found to be highly sensitive to the polar stratospheric cloud (PSC) scheme used in the model. Here the standard SLIMCAT full chemistry model, which uses a thermodynamic equilibrium PSC scheme, overpredicts the ozone loss for Arctic winter 2004/2005 due to the overestimation of denitrification and stronger chlorine activation than observed. A model run with a coupled detailed microphysical denitrification scheme, DLAPSE (Denitrification by Lagrangian Particle Sedimentation), is less denitrified than the standard model run and better reproduces the observed HNO3 as measured by Airborne SUbmillimeter Radiometer (ASUR) and Aura Microwave Limb Sounder (MLS) instruments. Overall, denitrification is responsible for a ~30 % enhancement in O3 depletion compared with simulations without denitrification for Arctic winter 2004/2005, which is slightly larger than the inferred impact of denitrification on Arctic ozone loss for previous winters from different CTMs simulations. The overestimated denitrification from standard SLIMCAT simulation causes ~5-10 % more ozone loss at ~17 km compared with the simulation using the DLAPSE PSC scheme for Arctic winter 2004/2005. The calculated partial column ozone loss from SLIMCAT using the DLAPSE scheme is about 130 DU by mid-March 2005, which compares well with the inferred column ozone loss from ozonesondes and satellite data (127±21 DU).

Feng, W.; Chipperfield, M. P.; Davies, S.; Mann, G. W.; Carslaw, K. S.; Dhomse, S.; Harvey, L.; Randall, C.; Santee, M. L.

2011-07-01

104

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

105

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

106

The great Arctic cyclone of August 2012  

NASA Astrophysics Data System (ADS)

On 2 August 2012 a dramatic storm formed over Siberia, moved into the Arctic, and died in the Canadian Arctic Archipelago on 14 August. During its lifetime its central pressure dropped to 966 hPa, leading it to be dubbed ‘The Great Arctic Cyclone of August 2012’. This cyclone occurred during a period when the sea ice extent was on the way to reaching a new satellite-era low, and its intense behavior was related to baroclinicity and a tropopause polar vortex. The pressure of the storm was the lowest of all Arctic August storms over our record starting in 1979, and the system was also the most extreme when a combination of key cyclone properties was considered. Even though, climatologically, summer is a ‘quiet’ time in the Arctic, when compared with all Arctic storms across the period it came in as the 13th most extreme storm, warranting the attribution of ‘Great’.

Simmonds, Ian; Rudeva, Irina

2012-12-01

107

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

108

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

Microsoft Academic Search

A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil assemblage discovered at Kakanaut in northeastern\\u000a Russia reveals that dinosaurs were still highly diversified in Arctic regions just before the Cretaceous–Tertiary mass extinction\\u000a event. Dinosaur eggshell fragments, belonging to hadrosaurids and non-avian theropods, indicate that at least several latest\\u000a Cretaceous dinosaur taxa could reproduce in polar region and were

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

2009-01-01

109

Observing the Arctic From Space: Educational Opportunities for an International Polar Year  

NASA Astrophysics Data System (ADS)

Recommendations for an International Polar Year (IPY) will require integrated circumpolar research projects using present and advanced technologies. The IPY will offer exceptional opportunities for participation by indigenous residents of the Arctic. Educational outreach will be an essential component of IPY programs, to improve science competence and citizen awareness through participation in IPY projects and utilization of educational products. An important and practical objective of IPY educational outreach is to recognize that the earth is a system and that it is best from space that we can acquire seasonal and secular atmospheric, terrestrial and oceanic environmental data. Acquisition of reliable ground truth data in support of remote sensing of geophysical and geochemical variables will be essential, especially with broad long-term coverage in the polar regions. It should be an essential element of the IPY program. In the United States NASA has developed a strategy for long-term monitoring of some key parameters needed to bring us closer to the answers we need regarding climate change in the Arctic and polar regions. Technology consists of a group of five polar satellites that make a suite of earth observations referred to as the "A-Train". Data from this group of satellites, as well as from the Orbital Carbon Observatory (OCO) and older Quikscat and new Seawinds radar missions, will provide focus for an education program based not only on the acquisition of polar data but also on how these data correlate with global observations. We recommend that an educational outreach secretariat be developed for each national program that will involve the indigenous people of the Arctic and elsewhere in acquisition of data relevant to satellite observations. The secretariat will provide for information transfer, coordination with scientific projects, opportunities for participation in project activities, communication of scientific results to the public, and greater participation of residents of circumpolar nations in polar science.

Kelley, J. J.; Yanow, G.; Alexander, V.; Johnson, L.

2003-12-01

110

3. Observing the Arctic from space: educational opportunities for an International Polar Year  

NASA Astrophysics Data System (ADS)

Recommendations for an International Polar Year (IPY) will require integrated circumpolar research projects using present and advanced technologies. The IPY will offer exceptional opportunities for participation by indigenous residents of the Arctic. Educational outreach will be an essential component of IPY programs, to improve science competence and citizen awareness through participation in IPY projects and utilization of educational products. An important and practical objective of IPY educational outreach is to recognize that the earth is a system and that it is best from space that we can acquire seasonal and secular atmospheric, terrestrial and oceanic environmental data. Acquisition of reliable ground truth data in support of remote sensing of geophysical and geochemical variables will be essential, especially with broad long-term coverage in the polar regions. It should be an essential element of the IPY program. In the United States NASA has developed a strategy for long-term monitoring of some key parameters needed to bring us closer to the answers we need regarding climate change in the Arctic and polar regions. Technology consists of a group of five polar satellites that make a suite of earth observations referred to as the "A-Train". Data from this group of satellites, as well as from the Orbital Carbon Observatory (OCO) and older Quikscat and new Seawinds radar missions, will provide focus for an education program based not only on the acquisition of polar data but also on how these data correlate with global observations. We recommend that an educational outreach secretariat be developed for each national program that will involve the indigenous people of the Arctic and elsewhere in acquisition of data relevant to satellite observations. The secretariat will provide for information transfer, coordination with scientific projects, opportunities for participation in project activities, communication of scientific results to the public, and greater participation of residents of circumpolar nations in polar science.

Kelley, J.; Yanow, G.; Alexander, V.; Johnson, L.

2003-04-01

111

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

112

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

113

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

114

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

115

Antarctic ozone variability inside the Polar Vortex estimated from balloon measurements  

NASA Astrophysics Data System (ADS)

13 yr of ozonesoundings at the Antarctic Belgrano II station (78° S, 34.6° W) have been analyzed to establish a climatology of stratospheric ozone and temperature over the area. The station is inside the polar vortex during the period of development of chemical ozone depletion. Weekly periodic profiles provide a suitable database for seasonal characterization of the evolution of stratospheric ozone, especially valuable during winter time when satellites and ground-based instruments based on solar radiation are lacking. The work is focused on ozone loss rate variability (August-October) and its recovery (November-December) at different layers identified according to the severity of ozone loss. The time window selected for the calculations covers the phase of a quasi-linear ozone reduction, about day 220 (mid August) to day 273 (end of September). Decrease of the total ozone column over Belgrano during spring is highly dependent on the meteorological conditions. Largest depletions (up to 59%) are reached in coldest years while warms winters exhibit significantly lower ozone loss (20%). It has been found that about 11% of the total O3 loss in the layer where maximum depletion occurs takes place before the sun has arrived as a result of transport of lower latitude air masses, providing evidence of mixing inside the vortex. Spatial homogeneity of the vortex has been examined by comparing Belgrano results with those previously obtained for South Pole Station (SPS) for the same altitude range and for 9 yr of overlapping data. Unexpected results show more than 25% larger ozone loss rate at SPS than at Belgrano. It has been found that the accumulated hours of sunlight are the dominant factor driving the ozone loss rate. According to the variability of the ozone-hole recovery, a clear connection between the timing of the breakup of the vortex and the monthly ozone content was found. Minimum ozone concentration of 57 DU in the 12-24 km layer remained in November for the longest vortex, while years when the final stratospheric warming took "very early", mean integrated ozone rises up to 160-180 DU.

Parrondo, M. C.; Gil, M.; Yela, M.; Johnson, B. J.; Ochoa, H. A.

2013-06-01

116

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

117

Detrital zircons of deep-sea sediments of the Arctic ocean - key to the understanding of High Polar Arctic tectonics  

NASA Astrophysics Data System (ADS)

Zircons from sedimentary rocks bear the information on composition of vast territories often inaccessible for geologic investigation but which are the source of material. The studies of modern beaches and fluvial deposits demonstrate the efficiency of reconstruction of composition and distribution of rock types based on clastic zircon characteristics (Zircon, 2003). We have studied nine 0,5 kg specimens (every meter) from gravity-corer sample of deep sea-bottom sedimentary cover within the Geophysicists Spur region (Lomonosov Ridge) which represent first 9 meters of the section formed during 70 000 years. Heavy fraction is composed by garnet, tourmaline, titanite, rutile and by 200-300 grains of zircon per sample. Zircons in all samples are different in morphology and inner structure: from faceted needle-like to perfectly rounded, from colorless to brown opaque, with thin growth zones and inherited cores, as well as homogeneous. U-Pb SIMS SHRIMP isotope dating (50 grain analyses for each sample) was applied to two key specimens from the depth of 12-14 and 505-507 cm. The age probability distribution diagrams show that the main age peaks are of 138-147, 200-300, 400-800 and 1845-2000 Ma; few grains of 2700 Ma and one grain is 3000 Ma old. Our previous data for the zircon age distribution for box-corer sample of hemipelagic sediment from the North Pole (Grikurov et al., 2011) revealed peaks of 160, 200-450 (max 260-300 Ma), 800, 1855, 2000 and 2600 Ma. Zircons from three samples above show common features: 1) presence of Archean grains (>2400 Ma), 2) defined age peak of 1800-2000 Ma (ca 30% of grains), 3) lack of Grenvillian age zircons, 4) youngest ages of 40-160 Ma. Thus, all three studied samples have very similar provenance source, the deposition time of sandstones, from which had mainly formed the modern (<30 000 years) sediments, is Jurassic (?140-160 Ma). About 50% of analyzed zircons falls to the age interval 200-500 Ma. However, grains distribution is appreciably different for Polar sample (200-450 Ma) and Geophysicists Spur (200, 300, 400-600 Ma). It is known, that formation of modern deep-sea sediments takes place mainly due to fluvial discharge (ca 90%), erosion of oceanic bedrocks and coastal beaches. Wind-borne component and extraterraneous dust are not significant (<1%). Transportation of continental material by icebergs (ice-rafted debris) is added to these sources in polar areas. Well-known Permian-Triassic sandstones of Arctic coast (including polar islands) are defined by the presence of Grenvillian age zircons - Canadian Arctic, Alaska, Greenland (Miller et al., 2006), while Jurassic-Cretaceous sandstones of the South Anjui Zone, Chukotka and New Siberian Islands of Russian Arctic (Miller et al., 2008) have clastic zircon with ages very similar to the obtained by us for deep-sea sediments. We suppose that modern deep-sea sediments were formed either due to ablation of these sandstones with distal transportation of detritus (highly unlikely), or due to weathering of similar rock of oceanic highs of Lomonosov Ridge. The last is more realistic because the similarity of the Lomonosov Ridge and north-east continental Arctic is proved by geophysical data (Jokat et al., 1992).

Shokalsky, S.; Morozov, A.; Petrov, O.; Belyatsky, B.; Rekant, P.; Shevchenko, S.; Sergeev, S.

2012-04-01

118

Numerical simulations of the synoptic conditions and development of Arctic outbreak polar lows  

NASA Astrophysics Data System (ADS)

Four cases satisfying the necessary conditions for development of Arctic outbreak polar lows have been investigated from numerical simulations. Characteristic synoptic conditions are a mature extratropical cyclone situated over Scandinavia and a northerly, baroclinic flow in the Norwegian Sea. This flow has a convective planetary boundary layer (PBL) caused by heat fluxes from the warm ocean in cold Arctic air masses coming from the sea ice areas to the north and west. The height of the PBL may reach 700 hPa and even more. The synoptic situation is also characterized by a dry intrusion of stratospheric air west of the cyclones. When the tropopause is defined by the surface of potential vorticity (PV) equal 2 PVU (1 PVU=10-6 m2 s-1 K kg-1), the intrusion lowers the tropopause typically down to levels between 450 and 750 hPa, bringing large positive anomalies of PV to levels normally in mid-troposphere. These synoptic conditions are ideal for cyclogenesis from mutual interaction of positive upper air and boundary layer PV anomalies. The Rossby height is high, which means that small-scale polar lows may form. It is found that simply the height between the tropopause and the top of the convective PBL is a good indicator of the risk of polar low formation. This height was found to be 2500 m or more in two of the cases when no polar lows were observed. When polar lows developed in the other two cases, heights of 1000 m or less were measured (in numerical simulations). The simulated development of these two polar lows has been investigated. The polar low cyclogenesis was found to be caused by the baroclinic instability in agreement with the conceptual model of Montgomery and Farrel. Diabatic intensification is important and seems to be necessary to seclude the warm core disturbance which is characteristic of Arctic outbreak polar lows. The seclusion process implies that warm air is being surrounded by cold air.

Grønås, Sigbjørn; Kvamstø, Nils Gunnar

1995-10-01

119

Satellite Observations of Arctic and Antarctic Polar Stratospheric Clouds and Atmospheric Composition  

NASA Astrophysics Data System (ADS)

We present an overview of polar stratospheric clouds (PSCs) and atmospheric composition during the 2008-2012 Arctic and Antarctic seasons using A-Train measurements of lidar backscatter and gas phase concentrations of HNO3, H2O, HCl and ClO. The processes of denitrification, dehydration and chlorine activation are investigated. PSC types are classified using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite which measures vertical profiles of aerosol and cloud backscatter at 532 nm (total and perpendicular polarization) and 1064 nm. Ambient temperature/pressure profiles and constituent gases are obtained from the Aura Microwave Limb Sounder (MLS). Since April 2008 these two instruments have flown in close formation in the A-Train, maintaining colocation across track to less than 10 km and with temporal sampling differences less than 30 seconds.

Lambert, A.; Santee, M. L.; Wu, D. L.

2012-12-01

120

Motion, collision and annihilation of polarization vortex pair in single crystalline BaTiO3 thin film  

NASA Astrophysics Data System (ADS)

Domain evolution of a single crystalline BaTiO3 thin film, initially possessing two vortex-antivortex pairs, placed under compressive displacement loading with a constant strain rate, is simulated using a molecular dynamics method based on the shell model. The evolution details, including the relative motion and collision between the vortices and antivortices and their annihilation, are carefully observed, and both the movement velocity and the equilibrium time after annihilation are estimated. When the vortex-antivortex pairs annihilate, the polarization configuration evolves into a 180° domain structure. These distinctive domain evolution characteristics could open up opportunities for designing ferroelectric nanodevices.

Tian, Xianbao; Yang, Xinhua; Wang, Peng; Peng, Di

2013-12-01

121

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

122

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

USGS Publications Warehouse

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

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

2003-01-01

123

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

124

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

PubMed

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 degrees 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. PMID:19089398

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

2009-04-01

125

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

126

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

PubMed

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

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

2012-04-01

127

Mixing and Chemical Ozone Loss during and after the Antarctic Polar Vortex Major Warming in September 2002.  

NASA Astrophysics Data System (ADS)

The 3D version of the Chemical Lagrangian Model of the Stratosphere (CLAMS) is used to study the transport of CH4 and O3 in the Antarctic stratosphere between 1 September and 30 November 2002, that is, over the time period when unprecedented major stratospheric warming in late September split the polar vortex into two parts. The isentropic and cross-isentropic velocities in CLAMS are derived from ECMWF winds and heating/cooling rates calculated with a radiation module. The irreversible part of transport, that is, mixing, is driven by the local horizontal strain and vertical shear rates with mixing parameters deduced from in situ observations.The CH4 distribution after the vortex split shows a completely different behavior above and below 600 K. Above this potential temperature level, until the beginning of November, a significant part of vortex air is transported into the midlatitudes up to 40°S. The lifetime of the vortex remnants formed after the vortex split decreases with the altitude with values of about 3 and 6 weeks at 900 and 700 K, respectively.Despite this enormous dynamical disturbance of the vortex, the intact part between 400 and 600 K that "survived" the major warming was strongly isolated from the extravortex air until the end of November. According to CLAMS simulations, the air masses within this part of the vortex did not experience any significant dilution with the midlatitude air.By transporting ozone in CLAMS as a passive tracer, the chemical ozone loss was estimated from the difference between the observed [Polar Ozone and Aerosol Measurement III (POAM III) and Halogen Occultation Experiment (HALOE)] and simulated ozone profiles. Starting from 1 September, up to 2.0 ppmv O3 around 480 K and about 70 Dobson units between 450 and 550 K were destroyed until the vortex was split. After the major warming, no additional ozone loss can be derived, but in the intact vortex part between 450 and 550 K, the accumulated ozone loss was "frozen in" until the end of November.

Konopka, Paul; Grooß, Jens-Uwe; Hoppel, Karl W.; Steinhorst, Hildegard-Maria; Müller, Rolf

2005-03-01

128

Polar Bears from Space: Assessing Satellite Imagery as a Tool to Track Arctic Wildlife  

PubMed Central

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 (: 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 (: 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; LaRue, Michelle; Lecomte, Nicolas; Atkinson, Stephen; Garshelis, David; Porter, Claire; Atwood, Todd

2014-01-01

129

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

130

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

131

Spectral Methods in Polar Coordinates with AN Application to the Stability of a Trailing Vortex.  

NASA Astrophysics Data System (ADS)

In cylindrical and spherical coordinates the coordinate singularity can decrease the accuracy or computational efficiency of the spectral method. The problem arises due to the increased resolution near the coordinate singularity. For time dependent advection problems it becomes a stiffness problem which forces one to choose an unusually small time step compared to other spectral methods which do not have coordinate singularities. In this dissertation we present two sets of basis functions which inherently do not suffer from any stiffness problem. The first set of basis functions consists of the eigenfunctions of a singular Sturm-Liouville equation and is suited for a spectral method on the unit disk in polar coordinates. The basis functions are polynomials. The second set of basis functions is algebraically mapped associated Legendre functions whose domain extends from the origin to infinity in the radial direction of a cylindrical coordinates. The basis functions are rational functions. These basis sets satisfy simple recurrence relations for important operations such as the multiplication of some elementary functions, differentiation, and the application of the Laplacian and Helmholtz operators. The forward and backward application of these recurrence relations can be made very efficient. We illustrate these new methods by some examples. The examples include the treatment of a vector field by its toroidal and poloidal components. As an application of practical importance, we apply the rational basis function method to simulate the nonlinear development of linearly unstable modes of an airplane trailing vortex with axial flow. It is found that the nonlinear development of the linearly unstable modes depends strongly on the swirl parameter q which is the ratio of the magnitude of swirling motion to that of the axial flow of the vortex. For q = 0.2 and q = 0.6, the vortex core breaks up significantly and the mean core radius becomes a few times larger than the unperturbed core radius. If q = 1.0, the mean core radius does not become larger than the unperturbed case even though instability develops initially.

Matsushima, Tatsuhito

132

The role of stationary and transient planetary waves in the maintenance of stratospheric polar vortex regimes in Northern Hemisphere winter  

NASA Astrophysics Data System (ADS)

Using 1958-2002 NCEP/NCAR reanalysis data, we investigate stationary and transient planetary wave propagation and its role in wave-mean flow interaction which influences the state of the polar vortex (PV) in the stratosphere in Northern Hemisphere (NH) winter. This is done by analyzing the Eliassen-Palm (E-P) flux and its divergence. We find that the stationary and transient waves propagate upward and equatorward in NH winter, with stronger upward propagation of stationary waves from the troposphere to the stratosphere, and stronger equatorward propagation of transient waves from mid-latitudes to the subtropics in the troposphere. Stationary waves exhibit more upward propagation in the polar stratosphere during the weak polar vortex regime (WVR) than during the strong polar vortex regime (SVR). On the other hand, transient waves have more upward propagation during SVR than during WVR in the subpolar stratosphere, with a domain of low frequency waves. With different paths of upward propagation, both stationary and transient waves contribute to the maintenance of the observed stratospheric PV regimes in NH winter.

Li, Qian; Graf, Hans-F.; Cui, Xuefeng

2011-01-01

133

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

Microsoft Academic Search

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

Rob Huebert

1995-01-01

134

Hematology of southern Beaufort Sea polar bears (2005-2007): biomarker for an Arctic ecosystem health sentinel.  

PubMed

Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ?5, than lactating adult females ages ?5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel. PMID:20617361

Kirk, Cassandra M; Amstrup, Steven; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M

2010-09-01

135

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

USGS Publications Warehouse

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

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

2010-01-01

136

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

137

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

Microsoft Academic Search

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

O. P. Persson

2004-01-01

138

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

139

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

140

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

141

Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate  

NASA Technical Reports Server (NTRS)

Recent satellite lidar measurements of cloud properties spanning a period of 5 years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anticorrelation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice!free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7% and 10%, respectively, as year average sea ice extent has decreased by 5% 7%. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Because longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

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

2010-01-01

142

The Influence of Arctic Sea Ice Extent on Polar Cloud Fraction and Vertical Structure and Implications for Regional Climate  

NASA Technical Reports Server (NTRS)

Recent satellite lidar measurements of cloud properties spanning a period of five years are used to examine a possible connection between Arctic sea ice amount and polar cloud fraction and vertical distribution. We find an anti-correlation between sea ice extent and cloud fraction with maximum cloudiness occurring over areas with little or no sea ice. We also find that over ice free regions, there is greater low cloud frequency and average optical depth. Most of the optical depth increase is due to the presence of geometrically thicker clouds over water. In addition, our analysis indicates that over the last 5 years, October and March average polar cloud fraction has increased by about 7 and 10 percent, respectively, as year average sea ice extent has decreased by 5 to 7 percent. The observed cloud changes are likely due to a number of effects including, but not limited to, the observed decrease in sea ice extent and thickness. Increasing cloud amount and changes in vertical distribution and optical properties have the potential to affect the radiative balance of the Arctic region by decreasing both the upwelling terrestrial longwave radiation and the downward shortwave solar radiation. Since longwave radiation dominates in the long polar winter, the overall effect of increasing low cloud cover is likely a warming of the Arctic and thus a positive climate feedback, possibly accelerating the melting of Arctic sea ice.

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

2010-01-01

143

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

144

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

145

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

146

Controlling the vortex core of thin Permalloy nano-cylinders dipolar coupled to Co polarizers  

NASA Astrophysics Data System (ADS)

We report a theoretical study of the vortex profile of in-plane magnetized PyTM nano-cylinders subjected to the stray field of perpendicular anisotropy Co nano-cylinders. We consider 6 nm thick PyTM cylinders dipolar coupled to 60 nm thick Co cylinders, at distances from 1.5 nm to 30 nm, with diameters (D) ranging from 45 nm to 105 nm. We find considerable reduction of critical diameter for stable PyTM magnetic vortices and spiral-vortex phases, as well as vortex core diameters twice as large as the bulk value.

Souza, C. M.; Dantas, Ana L.; Queiroz, I. S.; Carriço, A. S.

2014-05-01

147

Observation of spatial polarization structure near unfolding point of an optical vortex beam using a birefringent Mach-Zehnder interferometer  

NASA Astrophysics Data System (ADS)

A uniformly polarized optical vortex (OV) entering a birefringent crystal is known to unfold into complex polarization structures due to the separation of ordinary and extraordinary rays. The interplay between the topological structures in scalar and vector optics has been studied at the output of finite-length crystals. But the polarization transformation near the unfolding point where the beam initially enters the crystal has not been observed so far. In this paper, we experimentally investigate the spatial polarization structure very near the unfolding point of a uniformly polarized OV beam propagating in a birefringent crystal by constructing a birefringent interferometer. The unfolding point is reconstructed by folding back the two separated beams into a single beam using another identical birefringent crystal, resulting in a birefringent interferometer of Mach-Zehnder type. Small rotation of the second crystal produces output beams with varying separation near the unfolding point. The spatial polarization structure of the output beam is investigated by measuring the Stokes parameters. Such understanding of the connection between defects of scalar optics and vector optics through birefringence will help to shape the spatial polarization states of laser beams for various spectroscopic and microscopic applications.

Brundavanam, Maruthi M.; Miyamoto, Yoko; Singh, Rakesh K.; Naik, Dinesh N.; Takeda, Mitsuo; Nakagawa, Ken'ichi

2012-10-01

148

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

149

Arctic winter 2009/2010 and 2010/2011 in comparison: Denitrification and polar stratospheric cloud formation  

NASA Astrophysics Data System (ADS)

Polar Stratospheric Clouds (PSCs) and denitrification, the permanent removal of nitric acid (HNO3) by sedimenting HNO3 containing PSC particles, play a key role in stratospheric ozone depletion. The two recent Arctic winter 2009/2010 and 2010/2011 were both quite unique. The Arctic winter 2010/2011 was one of the coldest winter on record leading to the strongest depletion of ozone ever measured. Though the Arctic winter 2009/2010 was rather warm in the climatological sense it was distuinguished by a exceptionally cold stratosphere from mid December 2009 to mid January 2010 leading to prolonged PSC formation and strong denitrification. For investigating PSC formation during these two Arctic winter we apply ground-based measurements performed with the Esrange and the IRF lidar in the area of Kiruna, Northern Sweden (69° N 21° E) and space-borne lidar measurements from the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) Satellite together with microphysical box model simulations. To investigate denitrification during these two Arctic winter we apply measurements from the Odin Sub-Millimetre Radiometer (Odin/SMR) as well as measurements from the Microwave Limb Sounder on Aura (Aura/MLS). Though denitrification in 2009/2010 was until then the strongest in the entire Odin/SMR measurement period it was excelled by the 2010/2011 winter where denitrification was nearly as severe as in the Antarctic. PSC occurrance during both winter was also quite different. While PSCs were present during the Arctic winter 2010/2011 over nearly four months, from mid December to end of March, they were not as persistent as the ones that occurred during the shorter (one month) cold period during the Arctic winter 2009/2010.

Khosrawi, F.; Urban, J.; Pitts, M. C.; Voelger, P.; Achtert, P.; Santee, M. L.; Manney, G. L.; Murtagh, D.

2012-04-01

150

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

151

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

152

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

153

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

154

A comparison of Arctic lower stratospheric winter temperatures for 1988-89 with temperatures since 1964  

Microsoft Academic Search

Lower stratospheric temperatures during the Airborne Arctic Stratospheric Expedition are compared with temperatures available since January, 1964. January, 1989, was the coldest average January in the last 26 years at high altitude, lower stratospheric levels. There have been other months with temperatures almost as low as the level of January, 1989, and localized temperatures (e.g., minimum polar vortex temperatures) have

Ronald M. Nagatani; Alvin J. Miller; Melvyn E. Gelman; Paul A. Newman

1990-01-01

155

A comparison of Arctic lower stratospheric winter temperatures for 1988–89 with temperatures since 1964  

Microsoft Academic Search

Lower stratospheric temperatures during the Airborne Arctic Stratospheric Expedition are compared with temperatures available since January, 1964. January, 1989, was the coldest average January in the last 26 years at high latitude, lower stratospheric levels. There have been other months with temperatures almost as low as the level of January, 1989, and localized temperatures (e.g., minimum polar vortex temperatures) have

Ronald M. Nagatani; Alvin J. Miller; Melvyn E. Gelman; Paul A. Newman

1990-01-01

156

A comparison of Arctic lower stratospheric winter temperatures for 1988-89 with temperatures since 1964  

Microsoft Academic Search

Lower stratospheric temperatures during the Airborne Arctic Stratospheric Expedition are compared with temperatures available since January, 1964. January, 1989, was the coldest averaged January in the last 26 years at high latitude, lower stratospheric levels. There have been other months with temperatures almost as low as the level of January, 1989, and localized temperatures (e.g., minimum polar vortex temperatures) have

Ronald M. Nagatani; Alvin J. Miller; Melvyn E. Gelman; Paul A. Newman

1990-01-01

157

A comparison of Arctic lower stratospheric winter temperatures for 1988-89 with temperatures since 1964  

SciTech Connect

Lower stratospheric temperatures during the Airborne Arctic Stratospheric Expedition are compared with temperatures available since January, 1964. January, 1989, was the coldest average January in the last 26 years at high altitude, lower stratospheric levels. There have been other months with temperatures almost as low as the level of January, 1989, and localized temperatures (e.g., minimum polar vortex temperatures) have been lower than that encountered in January 1989. February, 1989, was warmer than average and March, 1989, had some of the highest polar vortex temperatures in the last 26 years. Conditions were therefore not very favorable for Polar Stratospheric Cloud (PSC) formation into early spring.

Nagatani, R.M.; Miller, A.J.; Gelman, M.E. (NOAA, Washington, DC (USA)); Newman, P.A. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

1990-03-01

158

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

159

Arctic Ocean.  

National Technical Information Service (NTIS)

The Arctic Ocean is the smallest of the Earth's four major oceans, covering 14x10(exp 6) sq km located entirely within the Arctic Circle (66 deg 33 min N). It is a major player in the climate of the north polar region and has a variable sea ice cover that...

C. L. Parkinson

2000-01-01

160

Analysis of the physical state of one Arctic polar stratospheric cloud based on observations  

NASA Astrophysics Data System (ADS)

During the Arctic Airborne Stratospheric Expedition (AASE) simultaneous measurements of aerosol size distribution and NO(y)(HN03 + NO + NO2 + 2(N205)) were made along ER-2 flight paths. The flow characteristics of the NO(y) instrument allow us to derive the condensed NO(y) amount (assumed to be HN03) present during polar stratospheric cloud (PSC) events. Analysis of the January 24th flight indicates that this condensed HN03 amount does not agree well with the aerosol volume if the observed PSCs are composed of solid nitric acid trihydrate (NAT), as is generally assumed. However, the composition agrees well with that predicted for liquid H2S04/HN03/H20 solution droplets using a new Aerosol Physical Chemistry Model (APCM). The agreement corresponds in detail to variations in temperature and humidity. The weight percentages of H2SO4, HN03, and H2O derived from the measurements all correspond to those predicted for ternary, liquid solutions.

Drdla, K.; Tabazadeh, A.; Turco, R. P.; Jacobson, M. Z.; Dye, J. E.; Twohy, C.; Baumgardner, D.

1994-11-01

161

Relative importance of dynamical and chemical contributions to Arctic wintertime ozone  

NASA Astrophysics Data System (ADS)

We present the first complete budget of the interannual variability in Arctic springtime ozone taking into account anthropogenic chemical and natural dynamical processes. For the winters 1991/1992 to 2003/2004 the Arctic chemical ozone loss is available from observations. This work investigates the dynamical supply of ozone to the Arctic polar vortex due to mean transport processes for the same winters. The ozone supply is quantified in a vortex-averaged framework using estimates of diabatic descent over winter. We find that the interannual variability of both dynamical ozone supply and chemical ozone loss contribute, in equal shares, to the variability of the total ozone change. Moreover, together they explain nearly all of the interannual variability of Arctic springtime column ozone. Variability in planetary wave activity, characterized by the Eliassen-Palm flux at 100 hPa, contributes significantly to the variability of ozone supply, chemical ozone loss and total springtime ozone.

Tegtmeier, S.; Rex, M.; Wohltmann, I.; Krüger, K.

2008-09-01

162

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

Microsoft Academic Search

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

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

2003-01-01

163

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

Microsoft Academic Search

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

Rob Huebert

1995-01-01

164

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

165

Saturn's South Polar Vortex Compared to Other Large Vortices in the Solar System  

Microsoft Academic Search

Observations made by the Imaging Science Subsystem (ISS), Visible and In- frared 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

U. A. Dyudina; A. P. Ingersoll; S. P. Ewald; A. R. Vasavada; R. A. West; K. H. Baines; T. W. Momary; J. M. Barbara; A. D. Del Genio; C. C. Porco; R. K. Achterberg; F. Flasar; A. A. Simon-Miller; L. N. Fletcher

2008-01-01

166

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

Microsoft Academic Search

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

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

2009-01-01

167

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

168

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

169

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

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

170

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

171

Differences in mercury bioaccumulation between polar bears (Ursus maritimus) from the Canadian high- and sub-Arctic.  

PubMed

Polar bears (Ursus maritimus) are being impacted by climate change and increased exposure to pollutants throughout their northern circumpolar range. In this study, we quantified concentrations of total mercury (THg) in the hair of polar bears from Canadian high- (southern Beaufort Sea, SBS) and sub- (western Hudson Bay, WHB) Arctic populations. Concentrations of THg in polar bears from the SBS population (14.8 ± 6.6 ?g g(-1)) were significantly higher than in polar bears from WHB (4.1 ± 1.0 ?g g(-1)). On the basis of ?(15)N signatures in hair, in conjunction with published ?(15)N signatures in particulate organic matter and sediments, we estimated that the pelagic and benthic food webs in the SBS are ? 4.7 and ? 4.0 trophic levels long, whereas in WHB they are only ? 3.6 and ? 3.3 trophic levels long. Furthermore, the more depleted ?(13)C ratios in hair from SBS polar bears relative to those from WHB suggests that SBS polar bears feed on food webs that are relatively more pelagic (and longer), whereas polar bears from WHB feed on those that are relatively more benthic (and shorter). Food web length and structure accounted for ? 67% of the variation we found in THg concentrations among all polar bears across both populations. The regional difference in polar bear hair THg concentrations was also likely due to regional differences in water-column concentrations of methyl Hg (the toxic form of Hg that biomagnifies through food webs) available for bioaccumulation at the base of the food webs. For example, concentrations of methylated Hg at mid-depths in the marine water column of the northern Canadian Arctic Archipelago were 79.8 ± 37.3 pg L(-1), whereas, in HB, they averaged only 38.3 ± 16.6 pg L(-1). We conclude that a longer food web and higher pelagic concentrations of methylated Hg available to initiate bioaccumulation in the BS resulted in higher concentrations of THg in polar bears from the SBS region compared to those inhabiting the western coast of HB. PMID:21678897

St Louis, Vincent L; Derocher, Andrew E; Stirling, Ian; Graydon, Jennifer A; Lee, Caroline; Jocksch, Erin; Richardson, Evan; Ghorpade, Sarah; Kwan, Alvin K; Kirk, Jane L; Lehnherr, Igor; Swanson, Heidi K

2011-07-15

172

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

173

Chlorine Partitioning in the Arctic Vortex During Winter 1995 Derived From Submillimeterwave Remote Sensing and in Situ Constituent Measurements  

NASA Technical Reports Server (NTRS)

High altitude balloon flights of a combined payload of the Submillimeterwave Limb Sounder and the whole air sampler instruments were performed on 27 January 1995 and 08 March 1995. Both flights were launched from sweden as part of the Second European Stratospheric Arctic and Mid-latitude Experiment (SESAME). Results of the first flight suggest that most of the available chlorine had been converted to CLOx in the observed air parcel, while warmer air in the second flight had much more HCl than CLOx.

Stachnik, R. A.; Hardy, J. C.; Engel, A.; Schmidt, U.

1995-01-01

174

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

175

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

176

Polar stratospheric clouds in the 1998-2003 Antarctic vortex: Microphysical modeling and Polar Ozone and Aerosol Measurement (POAM) III observations  

NASA Astrophysics Data System (ADS)

The Integrated Microphysics and Aerosol Chemistry on Trajectories (IMPACT) model is used to study polar stratospheric cloud (PSC) formation and evolution in the Antarctic vortex. The model is applied to individual air parcel trajectories driven by UK Met Office (UKMO) wind and temperature fields. The IMPACT model calculates the parcel microphysics, including the formation and sedimentation of ice, nitric acid trihydrate (NAT), sulfuric acid tetrahydrate (SAT), and supercooled ternary solution (STS) aerosols. Model results are validated by comparison with data obtained by the Polar Ozone and Aerosol Measurement (POAM) III solar occultation instrument and are examined for 6 years of POAM data (1998-2003). Comparisons of POAM water vapor and aerosol extinction measurements to the model results help to constrain three microphysical parameters influencing the formation and growth of both type I and type II PSCs. Principally, measurements of aerosol extinction prove to be valuable in differentiating model runs; the relationship of aerosol extinction to temperature is determined by the various particle types as they form and grow. Comparison of IMPACT calculations of this relationship to POAM measurements suggests that the initial fraction of nuclei available for heterogeneous NAT freezing is approximately 0.02% of all aerosols. Constraints are also placed on the accommodation coefficient of ice and the NAT-ice lattice compatibility. However, these two parameters have similar effects on the extinction-temperature relationship, and thus a range of values are permissible for each.

Benson, C. M.; Drdla, K.; Nedoluha, G. E.; Shettle, E. P.; Alfred, J.; Hoppel, K. W.

2006-09-01

177

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

178

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

179

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

180

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

181

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

182

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

183

Vortex Rotation in a Nb Thin Film: A Spin-Polarized Neutron Reflectivity and Magnetization Study  

Microsoft Academic Search

Spin-polarized neutron reflectivity (SPNR) and DC magnetization measurements are quantitatively compared for the magnetic field applied parallel to the plane of a 1370Åthick Nb film. Recently, it was shown that vortices could be detected by SPNR [1] and that the magnetization parallel to the film plane could be obtained. ([1] S.-W. Han et. al., Phys. Rev. B 59, 14692 (1999))

P. F. Miceli; S.-W. Han; J. Farmer; H. Kaiser; I. R. Roshchin; L. H. Greene

2000-01-01

184

Distribution and inventories of polychlorinated biphenyls in the polar mixed layer of seven pan-arctic shelf seas and the interior basins.  

PubMed

Assessment of the Arctic as a global repository of polychlorinated biphenyls (PCBs) and of uptake processes in the base of its marine food chain hinges on reliable information of PCB distribution in surface seawater, yet there is a scarcity of quality-assured PCB measurements in this key compartment. Here, surface seawater PCB concentrations and congener fingerprints are evaluated for all seven pan-Arctic shelf seas and for the interior basins. Particulate and dissolved PCBs were collected via trace-clean protocols on three basin-wide expeditions (AO-01, Beringia-2005, and ISSS-08). Concentrations of the sum of 13 abundant congeners (?13PCB) were 0.13-21 pg/L, with higher concentrations in the shelf seas and lower concentrations in the Central Arctic Basin. Trichlorinated PCBs constituted about half of the total loadings in the Eastern Arctic (Beaufort, Chukchi, East Siberian, and Laptev Seas) and in the Central Basin, indicating an atmospheric source. In contrast, hexachlorinated PCBs were more abundant than tri-PCBs in the western sector, suggesting a role also for waterborne transport from regions of heavy PCB consumption in North America and Europe. Finally, the inventory of ?13PCB in the polar mixed layer of the entire Arctic Ocean was 0.39 ton, which implies that only 0.0008% of historical PCB emissions are now residing in Arctic surface waters. PMID:21222432

Carrizo, Daniel; Gustafsson, Örjan

2011-02-15

185

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

186

Arctic technology and policy  

SciTech Connect

Topics covered include: legal regime of the arctic, including national and international legal frameworks that govern arctic resource development; environmental policy and socio-economic issues, focusing on the political and economic considerations of LNG transport in icebound waterways; risk and safety assessment for arctic offshore projects, drilling systems for the arctic; arctic offshore technology, including island, steel, and concrete structures; icebreaking technology, focusing on the current state of the art and indicating future research areas; arctic oceanography, summarizing characteristics of ice from field experiments pertaining to the design of structures, ships, and pipelines; arctic seismic exploration, detailing signal processes for underwater communication in the context of arctic geology and geophysics; ice morphology, providing information about ice shapes, particularly critical to the determination of overall strength of ice masses; remote sensing; modeling of arctic ice fields, including information about the design and construction of offshore facilities in polar areas; and engineering properties of ice, providing theoretical and experimental studies.

Dyer, I.; Chryssostomidis, C.

1984-01-01

187

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

NASA Astrophysics Data System (ADS)

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

188

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

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

189

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

NASA Astrophysics Data System (ADS)

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

Garfinkel, Chaim; Waugh, Darryn; Gerber, Edwin

2014-05-01

190

Interhemispheric distinctions between the polar vortex positions in the winter stratosphere and mesosphere from measurements with a SABER instrument aboard the TIMED satellite  

NASA Astrophysics Data System (ADS)

Distinctions between the longitudinal structures of circulation in the stratosphere and mesosphere/lower thermosphere of the Northern and Southern hemispheres are investigated on the basis of the temperature and geopotential distributions obtained with a SABER instrument (TIMED satellite) in the months of February and August in 2002 2005. The positions of the winter cyclone and polar vortex at stratospheric and mesospheric heights in 2002 2005 are compared to the climatic data over 1978 1998. At stratospheric heights, the mean position of the polar vortex’s center over several years changed insignificantly during the specified years (several degrees in latitude and longitude) in both the Southern and Northern hemispheres. At mesosphere/lower thermosphere heights, the polar vortex occupies the same position in the Southern Hemisphere each year during 2002 2005, and this position agrees with the estimates for 1996 1997. Parameters of stationary planetary waves with the zonal wave number 1 (SPW1) in the fields of temperature, geopotential, and wind are calculated from data on the temperature and geopotential. The height profiles of SPW1 amplitudes and phases calculated from the SABER instrument data for August in the Southern Hemisphere are in good agreement with the profiles of amplitudes and phases obtained from the direct wind measurements with HRDI and WINDII instruments. A strong interannual variability of SPW1 parameters is observed in the Northern Hemisphere. The calculation of the Eliassen-Palm flux and its divergence has shown that SPW1 penetrates into the mesosphere mainly from the stratosphere and slows down the zonal mean flux. However, in the Southern Hemisphere, there is a regular additional SPW1 source with the center at a height of about 65 km and a latitude of 55°S. Such a SPW1 source is, on average, absent in the Northern Hemisphere during 2002 2005; however, in some years (for example, in February 2004), its existence is possible.

Merzlyakov, E. G.; Solov'eva, T. V.

2008-06-01

191

Molecular hydrogen as a mesospheric hydrogen reservoir; evidence from tracer-tracer interrelationships in descended air measured within the northern polar stratospheric vortex  

NASA Astrophysics Data System (ADS)

The distribution and partitioning of all hydrogen-carrying species in and above the mesosphere inform our understanding of upper atmospheric chemistry and transport; however, many species are not easily measured. Molecular hydrogen (H2) is described as a mesospheric reservoir of hydrogen atoms released from methane (CH4) oxidation and water vapor (H2O) photolysis. Only limited indirect measurements and modeling studies have provided evidence for this reservoir until now. Measuring air that descends from upper levels within polar stratospheric vortices provides a unique opportunity to sample the chemical composition of the mesosphere at more accessible stratospheric altitudes. Such measurements were made of atmospheric H2 by the balloonborne, in situ Lightweight Airborne Chromatograph Experiment (LACE) instrument during the 1999-2000 SAGE III Ozone Loss and Validation Experiment (SOLVE). Vertical profiles of a number of tracers were made in November 1999 after the vortex formation and again in March 2000 just before vortex breakup. The tropospheric-stratospheric H2 profile shifted dramatically from being vertically uniform (~0.5 ppm) in the young vortex to exhibiting distinct minimum (~0.4 ppm) and maximum (~1 ppm) peak features after a winter of mixing and descent in the late polar vortex. Both observational and model results show that a significant fraction of mesospheric air was present in the late vortex, suggesting that the late vortex H2 features were of mesospheric origin. The goal of this study is to determine whether the chemical measurements made with LACE confirm the anticipated H2 mixing ratio peak in the mesosphere. Tracer-tracer interrelationships of H2 with concurrently measured tracers, such as SF6, CO, N2O, and CFCs, are used to determine the original altitude and mixing ratio of the H2 peak. A simple model of mixing and descent within the vortex will be used to infer the altitude distribution of H2 in the mesosphere by forcing its consistency with other measured tracers. Agreement of the results with extant numerical projections and indirect measurements is discussed. Further characterization of the mesospheric reservoir of hydrogen may contribute to the understanding of atomic H in the thermosphere and beyond.

Meredith, L. K.; Ray, E. A.; Moore, F. L.; Plumb, R. A.

2010-12-01

192

Arctic Ship Design Impacts: Green Arctic Patrol Vessel (GAPV) Project.  

National Technical Information Service (NTIS)

Arctic warming and the resulting polar ice break up is expected to increase traffic through the Arctic region for tourism, research, resource extraction, and transportation purposes. Understanding that the United States will have a strategic objective in ...

N. Buckley P. Field W. S. Weidle

2012-01-01

193

Ice navigation studies in the Alaskan Arctic using POLAR Class icebreakers  

Microsoft Academic Search

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

L. Brigham; R. Voelker

1985-01-01

194

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

195

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

PubMed

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

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

2014-01-01

196

Such Low Temperatures in the Arctic Region: How Can the Polar Bears Call It Home?  

ERIC Educational Resources Information Center

Presents an activity on polar bears that integrates language arts and science. Teaches the characteristics of organisms and how distinct environments support distinct organisms. Uses both mathematics and science skills and targets students at the K-4 grade level. (YDS)

Pringle, Rose M.

2002-01-01

197

Airborne lidar measurements of ozone during the 1989 airborne Arctic stratospheric expedition  

NASA Technical Reports Server (NTRS)

The NASA/NOAA Airborne Arctic Stratospheric Expedition (AASE) was conducted during the winter to study the conditions leading to possible ozone (O3) destruction in the wintertime Arctic stratosphere. As part of this experiment, the NASA-Langley airborne differential absorption lidar (DIAL) system was configured for operation on the NASA-Ames DS-8 aircraft to make measurements of O3 profiles from about 1 km above the aircraft to altitudes of 22 to 26 km. The airborne DIAL system remotely sensed O3 above the DC-8 by transmitting two laser beams at 10 Hz using wavelengths of 301.5 and 311 nm. Large scale distributions of O3 were obtained on 15 long range flights into the polar vortex during the AASE. Selected data samples are presented of O3 observed during these flights, general trends observed in O3 distributions, and correlations between these measurements and meteorological and chemical parameters. The O3 distribution observed on the first flight of the DC-8 into the polar vortex on Jan. 6 reflected the result of diabatic cooling of the air inside the vortex during the winter compared to the warmer air outside the vortex. On a potential temperature surface, the O3 mixing ratio generally increases when going from outside to inside the vortex.

Browell, Edward V.; Fenn, Marta A.; Kooi, Susan A.

1991-01-01

198

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

NASA Astrophysics Data System (ADS)

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

Haines-Stiles, G.; Akuginow, E.

2006-12-01

199

Vortex Vortex Interactions in the Winter Stratosphere.  

NASA Astrophysics Data System (ADS)

This paper examines the interaction of oppositely signed vortices in the compressible (non-Boussinesq) quasigeostrophic system, with a view to understanding vortex interactions in the polar winter stratosphere. A series of simplifying approximations leads to a two-vortex system whose dynamical properties are determined principally by two parameters: the ratio of the circulation of the vortices and the vertical separation of their centroids. For each point in this two-dimensional parameter space a family of equilibrium solutions exists, further parameterized by the horizontal separation of the vortex centroids, which are stable for horizontal separations greater than a critical value. The stable equilibria are characterized by vortex deformations that generally involve stronger deformations of the larger and/or lower of the two vortices. For smaller horizontal separations, the equilibria are unstable and a strongly nonlinear, time-dependent interaction takes place, typically involving the shedding of material from the larger vortex while the smaller vortex remains coherent. Qualitatively, the interactions resemble previous observations of certain stratospheric sudden warmings that involved the interaction of a growing anticyclonic circulation with the cyclonic polar vortex.


Scott, R. K.; Dritschel, D. G.

2006-02-01

200

GPS scintillation effects associated with polar cap patches, auroral arcs and blobs in European Arctic sector  

NASA Astrophysics Data System (ADS)

Both polar cap patches and auroral arcs are associated with irregularities that can affect the propagation of radio waves and thus disrupt the navigation system in the high latitudes. But which is the worst case remains unanswered. This study focuses on the direct comparison of the relative scintillation effects associated with different phenomena in high latitudes. The All Sky Camera located at Ny-Alesund, Svalbard observed six polar cap patches on January 13, 2013. The patches exited into the nightside auroral region in response to the ongoing substorms and then they are termed blobs. The collocated GPS scintillation monitor is used to study the scintillations produced by these different phenomena which are frequently observed at high latitudes. The amplitude scintillation index (S_4) was very low during this period, while the phase scintillation index (sigma_phi) indicated a disturbed ionospheric condition but responded differently to these three types of phenomena. Comparisons of the associated scintillation effects indicate that the blobs are the most violent scintillation source. Moreover, polar cap patches produce scintillation more effectively than auroral arcs do. Five of the six polar cap patches were observed to produce significant scintillations either on the edges or on the center of the patches, which imply most of the polar cap patches are associated with strong small scale irregularities. All of the scintillations produced by the pure auroral arcs were below 0.2 rad in this period. This study highlights the compound effects of the particle precipitations (auroral arcs) and high density plasma islands (patches) in developing the small scale irregularities. From the space weather forecasting perspective, particular attention is to be paid to polar cap patches exiting the polar cap at night in the European sector.

Jin, Yaqi; Moen, Jøran; Miloch, Wojciech

2014-05-01

201

FTIR measurements of HF, N{sub 2}O and CFCs during the Arctic polar night with the moon as light source, subsidence during winter 1992/93  

SciTech Connect

The author presents ground based measurements of HF, N{sub 2}O, CFC-12 (CF{sub 2}Cl{sub 2}) and CFC-22 (CHF{sub 2}Cl) vertical distributions from the Arctic winter. These long lived trace atmospheric gases can serve as tracers for atmospheric circulation studies, and here the authors analyze the data to obtain information on the vertical circulation in the atmosphere during the polar winter.

Notholt, J. [Alfred Wegener Institut fuer Polar und Meeresforschung, Potsdam (Germany)] [Alfred Wegener Institut fuer Polar und Meeresforschung, Potsdam (Germany)

1994-11-01

202

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

203

Will future Arctic ozone be affected by climate change?  

NASA Astrophysics Data System (ADS)

The northern hemisphere spring 2011 was characterized by a well developed stratospheric polar vortex with unusually low temperatures and severe ozone depletion in the Arctic lower stratosphere. This unexpected development has stimulated the discussion on the effect of climate change on stratospheric ozone depletion. Simulations with global climate and chemistry-climate models (CCMs) tend to suggest an enhanced dynamical forcing of the polar winter stratosphere in a future climate with increased greenhouse gas (GHG) concentrations, leading to more stratospheric sudden warmings and counteracting the global, GHG induced radiative cooling of the stratosphere. On the other hand, observational studies derived a stronger polar stratospheric cooling in those winters of the past decades that were not dynamically disturbed. If this cooling were due to climate change, more northern winters with extremely low polar stratospheric temperatures and associated severe Arctic ozone depletion should be expected in the future. In our study we will investigate the effect of increasing GHG concentrations on the future evolution of the northern polar stratosphere in winter. We will analyze results from a transient simulation of the ECHAM/MESSy Atmospheric Chemistry (EMAC) CCM of the period 1960-2100 including future changes in GHG concentrations and ozone depleting substances according to the CCMVal SCN-B2d scenario. We will look for future changes in stratospheric dynamical variability, such as the occurrence of stratospheric warmings, as well as changes in the occurrence of strong vortex events with extremely low temperatures. By comparing with a related simulation with fixed 1960s GHG concentrations (CCMVal SCN-B2c scenario) as well as supporting time-slice simulations we will be able to isolate the effect of GHG increases on the future polar meteorology and the conditions for Arctic ozone depletion.

Langematz, U.; Grunow, K.; Ayarzagüena, B.; Kubin, A.; Romanowsky, E.

2011-12-01

204

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

NASA Technical Reports Server (NTRS)

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

Macdonald, W. R.

1974-01-01

205

A polar low embedded in a blocking high over the Pacific Arctic  

NASA Astrophysics Data System (ADS)

A polar low (PL) is a short-lived phenomenon involving strong winds that occurs over polar oceans. In October 2009, the R/V Mirai encountered a PL with a 600-km-wide, comma-shaped cloud that developed over the Chukchi Sea. A shipboard Doppler radar and radiosondes were used to understand the fine structure of this PL. Analyses of low-level winds and the thermodynamic structure indicated that the development of the PL was decoupled from sea surface thermal forcing. The PL was likely triggered by an intrusion of a potential vorticity (PV) anomaly at the tropopause. A southerly warm advection associated with a blocking high over Alaska resulted in rapid development of the PL in front of the cold dome induced by the upper-level PV anomaly. The westerly winds after passage of the PL seemed to modify the upper-ocean structure dramatically.

Inoue, Jun; Hori, Masatake E.; Tachibana, Yoshihiro; Kikuchi, Takashi

2010-07-01

206

Arctic Polar Low Detection and Monitoring Using Atmospheric Water Vapor Retrievals from Satellite Passive Microwave Data  

Microsoft Academic Search

An approach for detecting and tracking polar lows (PLs) is developed based on satellite passive microwave data from two sensors: Special Sensor Microwave Imager (SSM\\/I) on board the Defense Meteorological Satellite Program satellite and Ad- vanced Microwave Scanning Radiometer-Earth Observing Sys- tem (AMSR-E) on board the Aqua satellite. This approach consists of two stages. During the first stage, the total

Leonid P. Bobylev; Elizaveta V. Zabolotskikh; Leonid M. Mitnik; Maia L. Mitnik

2011-01-01

207

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

Microsoft Academic Search

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

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

2008-01-01

208

Preliminary Analysis of Recent Arctic and Antarctic Climate Change Based on the Extended AVHRR Polar Pathfinder (APP-x) Dataset, 1982-2011  

NASA Astrophysics Data System (ADS)

The polar regions, i.e., the Arctic and the Antarctica, play a significant role in the global climate system due to their unique surface features and their interactions with lower latitudes. Given the harsh environment and sparse population, surface measurements are very costly. One of the most economic and efficient ways to obtain data is to use satellite remote sensing techniques that provide routine observations of remote areas. Compared to climate reanalysis data sets like NCAR/NCEP, NASA/MERRA, and ECMWF/ERA-40, satellite retrieved data products have a relatively high spatial resolution and time frequency. Here we introduce a well developed, recently updated and validated data set called the Extended AVHRR Polar Pathfinder (APP-x) data set that consists of twice daily AVHRR-based retrievals of surface, cloud, sea ice, and radiative properties for the period 1982 - 2011 over the Arctic and Antarctica at as high as 5 km resolutions. Almost all of the APP-x product algorithms have been published in the scientific literature, and most of the products have been validated with data collected during Arctic field experiments and with data from Arctic and Antarctic meteorological stations. Additional validation data will be obtained and used to provide up-to-date quantitative estimates of product accuracies and uncertainties since product validation is an ongoing issue. Satellite products have become increasingly important in studying recent climate change. Our products have been used before to derive many science findings that in some cases were counter-intuitive. The Arctic has been warming up at the doubled rate of the global average, sea ice has been constantly declining since 1980s, in particular after 2003, in correspondences with strong surface warming, cloudiness change, and NAO staging in negative phase. One of the important findings is that Arctic clouds are always taking a damping effect in the surface warming. This newly updated and extended APP-x data set will be used to detect the changes in surface, cloud, radiation, and cryosphere in the polar regions during the past three decades, and to determine the critical "turning points" over the full period 1982-2011. The associations of these "turning points" with the global climate change will be further investigated in terms of the important global climate events before and after.

Wang, X.; Liu, Y.

2012-12-01

209

Polar night retrievals of trace gases in the Arctic using the Extended-range Atmospheric Emitted Radiance Interferometer  

NASA Astrophysics Data System (ADS)

The Extended-range Atmospheric Emitted Radiance Interferometer (E-AERI) was installed at the Polar Environment Atmospheric Research Laboratory (PEARL) at Eureka, Nunavut, Canada in October 2008. Spectra from the E-AERI provide information about the radiative balance and budgets of trace gases in the Canadian high Arctic. Measurements are taken every seven minutes year-round, including polar night when the solar-viewing spectrometers at PEARL are not operated. This allows E-AERI measurements to fill the gap in the PEARL dataset during the four months of polar night. Measurements were taken year-round in 2008-2009 at the PEARL Ridge Lab, which is 610 m above sea-level, and from 2011-onwards at the Zero-Altitude PEARL Auxiliary Lab (0PAL), which is 15 km from the Ridge Lab at sea level. Total columns of O3, CO, CH4, and N2O have been retrieved using a modified version of the SFIT2 retrieval algorithm adapted for emission spectra. This provides the first nighttime measurements of these species at Eureka. Changes in the total columns driven by photochemistry and dynamics are observed. Analyses of E-AERI retrievals indicate accurate spectral fits (root-mean-square residuals < 1.5%) and a 10-15% uncertainty in the total column, depending on the trace gas. O3 comparisons between the E-AERI and a Bruker IFS 125HR Fourier transform infrared (FTIR) spectrometer, three Brewer spectrophotometers, two UV-visible ground-based spectrometers, and a System D'Analyse par Observations Zenithales (SAOZ) at PEARL are made from 2008-2009 and for 2011. 125HR CO, CH4, and N2O columns are also compared with the E-AERI measurements. Mean relative differences between the E-AERI and the other spectrometers are 1-14% (depending on the gas), which are less than the E-AERI's total column uncertainties. The E-AERI O3 and CO measurements are well correlated with the other spectrometers; the best correlation is with the 125HR (r > 0.92). The 24-h diurnal cycle and 365-day seasonal cycle of CO are observed and their amplitudes are quantified by the E-AERI (6-12% and 46%, respectively). The seasonal variability of H2O has an impact on the retrievals, leading to larger uncertainties in the summer months. Despite increased water vapour at the lower-altitude site 0PAL, measurements at 0PAL are consistent with measurements at PEARL.

Mariani, Z.; Strong, K.; Palm, M.; Lindenmaier, R.; Adams, C.; Zhao, X.; Savastiouk, V.; McElroy, C. T.; Goutail, F.; Drummond, J. R.

2013-01-01

210

Deep lakes in the Polar Urals - unique archives for reconstructing the Quaternary climate and glacial history in the Russian Arctic  

NASA Astrophysics Data System (ADS)

A lake coring campaign in the Polar Urals is carried out within the framework of the Norwegian-Russian IPY-project “The Ice Age Development and Human Settlement in Northern Eurasia” (ICEHUS). The overall aim of the project is to improve the description and understanding of the Late Quaternary environmental and climate changes in the Russian Arctic and how these changes may have affected the early human occupation. In order to obtain a continuous record of climate variability back in time seismic records and sediment cores have been collected from selected mountain lakes. The summer of 2009 we cored two lakes situated near the water shed in the interior northernmost Urals. Seismic profiles show that both these glacially eroded basins contain thick sequences of Quaternary sediments. The thickest strata were found in Bolshoye Shuchye, the largest and deepest lake in the Ural Mountains. This lake is 13 km long and 140 m deep and contains more than 130 m of acoustically laminated sediments. These strata probably accumulated over a rather long time span, possibly covering several interglacial-glacial cycles. Up to 24 m long cores were obtained from the lake floors. We anticipate that they will provide unique high resolution records of the climate and glacial history during the last Ice Age. The seismic records and the sediment cores will form a well-founded basis for assessing the potential and possibilities to core also the deeper strata that could not be reached with the applied coring equipment. In view of the obtained results from the investigated basins, as well as other geological and geochronological data from the surrounding areas, we find it highly unlikely that any glaciers extended into these lakes during the Last Glacial Maximum (LGM), supporting our current hypothesis that the local glaciers in the Polar Urals remained small during the LGM. Our observations indicate that the mountain valleys have been essentially ice free since Marine Isotope Stage 4, at around 70-60,000 yrs ago. At this time, the major valley systems in the Polar Urals seem to have been inundated by an ice sheet advance from the Kara Sea. Fresh results from the coring campaign will be presented during the meeting.

Svendsen, J.; Gyllencreutz, R.; Henriksen, M.; Lohne, O. S.; Mangerud, J.; Nazarov, D.

2009-12-01

211

Comparative hepatic in vitro depletion and metabolite formation of major perfluorooctane sulfonate precursors in arctic polar bear, beluga whale, and ringed seal.  

PubMed

Perfluorooctane sulfonate (PFOS) has been reported to be among the most concentrated persistent organic pollutants in Arctic marine wildlife. The present study examined the in vitro depletion of major PFOS precursors, N-ethyl-perfluorooctane sulfonamide (N-EtFOSA) and perfluorooctane sulfonamide (FOSA), as well as metabolite formation using an assay based on enzymatically viable liver microsomes for three top Arctic marine mammalian predators, polar bear (Ursus maritimus), beluga whale (Delphinapterus leucas), and ringed seal (Pusa hispida), and in laboratory rat (Rattus rattus) serving as a general mammalian model and positive control. Rat assays showed that N-EtFOSA (38nM or 150ngmL(-1)) to FOSA metabolism was >90% complete after 10min, and at a rate of 23pmolmin(-1)mg(-1) protein. Examining all species in a full 90min incubation assay, there was >95% N-EtFOSA depletion for the rat active control and polar bear microsomes, ?65% for ringed seals, and negligible depletion of N-EtFOSA for beluga whale. Concomitantly, the corresponding in vitro formation of FOSA from N-EtFOSA was also quantitatively rat?polar bear>ringed seal>beluga whale. A lack of enzymatic ability and/or a rate too slow to be detected likely explains the lack of N-EtFOSA to FOSA transformation for beluga whale. In the same assays, the depletion of the FOSA metabolite was insignificant (p>0.01) and with no concomitant formation of PFOS metabolite. This suggests that, in part, a source of FOSA is the biotransformation of accumulated N-EtFOSA in free-ranging Arctic ringed seal and polar bear. PMID:25048910

Letcher, Robert J; Chu, Shaogang; McKinney, Melissa A; Tomy, Gregg T; Sonne, Christian; Dietz, Rune

2014-10-01

212

Variability of atmospheric winds and waves in the Arctic polar mesosphere during a stratospheric sudden warming  

NASA Astrophysics Data System (ADS)

A ground-based wide angle Michelson Interferometer was used to monitor the temporal variation of winds and waves in the mesopause region at Resolute Bay, Canada (74.9°N, 94.9°W) during a stratospheric warming event of February 2001. Observed variability of zonal and meridional winds is compared to the daily mean temperature fields at 3.16 hPa from assimilated stratospheric data. Reversal of eastward zonal winds is seen to occur during maximum mean temperatures in the stratospheric polar cap. Spectral analysis of the wind-velocity time series shows the evolution of different periodicities and their amplitudes. A cool period between two warming events shows a decrease in the amplitude of the semi-diurnal tide and an increase in the power of waves shorter than 12 hours before peak stratospheric temperatures are reached.

Bhattacharya, Yajnavalkya; Shepherd, G. G.; Brown, S.

2004-12-01

213

Immobilization of polar bears (Ursus maritimus) with Telazol in the Canadian Arctic.  

PubMed

In 1986, 213 polar bears (Ursus maritimus) were immobilized with Telazol on the sea ice of the eastern Beaufort Sea during April and May, and 106 along the western coast of Hudson Bay near Churchill, Manitoba (Canada) in September. No animals died from handling. The efficacy of this drug at different seasons and the physiological responses of the immobilized bears were compared. A single injection of 8 to 9 mg of Telazol per kg of body weight gave a rapid full immobilization with satisfactory analgesia, and faster recovery than other drugs for which there is no antagonist. The reactions of the bears could be reliably and easily interpreted from a safe distance before the animal was approached. There was a wide range of tolerance to high dosages and bears appeared able to thermoregulate while immobilized. The mortality rate due to handling was lower than with any other drug used to date. PMID:2716095

Stirling, I; Spencer, C; Andriashek, D

1989-04-01

214

The Arctic Crossroads: Environmental Challenges for Russia  

Microsoft Academic Search

The Arctic region – a northern polar region of the Earth occupies an area down from the Arctic Pole and comprises the Arctic Ocean, northern parts around the Northern Pole.[1] It consists of a vast, ice-covered ocean surrounded by permafrost. The Arctic is known for its rich reserves of natural resources – oil, gas minerals, fresh water, fish, the economic

Irina Krasnova

2012-01-01

215

Polar Bears  

NSDL National Science Digital Library

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

Thomas, Mr.

2010-09-27

216

What Controls the Temperature of the Arctic Stratosphere during the Spring?  

NASA Technical Reports Server (NTRS)

Understanding the mechanisms that control the temperature of the polar lower stratosphere during spring is key to understanding ozone loss in the Arctic polar vortex. Spring ozone loss rates are directly tied to polar stratospheric temperatures by the formation of polar stratospheric clouds, and the conversion of chlorine species to reactive forms on these cloud particle surfaces. In this paper, we study those factors that control temperatures in the polar lower stratosphere. We use the National Centers for Environmental Prediction (NCEP)/NCAR reanalysis data covering the last two decades to investigate how planetary wave driving of the stratosphere is connected to polar temperatures. In particular, we show that planetary waves forced in the troposphere in mid- to late winter (January-February) are principally responsible for the mean polar temperature during the March period. These planetary waves are forced by both thermal and orographic processes in the troposphere, and propagate into the stratosphere in the mid and high latitudes. Strong mid-winter planetary wave forcing leads to a warmer Arctic lower stratosphere in early spring, while weak mid-winter forcing leads to cooler Arctic temperatures.

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

2000-01-01

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

218

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

PubMed Central

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

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

2014-01-01

219

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

PubMed

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

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

2014-03-22

220

A CCM simulation of the breakup of the Antarctic polar vortex in the years 1980-2004 under the CCMVal scenarios  

NASA Astrophysics Data System (ADS)

The changes in breakup time of the Antarctic polar vortex in the years 1980-2004 are examined using the output of chemistry climate model (CCM) calculations, data from the National Centers for Environmental Prediction/the National Center for Atmospheric Research (NCEP/NCAR) Reanalysis, and data from the European Center for Medium-Range Weather Forecasts Reanalysis (ERA40). The CCM used in this study is from the Center for Climate System Research/National Institute for Environmental Studies (CCSR/NIES). The CCM calculations are performed with the two ensemble members for REF1 scenario of the chemistry climate model validation (CCMVal) and the one ensemble member for the REF2 scenario. CCM simulates the development of the ozone hole from 1982 to 2000, as observed with a total ozone mapping spectrometer (TOMS), although the year-to-year variation is different from the observation owing to the internal variability of CCM and the ozone decreasing trends of CCM ozone in the two ensemble members of REF1 are underestimated. The trends in temperature and zonal mean zonal wind are analyzed and compared with the observations. There is consistency among the trends in zonal mean temperature, zonal mean zonal wind, and total ozone, but they differ among the ensemble members and observations. The diabatic heating rates and Eliassen-Palm flux fields are investigated in order to explain the differences. A delay trend in the breakup time of the Antarctic polar vortex is obtained for the period of 1980-1999 in the NCEP/NCAR and ERA40 data. A similar trend is also obtained from the CCM simulations, with statistical significance in one ensemble member of REF1 and REF2. Because the trends of the observations in the EP flux from the troposphere and its deposition in the lower stratosphere are consistent with an advanced breakup date of the polar vortex and because the trends of the CCM simulations are very small, it is likely that the Antarctic ozone depletion had some effect on the delay during the period 1980-1999. From 2000 to 2004, the NCEP/NCAR data show a large variation in breakup time, which makes the delay trend much less important. It is likely that the large variation in wave flux masked the effects of the ozone loss during that period. The two ensemble members of the REF1 simulation do not show such a dramatic change in the trend for the period 2000-2004, whereas REF2 shows a change in the trend for that period.

Akiyoshi, H.; Zhou, L. B.; Yamashita, Y.; Sakamoto, K.; Yoshiki, M.; Nagashima, T.; Takahashi, M.; Kurokawa, J.; Takigawa, M.; Imamura, T.

2009-02-01

221

The area of the stratospheric polar vortex as a diagnostic for tracer transport on an isentropic surface  

NASA Technical Reports Server (NTRS)

Daily isentropic distributions of Ertel potential vorticity, O3, water vapor, and HNO3 at the 850-K level of the Northern-Hemisphere stratosphere are determined on the basis of data from the Limb IR Monitor of the Stratosphere (Gille and Russell, 1984) on Nimbus 7 for the period October 25, 1978-April 2, 1979. The results are presented in graphs and maps and analyzed in detail. The surf-zone main-vortex structure identified by McIntyre and Palmer (1983 and 1984) is observed, superimposed on the seasonal patterns, with expansion of the surf zone and shrinking of the main vortex as the winter progresses. Irreversible mixing is found to be the dominant mechanism controlling the redistribution of all measured species except HNO3.

Butchart, N.; Remsberg, E. E.

1986-01-01

222

Arctic hurricanes  

NASA Astrophysics Data System (ADS)

The devastating winter storms that swoop across the Arctic, endangering offshore oil rigs, shipping, and fishing operations in their paths, are the subject of current study by a team of weather researchers from the National Oceanic and Atmospheric Administration (NOAA). As part of the study, U.S. scientists and those from several other countries also will attempt to estimate how much carbon dioxide is transferred from the atmosphere into the North Atlantic's deep waters during winter storms.A typical polar low, like a hurricane, has a spiral cloud pattern and winds exceeding 120 km per hour, said Melvyn Shapiro, senior meteorologist on the polar-low study. The storms are smaller than most hurricanes, however, and rarely have a diameter greater than 320 km. Some, but not all, develop an “eye,” like a hurricane. Polar lows, only recently documented from polar orbiting satellite imagery, appear to form primarily from October to April, but peak in February.

223

Correlation of N2O and ozone in the Southern Polar vortex during the airborne Antarctic ozone experiment  

NASA Technical Reports Server (NTRS)

In situ N20 mixing ratios, measured by an airborne laser spectrometer (ATLAS), have been used along with in situ ozone measurements to determine the correlation of N2O and ozone in the Antarctic stratosphere during the late austral winter. During the 1987 Airborne Antarctic Ozone Experiment (AAOE), N2O data were collected by a laser absorption spectrometer on board the ER-2 on five ferry flights between Ames Research Center (37 deg N) and Punta Arenas, Chile (53 deg S), and on twelve flights over Antarctica (53 S to 72 S). Of all the trace gas species measured by instruments on board the ER-2, only one showed a relationship to the N2O/O3 correlations in the vortex. With few exceptions, positive N20/O3 correlations coincided with total water mixing ratios of greater than 2.9 ppmv, and total water mixing ratios of less than 2.9 ppmv corresponded to negative correlations. The lower water mixing ratios, or dehydrated regions, are colocated with the negative correlations within the vortex, while the wetter regions always occur near the vortex edge.

Strahan, S. E.; Loewenstein, M.; Podolske, J. R.; Starr, Walter L.; Proffitt, M. H.; Kelly, K. K.; Chan, K. Roland

1988-01-01

224

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

NASA Astrophysics Data System (ADS)

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

Ogg, James G.; Steiner, Maureen B.

1991-10-01

225

Arctic Melting  

NSDL National Science Digital Library

In this radio broadcast, a panel of experts joins National Public Radio journalist Diane Rehm to discuss rising temperatures at the North Pole and what the melting may mean for the climate, national boundaries, and oil exploration. There is discussion of the 1982 U.N. convention, Law of the Sea, which is guiding new mapping due to arctic melting and changing coastlines; and why the decreasing need for Arctic ice-breakers is making oil exploration mapping easier. There is explanation of why the Antarctic may melt a couple of decades after the Arctic; why we know sea levels will rise as polar ice melts; and why we know humans are causing the melting, as opposed to astronomical configurations or other natural causes leading to melting cycles. The broadcast is 51 minutes in length, but the discussion about the Arctic starts 32 minutes into the program and lasts 19 minutes. You may listen to the archived broadcast in Windows Media or Real Audio format.

2011-06-15

226

Unraveling the empirical relationship between Arctic stratospheric ozone loss and temperature  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

227

Pedogenic Gradients of the Polar Regions.  

National Technical Information Service (NTIS)

Soils of the polar regions are divided into three zones--Arctic Brown, Polar Desert, and Cold Desert. The Arctic Brown soil coincides approximately with the arctic tundra belt, the Polar Desert zone is penecontiguous with the high arctic, and the Cold Des...

J. C. F. Tedrow

1967-01-01

228

Arctic Ocean  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

229

Aura Microwave Limb Sounder Observations of Dynamics and Transport During the Record-Breaking 2009 Arctic Stratospheric Major Warming  

NASA Technical Reports Server (NTRS)

A major stratospheric sudden warming (SSW) in January 2009 was the strongest and most prolonged on record. Aura Microwave Limb Sounder (MLS) observations are used to provide an overview of dynamics and transport during the 2009 SSW, and to compare with the intense, long-lasting SSW in January 2006. The Arctic polar vortex split during the 2009 SSW, whereas the 2006 SSW was a vortex displacement event. Winds reversed to easterly more rapidly and reverted to westerly more slowly in 2009 than in 2006. More mixing of trace gases out of the vortex during the decay of the vortex fragments, and less before the fulfillment of major SSW criteria, was seen in 2009 than in 2006; persistent well-defined fragments of vortex and anticyclone air were more prevalent in 2009. The 2009 SSW had a more profound impact on the lower stratosphere than any previously observed SSW, with no significant recovery of the vortex in that region. The stratopause breakdown and subsequent reformation at very high altitude, accompanied by enhanced descent into a rapidly strengthening upper stratospheric vortex, were similar in 2009 and 2006. Many differences between 2006 and 2009 appear to be related to the different character of the SSWs in the two years.

Manney, Gloria L.; Schwartz, Michael J.; Krueger, Kirstin; Santee, Michelle L.; Pawson, Steven; Lee, Jae N.; Daffer, William H.; Fuller, Ryan A.; Livesey, Nathaniel J.

2009-01-01

230

Redistribution of nitric acid in the Arctic lower stratosphere during the winter of 1996-1997  

NASA Astrophysics Data System (ADS)

Vertical profiles of HNO3, N2O, O3, and the aerosol extinction coefficient at 780 nm were observed by the Improved Limb Atmospheric Spectrometer (ILAS) on board the Advanced Earth Observing Satellite (ADEOS) during the Arctic winter of 1996-1997. Irreversible redistribution of HNO3 is evaluated using HNO3-N2O and HNO3-O3 correlations. Denitrification and nitrification started to be observed just after the Arctic vortex cooled to below the ice frost point (TICE) on February 10. Trajectory analyses show that denitrification occurred only in air masses, which were once cooled to near TICE and were kept at temperatures below the nitric acid trihydrate saturation threshold continuously for more than 4 days. Such a temperature history provides the necessary conditions for nucleation and growth of particles causing denitrification. The average extent of denitrification at 19 km reached 43% at the center of the vortex, suggesting that stratospheric ozone could be affected by denitrification deep inside the vortex. Denitrification (>2 ppbv) and nitrification (>1 ppbv) covered 40±10% and 35±10% of the vortex area, respectively. Redistributed numbers of HNO3 molecules at each altitude were calculated by integrating the area-weighted changes in the HNO3 concentration. The decreases in total HNO3 concentration at 17-21 km in late February and early March agreed with the increases at 12-15 km to within 25%, confirming conservation of HNO3 during sedimentation and evaporation of HNO3-containing polar stratospheric cloud particles.

Irie, H.; Koike, M.; Kondo, Y.; Bodeker, G. E.; Danilin, M. Y.; Sasano, Y.

2001-10-01

231

Functional characterization of parvalbumin from the Arctic cod ( Boreogadus saida): Similarity in calcium affinity among parvalbumins from polar teleosts  

Microsoft Academic Search

Calcium dissociation constants (KD) were measured as a function of temperature for parvalbumin, a small acidic protein expressed abundantly in fast-twitch muscle, from the Arctic cod (Boreogadus saida) and compared to values previously determined for Antarctic and temperate zone teleosts. Estimates of KD were derived independently from fluorometric titrations and calorimetry. In addition, the primary structure of B. saida parvalbumin

Jeffrey R. Erickson; Timothy S. Moerland

2006-01-01

232

A study of the vertical scale of halogen chemistry in the Arctic troposphere during Polar Sunrise at Barrow, Alaska  

Microsoft Academic Search

The vertical extent and impact of halogen chemistry in the Arctic springtime was investigated through balloon-based measurement of several atmospheric chemical components. Various chemical species, including volatile organic compounds (VOCs), ozone, and elemental mercury, that are modified by halogen chemistry were measured from the surface to ?300 m during late March through mid-April 2005 in Barrow, Alaska. It is observed

Philip J. Tackett; Aubrey E. Cavender; Adam D. Keil; Paul B. Shepson; Jan W. Bottenheim; Samuel Morin; John Deary; Alexandra Steffen; Chris Doerge

2007-01-01

233

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

PubMed

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

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

2008-12-01

234

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

PubMed

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

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

2013-09-01

235

Moisture transport and Atmospheric circulation in the Arctic  

NASA Astrophysics Data System (ADS)

Cyclones are an important feature of the Mid-Latitudes and Arctic Climates. They are a main transporter of warm moist energy from the sub tropics to the poles. The Arctic Winter is dominated by highly stable conditions for most of the season due to a low level temperature inversion caused by a radiation deficit at the surface. This temperature inversion is a ubiquitous feature of the Arctic Winter Climate and can persist for up to weeks at a time. The inversion can be destroyed during the passage of a cyclone advecting moisture and warming the surface. In the absence of an inversion, and in the presence of this warm moist air mass, clouds can form quite readily and as such influence the radiative processes and energy budget of the Arctic. Wind stress caused by a passing cyclones also has the tendency to cause break-up of the ice sheet by induced rotation, deformation and divergence at the surface. For these reasons, we wish to understand the mechanisms of warm moisture advection into the Arctic from lower latitudes and how these mechanisms are controlled. The body of work in this area has been growing and gaining momentum in recent years (Stramler et al. 2011; Morrison et al. 2012; Screen et al. 2011). However, there has been no in depth analysis of the underlying dynamics to date. Improving our understanding of Arctic dynamics becomes increasingly important in the context of climate change. Many models agree that a northward shift of the storm track is likely in the future, which could have large impacts in the Arctic, particularly the sea ice. A climatology of six-day forward and backward trajectories starting from multiple heights around 70 N is constructed using the 22 year ECMWF reanalysis dataset (ERA-INT). The data is 6 hourly with a horizontal resolution of 1 degree on 16 pressure levels. Our methodology here is inspired by previous studies examining flow patterns through cyclones in the mid-latitudes. We apply these earlier mid-latitude methods in the Arctic. We investigate an Arctic trajectory dataset and provide a phenomenological/descriptive analysis of these trajectories, including key meteorological variables carried along trajectories. The trajectory climatology is linked to a previously established cyclone climatology dataset from Hanley and Caballero (2011). We associate trajectories and the meteorological variables they are carrying to cyclones in this dataset. A climatology of 'Arctic-influencing' cyclones is constructed from the cyclone dataset. The resilience of the polar vortex and its effect on circulation, via blocking and breaking, is examined in relation to our trajectory climatology.

Woods, Cian; Caballero, Rodrigo

2013-04-01

236

Arctic Research Opportunities  

NSF Publications Database

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

237

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

PubMed Central

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

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

2014-01-01

238

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

PubMed

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

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

2014-07-13

239

Airborne Arctic Stratospheric Expedition 2: Air Parcel Trajectories  

NASA Technical Reports Server (NTRS)

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

1993-01-01

240

Observations of stratospheric source gas profiles during the Arctic winter  

NASA Technical Reports Server (NTRS)

An international campaign was performed at ESRANGE rocket base, near Kiruna, Sweden (68 N) from January 4 to February 15 in order to investigate the Chemistry of Ozone in the Polar Stratosphere (CHEOPS). Within the framework of this campaign two sets of large stratospheric air samples were collected by means of a balloon borne cryogenic air sampler. The two balloons were launched on February 1, and February 10, 1988. At present the samples are analyzed in our laboratory for their contents of several long lived trace gases such as CH4, N2O, H2, CO2, CO and the major halocarbons CH3Cl, CFCl3, CF2Cl2, CCl4, CH3CCl3, and C2F3Cl3. The vertical profiles derived from these samples will be presented and compared with previous observations made in February 1987. The data will be discussed in view of the dynamical evolution of the Arctic polar vortex during this winter.

Schmidt, U.; Bauer, R.; Kulessa, G.; Klein, E.; Schubert, B.

1988-01-01

241

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

Microsoft Academic Search

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

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

2010-01-01

242

Changing Global Circumpolar Vortex  

NASA Astrophysics Data System (ADS)

Observations and projections of the circumpolar vortex (CV) in both hemispheres are examined in the context of climate change. Long-term (1951~2100) maps and statistics of daily/monthly CV size, perimeter and circularity ratio (CR) are produced from the NCEP/NCAR reanalysis I (1951~present) and IPCC CMIP5 (present~2100) modeled 500hPa pressure data sets using Geographic Information System (GIS) methods. Analyses of daily/monthly data show that the size and perimeter of the Northern Hemisphere CV have shrunk, particularly in spring and summer, while pattern changes are not seen around the Antarctica. No obvious change in the CR of the CV in either hemisphere indicates that abnormal temperature events such as cold surges in winter and heat waves in summer around circumpolar regions still occur periodically in the recent warmer climate. Pattern changes observed in the Northern Hemisphere may be associated with the complexity of the land-ocean distribution and Arctic cryospheric feedbacks (e.g. the reduction of albedo due to melting Arctic sea ice and reduced continental snow cover). The absence of notable changes in the Southern Hemisphere may be due to less atmosphere warming or cryospheric changes over Antarctica and the Southern Ocean. Projected future CV characteristics will also be discussed in detail. Keywords: circumpolar vortex, cryospheric feedbacks, climate change, Geographic Information System (GIS)

Choi, G.; Robinson, D. A.

2013-12-01

243

Health effects from long-range transported contaminants in Arctic top predators: An integrated review based on studies of polar bears and relevant model species.  

PubMed

The aim of this review is to provide a thorough overview of the health effects from the complexed biomagnified mixture of long-range transported industrial organochlorines (OCs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs) and mercury (Hg) on polar bear (Ursus maritimus) health. Multiple scientific studies of polar bears indicate negative relationships between exposure to these contaminants and health parameters; however, these are all of a correlative nature and do not represent true cause-and-effects. Therefore, information from controlled studies of farmed Norwegian Arctic foxes (Vulpes lagopus) and housed East and West Greenland sledge dogs (Canis familiaris) were included as supportive weight of evidence in the clarification of contaminant exposure and health effects in polar bears. The review showed that hormone and vitamin concentrations, liver, kidney and thyroid gland morphology as well as reproductive and immune systems of polar bears are likely to be influenced by contaminant exposure. Furthermore, exclusively based on polar bear contaminant studies, bone density reduction and neurochemical disruption and DNA hypomethylation of the brain stem seemed to occur. The range of tissue concentration, at which these alterations were observed in polar bears, were ca. 1-70,000 ng/g lw for OCs (blood plasma concentrations of some PCB metabolites even higher), ca. 1-1000 ng/g lw for PBDEs and for PFCs and Hg 114-3052 ng/g ww and 0.1-50 microg/g ww, respectively. Similar concentrations were found in farmed foxes and housed sledge dogs while the lack of dose response designs did not allow an estimation of threshold levels for oral exposure and accumulated tissue concentrations. Nor was it possible to pinpoint a specific group of contaminants being more important than others nor analyze their interactions. For East Greenland polar bears the corresponding daily SigmaOC and SigmaPBDE oral exposure was estimated to be 35 and 0.34 microg/kg body weight, respectively. Furthermore, PFC concentrations, at which population effect levels could occur, are likely to be reached around year 2012 for the East Greenland polar bear subpopulation if current increasing temporal trends continue. Such proposed reproductive population effects were supported by physiological based pharmacokinetic (PBPK) modelling of critical body residues (CBR) with risk quotients >or=1 for SigmaPCB, dieldrin, SigmaPFC and SigmaOHC (organohalogen contaminant). The estimated daily TEQ for East Greenland polar bears and East Greenland sledge dogs were 32-281-folds above WHO SigmaTEQ guidelines for humans. Compared to human tolerable daily intake (TDI), these were exceeded for PCBs, dieldrin, chlordanes and SigmaHCH in East Greenland polar bears. Comparisons like these should be done with caution, but together with the CBR modelling and T-score estimations, these were the only available tools for polar bear risk evaluation. In conclusion, polar bears seem to be susceptible to contaminant induced stress that may have an overall sub-clinical impact on their health and population status via impacts on their immune and reproductive systems. PMID:20398940

Sonne, Christian

2010-07-01

244

Non-stochastic colonization by pioneer plants after deglaciation in a polar oasis of the Canadian High Arctic  

NASA Astrophysics Data System (ADS)

Initial plant colonization is critical in determining subsequent ecosystem development. In a High-Arctic oasis showing atypical “directional primary succession”, we quantified the microhabitat characteristics associated with colonization by pioneer vascular plants of a bare moraine. The study moraine, formed during the Little Ice Age, is located within the proglacial area at the southern front of Arklio Glacier, Ellesmere Island, Canada. We established two line-transects on this moraine to quantify microhabitats for vascular species. Microsites favorable for plants were concave depressions, probably increasing the likelihood of colonization. At microsites distant from stable boulders, which probably protect seeds/seedlings from wind desiccation, plant colonization was less likely. Furthermore, favorable microhabitat properties differed depending on topographical location within the moraine, suggesting that, even within a single moraine, microhabitats favorable for plant colonization are heterogeneously-distributed. This moraine was characterized by two major pioneer species, Epilobium latifolium and Salix arctica. Their species-specific microhabitat requirements highlight the importance of biotic factors in colonization processes. Favorable sites for plants are generally distributed at random in harsh environments. However, we showed that initial plant colonization is a deterministic process rather than random, indicating the possibility of non-stochastic processes even during the early phase of ecosystem development in High-Arctic ecosystems.

Mori, Akira S.; Uchida, Masaki; Kanda, Hiroshi

2013-09-01

245

Polar stratospheric cloud climatology based on Stratospheric Aerosol Measurement II observations from 1978 to 1989  

NASA Technical Reports Server (NTRS)

The probability of polar stratospheric cloud (PSC) occurrence in the Antarctic and Arctic has been estimated using Stratospheric Aerosol Measurement (SAM) II aerosol extinction data from 1978 to 1989. Antarctic PSCs are typically observed by SAM II from mid-May to early November, with a maximum zonal average probability of about 0.6 at 18-20 km in August. The typical Arctic PSC season extends only from late November to early March, with a peak zonal average probability of about 0.1 in early February at 20-22 km. There is considerable year-to-year variability in Arctic PSC sightings because of changes in the dynamics of the northern polar vortex. Year-to-year variability in Antarctic sightings is most prominent in the number of late season clouds. Maximum PSC sighting probabilities in both polar regions occur in the region from 90 deg W through the Greenwich meridian to 90 deg E, where temperatures are coldest on average. Arctic sighting probabilities approach zero outside this region, but clouds have been sighted in the Antarctic at all longitudes during most months. Inferred PSC formation temperatures remain constant throughout the Arctic winter and are similar to those in early Antarctic winter. PSC formation temperatures in the Antarctic drop markedly in the 15 to 20-km region by September, a pattern consistent with the irreversible loss of HNO3 and H2O vapor in sedimenting PSC particles.

Poole, Lamont R.; Pitts, Michael C.

1994-01-01

246

Arctic Circle  

NSDL National Science Digital Library

Extensive information on the Arctic Circle. Highly acclaimed website features: natural resources, history and culture, society equity and environmental justice, a museum, a virtual classroom, and an Arctic forum, a discussion group for visitors. A wealth of information concerning the Arctic is at your fingertips. Site also includes information on Arctic legislation, natural resource management, stories about indigenous people, art and photo gallery, and GIS. Also features Arctic literature, music, and media.

247

Mapping Arctic circumpolar albedo at 250-m spatial resolution during International Polar Year by fusion of MODIS/TERRA land bands B1-B7  

NASA Astrophysics Data System (ADS)

The time series of spatially-enhanced MODIS surface albedo for the Arctic circumpolar zone (9,000km × 9,000km) are generated as the Canada Centre for Remote Sensing (CCRS) contribution to the Canadian component of the International Polar Year (IPY) Program. The imagery is obtained by a fusion of MODIS bands B1-B2 observed at 250-meter spatial resolution with bands B3-B7 observed at 500-meter spatial resolution to satisfy the Global Climate Observing System (GCOS) requirements for spatial resolution of satellite products for climate. The fusion method employed an adaptive regression and normalization to preserve the image radiometric properties. A new cloud and cloud shadow detection method and clear-sky compositing scheme were employed for the 250m multi-spectral data. Unlike standard MODIS products divided into separate thematic categories, this new product is spatially continuous over the entire circumpolar area and includes all surface types: land, ocean, snow/ice. New bi-directional reflectance distribution model based on POLDER multiangular observations is employed. This model accounts better for the hot-spot effect and makes distinction between surfaces covered by a canopy and surfaces with specular reflection, such as water and snow/ice. By the end of the IPY in 2009, a decade long (2000-2009) time series of these data at 10-day intervals will be available to document the state and variability of the Arctic region at high spatial and temporal resolution. This study is conducted at the Canada Centre for Remote Sensing (CCRS), Earth Sciences Sector of the Department of Natural Resources Canada as part of the Project J35 of the Program on "Enhancing Resilience in a Changing Climate" and the "Climate Change and Ecosystem Impact" Project supported by the Canadian Space Agency through the Government Related Initiatives Program (GRIP). The MODIS data were acquired through the NASA Distributed Active Archive Center (DAAC).

Trishchenko, Alexander; Luo, Yi; Khlopenkov, Konstantin; Park, William; Wang, Shusen

248

In situ measurements of BrO in the Arctic stratosphere  

NASA Technical Reports Server (NTRS)

Mixing ratios of BrO have been measured in the Arctic lower statosphere with an instrument mounted on the NASA ER-2 aircraft. Observations from fourteen flights above the Arctic Circle in January and February of 1989 defined mixing ratios within the vortex of 4 + or - 2 parts per trillion by volume (pptv) at a potential temperature of 400 K, rising to 8 + or - 2 pptv at 470 K. These values are twice as large as values found at equivalent potential temperatures at lower latitudes, and are comparable to the mixing ratios found inside the antarctic polar vortex. Within the statistical uncertainty of the measurements, no BrO was observed in darkness at any time either inside or outside of the vortex, indicating that active bromine was sequestered in long-lived reservoirs, probably BrONO2 and BrCl. These measurements, in conjuction with measurements of ClO, demonstrate that the interaction of bromine and chlorine could represent a major sink for ozone in the presence of sunlight.

Toohey, D. W.; Anderson, J. G.; Brune, W. H.; Chan, K. R.

1990-01-01

249

2009/2010 Eurasian Cold Winter and Loss of Arctic Sea-ice over Barents/Kara Sea  

NASA Astrophysics Data System (ADS)

In 2009/2010 winter, a few extreme cold events and heavy snowfall occurred over central North America, north western Europe, and East Asia exerting a severe social and economic impacts. In this study, we performed modeling experiments to examine the role of substantially reduced Arctic sea-ice over Barents/Kara Sea on the 2009/2010 cold winters. Although several previous studies investigated cause of the extreme events and emphasized the large snow-covered area over Siberia in autumn 2009, we note that the area extent of Arctic sea-ice over Barents/Kara sea in autumn 2009 was anomalously low and the possible impact from Arctic for the extreme cold events has not been presented. To investigate the influence from the Arctic, we designed three model runs using Community Atmosphere Model Version 3 (CAM3). Each simulation differs by the prescribed surface boundary conditions: (a) CTRL - climatological seasonal cycle of sea surface temperature (SST) and sea-ice concentration (SIC) are prescribed everywhere, (b) EXP_65N - SST and SIC inside the Arctic circle (north of 65°N) are replaced by 2009/2010 values. Elsewhere, the climatology is used, (c) EXP_BK - Same with (b) except that SIC and SST are fixed only over Barents/Kara Sea where the sea-ice area dropped significantly in 2009/2010 winter. Model results from EXP_65N and EXP_BK commonly showed a large increase of air temperature in the lower troposphere where Arctic sea-ice showed a large reduction. Also, compared with the observation, model successfully captured thickened geopotential height in the Arctic and showed downstream wave propagation toward midlatitude. From the analysis, we reveal that this large dipolar Arctic-midlatitude teleconnection pattern in the upper troposphere easily propagate upward and played a role in the weakening of polar vortex. This is also confirmed in the observation. However, the timing of excitation of upward propagating wave in EXP_65N and EXP_BK were different and thus the timing of weakening of polar vortex also differs in each experiment. Unlike with our expectation, both EXP_65N and EXP_BK did not capture the abrupt increase of snow-cover in the observation over Siberian region in autumn 2009. Therefore, given the successful reproduction of key observed features of cold winter 2009/2010 by EXP_65N and EXP_BK, we conclude that Arctic sea-ice in autumn 2009 played a key role for the subsequent development of cold winter 2009/2010 and the role was largely independent with the autumn snow-cover.

Shim, T.; Kim, B.; Kim, S.

2012-12-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2012-04-01

251

Arctic Story Puzzles  

NSDL National Science Digital Library

This activity has three story puzzles learners can solve to learn about life in the Arctic. Through this story-sequencing activity, learners will explore how life for polar bears and the native Inuit people is being affected by climate change. Activity includes three puzzles as PDF files.

History, American M.

2007-01-01

252

The Influence of Stratospheric Vortex Displacements and Splits on Surface Climate  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

253

Generation and dynamics of vortex lattices in coherent exciton-polariton fields.  

PubMed

Vortex dynamics in coherent ensembles of exciton polaritons (condensates) is studied in the framework of the polarization-dependent Gross-Pitaevskii equation. Vortex lattices can be resonantly excited in the polariton field by the interference of three or more optical pumps. Vortex-antivortex pairs can also appear in polariton condensates due to scattering with disorder. The nonlinear vortex dynamics is characterized by interactions of vortex cores and vortex-antivortex recombination. PMID:18999864

Liew, T C H; Rubo, Yuri G; Kavokin, A V

2008-10-31

254

SOME ASPECTS OF THE THERMAL ENERGY EXCHANGE ON THE SOUTH POLAR SNOW FIELD AND ARCTIC ICE PACK1  

Microsoft Academic Search

Solar and terrestrial radiation measurements that were obtained at Amundsen-Scot>t (South Pole) Station and on Ice lsland (Bravo) T-3 are presented for representative summer and winter months. Of the South Polar net radiation loss during April 1958, approximately 20 percent of the energy came from the snow and 80 percent from the air. The actual atmospheric cooling rate during that

KIRBY J. HANSON

1961-01-01

255

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

256

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

PubMed

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

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

2006-02-15

257

Live from the Arctic  

NASA Astrophysics Data System (ADS)

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

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

2003-12-01

258

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

Microsoft Academic Search

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

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

1983-01-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

260

Arctic Research Opportunities  

NSF Publications Database

Arctic research is supported at NSF by the Office of Polar Programs (OPP), Arctic Sciences Section (http://www.nsf.gov/div/index.jsp?div=ARC), in the Office of the Director, as well as by a number of other programs within the Foundation. Proposals should be written and planned in accordance with NSF's Grant Proposal Guide (http://www.nsf.gov/publications/pub_summ.jsp?ods_key=gpg), OPP's Guidelines and Award Conditions for Scientific Data (OPP 9-91 available on the OPP website http://www.nsf....

261

Arctic Research and Writing  

NSDL National Science Digital Library

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

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

2009-01-01

262

Vortex formation and instability in the left ventricle  

NASA Astrophysics Data System (ADS)

We study the formation of the mitral vortex ring during early diastolic filling in a patient-specific left ventricle (LV) using direct numerical simulation. The geometry of the left ventricle is reconstructed from Magnetic Resonance Imaging (MRI) data of a healthy human subject. The left ventricular kinematics is modeled via a cell-based activation methodology, which is inspired by cardiac electro-physiology and yields physiologic LV wall motion. In the fluid dynamics videos, we describe in detail the three-dimensional structure of the mitral vortex ring, which is formed during early diastolic filling. The ring starts to deform as it propagates toward the apex of the heart and becomes inclined. The trailing secondary vortex tubes are formed as the result of interaction between the vortex ring and the LV wall. These vortex tubes wrap around the circumference and begin to interact with and destabilize the mitral vortex ring. At the end of diastole, the vortex ring impinges on the LV wall and the large-scale intraventricular flow rotates in clockwise direction. We show for the first time that the mitral vortex ring evolution is dominated by a number of vortex-vortex and vortex-wall interactions, including lateral straining and deformation of vortex ring, the interaction of two vortex tubes with unequal strengths, helicity polarization of vortex tubes and twisting instabilities of the vortex cores.

Le, Trung Bao; Sotiropoulos, Fotis; Coffey, Dane; Keefe, Daniel

2012-09-01

263

Generation of broadband terahertz vortex beams.  

PubMed

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

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

2014-07-01

264

Tunable eigenmodes of coupled magnetic vortex oscillators  

NASA Astrophysics Data System (ADS)

We study the magnetization dynamics of coupled vortices in arrays of Permalloy disks via analytical calculations and scanning transmission x-ray microscopy. The Thiele approach is used to derive linear equations of motion of the vortices. Thereby, vortex motions following a nanosecond field pulse are described by a superposition of eigenmodes that depend on the vortex polarizations. Eigenmodes are calculated for a specific polarization pattern of a 3 × 3 vortex array. With magnetic field pulses distinct oscillations are excited and imaged in space and time. The calculated eigenmodes precisely describe the measured oscillations.

Hänze, Max; Adolff, Christian F.; Weigand, Markus; Meier, Guido

2014-05-01

265

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

266

Stratospheric ozone loss in the 1996/1997 Arctic winter: Evaluation based on multiple trajectory analysis for double-sounded air parcels by ILAS  

NASA Astrophysics Data System (ADS)

Quantitative chemical ozone loss rates and amounts in the Arctic polar vortex for the spring of 1997 are analyzed based on ozone profile data obtained by the Improved Limb Atmospheric Spectrometer (ILAS) using an extension of the Match technique. In this study, we calculated additional multiple trajectories and set very strict criteria to overcome the weakness of the satellite sensor data (lower vertical resolution and larger sampling air mass volume) and to identify more accurately a double-sounded air mass. On the average inside the inner edge of the vortex boundary (north of about 70°N equivalent latitude), the local ozone loss rate was 50-80 ppbv/day at the maximum during late February between the levels of 450 and 500 K potential temperatures. The integrated ozone loss during February to March reached 2.0 ± 0.1 ppmv at 475-529 K levels, and the column ozone loss between 400 and 600 K during the 2 months was 96 ± 0.3 DU. Using a relative potential vorticity (rPV) scale, the vortex was divided into some rPV belts, and it was shown that the magnitude of the ozone loss increased gradually toward the vortex center from the edge. The maximum ozone loss rate of 6.0 ± 0.6 ppbv/sunlit hour near the vortex center was higher than near the vortex edge by a factor of 2-3. When we expanded the area of interest to include all the data obtained inside the vortex edge (north of about 65°N equivalent latitude), the local ozone loss rate was about 50 ppbv/day at the maximum. This value is slightly larger than that estimated by the Match analysis using ozonesondes for the same winter by ˜10 ppbv/day. Temperature histories of double-sounded air parcels indicated that the extreme ozone loss in the innermost part of the vortex was observed when the air parcel experienced temperatures below TNAT during the two soundings and had experienced temperatures near Tice in the 10 days prior to the first sounding. These facts suggest that the high ozone loss rate deep inside the vortex in the 1997 Arctic early spring correlates with the presence of type Ia polar stratospheric clouds (PSCs).

Terao, Yukio; Sasano, Yasuhiro; Nakajima, Hideaki; Tanaka, H. L.; Yasunari, Tetsuzo

2002-12-01

267

Polar low monitoring  

NASA Astrophysics Data System (ADS)

Polar lows are intense mesoscale atmospheric low pressure weather systems, developing poleward of the main baroclinic zone and associated with high surface wind speeds. Small size and short lifetime, sparse in-situ observations in the regions of their development complicate polar low study. Our knowledge of polar lows and mesocyclones has come almost entirely during the period of satellite remote sensing since, by virtue of their small horizontal scale, it was rarely possible to analyse these lows on conventional weather charts using only the data from the synoptic observing network. However, the effects of intense polar lows have been felt by coastal communities and seafarers since the earliest times. These weather systems are thought to be responsible for the loss of many small vessels over the centuries, although the nature of the storms was not understood and their arrival could not be predicted. The actuality of the polar low research is stipulated by their high destructive power: they are a threat to such businesses as oil and gas exploration, fisheries and shipping. They could worsen because of global warming: a shrinking of sea ice around the North Pole, which thawed to its record minimum in the summer of 2007, is likely to give rise to more powerful storms that form only over open water and can cause hurricane-strength winds. Therefore, study of polar lows, their timely detection, tracking and forecasting represents a challenge for today meteorology. Satellite passive microwave data, starting from Special Sensor Microwave Imager (SSM/I) onboard Defense Meteorological Satellite Program (DMSP) satellite, remain invaluable source of regularly available remotely sensed data to study polar lows. The sounding in this spectral range has several advantages in comparison with observations in visible and infrared ranges and Synthetic Aperture Radar (SAR) data: independence on day time and clouds, regularity and high temporal resolution in Polar Regions. Satellite passive microwave data make it possible to retrieve several important atmospheric and oceanic parameters inside the polar lows, such as sea surface wind speed, water vapour content in the atmosphere, total liquid water content in the clouds and others, providing not only qualitative image of a vortex, but also quantitative information about these severe events, constituting a promising tool for their study and monitoring. An approach for detection and tracking of polar lows is developed utilizing the data from two sensors: SSM/I onboard DMSP and Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) onboard Aqua satellite. This approach consists of two stages. At the first stage total atmospheric water vapor fields are retrieved from SSM/I and AMSRE-E measurement data using precise Arctic polar algorithms, developed at NIERSC. These algorithms are applicable over open water. They have high retrieval accuracies under a wide range of environmental conditions. Algorithms are based on numerical simulation of brightness temperatures and their inversion by means of Neural Networks. At the second stage the vortex structures are detected in these fields, polar lows are identified and tracked and some of their parameters are calculated. A few case studies are comprehensively conducted based on SSM/I and AMSRE-E measurements and using other satellite data including visible, infrared and SAR images, QuickScat Scatterometer wind fields, surface analysis maps and re-analysis data, which demonstrated the advantages of satellite passive microwave data usage in the polar low studies.

Bobylev, Leonid; Zabolotskikh, Elizaveta; Mitnik, Leonid

2010-05-01

268

Islands of the Arctic  

NASA Astrophysics Data System (ADS)

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

Dowdeswell, Julian; Hambrey, Michael

2002-11-01

269

Canada's Polar Environments: Land  

NSDL National Science Digital Library

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

270

Interhemispheric differences in polar stratospheric HNO{sub 3}, H{sub 2}O, ClO, and O{sub 3}  

SciTech Connect

Simultaneous global measurements of nitric acid (HNO{sub 3}), water (H{sub 2}O), chlorine monoxide (ClO), and ozone (O{sub 3}) in the stratosphere have been obtained over complete annual cycles in both hemispheres by the Microwave Limb Sounder on the Upper Atmosphere Research Satellite. A sizeable decrease in gas-phase HNO{sub 3} was evident in the lower stratospheric vortex over Antarctica by early June 1992, followed by a significant reduction in gas-phase H{sub 2}O after mid-July. By mid-August, near the time of peak ClO, abundances of gas-phase HNO{sub 3} and H{sub 2}O were extremely low. The concentrations of HNO{sub 3} and H{sub 2}O over Antarctica remained depressed into November, well after temperatures in the lower stratosphere had risen above the evaporation threshold for polar stratospheric clouds, implying that denitrification and dehydration had occurred. No large decreases in either gas-phase HNO{sub 3} or H{sub 2}O were observed in the 1992-1993 Arctic winter vortex. Although ClO was enhanced over the Arctic as it was over the Antarctic, Arctic O{sub 3} depletion was substantially smaller than that over Antarctica. A major factor currently limiting the formation of an Arctic ozone {open_quotes}hole{close_quotes} is the lack of denitrification in the northern polar vortex, but future cooling of the lower stratosphere could lead to more intense denitrification and consequently larger losses of Arctic ozone. 34 refs., 2 figs.

Santee, M.L.; Read, W.G.; Waters, J.W.; Froidevaux, L.; Manney, G.L.; Flower, D.A.; Jarnot, R.F. [Jet Propulsion Lab., Pasadena, CA (United States); Harwood, R.S. [Edinburgh Univ. (United Kingdom)

1995-02-10

271

Near UV atmospheric absorption measurements of column abundances during Airborne Arctic Stratospheric Expedition, January-February 1989: 1. Technique and NO sub 2 observations  

SciTech Connect

Spectroscopic measurements of column abundances of NO{sub 2} were carried out from the NASA DC-8 airplane during the Airborne Arctic Stratospheric Expedition in January and February 1989. Stratospheric airmasses inside and close to the polar vortex were found to be highly depleted of NO{sub 2} with lowest vertical column abundances of NO{sub 2} below 2 {times} 10{sup 14} cm{sup {minus}2} compared to abundances of 3-5 {times} 10{sup 15} cm{sup {minus}2} south of 50{degree}N in winter (WMO, 1985).

Wahner, A.; Callies, J.; Dorn, H.P.; Platt, U.; Schiller, C. (Kernforschungsanlage Juelich (West Germany))

1990-03-01

272

Arctic Sea Ice Thickness Distribution as an Indicator of Arctic Climate Change - Synthesis of Model Results and Observations  

Microsoft Academic Search

The Arctic region is an integral part of the Earth's climate system through its influence on global surface energy and moisture fluxes and on atmospheric and oceanic circulation. Within the Arctic, its sea ice cover is possibly the most sensitive indicator of the polar amplified global warming and of the state of Arctic climate system as a whole. Hence changes

Wieslaw Maslowski; Jaclyn Clement Kinney; Jaromir Jakacki; Robert Osinski; Jay Zwally

2010-01-01

273

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

NASA Astrophysics Data System (ADS)

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

Pérot, K.; Urban, J.; Murtagh, D. P.

2014-02-01

274

Brownian vortexes  

NASA Astrophysics Data System (ADS)

Mechanical equilibrium at zero temperature does not necessarily imply thermodynamic equilibrium at finite temperature for a particle confined by a static but nonconservative force field. Instead, the diffusing particle can enter into a steady state characterized by toroidal circulation in the probability flux, which we call a Brownian vortex. The circulatory bias in the particle’s thermally driven trajectory is not simply a deterministic response to the solenoidal component of the force but rather reflects interplay between advection and diffusion in which thermal fluctuations extract work from the nonconservative force field. As an example of this previously unrecognized class of stochastic heat engines, we consider a colloidal sphere diffusing in a conventional optical tweezer. We demonstrate both theoretically and experimentally that nonconservative optical forces bias the particle’s fluctuations into toroidal vortexes whose circulation can reverse direction with temperature or laser power.

Sun, Bo; Lin, Jiayi; Darby, Ellis; Grosberg, Alexander Y.; Grier, David G.

2009-07-01

275

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

276

Pineal and Photoperiodism in Arctic Species.  

National Technical Information Service (NTIS)

This chapter will describe the seasonal cycles of day-light and temperature in polar regions, will outline the reproductive cycles of arctic birds and mammals, and will review what is known about pineal physiology of these species. (Author)

G. E. Folk

1977-01-01

277

Anisotropic and Long-Range Vortex Interactions in Two-Dimensional Dipolar Bose Gases  

NASA Astrophysics Data System (ADS)

We perform a theoretical study into how dipole-dipole interactions modify the properties of superfluid vortices within the context of a two-dimensional atomic Bose gas of co-oriented dipoles. The reduced density at a vortex acts like a giant antidipole, changing the density profile and generating an effective dipolar potential centred at the vortex core whose most slowly decaying terms go as 1/?2 and ln?(?)/?3. These effects modify the vortex-vortex interaction which, in particular, becomes anisotropic for dipoles polarized in the plane. Striking modifications to vortex-vortex dynamics are demonstrated, i.e., anisotropic corotation dynamics and the suppression of vortex annihilation.

Mulkerin, B. C.; van Bijnen, R. M. W.; O'Dell, D. H. J.; Martin, A. M.; Parker, N. G.

2013-10-01

278

One more step toward a warmer Arctic  

Microsoft Academic Search

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

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

2005-01-01

279

Water vapour variability and trends in the Arctic stratosphere  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

280

How Model Differences in Stratospheric Transport can Influence Polar Ozone Recovery  

NASA Astrophysics Data System (ADS)

We examine 3 Global Modeling Initiative (GMI) chemistry and transport simulations that have the same WMO A2 source gas boundary conditions for 1980-2025 but different stratospheric circulations and Arctic temperatures. We examine the evolution of Cly in each polar vortex and compare the models' ozone response. Two simulations of the GMI stratospheric model were run at 2ox2.5o resolution. One had a repeating cold Arctic winter with abundant PSCs; the other had a repeating dynamically active, warm winter with almost no PSCs. Maximum Cly in the cold simulation was 2.9 ppb in 2000 and was slightly lower in the warm simulation. The cold winter showed greater sensitivity to Cly and consequently recovered at a faster rate. Nevertheless, both are projected to recover at about the same time. The factors controlling recovery are the halogen boundary condition and mean stratospheric circulation (i.e., age of air), both of which are nearly the same in these simulations. The differences between these simulations demonstrate that interannual variation in transport will play a large role in the appearance of Arctic ozone recovery. Age of air is a diagnostic for stratospheric circulation, but it does not assess the credibility of specific model transport processes. We compare the two simulations above with a GMI simulation run at 4ox5o resolution. All 3 models compare extremely well with mean age determined from aircraft CO2, but the lower resolution model has considerably lower vortex Cly. The low Cly is caused by a leaky vortex which leads to two credibility problems: the leaky vortex can't produce near complete O3 loss because it doesn't maintain the necessary high levels of Cly, and the leakiness causes the model to respond faster to reductions in chlorine, allowing it return to 1980 levels sooner. Models used to predict ozone recovery need to demonstrate a strong Antarctic mixing barrier.

Strahan, S. E.; Douglass, A. R.; Stolarski, R. S.

2006-05-01

281

Record-breaking Ozone Loss during Arctic Winter 2010/2011: Comparison with Arctic Winter 1996/1997  

NASA Astrophysics Data System (ADS)

Polar processing and chemical ozone loss is analysed during the Arctic winter/spring 2010/2011. The analyses with temperatures and potential vorticity (PV) data show a prolonged vortex from early December through mid-April. The PV maps illustrate strong vortex persistence in the lower stratosphere between 450 and 675 K, showing similar evolution with time. The minimum temperatures extracted from ECMWF data at 40-90°N show values below 195 K for a record period of first week of December through second week of April, indicating the longest period of colder temperatures for 17 years. At 10 hPa, there was a warming of about 10 K at 60°N and 40 K at 90°N around mid-January. The heat flux also showed high values in line with the increase in temperatures, of about 425 m K/s at 60°N at the same pressure level. However, the westerlies were strong (e.g. 35-45 m/s at 60°N) enough to keep the vortex intact until mid-April. Because of the cold temperatures in late winter and early spring, large areas of Polar Stratospheric Clouds (PSC) were found in the 400-600 K isentropic level range. Though the maximum values of PSCs area are smaller compared to other cold winters such as 2005, the extended period of presence of PSCs during this winter was exceptional, especially in late February-mid-March, in agreement with the cold temperatures during the period. Ozone loss analyses with high resolution Mimosa-Chim chemical transport model simulations show that the loss started by early January, and was about 0.5 ppmv in late January. The loss progressed slowly to 1 ppmv by the end of February, and then intensified by early March. The ozone depletion estimated by the passive method finds a maximum value of about 2-2.3 ppmv by the end of March-early April in the 450-550K range inside the vortex, which coincides with the areas of PSCs and high chlorine activation. This is the largest loss ever estimated with this model for any Arctic winter. It is consistent with the unprecedented chlorine activation that occurred in the winter, as the modeled ClO values show about 1.7 ppbv in early January and about 1 ppbv in March at 450-550K. This is longest period of chlorine activation noted among the Arctic winters. The ozone partial column loss reaches about 115-150 DU in the range 350 - 550 K. These model results for ozone, ozone loss and ClO are in good agreement with those found from Aura Microwave Limb Sounder observations. Since the winter 1996/1997 was also very cold in March - April, a comparison between both winters 2011 and 1997 will be presented, based on temperature, PV, Heat flux data and ozone loss estimations. Similarities and differences in the polar processing and ozone loss during both winters will be discussed using various measurements and model simulations. Copyright 2011. All rights reserved.

Godin Beekmann, S.; Kuttipurath, J.; Lefèvre, F.; Santee, M. L.; Froidevaux, L.

2011-12-01

282

Climatology of the Martian Polar Vortices  

NASA Astrophysics Data System (ADS)

In the martian atmosphere, as in the terrestrial stratosphere, an intense cyclonic vortex forms over the winter pole. This vortex is known as the polar vortex and its edge is associated with the strong westerly jet that occurs over mid-latitudes during the winter season. The weather on Mars over the mid-to-high winter latitudes is heavily influenced by the polar vortex. However, the size, shape, and position of the vortex are not well characterized. Previous work has shown that the shape of the vortex can be deformed by baroclinic activity. Earlier work has also shown that southern-hemisphere dust activity can push the center of the northern vortex off the pole, resulting in marked deviations in the northern-hemisphere jet stream. It remains unknown how often such deformations in vortex shape and shifts in vortex position occur. Another feature of the vortex that remains poorly characterized is its strength. A strong vortex acts as a barrier against mixing, causing the winter air over the pole to become very cold, while a weak vortex permits mixing and is associated with less-cold polar temperatures. How frequently each of these phases occur and how long they persist remain unanswered questions. Here, we use temperature observations from the Mars Reconnaissance Orbiter Mars Climate Sounder to diagnose the size, shape, position, and strength of the polar vortex. We report the daily and seasonal behavior of both the northern and southern vortices.

McDunn, T. L.; Kass, D. M.; McCleese, D. J.; Kleinboehl, A.; Schofield, J. T.

2013-12-01

283

Natural shaping of the cylindrically polarized beams.  

PubMed

We have experimentally and theoretically shown that the circularly polarized beam bearing a singly charged optical vortex propagating through a uniaxial crystal can be split after focusing into the radially and azimuthally polarized beams in the vicinity of the focal area provided that the polarization handedness and the vortex topological charge have opposite signs. PMID:21081997

Fadeyeva, T; Shvedov, V; Shostka, N; Alexeyev, C; Volyar, A

2010-11-15

284

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

NASA Astrophysics Data System (ADS)

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

Li, King-Fai; Tung, Ka-Kit

2014-05-01

285

The Surface Impacts of Arctic Stratospheric Ozone Variability  

NASA Astrophysics Data System (ADS)

Unlike the near complete destruction of stratospheric ozone in the Antarctic every spring due to anthropogenic cholorofluorocarbon emissions, ozone concentrations in the Arctic stratosphere in winter and spring are highly variable from year to year. Most global climate models (GCMs) prescribe the seasonal cycle of and the trend in ozone but do not include its interannual variability. Here, we investigate the extent to which this variability in Arctic stratospheric ozone influences the surface climate of the Northern Hemisphere. To do this, we examine the difference between model integrations with prescribed low (LO; -25% relative to the 1980-2000 climatological model ozone) and high (HI; +25%) winter/spring stratospheric ozone from 50-90N, using the Community Atmosphere Model Version 3. The most striking differences between the LO and HI ensembles occur in April and May with significant cooling in the Arctic lower stratosphere and a strengthening of the polar vortex, resulting in a delayed final warming in the LO ozone ensemble relative to the HI ensemble by approximately two weeks. In the zonal mean, the LO minus HI response resembles the positive phase of the Northern Annular Mode, with low (high) sea level pressure over the poles (mid-latitudes) and a poleward shift of the mid-latitude jet. The poleward shifted jet in the LO integration is accompanied by a significant poleward shift in extratropical precipitation in spring. Regionally, the most significant changes in the tropospheric zonal winds, precipitation and surface temperature occur in Eastern North America and over the North Atlantic. Our work suggests that, by lacking interannual stratosheric ozone variability, most present generation GCMs may be missing an important source of natural, extratropical variability.

Smith, K. L.; Polvani, L. M.; Correa, G. J.

2013-12-01

286

Arctic transport climatologies for the International Arctic System for Observing the Atmosphere (IASOA) and POLARCAT  

Microsoft Academic Search

Several intensive campaigns have recently focused on the transformation and transport of pollutants to the Arctic. During the International Polar Year large-scale coordinated aircraft campaigns will be conducted throughout the circum-Arctic as a part of the POLARCAT project. Additionally, measurements at surface based sites in the IASOA network will be coordinated to capture unique transport events. Toward improved interpretation of

J. F. Burkhart; B. F. John; A. Stohl; S. Eckhardt; T. Uttal; I. Ocko; K. Tørseth

2007-01-01

287

Singular vortex  

SciTech Connect

During implementation of the PODMODELI-program for the equation of gas dynamics it became clear that the equations have many partial invariant solutions, most of which have not been studied previously. Such solutions require special analysis, which sometimes is not trivial. Our attention was attracted by solutions generated by the rotation group O(3), which is allowed by the equations of gas dynamics. What is specific here is that solutions invariant under O(3), which are known as spherically symmetric solutions, are singular invariant solutions from the standpoint of group analysis. For the group O(3), however, the necessary conditions for the existence of nonsingular partially invariant solutions are rank two and defect one. These solutions are characterized by the fact that their invariant components are spherically symmetric, but their velocity vector component tangential to the sphere is nonzero. It turned out that a fairly broad class of new solutions is opened up here. The aim of this study is to demonstrate that such solutions do exist and to make a general analysis of them. The kinematics and dynamics of the respective motions of the gas are very involved and the details are not yet very clear. A singular vortex is distinguished as an exact solution with a special initial distribution of the tangential component. Particular examples of such exact solutions are given here. In addition, we consider the case of steady-state flow of an incompressible liquid, where solutions of the singular vortex type exist and are fairly foreseeable.

Ovsyannikov, L.V. [M.A. Lavrent`ev Hydrodynamics Institute, Novosibirsk (Russian Federation)

1995-11-01

288

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

National Technical Information Service (NTIS)

During the POLARCAT summer campaign in 2008, two episodes (2 5 July and 7 10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian for...

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

2011-01-01

289

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

Microsoft Academic Search

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

Claude R Joiris

2000-01-01

290

Arctic energy technologies workshop: proceedings  

SciTech Connect

The objectives of this ''Arctic Energy Technologies Workshop'' were threefold: To acquaint participants with the current US Department of Energy, Office of Fossil Energy, Arctic and Offshore Research Program. To obtain information on Arctic oil and gas development problem areas, and on current and planned research. To provide an opportunity for technical information exchange among engineers, geologists, geophysicists, physical scientists, oceanographers, statisticians, analysts, and other participants engaged in similar research areas. The first section of the proceedings is the keynote address ''Current Arctic Offshore Technology'', presented by Kenneth Croasdale, of K.R. Croasdale and Associates, Ltd., Calgary, Alberta, Canada. The second section of the proceedings includes 14 technical papers presented in two sessions at the Workshop: Sea Ice Research, and Seafloor/Soils Research. The third section of the proceedings includes the summaries of four work-group discussion sessions from the second day of the meeting: (1) Arctic Offshore Structures, (2) Arctic Offshore Pipelines, (3) Subice Development Systems, and (4) Polar-Capable Ice Vessels. The work groups addressed state-of-the-art, technical issues, R and D needs, and environmental concerns in these four areas. All papers in this proceedings have been processed for inclusion in the Energy Data Base.

Not Available

1985-04-01

291

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

Microsoft Academic Search

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

Ramón Hegedüs; Susanne Åkesson; Gábor Horváth

2007-01-01

292

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

293

MAMM (Methane and other greenhouse gases in the Arctic - Measurements, process studies and Modelling) progress report  

NASA Astrophysics Data System (ADS)

MAMM consortium (led by JA Pyle, Univ. Cambridge, with partners from Univ. East Anglia; Univ. Manchester; Royal Holloway, Univ. of London; NERC Centre for Ecology and Hydrology). The UK MAMM project (Methane and other greenhouse gases in the Arctic - Measurements, process studies and Modelling) is designed to improve quantitative knowledge of Arctic methane and other greenhouse gases from various sources (e.g. wetlands, natural gas, clathrates), to determine magnitudes and spatial distributions, and to develop process understanding (e.g. dependence of fluxes on temperature). In Arctic Finland, Sweden, Norway and Spitsbergen, intensive low-level aircraft campaigns (flights in spring, summer, autumn 2012 and 2013, with the UK FAAM BAe146 aircraft) are designed to measure concentrations of CH4 and other gases across the Arctic by time and location, with in situ sampling for ?13CCH4 at selected sites on land (Zeppelin, Pallas, Alert) and Keeling-plot diel determination of wetland source signatures. High altitude flights sampled stratosphere-troposphere exchange in the Arctic to assess the impact of the polar vortex on methane isotope budgets. Methane column profiles are measured by combining ground based eddy covariance and chamber measurements with aircraft measurements, using a landscape-scale box model approach and flying up and downwind of source regions. Airborne remote sensing is being used to retrieve CH4 columns for comparison with in-situ profiles and testing of hyperspectral retrieval methods from satellite platforms. Longer-term time series measurements are also being established in Kjølnes, northern Norway, for a range of greenhouse and related species via continuous or flask/bag sampling. Modelling studies are in progress to assess the overall Arctic influence on the global methane budget, including detailed back-trajectory analysis of the measurements, especially the isotopic data, to identify sources of methane by location, type (e.g. gasfield, wetland, biomass fire, clathrate), and seasonality / event, and also regional source analysis using the NAME particle dispersion model. Chemistry/climate modelling is used to assess the role of the Arctic in recent changes in atmospheric methane and to perform projections for future change.

Nisbet, E. G.; Pyle, J. A.

2012-12-01

294

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

295

Arctic National Wildlife Refuge  

NSDL National Science Digital Library

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

296

Global impacts of Arctic climate processes  

Microsoft Academic Search

The polar regions are experiencing major climate and environmental changes due to the combined effects of natural variability and global warming. To address regional Arctic climate processes and their global feedbacks, 53 experts from the United States, Canada, Europe, and Russia gathered for a recent workshop at the Alfred Wegener Institute for Polar and Marine Research, in Potsdam, Germany.The workshop,

Klaus Dethloff; Annette Rinke; Hugh Morrison; Wolfgang Dorn; Ruediger Gerdes; Wieslaw Maslowski; Vladimir Kattsov; Manfred A. Lange; Klaus Görgen; Amanda Lynch

2005-01-01

297

Arctic Council  

NSDL National Science Digital Library

Formed in 1996, the Arctic Council represents a unique forum for cooperation between eight national governments and the indigenous peoples of the region. The member states of the Council include Canada, Denmark, Finland, Iceland, Norway, the Russian Federation, Sweden, and the United States, along with six representatives that speak on behalf of various indigenous groups. Most of the Council's activities are centered around a primary mandate, which is to serve as a regional forum for sustainable development. The What's New area is a good way to find out about the most recent activities, as it contains recent official statements from senior-level officials in the Council, along with announcements about upcoming events. The activities section is equally worth a look and serves the function of an online archive of current project information for such activities as the Arctic Monitoring Assessment Program and the Conservation of Arctic Flora and Fauna Initiative.

298

Arctic Net  

NSDL National Science Digital Library

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

299

Arctic Meltdown  

NSDL National Science Digital Library

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

2011-11-29

300

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

301

Recent dynamics of arctic and sub-arctic vegetation  

NASA Astrophysics Data System (ADS)

We present a focus issue of Environmental Research Letters on the ‘Recent dynamics of arctic and sub-arctic vegetation’. The focus issue includes three perspective articles (Verbyla 2011 Environ. Res. Lett. 6 041003, Williams et al 2011 Environ. Res. Lett. 6 041004, Loranty and Goetz 2012 Environ. Res. Lett. 7 011005) and 22 research articles. The focus issue arose as a result of heightened interest in the response of high-latitude vegetation to natural and anthropogenic changes in climate and disturbance regimes, and the consequences that these vegetation changes might have for northern ecosystems. A special session at the December 2010 American Geophysical Union Meeting on the ‘Greening of the Arctic’ spurred the call for papers. Many of the resulting articles stem from intensive research efforts stimulated by International Polar Year projects and the growing acknowledgment of ongoing climate change impacts in northern terrestrial ecosystems.

Epstein, Howard E.; Myers-Smith, Isla; Walker, Donald A.

2013-03-01

302

Vortex Buckyball  

NASA Astrophysics Data System (ADS)

Buckminsterfullerene, C60, is a molecule with perfect symmetry made up of 60 carbon atoms arranged in the shape of a soccer ball and resembling a geodesic dome. The hexagonal and pentagonal patches making up the soccer ball are sewn together such that there are exactly 60 vertices with 3 edges intersecting at each vertex. Geometric structure of the C60 molecule is that of a truncated icosahedron with a single carbon atom occupying each vertex. Such a structure is obtained from an icosahedron by truncating each of the 12 vertices, resulting in a 5-membered ring at the location of each vertex and a 6-membered ring corresponding to each icosahedral face. In this paper, it will be shown that 60 point vortex atoms corresponding to the buckyball configuration undergo spontaneous clustering, each cluster undergoing periodic motion with characteristic frequency proportional to number of co-orbiting vortices. Generalizing the frequency relation for an isolated ring, the interacting clusters are shown to modify the ring frequencies such that the latter can be scale-fitted by an r^-a relation where r is the radius of the periodic orbit and 'a' is a constant.

Khushalani, Bharat

2004-05-01

303

Arctic technology and policy  

Microsoft Academic Search

Topics covered include: legal regime of the arctic, including national and international legal frameworks that govern arctic resource development; environmental policy and socio-economic issues, focusing on the political and economic considerations of LNG transport in icebound waterways; risk and safety assessment for arctic offshore projects, drilling systems for the arctic; arctic offshore technology, including island, steel, and concrete structures; icebreaking

I. Dyer; C. Chryssostomidis

1984-01-01

304

Arctic UTLS composition measured by the MARSCHALS instrument during the PREMIEREX and ESSENCE campaigns  

NASA Astrophysics Data System (ADS)

An overview of the results obtained by the MARSCHALS (Millimetre-wave Airborne Receivers for Spectroscopic CHaracterisation in Atmospheric Limb Sounding) instrument during Premier-Ex (March 2010, Kiruna, Sweden) and ESSenCe 2011 (December 2011, Kiruna, Sweden) aircraft Arctic campaigns is presented. The two campaigns were part of the activities conducted as preparatory studies for PREMIER (Process Exploration through Measurements of Infrared and millimeter-wave Emitted Radiation), one of the three candidate core missions of ESA Earth Explorer 7. The primary objective of PREMIER is to gain a better understanding of the processes that are linking atmospheric chemistry and dynamics with climate. PREMIER will achieve this by observing the Upper Troposphere / Lower Stratosphere (UTLS) - a region of particular importance in the study of climate change - with unprecedented spatial and temporal resolution. PREMIER combines the complementary capabilities of two limb-sounders in the infrared and millimeter-wave spectral regions and MARSCHALS was developed as an airborne demonstrator of the PREMIER millimeter-wave spectrometer. In the frame of the two Arctic campaigns, MARSCHALS sampled the Arctic UTLS retrieving vertical profiles of its main atmospheric targets (T, H2O, O3, HNO3, N2O, CO). The obtained vertical profiles have been used to investigate chemical and dynamical processes taking place in the Arctic atmosphere. In particular, we found the presence of filaments of vortex air during the Premier-Ex campaign and of re-nitrification or HNO3 redistribution due to sedimentation followed by evaporation of Polar Stratospheric Cloud (PSC) particles during the ESSenCe campaign. Furthermore, the results of the comparisonbetween MARSCHALS and MIPAS-STR products as well as the state of the atmosphere during the ESSenCe campaign simulated by theCLaMS (Chemical Lagrangian Model of the Stratosphere) and EMAC (ECHAM/MESSy Atmospheric Chemistry) models will be presented.

Cortesi, Ugo; Castelli, Elisa; Del Bianco, Samuele; Dinelli, Bianca Maria; Gerber, Daniel; Kerridge, Brian; Oelhaf, Hermann; Woiwode, Wolfgang; Vogel, Baerbel; Sinnhuber, Bjoern-Martin; Ruhnke, Roland

2013-04-01

305

Aerodynamics of Vortex Generators.  

National Technical Information Service (NTIS)

An experimental and theoretical study was undertaken of the separation delay and dramatic boundary-layer thinning that can occur in vortex-generator installations. Wind tunnel measurements of the dynamic-pressure profile downstream of a vortex generator w...

R. E. Breidenthal D. A. Russell

1988-01-01

306

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

NASA Technical Reports Server (NTRS)

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

Dahlberg, Steven P.; Bowman, Kenneth P.

1994-01-01

307

Polar Explorers - Issue 18, February 2010  

NSDL National Science Digital Library

This issue of the free online magazine, Beyond Penguins and Polar Bears, explores the historical and current exploration of the Arctic and Antarctica and provides resources that help elementary teachers incorporate a study of polar explorers into their curriculum.

University, The O.

308

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

309

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

310

Propagation of a vortex Airy beam in chiral medium  

NASA Astrophysics Data System (ADS)

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

Liu, Xiayin; Zhao, Daomu

2014-06-01

311

Arctic terrestrial ecosystem contamination.  

PubMed

Limited data have been collected on the presence of contaminants in the Arctic terrestrial ecosystem, with the exception of radioactive fallout from atmospheric weapons testing. Although southern and temperate biological systems have largely cleansed themselves of radioactive fallout deposited during the 1950s and 1960s, Arctic environments have not. Lichens accumulate radioactivity more than many other plants because of their large surface area and long life span; the presence and persistence of radioisotopes in the Arctic is of concern because of the lichen----reindeer----human ecosystem. Effective biological half-life of cesium 137 is reckoned to be substantially less than its physical half-life. The database on organochlorines in Canadian Arctic terrestrial mammals and birds is very limited, but indications are that the air/plant/animal contaminant pathway is the major route of these compounds into the terrestrial food chain. For terrestrial herbivores, the most abundant organochlorine is usually hexachlorobenzene followed by hexachlorocyclohexane isomers. PCB accumulation favours the hexachlorobiphenyl, pentachlorobiphenyl and heptachlorobiphenyl homologous series. The concentrations of the various classes of organochlorine compounds are substantially lower in terrestrial herbivore tissues than in marine mammal tissues. PCBs and DDT are the most abundant residues in peregrine falcons (a terrestrial carnivore) reaching average levels of 9.2 and 10.4 micrograms.g-1, respectively, more than 10 times higher than other organochlorines and higher than in marine mammals, including the polar bear. Contaminants from local sources include metals from mining activities, hydrocarbons and waste drilling fluids from oil and gas exploration and production, wastes from DEW line sites, naturally occurring radionuclides associated with uranium mineralization, and smoke containing SO2 and H2SO4 aerosol from the Smoking Hills at Cape Bathurst, N.W.T. PMID:1355310

Thomas, D J; Tracey, B; Marshall, H; Norstrom, R J

1992-07-15

312

Reconnection of vortex tubes  

Microsoft Academic Search

The mechanism of vortex reconnection is investigated by solving the Navier-Stokes equation numerically starting with a trefoiled closed knotted vortex tube. A new type of vortex reconnection mechanism-bridging-is observed. Small regions of high-vorticity burst out of the vortex tube. grow up and bridge different portions of the tube. A relation between the change of the helicity and the mechanism of

S. Kida; M. Takaoka

1988-01-01

313

Where Does the Arctic Begin? End?  

NSDL National Science Digital Library

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

Fries-Gaither, Jessica

2011-01-01

314

Turbulence inside a vortex  

Microsoft Academic Search

Following Bradshaw's analogy between rotating and stratified flows, the turbulence within a vortex is analyzed using a new model for stratified entrainment. At the vortex radius where the tangential velocity is a maximum, the model predicts that the flow is so strongly ``stratified'' that even the smallest turbulent eddies are incapable of transporting fluid there. The growth of the vortex

Aline J. Cotel; Robert E. Breidenthal

1999-01-01

315

Turbulence inside a vortex  

Microsoft Academic Search

Following Bradshaw’s analogy between rotating and stratified flows, the turbulence within a vortex is analyzed using a new model for stratified entrainment. At the vortex radius where the tangential velocity is a maximum, the model predicts that the flow is so strongly “stratified” that even the smallest turbulent eddies are incapable of transporting fluid there. The growth of the vortex

Aline J. Cotel; Robert E. Breidenthal

1999-01-01

316

Vortex Apparatus and Demonstrations  

Microsoft Academic Search

Vortex flow, from millimeter to kilometer in scale, is important in many scientific and technological areas.1 Examples are seen in water strider locomotion, from industrial pipe flow (wastewater treatment) to air traffic control (safe distance between aircrafts on a runway ready for takeoff) to atmospheric studies.2-5 In this paper, we focus on a particular vortex known as bathtub vortex (BTV).

Said Shakerin

2010-01-01

317

Arctic Change Information for a Broad Audience  

NASA Astrophysics Data System (ADS)

Demonstrable environmental changes have occurred in the Arctic over the past three decades. NOAA's Arctic Theme Page is a rich resource web site focused on high latitude studies and the Arctic, with links to widely distributed data and information focused on the Arctic. Included is a collection of essays on relevant topics by experts in Arctic research. The website has proven useful to a wide audience, including scientists, students, teachers, decision makers and the general public, as indicated through recognition by USA Today, Science magazine, etc. (http://www.arctic.noaa.gov) Working jointly with NSF and the University of Washington's Polar Science Center as part of the Study of Environmental Arctic Change (SEARCH) program, NOAA has developed a website for access to pan-Arctic time series spanning diverse data types including climate indices, atmospheric, oceanic, sea ice, terrestrial, biological and fisheries. Modest analysis functions and more detailed analysis results are provided. (http://www.unaami.noaa.gov/). This paper will describe development of an Artic Change Detection status website to provide a direct and comprehensive view of previous and ongoing change in the Arctic for a broad climate community. For example, composite metrics are developed using principal component analysis based on 86 multivariate pan-Arctic time series for seven data types. Two of these metrics can be interpreted as a regime change/trend component and an interdecadal component. Changes can also be visually observed through tracking of 28 separate biophysical indicators. Results will be presented in the form of a web site with relevant, easily understood, value-added knowledge backed by peer review from Arctic scientists and scientific journals.

Soreide, N. N.; Overland, J. E.; Calder, J.

2002-12-01

318

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. Founded in 1988 to serve as a forum for advancing interdisciplinary studies of the Arctic, ARCUS synthesizes and disseminates scientific information on arctic research and educates scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS works closely with national and international stakeholders in advancing science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program for K-12 educators and researchers to work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic community to keep apprised of relevant news, meetings, and announcements. - Project Office for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Fox, S. E.; Wiggins, H. V.; Creek, K. R.

2012-12-01

319

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. ARCUS was formed in 1988 to serve as a forum for planning, facilitating, coordinating, and implementing interdisciplinary studies of the Arctic; to act as a synthesizer and disseminator of scientific information on arctic research; and to educate scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS, in collaboration with the broader science community, relevant agencies and organizations, and other stakeholders, coordinates science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program whereby K-12 educators and researchers work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic science community to keep apprised of relevant news, meetings, and announcements. - Coordination for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic.

Fox, S. E.; Wiggins, H. V.

2011-12-01

320

The Arctic Research Consortium of the United States (ARCUS)  

NASA Astrophysics Data System (ADS)

The Arctic Research Consortium of the United States (ARCUS) is a nonprofit membership organization composed of universities and institutions that have a substantial commitment to research in the Arctic. Founded in 1988 to serve as a forum for advancing interdisciplinary studies of the Arctic, ARCUS synthesizes and disseminates scientific information on arctic research and educates scientists and the general public about the needs and opportunities for research in the Arctic. ARCUS works closely with national and international stakeholders in advancing science planning and educational activities across disciplinary and organizational boundaries. Examples of ARCUS projects include: - Arctic Sea Ice Outlook - an international effort that provides monthly summer reports synthesizing community estimates of the expected sea ice minimum. - Sea Ice for Walrus Outlook - a resource for Alaska Native subsistence hunters, coastal communities, and others that provides weekly reports with information on sea ice conditions relevant to walrus in Alaska waters. - PolarTREC (Teachers and Researchers Exploring and Collaborating) - a program for K-12 educators and researchers to work together in hands-on field experiences in the Arctic and Antarctic to advance polar science education. - ArcticInfo mailing list, Witness the Arctic newsletter, and the Arctic Calendar - communication tools for the arctic community to keep apprised of relevant news, meetings, and announcements. - Project Office for the Study of Environmental Arctic Change (SEARCH) program, which aims to provide scientific understanding of arctic environmental change to help society understand and respond to a rapidly changing Arctic. More information about these and other ARCUS activities can be found at the ARCUS website at: http://www.arcus.org.

Creek, K. R.; Fox, S. E.

2013-12-01

321

Influence of Mountain Waves and NAT Nucleation Mechanisms on Polar Stratospheric Cloud Formation at Local and Synoptic Scales during the 1999-2000 Arctic Winter.  

National Technical Information Service (NTIS)

A scheme for introducing mountain wave-induced temperature perturbations in a microphysical polar stratospheric cloud (PSC) model has been developed. A data set of temperature fluctuations attributable to mountain waves as computed by the Mountain Wave Fo...

B. Knudsen E. V. Browell N. Larsen S. D. Eckermann S. H. Svendsen

2005-01-01

322

Proceedings of the eighth international conference on offshore mechanics and Arctic engineering. 1989  

SciTech Connect

This book contains papers presented at a conference on arctic and polar technology. The topics covered are: Ice properties; Ice mechanics and dynamics; Spray ice technology; Ice forces; Ice accretion; Standards on arctic developments; The Barents Sea; and Arctic structures and drilling.

Sinha, N.K. (National Research Council of Canada, Ottawa, ON (Canada)); Sodhi, D.S. (Army Cold Regions Research and Engineering Lab., Hanover, NH (USA)); Chung, J.S. (Colorado School of Mines, Golden, CO (USA))

1989-01-01

323

Modeling transport, fate, and lifetime of riverine DOC in the Arctic Ocean  

Microsoft Academic Search

We use a numerical model to examine the fate of riverine fluxes of dissolved organic carbon (DOC) in the Arctic basin. The model is based on the Arctic sector of an eddy-permitting ocean model (MITgcm), where the spherical domain is projected onto a cube to avoid polar a singularity in the Arctic region. The physical model is forced by time-varying

M. Manizza; M. J. Follows; S. Dutkiewicz; C. N. Hill; D. Menemenlis; J. W. McClelland; B. J. Peterson

2007-01-01

324

Freshwater Fluxes from the Arctic into the North Atlantic Ocean: 1979-2002 Model Results  

Microsoft Academic Search

The recent warming trend in the Arctic region and its future projections has direct implications for this region's hydrological cycle and the global thermohaline circulation. A quantitative analysis of the freshwater export from the Arctic Ocean through the Canadian Arctic Archipelago (CAA) and Fram Strait into the active convection regions of the sub-polar North Atlantic is presented using model output

C. E. Williams; W. Maslowski; J. C. Clement; A. J. Semtner

2004-01-01

325

In Situ Measurements of the ClO/HCl Ratio: Heterogeneous Processing on Sulfate Aerosols and Polar Stratospheric Clouds  

NASA Technical Reports Server (NTRS)

Simultaneous in situ measurements of stratospheric ClO and HCl have been made for the first time, during numerous flights of the ER-2 aircraft covering latitudes 24-90 deg. N from October 1991 through March 1992. The ClO/HCl ratio is identified as a key indicator of heterogeneous processing both outside and within the Arctic polar vortex. For ClO mixing ratios below about 120 pptv, remarkably constant ClO/HCl values of about 15% characterize the lower stratosphere. The observed values are significantly higher than those derived from a 2-D model using either gas phase photochemistry alone (2%), or including heterogeneous sulfate chemistry (5-10%). During the Arctic early spring, after conversion of HCl into reactive chlorine has taken place, the vortex edge is poorly defined by ClO levels. Loss of HCl and its slow recovery following low-temperature polar heterogeneous chemistry distinguishes HCl as a new and unique dynamical tracer of PSC-processed air.

Webster, C. R.; May, R. D.; Toohey, D. W.; Avallone, L. M.; Anderson, J. G.; Solomon, S.

1993-01-01

326

In Situ Measurements of the ClO/HCl Ratio: Heterogeneous Processing on Sulfate Aerosols and Polar Stratospheric Clouds  

NASA Technical Reports Server (NTRS)

Simultaneous in situ measurements of stratospheric ClO and HCl have been made for the first time, during numerous flights of the ER-2 aircraft covering latitudes 24-90 deg N from October 1991 through March 1992. The ClO/HCl ratio is identified as a key indicator of heterogeneous processing both outside and within the Arctic polar vortex. For ClO mixing ratios below about 120 pptv, remarkably constant ClO/HCl values of about 15% characterize the lower stratosphere. The observed values are significantly higher than those derived from a 2-D model using either gas phase photochemistry alone (2%), or including heterogeneous sulfate chemistry (5-10%). During the Arctic early spring, after conversion of HCl into reactive chlorine has taken place, the vortex edge is poorly defined by ClO levels. Loss of HCl and its slow recovery following low-temperature polar heterogeneous chemistry distinguishes HCl as a new and unique dynamical tracer of PSC-processed air.

Webster, C. R.; May, R. D.; Toohey, D. W.; Avallone, L. M.; Anderson, J. G.; Solomon, S.

1993-01-01

327

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

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2005-01-01

328

Summer Solar Radiation in the Canadian High Arctic  

Microsoft Academic Search

The limited number of weather stations in the Canadian Arctic Islands has prevented the mapping of incoming shortwave radiation. A cloud layer model, using cloud observations reported by summer field camps supported by the Polar Continental Shelf Project, allows the computation of solar radiation for these widely scattered arctic sites.The calculated values were combined with the measured data from the

MING-KO WOO; KATHY L. YOUNG

1996-01-01

329

Potential for Mercury Reduction by Microbes in the High Arctic  

Microsoft Academic Search

The contamination of polar regions due to the global distribution of anthropogenic pollutants is of great concern because it leads to the bioaccumulation of toxic substances, methylmercury among them, in Arctic food chains. Here we present the first evidence that microbes in the high Arctic possess and express diverse merA genes, which specify the reduction of ionic mercury (Hg(II)) to

Alexandre J. Poulain; Sinead M. Nõ ´ Chadhain; Parisa A. Ariya; Marc Amyot; Edenise Garcia; Peter G. C. Campbell; Gerben J. Zylstra; Tamar Barkay

2007-01-01

330

Arctic Cooling  

NSDL National Science Digital Library

Most scientists agree that human activities are causing the global climate to heat up. However, in this radio broadcast, two scientists from Alaska explain how nature still has a big say in how much the Arctic heats up and that recent warming is part of a natural cycle, occurring over thousands of years. The clip from 2005 is 3 minutes and 54 seconds in length.

331

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

NASA Astrophysics Data System (ADS)

During the POLARCAT summer campaign in 2008, two episodes (2-5 July and 7-10 July 2008) occurred where low-pressure systems traveled from Siberia across the Arctic Ocean towards the North Pole. The two cyclones had extensive smoke plumes from Siberian forest fires embedded in their associated air masses, creating an excellent opportunity to use satellite and aircraft observations to validate the performance of atmospheric transport models in the Arctic, which is a challenging model domain due to numerical and other complications. Here we compare transport simulations of carbon monoxide (CO) from the Lagrangian transport model FLEXPART, the Eulerian chemical transport model TOMCAT, and the limited-area chemical transport model WRF-Chem. Retrievals of total column CO from the IASI passive infrared sensor onboard the MetOp-A satellite are used as a total column CO reference for the two simulations. Analysis of CALIPSO lidar curtains and in situ aircraft measurements provide further independent reference points to assess how reliable the model simulations are and what the main limitations are. The horizontal structure of mid-latitude pollution plumes agrees well between the IASI total column CO and the two model simulations. Thereby, finer-scale structures are too quickly diffused in the Eulerian model. In absolute numbers the total CO fields is highest in the satellite observations, followed by the FLEXPART and the TOMCAT model. Aircraft data suggest that the satellite data are biased high. The multi-data, multi-model approach allows separating the influences of meteorological fields, model realisation, and grid type on the plume structure. Results indicate very good agreement between simulated and observed total column CO fields, but also highlight the difficulty to identify a data set that most realistically represents the actual state of the atmosphere.

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

2010-12-01

332

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

NASA Astrophysics Data System (ADS)

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

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

2010-11-01

333

Winter's Polar Vortex Ushers in Spring's 'Pollen Vortex'  

MedlinePLUS

... experts say that the long, cold winter kept trees dormant for longer than usual, which means tree pollen season will overlap with grass pollen and ... the Chicago area in February because that's when tree pollen usually starts. "It was impossible in February ...

334

Canada's Polar Environments: Marine Waters  

NSDL National Science Digital Library

This site contains information about the three ecozones in the marine waters of polar Canada: The Arctic Archipelago Marine Ecozone, the Arctic Basin, and the Northwest Atlantic Ecozone. The features section describes the physical characteristics of the deep Arctic Basin and shallow Continental Shelf water settings and the major currents responsible for water movement in the Arctic, as well as three features (leads, polynyas, tides) that have important effects on Arctic life. Information is also provided about icebergs, ice islands, ice shelves, sea ice, and the polar ice cap. Information about icebergs in the Davis Straight, frost flowers, iceblink, water sky, the Northwest Passage and open water at the North Pole is offered in the cool facts section.

335

On the Influence of North Pacific Sea Surface Temperature on the Arctic Winter Climate  

NASA Technical Reports Server (NTRS)

Differences between two ensembles of Goddard Earth Observing System Chemistry-Climate Model simulations isolate the impact of North Pacific sea surface temperatures (SSTs) on the Arctic winter climate. One ensemble of extended winter season forecasts is forced by unusually high SSTs in the North Pacific, while in the second ensemble SSTs in the North Pacific are unusually low. High Low differences are consistent with a weakened Western Pacific atmospheric teleconnection pattern, and in particular, a weakening of the Aleutian low. This relative change in tropospheric circulation inhibits planetary wave propagation into the stratosphere, in turn reducing polar stratospheric temperature in mid- and late winter. The number of winters with sudden stratospheric warmings is approximately tripled in the Low ensemble as compared with the High ensemble. Enhanced North Pacific SSTs, and thus a more stable and persistent Arctic vortex, lead to a relative decrease in lower stratospheric ozone in late winter, affecting the April clear-sky UV index at Northern Hemisphere mid-latitudes.

Hurwitz, Margaret M.; Newman, P. A.; Garfinkel, C. I.

2012-01-01

336

Forced and Periodic Vortex Breakdown in a Vortex Valve.  

National Technical Information Service (NTIS)

Forced or periodic vortex breakdown resulting from the instability of the impingement, in a vortex valve, of two equal and opposite jets is investigated. Experiments were conducted with a system consisting of a vortex chamber, two tangential jets, and two...

S. Phasook

1968-01-01

337

Arctic Research of the United States, Spring 1990, volume 4  

NASA Astrophysics Data System (ADS)

This is a journal for national and international audiences of government officials, scientists, engineers, educators, Arctic residents, and other people interested in Arctic-related topics. Reports cover a broad spectrum of life in the Arctic including such topics as fish, game, health, social services, science, engineering, environment, oceanography, international activities, international cooperation, global change, conferences, polar libraries, data, policies, research, and history. The emphasis in this issue is on the importance of the Arctic Ocean and its marginal seas to U.S. national interests, including fisheries, the oil and gas industries, and global climate change processes.

Brown, Jerry; Bowen, Stephen

338

Arctic chlorine activation and ozone depletion: Comparison of chemistry transport models with satellite observations.  

NASA Astrophysics Data System (ADS)

The accurate simulation of Arctic stratospheric ozone depletion has been an issue for two decades. However, there are still notable quantitative discrepancies between the models and observations. We show results from the SLIMCAT and CLaMS 3D chemistry-transport models that differ in some aspects of simulated chlorine activation and descent in the polar vortex. Consequently, the estimates of accumulated ozone depletion in the polar vortex for these two models in cold Arctic winters still largely disagree. As shown recently by Santee et al. (JGR, 2008) using MLS and ACE data, the extent of chlorine activation for the cold Arctic winter of 2004/2005 within the basic SLIMCAT model is overestimated with the likely consequence of too much simulated ozone depletion. In contrast, the CLaMS simulation for the same winter shows too little chlorine activation compared to observations, and therefore likely too little loss. For SLIMCAT the version used by Santee et al. has been updated to replace the equilibrium treatment of NAT PSCs with a Lagrangian microphysical scheme. This leads to smaller regions of NAT particles and less denitrification, in better agreement with observations. The impact of this on the modeled extent of chlorine activation will be discussed. For CLaMS we have changed the parameterization of heterogeneous reactions on liquid aerosols from Carslaw et al. to that of Shi et al. (2001), with which chlorine activation on liquid aerosol becomes more efficient. In turn, the simulated chlorine activation agrees better with the observations. The impact of these model changes on chlorine activation and ozone loss will be assessed and remaining model-observation discrepancies will be discussed in terms of different model formulations. We will also show the impact of recent lab measurements of Cl2O2 absorption cross sections by von Hobe et al. (2009) on the simulated ozone depletion. References: von Hobe, M., F. Stroh, H. Beckers, T. Benter, and H. Willner, The UV/Vis absorption spectrum of matrix isolated dichlorine peroxide, ClOOCl, Phys. Chem. Chem. Phys. , doi:10.1039/B814373K, 2009. Santee M. L., I. A. MacKenzie, G. L. Manney, M. P. Chipperfield, P. F. Bernath, K. A. Walker, C. D. Boone, L. Froidevaux, N. J. Livesey, J. W. Waters, A study of stratospheric chlorine partitioning based on new satellite measurements and modeling, J. Geophys. Res., 113, D12307, doi:10.1029/2007JD009057, 2008. Shi, Q., J. Jayne, C. Kolb, D. Worsnop, and P. Davidovits, Kinetic model for reaction of ClONO2 with H2O and HCl and HOCl with HCl in sulfuric acid solutions, J. Geophys. Res., 106, 24259-24274, 2001.

Grooß, J.-U.; Wegner, T.; Müller, R.; Chipperfield, M. P.; Feng, W.; Santee, M. L.

2009-04-01

339

Wake vortex technology  

NASA Technical Reports Server (NTRS)

A brief overview of the highlights of NASA's wake vortex minimization program is presented. The significant results of this program are summarized as follows: (1) it is technically feasible to reduce significantly the rolling upset created on a trailing aircraft; (2) the basic principles or methods by which reduction in the vortex strength can be achieved have been identified; and (3) an analytical capability for investigating aircraft vortex wakes has been developed.

Dunham, R. E., Jr.; Barber, M. R.; Croom, D. R.

1978-01-01

340

Depositional Environments and Sediment Characteristics of the Colville and Adjacent Deltas, Northern Arctic Alaska.  

National Technical Information Service (NTIS)

Polar deltas, typified by those on Alaska's North Slope, which have their drainage basins totally in the permafrost region and discharge into a polar sea, are significantly different from lower latitude deltas. In the arctic, features classically related ...

A. S. Naidu T. C. Mowatt

1975-01-01

341

Influence of mountain waves and NAT nucleation mechanisms on Polar Stratospheric Cloud formation at local and synoptic scales during the 1999 2000 Arctic winter  

NASA Astrophysics Data System (ADS)

A scheme for introducing mountain wave-induced temperature pertubations in a microphysical PSC model has been developed. A data set of temperature fluctuations attributable to mountain waves as computed by the Mountain Wave Forecast Model (MWFM-2) has been used for the study. The PSC model has variable microphysics, enabling different nucleation mechanisms for nitric acid trihydrate, NAT, to be employed. In particular, the difference between the formation of NAT and ice particles in a scenario where NAT formation is not dependent on preexisting ice particles, allowing NAT to form at temperatures above the ice frost point, Tice, and a scenario, where NAT nucleation is dependent on preexisting ice particles, is examined. The performance of the microphysical model in the different microphysical scenarios and a number of temperature scenarios with and without the influence of mountain waves is tested through comparisons with lidar measurements of PSCs made from the NASA DC-8 on 23 and 25 January during the SOLVE/THESEO 2000 campaign in the 1999-2000 winter and the effect of mountain waves on local PSC production is evaluated in the different microphysical scenarios. Mountain wave-induced temperature fluctuations are introduced in vortex-covering model runs, extending the full 1999-2000 winter season, and the effect of mountain waves on large-scale PSC production is estimated in the different microphysical scenarios.

Svendsen, S. H.; Larsen, N.; Knudsen, B.; Eckermann, S. D.; Browell, E. V.

2004-08-01

342

Cruise to the Chukchi Borderland, Arctic Ocean  

NASA Astrophysics Data System (ADS)

Oceanography and geology were the principal focuses of the U.S. Geological Survey-sponsored expedition Arctic Summer West '92, which traveled to the eastern part of the Chukchi Borderland of the Amerasia Basin, western Arctic Ocean. The expedition took place from August 20 to September 25, 1992, aboard the Coast Guard cutter Polar Star. USGS investigated the geologic framework and tectonic origin of the borderland, Arctic Quaternary paleoclimate, sea-ice transport of particulate matter in the Beaufort Gyre, and possible radionuclide contamination of the water column and seafloor off Alaska from sources in the Russian Arctic. Researchers from five other institutions studied the area's oceanography, age of the water column, paleoenvironment of the Holocene sediment, physical properties and synthetic-aperture radar backscatter of sea ice, and the drop-stone content of late Quaternary sediment.

West Scientific Party, 1992 Arctic Summer; Grantz, Arthur

343

Carbon sources for lake food webs in the Canadian High Arctic and other regions of Arctic North America  

Microsoft Academic Search

We investigated the role of autochthonous and terrestrial carbon in supporting aquatic food webs in the Canadian High Arctic\\u000a by determining the diet of the dominant primary consumer, aquatic chironomids. These organisms were studied in fresh waters\\u000a on 3 islands of the Arctic Archipelago (~74–76°N) including barren polar desert watersheds and a polar oasis with lush meadows.\\u000a Stomach content analysis

John Chételat; Louise Cloutier; Marc Amyot

2010-01-01

344

Detection of the phase shift from a single Abrikosov vortex.  

PubMed

We probe a quantum mechanical phase rotation induced by a single Abrikosov vortex in a superconducting lead, using a Josephson junction, made at the edge of the lead, as a phase-sensitive detector. We observe that the vortex induces a Josephson phase shift equal to the polar angle of the vortex within the junction length. When the vortex is close to the junction it induces a ? step in the Josephson phase difference, leading to a controllable and reversible switching of the junction into the 0-? state. This in turn results in an unusual ?(0)/2 quantization of the flux in the junction. The vortex may hence act as a tunable "phase battery" for quantum electronics. PMID:20867200

Golod, T; Rydh, A; Krasnov, V M

2010-06-01

345

The Remarkable 2003--2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s  

NASA Technical Reports Server (NTRS)

The 2003-2004 Arctic winter was remarkable in the approximately 50-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly 2 months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with 2 previous years, 1984-1985 and 1986-1987, with prolonged midwinter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over 2 standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (7 in the past 6 years) is unprecedented. Lower stratospheric temperatures were unusually high during 6 of the past 7 years, with 5 having much lower than usual potential for polar stratospheric cloud (PSC) formation and ozone loss (nearly none in 1998-1999, 2001-2002, and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of 5 of the last 7 years with very low PSC potential would be expected to occur randomly once every 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

Manney, Gloria L.; Kruger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

2005-01-01

346

Coupled vortex oscillations in spatially separated permalloy squares.  

PubMed

We experimentally study the magnetization dynamics of pairs of micron-sized permalloy squares coupled via their stray fields. The trajectories of the vortex cores in the Landau-domain patterns of the squares are mapped in real space using time-resolved scanning transmission x-ray microscopy. After excitation of one of the vortex cores with a short magnetic-field pulse, the system behaves like coupled harmonic oscillators. The coupling strength depends on the separation between the squares and the configuration of the vortex-core polarizations. Considering the excitation via a rotating in-plane magnetic field, it can be understood that only a weak response of the second vortex core is observed for equal core polarizations. PMID:21517417

Vogel, Andreas; Kamionka, Thomas; Martens, Michael; Drews, André; Chou, Kang Wei; Tyliszczak, Tolek; Stoll, Hermann; Van Waeyenberge, Bartel; Meier, Guido

2011-04-01

347

Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations.  

PubMed

Polar bears (Ursus maritimus) have experienced substantial changes in the seasonal availability of sea ice habitat in parts of their range, including the Beaufort, Chukchi, and Bering Seas. In this study, we compared the body size, condition, and recruitment of polar bears captured in the Chukchi and Bering Seas (CS) between two periods (1986-1994 and 2008-2011) when declines in sea ice habitat occurred. In addition, we compared metrics for the CS population 2008-2011 with those of the adjacent southern Beaufort Sea (SB) population where loss in sea ice habitat has been associated with declines in body condition, size, recruitment, and survival. We evaluated how variation in body condition and recruitment were related to feeding ecology. Comparing habitat conditions between populations, there were twice as many reduced ice days over continental shelf waters per year during 2008-2011 in the SB than in the CS. CS polar bears were larger and in better condition, and appeared to have higher reproduction than SB bears. Although SB and CS bears had similar diets, twice as many bears were fasting in spring in the SB than in the CS. Between 1986-1994 and 2008-2011, body size, condition, and recruitment indices in the CS were not reduced despite a 44-day increase in the number of reduced ice days. Bears in the CS exhibited large body size, good body condition, and high indices of recruitment compared to most other populations measured to date. Higher biological productivity and prey availability in the CS relative to the SB, and a shorter recent history of reduced sea ice habitat, may explain the maintenance of condition and recruitment of CS bears. Geographic differences in the response of polar bears to climate change are relevant to range-wide forecasts for this and other ice-dependent species. PMID:23913506

Rode, Karyn D; Regehr, Eric V; Douglas, David C; Durner, George; Derocher, Andrew E; Thiemann, Gregory W; Budge, Suzanne M

2014-01-01

348

Defining the Vortex Boundary Using N2O Measurements  

NASA Technical Reports Server (NTRS)

Defining the stratospheric vortex boundary is typically done using; the Nash criterion,(a) which determines the maximum gradient of Ertel's potential vorticity (EPV) in the vicinity of maximum zonal winds. However, such a procedure is insensitive to small-scale variations near the boundary, because EPV maps rely on interpolation from sparse data, and are therefore only accurate over large areas. An examination was made of high-speed N2O measurements during SOLVE, from Argus ER-2 flights across the vortex boundary in the 1999-2000 Arctic winter, to see whether sharp changes in N2O concentrations co-occur sufficiently well with the Nash definition of the vortex edge to serve as a reliable alternate definition.

Greenblatt, Jeffery; Jost, Hans-Jurg; Loewenstein, Max; Podolske, James R.; Newman, Paul A.; Lait, Leslie R.; Hipskind, R. Stephen (Technical Monitor)

2000-01-01

349

Dynamic decay of a single vortex into vortex-antivortex pairs  

NASA Astrophysics Data System (ADS)

A variety of metastable states, including vortices, antivortices, and their combinations, is typical for magnetically soft, thin films and patterned structures. The physics of individual spin vortices in patterned structures has been rather extensively explored. In contrast, there are few studies of the vortex-antivortex-vortex (v-av-v) system, in part because the configuration is rather challenging to obtain experimentally. We demonstrate herein how a recently proposed resonant-spin-ordering technique can be used to induce the dynamic decay of a single vortex into v-av states in elongated elements. The approach is based on first driving the system from the linear regime of constant vortex gyrations to the non-linear regime of vortex-core reversals at a fixed excitation frequency, and then subsequently reducing the excitation field back to the linear regime. This procedure stabilizes the system into a v-av-v state that is completely decoupled from the initialization excitation frequency. The newly acquired state is stable in remanence. The dynamic response of this system is expected to demonstrate a number of collective modes, depending on the combination of the vortex core polarities, and/or the excitation field direction, and, hence, is of interest for future studies.

Lendínez, Sergi; Jain, Shikha; Novosad, Valentyn; Fradin, Frank Y.; Pearson, John E.; Tejada, Javier; Bader, Samuel D.

2014-05-01

350

2011 Arctic ozone depletion as seen by ESA-ENVISAT Atmospheric-Chemistry sensors  

NASA Astrophysics Data System (ADS)

Three Atmospheric-Chemistry sensors on-board the ENVISAT satellite (GOMOS, MIPAS, and SCIAMACHY) sound the Earth's atmosphere since about nine years and provide to the science community three separated, but complementary data sets of the most interesting atmospheric trace gases. These extended and coherent data sets, generated with ESA operational processors, give a historical overview over seasonal and long-term trends of geophysical parameters and allow investigating major atmospheric phenomena and natural events. During March 2011, ESA's satellite ENVISAT detected the severe ozone depletion above the Euro-Atlantic sector of the Northern Hemisphere. This record-breaking loss for the ozone layer over the North Pole was mainly caused by unusual polar vortex conditions characterized by very low temperatures in the Arctic stratosphere. This paper presents the chemical ozone depletion over the Arctic regions as detected by SCIAMACHY, MIPAS and GOMOS during spring of 2011. Global maps of total ozone column and vertical ozone profiles along the mission's lifetime clearly show the unprecedented Arctic ozone loss for 2011 with the subsequent migration of ozone depleted air masses towards lower latitudes. ENVISAT's atmospheric measurements reveal changes in the composition of the ozone-related chemical species and permit to point out the chemical correlations of the ozone distribution with nitrogen and chlorine compounds and with the evolution of stratospheric temperatures. The synergistic use of ESA operational data sets from the three instruments allows to closely monitor the occurrence and extension of seasonal ozone depletion events, and to draw a comprehensive picture of all chemistry processes involved in the full atmospheric range.

Brizzi, G.; Niro, F.; Saavedra de Miguel, L.; Dehn, A.; Scarpino, G.; Fehr, T.; von Kuhlmann, R.

2011-12-01

351

Ferroelectric nanostructure having switchable multi-stable vortex states  

DOEpatents

A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

Naumov, Ivan I. (Fayetteville, AR) [Fayetteville, AR; Bellaiche, Laurent M. (Fayetteville, AR) [Fayetteville, AR; Prosandeev, Sergey A. (Fayetteville, AR) [Fayetteville, AR; Ponomareva, Inna V. (Fayetteville, AR) [Fayetteville, AR; Kornev, Igor A. (Fayetteville, AR) [Fayetteville, AR

2009-09-22

352

Electrostatically Enhanced Vortex Separator  

NASA Technical Reports Server (NTRS)

Proposed device removes fine particles from high-pressure exhaust gas of chemical reactor. Negatively charged sectors on rotating disks in vortex generator attracts positively charged particles from main stream of exhaust gas. Electrostatic charge enhances particle-separating action of vortex. Gas without particles released to atmosphere.

Collins, Earl R.

1993-01-01

353

Improved vortex reactor system  

DOEpatents

An improved vortex reactor system for affecting fast pyrolysis of biomass and Refuse Derived Fuel (RDF) feed materials comprising: a vortex reactor having its axis vertically disposed in relation to a jet of a horizontally disposed steam ejector that impels feed materials from a feeder and solids from a recycle loop along with a motive gas into a top part of said reactor.

Diebold, James P. (Lakewood, CO); Scahill, John W. (Evergreen, CO)

1995-01-01

354

Vortex diode jet  

DOEpatents

A fluid transfer system that combines a vortex diode with a jet ejector to transfer liquid from one tank to a second tank by a gas pressurization method having no moving mechanical parts in the fluid system. The vortex diode is a device that has a high resistance to flow in one direction and a low resistance to flow in the other.

Houck, Edward D. (Idaho Falls, ID)

1994-01-01

355

Vortex tube optimization theory  

Microsoft Academic Search

The Ranque–Hilsch vortex tube splits a single high pressure stream of gas into cold and warm streams. Simple models for the vortex tube combined with regenerative precooling are given from which an optimization can be undertaken. Two such optimizations are needed: the first shows that at any given cut or fraction of the cold stream, the best refrigerative load, allowing

Jeffery Lewins; Adrian Bejan

1999-01-01

356

Scientist Examines Tornado Vortex  

NASA Technical Reports Server (NTRS)

In this Quick Time movie, a scientist examines what appears to be a tornado vortex (blue) coming out of a thunderstorm. The scientist uses 3D glasses to be able to see in 3 dimensions the different flows going out into the vortex. Earth science and weather studies are an important ongoing function of NASA and its affiliates.

1999-01-01

357

Reconciliation of essential process parameters for an enhanced predictability of Arctic stratospheric ozone loss and its climate interactions  

NASA Astrophysics Data System (ADS)

Significant reductions in stratospheric ozone occur inside the polar vortices each spring when chlorine radicals produced by heterogeneous reactions on cold particle surfaces in winter destroy ozone mainly in two catalytic cycles, the ClO dimer cycle and the ClO/BrO cycle. Chlorofluorocarbons (CFCs), which are responsible for most of the chlorine currently present in the stratosphere, have been banned by the Montreal Protocol and its amendments, and the ozone layer is predicted to recover to 1980 levels within the next few decades. During the same period, however, climate change is expected to alter the temperature, circulation patterns and chemical composition in the stratosphere, and possible geo-engineering ventures to mitigate climate change may lead to additional changes. To realistically predict the response of the ozone layer to such influences requires the correct representation of all relevant processes. The European project RECONCILE has comprehensively addressed remaining questions in the context of polar ozone depletion, with the objective to quantify the rates of some of the most relevant, yet still uncertain physical and chemical processes. To this end RECONCILE used a broad approach of laboratory experiments, two field missions in the Arctic winter 2009/10 employing the high altitude research aircraft M55-Geophysica and an extensive match ozone sonde campaign, as well as microphysical and chemical transport modelling and data assimilation. Some of the main outcomes of RECONCILE are as follows: (1) vortex meteorology: the 2009/10 Arctic winter was unusually cold at stratospheric levels during the six-week period from mid-December 2009 until the end of January 2010, with reduced transport and mixing across the polar vortex edge; polar vortex stability and how it is influenced by dynamic processes in the troposphere has led to unprecedented, synoptic-scale stratospheric regions with temperatures below the frost point; in these regions stratospheric ice clouds have been observed, extending over >106km2 during more than 3 weeks. (2) Particle microphysics: heterogeneous nucleation of nitric acid trihydrate (NAT) particles in the absence of ice has been unambiguously demonstrated; conversely, the synoptic scale ice clouds also appear to nucleate heterogeneously; a variety of possible heterogeneous nuclei has been characterised by chemical analysis of the non-volatile fraction of the background aerosol; substantial formation of solid particles and denitrification via their sedimentation has been observed and model parameterizations have been improved. (3) Chemistry: strong evidence has been found for significant chlorine activation not only on polar stratospheric clouds (PSCs) but also on cold binary aerosol; laboratory experiments and field data on the ClOOCl photolysis rate and other kinetic parameters have been shown to be consistent with an adequate degree of certainty; no evidence has been found that would support the existence of yet unknown chemical mechanisms making a significant contribution to polar ozone loss. (4) Global modelling: results from process studies have been implemented in a prognostic chemistry climate model (CCM); simulations with improved parameterisations of processes relevant for polar ozone depletion are evaluated against satellite data and other long term records using data assimilation and detrended fluctuation analysis. Finally, measurements and process studies within RECONCILE were also applied to the winter 2010/11, when special meteorological conditions led to the highest chemical ozone loss ever observed in the Arctic. In addition to quantifying the 2010/11 ozone loss and to understand its causes including possible connections to climate change, its impacts were addressed, such as changes in surface ultraviolet (UV) radiation in the densely populated northern mid-latitudes.

von Hobe, M.; Bekki, S.; Borrmann, S.; Cairo, F.; D'Amato, F.; Di Donfrancesco, G.; Dörnbrack, A.; Ebersoldt, A.; Ebert, M.; Emde, C.; Engel, I.; Ern, M.; Frey, W.; Griessbach, S.; Grooß, J.-U.; Gulde, T.; Günther, G.; Hösen, E.; Hoffmann, L.; Homonnai, V.; Hoyle, C. R.; Isaksen, I. S. A.; Jackson, D. R.; Jánosi, I. M.; Kandler, K.; Kalicinsky, C.; Keil, A.; Khaykin, S. M.; Khosrawi, F.; Kivi, R.; Kuttippurath, J.; Laube, J. C.; Lefèvre, F.; Lehmann, R.; Ludmann, S.; Luo, B. P.; Marchand, M.; Meyer, J.; Mitev, V.; Molleker, S.; Müller, R.; Oelhaf, H.; Olschewski, F.; Orsolini, Y.; Peter, T.; Pfeilsticker, K.; Piesch, C.; Pitts, M. C.; Poole, L. R.; Pope, F. D.; Ravegnani, F.; Rex, M.; Riese, M.; Röckmann, T.; Rognerud, B.; Roiger, A.; Rolf, C.; Santee, M. L.; Scheibe, M.; Schiller, C.; Schlager, H.; Siciliani de Cumis, M.; Sitnikov, N.; Søvde, O. A.; Spang, R.; Spelten, N.; Stordal, F.; Sumi?ska-Ebersoldt, O.; Viciani, S.; Volk, C. M.; vom Scheidt, M.; Ulanovski, A.; von der Gathen, P.; Walker, K.; Wegner, T.; Weigel, R.; Weinbuch, S.; Wetzel, G.; Wienhold, F. G.; Wintel, J.; Wohltmann, I.; Woiwode, W.; Young, I. A. K.; Yushkov, V.; Zobrist, B.; Stroh, F.

2012-11-01

358

Eastern - Western Arctic Sea Ice Analysis 1985.  

National Technical Information Service (NTIS)

This publication is the twelfth in a continuing yearly series of Arctic sea ice atlases prepared in the Joint Ice Center at the Naval Polar Oceanography Center, Suitland. The atlas contains weekly charts depicting Northern Hemisphere and Great Lakes ice c...

1985-01-01

359

Arctic and Antarctic Birds: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Arctic and Antarctic Birds issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Fries-Gaither, Jessica; Shiverdecker, Terry

360

Arctic Warming - a Perspective from Svalbard  

Microsoft Academic Search

During the International Polar Year many projects connected to IGBP science will be implemented, mostly within the Arctic and Antarctic areas. This glaciology project is connected to the IPY via the projects IPY-GLACIODYN and IPY-KINNVIKA, and has been carried out since 1997 on the Lomosovfonna ice field on central Spitsbergen in the Svalbard archipelago, and, in this respect, has a

V. Pohjola

2007-01-01

361

Peoples of the Arctic: Unit Outlines  

NSDL National Science Digital Library

This article assembles free resources from the Peoples of the Arctic issue of the Beyond Penguins and Polar Bears cyberzine into a unit outline based on the 5E learning cycle framework. Outlines are provided for Grades K-2 and 3-5.

Fries-Gaither, Jessica

362

Evolution of vortex knots  

NASA Astrophysics Data System (ADS)

For the first time since Lord Kelvin's original conjectures of 1875 we address and study the time evolution of vortex knots in the context of the Euler equations. The vortex knot is given by a thin vortex filament in the shape of a torus knot [script T]p,q (p>1, q>1; p, q co-prime integers). The time evolution is studied numerically by using the Biot Savart (BS) induction law and the localized induction approximation (LIA) equation. Results obtained using the two methods are compared to each other and to the analytic stability analysis of Ricca (1993, 1995). The most interesting finding is that thin vortex knots which are unstable under the LIA have a greatly extended lifetime when the BS law is used. These results provide useful information for modelling complex structures by using elementary vortex knots.

Ricca, Renzo L.; Samuels, David C.; Barenghi, Carlo F.

1999-07-01

363

Vortex control: Further encounters  

NASA Technical Reports Server (NTRS)

The progress of continuing investigations on vortex control techniques is updated. The following topics are briefly discussed: (1) vortex flaps adapted for high-alpha control; (2) alleviation of leading edge extension (LEX) vortex induced twin-tail buffet; (3) controlled decoupling of interactive forebody chine and wing vortices; (4) forebody vortex manipulation by mechanical and pneumatic techniques; and (5) stall-departure alleviation of high aspect-ratio wings. Salient results of exploratory low speed wind tunned experiments are presented. The investigations, primarily aimed at concept validation, were performed on generic configurations utilizing flow visualizations and pressure and balance measurements. Selected results illustrate the efficacy and potential for development of specific vortex control concepts for improved high-alpha configuration aerodynamics.

Rao, Dhanvada M.

1991-01-01

364

Aerodynamics of vortex generators  

NASA Technical Reports Server (NTRS)

An experimental and theoretical study was undertaken of the separation delay and dramatic boundary-layer thinning that can occur in vortex-generator installations. Wind tunnel measurements of the dynamic-pressure profile downstream of a vortex generator were found to compare under certain conditions with that downstream of a suction slit, while water-tunnel visualization studies of vortex-generator height and geometry suggested optimum configurations, and only a minor effect of base porosity. A series of progressively more complex inviscid flow models was developed to be applied to a 3-D integral boundary-layer code. This code predicted layer thinning downstream of the suction site of the vortex models, and other observed features. Thin-layer Navier-Stokes equations are now being used with the ultimate goal of clarifying the physical processes involved in vortex generator performance and developing calculational procedures capable of predicting it.

Breidenthal, Robert E., Jr.; Russell, David A.

1988-01-01

365

Proceedings of the Symposium on the Arctic Heat Budget and Atmospheric Circulation, 31 January Through 4 February 1966, Lake Arrowhead, California.  

National Technical Information Service (NTIS)

Contents: Polar ice and climate; The Arctic heat budget and atmospheric circulation; Stochastic models of air--sea interaction and climatic fluctuation; Heat regime of the Soviet Arctic related to the main atmospheric circulation patterns and their many v...

J. O. Fletcher

1966-01-01

366

Characteristics of atmospheric gravity wave activity in the polar regions revealed by GPS radio occultation data with CHAMP  

NASA Astrophysics Data System (ADS)

Using GPS radio occultation data during 2001-2005, we studied the climatological behavior of atmospheric gravity waves in the polar stratosphere. We calculated temperature fluctuations with vertical wavelengths shorter than 7 km and then determined the wave potential energy, E p , every month in a longitude-latitude cell of 20° × 10° between 12 km and 33 km. In the Arctic region (50-90°N), E p shows an annual variation with maximum in winter, consistent with the zonal mean horizontal wind, V, and the Eliassen-Palm (E-P) flux, F z . The large F z values indicate higher planetary wave activity, resulting in distortion of the polar vortex. The unbalanced flow can then excite gravity waves through geostrophic adjustment. In the Antarctic region (50-90°S), E p gradually increases during winter and reaches its maximum in spring before decreasing rapidly. The time derivative of V coincides with the E p peak and the horizontal distribution of E p has a similar structure to V, suggesting that the E p enhancement is closely related to the decay of the polar vortex. During major warming events over the Arctic, the divergence of E-P flux, ?F, was enhanced, coinciding with large E p . In the Antarctic, ?F strongly correlates with E p in spring. Gravity waves seem to be effectively generated through planetary wave transience and/or breaking. Orographic generation of gravity waves seems to be important in limited areas only, such as Scandinavia and the Antarctic Peninsula, showing that it is less important than the polar night jet in determining the climatological behavior of gravity waves.

Hei, Hayato; Tsuda, Toshitaka; Hirooka, Toshihiko

2008-02-01

367

Expanded record of Quaternary oceanographic change: Amerasian Arctic Ocean  

USGS Publications Warehouse

Four sediment cores collected from the Northwind and Mendeleyev ridges, Arctic Ocean, from 1089 m to 1909 m water depth, provide an oceanographic record extending back into the Matuyama reversed polarity chron. Benthic foraminiferal analyses show four prominent assemblage zones: Bolivina arctica, Cassidulina teretis, Bulimina aculeata, and Oridorsalis tener from the upper Matuyama reversed polarity chronozone through the Brunhes normal polarity chronozone. These assemblage zones represent depth-dependent benthic foraminiferal biofacies changes associated with oceanographic events that occurred in the Amerasian basin at ??? 780 and 300 ka, and indicate oceanographic influence from the North Atlantic. Recognition of these benthic assemblage zones in Arctic cores from the Alpha Ridge indicates that the benthic foraminiferal zonations in intermediate to deep water (>1000 m) Arctic cores may be more useful than preexisting lithostratigraphic zonations and should provide important information pertaining to the Quaternary paleoceanographic evolution of the Arctic Ocean.

Ishman, S. E.; Polyak, L. V.; Poore, R. Z.

1996-01-01

368

High Speed Vortex Flows  

NASA Technical Reports Server (NTRS)

A review of the research conducted at the National Aeronautics and Space Administration (NASA), Langley Research Center (LaRC) into high-speed vortex flows during the 1970s, 1980s, and 1990s is presented. The data reviewed is for flat plates, cavities, bodies, missiles, wings, and aircraft. These data are presented and discussed relative to the design of future vehicles. Also presented is a brief historical review of the extensive body of high-speed vortex flow research from the 1940s to the present in order to provide perspective of the NASA LaRC's high-speed research results. Data are presented which show the types of vortex structures which occur at supersonic speeds and the impact of these flow structures to vehicle performance and control is discussed. The data presented shows the presence of both small- and large scale vortex structures for a variety of vehicles, from missiles to transports. For cavities, the data show very complex multiple vortex structures exist at all combinations of cavity depth to length ratios and Mach number. The data for missiles show the existence of very strong interference effects between body and/or fin vortices and the downstream fins. It was shown that these vortex flow interference effects could be both positive and negative. Data are shown which highlights the effect that leading-edge sweep, leading-edge bluntness, wing thickness, location of maximum thickness, and camber has on the aerodynamics of and flow over delta wings. The observed flow fields for delta wings (i.e. separation bubble, classical vortex, vortex with shock, etc.) are discussed in the context of' aircraft design. And data have been shown that indicate that aerodynamic performance improvements are available by considering vortex flows as a primary design feature. Finally a discussing of a design approach for wings which utilize vortex flows for improved aerodynamic performance at supersonic speed is presented.

Wood, Richard M.; Wilcox, Floyd J., Jr.; Bauer, Steven X. S.; Allen, Jerry M.

2000-01-01

369

Influence of mountain waves and NAT nucleation mechanisms on polar stratospheric cloud formation at local and synoptic scales during the 1999-2000 Arctic winter  

NASA Astrophysics Data System (ADS)

A scheme for introducing mountain wave-induced temperature pertubations in a microphysical PSC model has been developed. A data set of temperature fluctuations attributable to mountain waves as computed by the Mountain Wave Forecast Model (MWFM-2) has been used for the study. The PSC model has variable microphysics, enabling different nucleation mechanisms for nitric acid trihydrate, NAT, to be employed. In particular, the difference between the formation of NAT and ice particles in a scenario where NAT formation is not dependent on preexisting ice particles, allowing NAT to form at temperatures above the ice frost point, Tice, and a scenario, where NAT nucleation is dependent on preexisting ice particles, is examined. The performance of the microphysical model in the different microphysical scenarios and a number of temperature scenarios with and without the influence of mountain waves is tested through comparisons with lidar measurements of PSCs made from the NASA DC-8 on 23 and 25 January during the SOLVE/THESEO 2000 campaign in the 1999-2000 winter and the effect of mountain waves on local PSC production is evaluated in the different microphysical scenarios. Mountain waves are seen to have a pronounced effect on the amount of ice particles formed in the simulations. Quantitative comparisons of the amount of solids seen in the observations and the amount of solids produced in the simulations show the best correspondence when NAT formation is allowed to take place at temperatures above Tice. Mountain wave-induced temperature fluctuations are introduced in vortex-covering model runs, extending the full 1999-2000 winter season, and the effect of mountain waves on large-scale PSC production is estimated in the different microphysical scenarios. It is seen that regardless of the choice of microphysics ice particles only form as a consequence of mountain waves whereas NAT particles form readily as a consequence of the synoptic conditions alone if NAT nucleation above Tice is included in the simulations. Regardless of the choice of microphysics, the inclusion of mountain waves increases the amount of NAT particles by as much as 10%. For a given temperature scenario the choice of NAT nucleation mechanism may alter the amount of NAT substantially; three-fold increases are easily found when switching from the scenario which requires pre-existing ice particles in order for NAT to form to the scenario where NAT forms independently of ice.

Svendsen, S. H.; Larsen, N.; Knudsen, B.; Eckermann, S. D.; Browell, E. V.

2005-03-01

370

Arctic Asteroid!  

NSDL National Science Digital Library

The National Aeronautics and Space Administration's (NASA) news service provides this report on the composition of the meteor that put on a brilliant sky show before landing in Western Canada this January. The fragments of the meteorite fell into a frozen lake, so they were not recovered for study until the lake began to thaw this April. Analyses of the pieces that were recovered suggest that the fallen object had a relatively rare composition and was "...about seven meters across and 200 to 250 metric tons. This wasn't your average meteoroid -- it was basically a C-class asteroid detonating in the atmosphere over the Arctic!" says Dr. Peter Brown of the University of Western Ontario. Visit the site for the full report.

371

Real-time Data Assimilation of satellite derived ice concentration into the Arctic Cap Nowcast\\/Forecast System (ACNFS)  

Microsoft Academic Search

Over the last decade, ice conditions in the Arctic have changed dramatically resulting in the Arctic having a minimum in ice extent during the summers of 2007, 2008 and 2010. With this rapidly changing polar environment, the need for accurate ice forecasts is essential. The Naval Research Laboratory (NRL) has developed the Arctic Cap Nowcast\\/Forecast System (ACNFS), a two-way coupled

P. G. Posey; D. A. Hebert; E. J. Metzger; A. J. Wallcraft; J. A Cummings; R. H. Preller; O. M. Smedstad; M. W. Phelps

2011-01-01

372

Hollow vortex Gaussian beams  

NASA Astrophysics Data System (ADS)

A kind of hollow vortex Gaussian beam is introduced. Based on the Collins integral, an analytical propagation formula of a hollow vortex Gaussian beam through a paraxial ABCD optical system is derived. Due to the special distribution of the optical field, which is caused by the initial vortex phase, the dark region of a hollow vortex Gaussian beam will not disappear upon propagation. The analytical expressions for the beam propagation factor, the kurtosis parameter, and the orbital angular momentum density of a hollow vortex Gaussian beam passing through a paraxial ABCD optical system are also derived, respectively. The beam propagation factor is determined by the beam order and the topological charge. The kurtosis parameter and the orbital angular momentum density depend on beam order n, topological charge m, parameter ?, and transfer matrix elements A and D. As a numerical example, the propagation properties of a hollow vortex Gaussian beam in free space are demonstrated. The hollow vortex Gaussian beam has eminent propagation stability and has crucial application prospects in optical micromanipulation.

Zhou, GuoQuan; Cai, YangJian; Dai, ChaoQing

2013-05-01

373

Green Arctic Patrol Vessel.  

National Technical Information Service (NTIS)

Arctic warming is expected to drive increased traffic through the Arctic region for tourism, research, resource extraction and transportation purposes. Understanding the US will have a strategic objective in the region in the coming decades, the current U...

N. Buckley P. Field W. S. Weidle

2011-01-01

374

Arctic Ocean Studies Progress.  

National Technical Information Service (NTIS)

Magnetic stratigraphy has been established as a viable tool for Arctic Ocean Pliocene and Pleistocene deposits. This has given data on sedimentation rates, as well. Foraminifera have allowed interpretation of broad ecologic conditions of Arctic Ocean and ...

D. L. Clark

1973-01-01

375

Arctic Rabies - A Review  

PubMed Central

Rabies seems to persist throughout most arctic regions, and the northern parts of Norway, Sweden and Finland, i