scholarly journals Observations of the anisotropy of cosmic rays at TeV–PeV

2014 ◽  
Vol 1 ◽  
pp. 33-37 ◽  
Author(s):  
S. BenZvi
Keyword(s):  
Cosmic Rays ◽  
High Altitude ◽  
Southern Hemisphere ◽  
Energy Dependence ◽  
Northern Hemisphere ◽  
Energy Band ◽  
The Past ◽  
Small Scales ◽  
Northern And Southern Hemispheres

Abstract. During the past decade, multiple observatories have reported significant observations of the anisotropy of cosmic rays in the TeV energy band. The anisotropy has been observed at large scales and small scales in both the Northern and Southern Hemispheres. The source of the anisotropy is not well-understood, though both a galactic and a heliospheric origin have been suggested. We discuss recent observations of the shape and energy dependence of the anisotropy, with particular attention to measurements by the IceCube Neutrino Observatory in the Southern Hemisphere and the Milagro and High-Altitude Water Cherenkov (HAWC) observatories in the Northern Hemisphere.

scholarly journals Hemispheric asymmetry in stratospheric NO<sub>2</sub> trends

2017 ◽  
Vol 17 (21) ◽  
pp. 13373-13389 ◽  
Author(s):  
Margarita Yela ◽  
Manuel Gil-Ojeda ◽  
Mónica Navarro-Comas ◽  
David Gonzalez-Bartolomé ◽  
Olga Puentedura ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Hemispheric Asymmetry ◽  
Polar Vortex ◽  
N2o Decomposition ◽  
Atmospheric Composition ◽  
Vertical Column ◽  
The Past ◽  
Vertical Column Density ◽  
Decadal Trend

Abstract. Over 20 years of stratospheric NO2 vertical column density (VCD) data from ground-based zenith DOAS spectrometers were used for trend analysis, specifically, via multiple linear regression. Spectrometers from the Network for the Detection of Atmospheric Composition Change (NDACC) cover the subtropical latitudes in the Northern Hemisphere (Izaña, 28° N), the southern Subantarctic (Ushuaia, 55° S) and Antarctica (Marambio, 64° S, and Belgrano, 78° S). The results show that for the period 1993–2014, a mean positive decadal trend of +8.7 % was found in the subtropical Northern Hemisphere stations, and negative decadal trends of −8.7 and −13.8 % were found in the Southern Hemisphere at Ushuaia and Marambio, respectively; all trends are statistically significant at 95 %. Belgrano only shows a significant decadal trend of −11.3 % in the summer/autumn period. Most of the trends result from variations after 2005. The trend in the diurnal build-up per hour (DBU) was used to estimate the change in the rate of N2O5 conversion to NO2 during the day. With minor differences, the results reproduce those obtained for NO2. The trends computed for individual months show large month-to-month variability. At Izaña, the maximum occurs in December (+13.1 %), dropping abruptly to lower values in the first part of the year. In the Southern Hemisphere, the polar vortex dominates the monthly distributions of the trends. At Marambio, the maximum occurs in mid-winter (−21 %), whereas at the same time, the Ushuaia trend is close to its annual minimum (−7 %). The large difference in the trends at these two relatively close stations suggests a vortex shift towards the Atlantic/South American area over the past few years. Finally, the hemispheric asymmetry obtained in this work is discussed in the framework of the results obtained by previous works that considered tracer analysis and Brewer–Dobson circulation. The results obtained here provide evidence that the NO2 produced by N2O decomposition is not the only cause of the observed trend in the stratosphere and support recent publications pointing to a dynamical redistribution starting in the past decade.

Measuring 14C Concentration in Wine to Monitor Global Distribution of 14C

Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1827-1833
Author(s):  
Hirohisa Sakurai ◽  
Saori Namai ◽  
Emiko Inui ◽  
Fuyuki Tokanai ◽  
Kazuhiro Kato ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Correlation Coefficient ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Accelerator Mass Spectrometry ◽  
Liquid Scintillation Counting ◽  
Liquid Scintillation ◽  
Fossil Fuel ◽  
Scintillation Counting ◽  
Northern And Southern Hemispheres

Using liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS), radiocarbon concentrations were measured for wine from 8 wineries located in 7 countries in the Northern and Southern hemispheres. The 14C concentrations of ethanol and residual materials in the wine were correlated (correlation coefficient 0.82). The δ14C measurements of wine samples from the mid-latitudes in the Northern Hemisphere were approximately 1l% lower than the extrapolations from Schauinsland data, suggesting a local fossil fuel effect. δ14C measurements from the wine samples from the Southern Hemisphere were higher than those from the Northern Hemisphere. The offsets of the 4 wine δ14C measurements were significant, with values between approximately 8% and 15%. Because the harvest years of the mixed grapes were estimated to be 7–12 yr older than their vintage years, this leads to a caveat when determining the 14C concentrations of the year using the wine vintage.

Recent Stratospheric Climate Trends as Evidenced in Radiosonde Data: Global Structure and Tropospheric Linkages

2005 ◽  
Vol 18 (22) ◽  
pp. 4785-4795 ◽  
Author(s):  
David W. J. Thompson ◽  
Susan Solomon
Keyword(s):  
Radiative Transfer ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Global Structure ◽  
Current Understanding ◽  
Radiosonde Data ◽  
Climate Trends ◽  
The Past ◽  
Stratospheric Temperature ◽  
Temperature Trends

Abstract The global structure of recent stratospheric climate trends is examined in radiosonde data. In contrast to conclusions published in previous assessments of stratospheric temperature trends, it is demonstrated that in the annual mean the tropical stratosphere has cooled substantially over the past few decades. The cooling of the tropical stratosphere is apparent in both nighttime and adjusted radiosonde data, and seems to be robust to changes in radiosonde instrumentation. The meridional structure of the annual-mean stratospheric trends is not consistent with our current understanding of radiative transfer and constituent trends but is consistent with increased upwelling in the tropical stratosphere. The annual-mean cooling of the tropical stratosphere is juxtaposed against seasonally varying trends in the extratropical stratosphere dominated by the well-known springtime cooling at polar latitudes. The polar stratospheric trends are accompanied by similarly signed trends at tropospheric levels in the Southern Hemisphere but not in the Northern Hemisphere.

The migration and evolution of floras in the southern hemisphere

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 325-328 ◽  
Author(s):  
P. H. Raven
Keyword(s):  
North America ◽  
South America ◽  
Southern Hemisphere ◽  
Relative Position ◽  
Southern South America ◽  
The Past ◽  
Main Pathway ◽  
Set Up ◽  
Warm Temperate ◽  
Northern And Southern Hemispheres

As modern groups of angiosperms have appeared over a period of more than 80 million years, the relative position of the southern continents has changed. For the First 20 m.y. of this period, opportunities for migration were good between Africa and Europe, and this constituted the main pathway for migration between the northern and southern hemispheres. South America progressively moved away from Africa and towards North America over the past 90 m.y. Southern South America and Australasia shared a rich, warm temperate rainforest flora until about 40 m.y. ago. The development of modern climates during the past 10 m.y. has set up modern patterns of vegetation.

scholarly journals 14C Calibration in the Southern Hemisphere and the Date of the Last Taupo Eruption: Evidence from Tree-Ring Sequences

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 155-163 ◽  
Author(s):  
R. J. Sparks ◽  
W. H. Melhuish ◽  
J.W. A. McKee ◽  
John Ogden ◽  
J. G. Palmer ◽  
...  
Keyword(s):  
New Zealand ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Tree Ring ◽  
Tree Rings ◽  
Calibration Curve ◽  
Systematic Difference ◽  
Calibration Data ◽  
Northern And Southern Hemispheres

Tree rings from a section of Prumnopitys taxifolia (matai) covering the period ad 1335–1745 have been radiocarbon dated and used to generate a 14C calibration curve for southern hemisphere wood. Comparison of this curve with calibration data for northern hemisphere wood does not show a systematic difference between 14C ages measured in the northern and southern hemispheres. A floating chronology covering 270 yr and terminating at the last Taupo (New Zealand) eruption, derived from a sequence of 10-yr samples of tree rings from Phyllocladus trichomanoides (celery pine, or tanekaha), is also consistent with the absence of a systematic north-south difference, and together with the matai data, fixes the date of the Taupo eruption at ad 232 ± 15.

Comparison of magnetic observations in the Northern and Southern Hemispheres (summary only)

1977 ◽  
Vol 279 (963) ◽  
pp. 273-273
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Auroral Zone ◽  
Polar Night ◽  
Polar Caps ◽  
Magnetic Variation ◽  
A Current ◽  
Northern And Southern Hemispheres

A special feature of the regular daily magnetic variation S R at sub-auroral latitudes in both hemispheres can be considered as equivalent to the temporary flow, during a few hours of each U.T. day, of a current circulating all around the auroral zone (clockwise in the Northern Hemisphere, anticlockwise in the Southern Hemisphere); its intensity is the largest at the summer of each hemisphere. This current may be related to the S R variation inside the polar caps, which is deeply different from the S Pq described by Nagata and Kokubun (in fact, that variation is nothing but a residue of the S D variation on quiet days on these regions) and from the Mansurov— Svalgaard effect. The source of this phenomenon, an integrant part of the S R , is probably corpuscular since it still occurs during the polar night. Further investigations would be of great interest.

scholarly journals Absence of a Medieval Climate Anomaly, Little Ice Age and twentieth century warming in Skarvsnes, Lützow Holm Bay, East Antarctica

2014 ◽  
Vol 26 (5) ◽  
pp. 585-598 ◽  
Author(s):  
Ines Tavernier ◽  
Elie Verleyen ◽  
Dominic A. Hodgson ◽  
Katrien Heirman ◽  
Stephen J. Roberts ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Little Ice Age ◽  
Environmental Changes ◽  
Open Water ◽  
Ice Age ◽  
Medieval Climate Anomaly ◽  
Climate Anomaly ◽  
The Past

AbstractPalaeoclimate changes, such as the Medieval Climate Anomaly and the Little Ice Age, are well-defined in the Northern Hemisphere during the past 2000 years. In contrast, these anomalies appear to be either absent, or less well-defined, in high-latitude regions of the Southern Hemisphere. Here, we inferred environmental changes during the past two millennia from proxies in a sediment core from Mago Ike, an East Antarctic lake in Skarvsnes (Lützow Holm Bay). Variations in lake primary production were inferred from fossil pigments, sedimentological and geochemical proxies and combined with absolute diatom counts to infer past diatom productivity and community changes. Three distinct stratigraphic zones were recognized, resulting from a shift from marine to lacustrine conditions with a clear transition zone in between. The presence of open-water marine diatoms indicates a coastal zone seasonally free of sea ice between c. 2120–1500 cal yr bp. Subsequently, the lake became isolated from the ocean due to isostatic uplift. Freshwater conditions were established from c. 1120 cal yr bp onwards after which the proxies are considered highly sensitive to temperature changes. There is no evidence for a Medieval Climate Anomaly, Little Ice Age or twentieth century warming in our lake sediment record suggesting that studies that have imposed Northern Hemisphere climate anomalies onto Southern Hemisphere palaeoclimate records should be treated with caution.

scholarly journals Age of stratospheric air in the ERA-Interim

2012 ◽  
Vol 12 (7) ◽  
pp. 17087-17134 ◽  
Author(s):  
M. Diallo ◽  
B. Legras ◽  
A. Chedin
Keyword(s):  
High Altitude ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Lower Stratosphere ◽  
Transport Model ◽  
Maximum Amplitude ◽  
Positive Trend ◽  
Heating Rates ◽  
Annual Modulation ◽  
The Mean

Abstract. The age of stratospheric air is calculated over 22 yr of the ERA-Interim reanalysis using an off-line Lagrangian transport model and heating rates. At low and mid-latitudes, the mean age of air is in good agreement with observed ages from aircraft flights, high altitude balloons and satellite observations of CO2 and SF6. The mid-latitude age spectrum in the lower stratosphere exhibits a long tail with a peak at 0.5 yr, which is maximum at the end of the winter, and a secondary flat maximum between 4 and 5 yr due to the combination of fast and slow branches of the Brewer-Dobson circulation and the reinforced barrier effect of the jet. At higher altitudes, the age spectrum exhibits the footprint of the annual modulation of the deep Brewer-Dobson circulation. The variability of the mean age is analysed through a decomposition in terms of annual cycle, QBO, ENSO and trend. The annual modulation is the dominating signal in the lower stratosphere and in the tropical pipe with amplitude up to one year. The phase of the oscillation is opposite in both hemisphere beyond 20° and is also reversed below and above 25 km with maximun arising in mid-March in the Northern Hemisphere and in mid-September in the Southern Hemisphere. The tropical pipe signal is in phase with the lower southern stratosphere and the mid northern stratosphere. The maximum amplitude of the QBO modulation is of about 0.5 yr and is mostly concentrated within the tropics between 25 and 35 km. It lags the QBO wind at 30 hPa by about 8 months. The ENSO signal is small and limited to the lower northen stratosphere. The trend is significant and negative, of the order of −0.3 to −0.5 yr dec−1, within the lower stratosphere in the Southern Hemisphere and under 40° N in the Northern Hemisphere below 25 km. It is positive (of the order of 0.3 yr dec−1) in the mid stratosphere but there is no region of consistent significance. This suggests that the shallow and deep Brewer-Dobson circulations may evolve in opposite directions. It is however difficult to estimate a reliable long-term trend from only 22 yr of data. For instance, a positive trend is found in the lower stratosphere if only the second half of the period is considered in agreement with MIPAS SF6 data excepted in the northern polar region and at high altitude. Finally, it is found that the long lasting influence of the Pinatubo eruption can be seen on the age of air from June 1991 until the end of 1993 and can bias the statistics encompassing this period. In our analysis, this eruption shifts the trend towards negative values by about 0.2 to 0.3 yr dec−1.

scholarly journals A Southern Hemisphere Search for a Nonrandom Component in Cosmic Rays

1981 ◽  
Vol 34 (5) ◽  
pp. 591 ◽  
Author(s):  
RW Clay ◽  
BR Dawson
Keyword(s):  
Cosmic Rays ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Cosmic Radiation ◽  
Positive Effect

A search has been made for a nonrandom component in Southern Hemisphere cosmic radiation with energies greater than ~ 10'4 eV. We find no evidence to correspond to the positive effect reported in the Northern Hemisphere by Bhat et al.

scholarly journals Recent warming inconsistent with natural association between temperature and atmospheric circulation over the last 2000 years

2006 ◽  
Vol 2 (3) ◽  
pp. 327-355 ◽  
Author(s):  
P. A. Mayewski ◽  
K. A. Maasch
Keyword(s):  
Climate Variability ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
High Latitude ◽  
Natural Climate Variability ◽  
The Past ◽  
Past 2000 Years ◽  
Hemisphere Temperature ◽  
Natural Climate

Abstract. Comparison between proxies for atmospheric circulation and temperature reveals associations over the last few decades that are inconsistent with those of the past 2000 years. Notably, patterns of middle to high latitude atmospheric circulation in both hemispheres are still within the range of variability of the last 6–10 centuries while, as demonstrated by Mann and Jones (2003), Northern Hemisphere temperatures over recent decades are the highest of the last 2000 years. Further, recent temperature change precedes change in middle to high latitude atmospheric circulation unlike the two most notable changes in climate of the past 2000 years during which change in atmospheric circulation preceded or coincided with change in temperature. In addition, the most prominent change in Southern Hemisphere temperature and atmospheric circulation of the past 2000, and probably 9000 years, precedes change in temperature and atmospheric circulation in the Northern Hemisphere unlike the recent change in Northern Hemisphere temperature that leads. These findings provide new verification that recent rise in temperature is inconsistent with natural climate variability and is most likely related to anthropogenic activity in the form of enhanced greenhouse gases. From our investigation we conclude that the delayed warming over much of the Southern Hemisphere may be, in addition to other factors, a consequence of underpinning by natural climate variability. Further bipolar comparison of proxy records of atmospheric circulation demonstrates that change in atmospheric circulation in the Southern Hemisphere led by 400 years, the most abrupt change in Northern Hemisphere atmospheric circulation of the last 9000 years. This finding may be highly relevant to understanding a future when warming becomes more fully established in the Southern Hemisphere.

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