scholarly journals Evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 Eyjafjallajökull eruption using lidar observations and NAME simulations

2011 ◽  
Vol 116 ◽  
Author(s):  
H. F. Dacre ◽  
A. L. M. Grant ◽  
R. J. Hogan ◽  
S. E. Belcher ◽  
D. J. Thomson ◽  
...  
Keyword(s):  
Initial Phase ◽  
Ash Plume ◽  
Lidar Observations

scholarly journals Airborne lidar observations of the 2010 Eyjafjallajökull volcanic ash plume

2011 ◽  
Vol 116 ◽  
Author(s):  
Franco Marenco ◽  
Ben Johnson ◽  
Kate Turnbull ◽  
Stuart Newman ◽  
Jim Haywood ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Airborne Lidar ◽  
Ash Plume ◽  
Lidar Observations

scholarly journals Observation of Polar Stratospheric Clouds down to the Mediterranean coast

2007 ◽  
Vol 7 (19) ◽  
pp. 5275-5281 ◽  
Author(s):  
P. Keckhut ◽  
Ch. David ◽  
M. Marchand ◽  
S. Bekki ◽  
J. Jumelet ◽  
...  
Keyword(s):  
Initial Phase ◽  
Western Europe ◽  
Transport Model ◽  
Polar Vortex ◽  
Mediterranean Coast ◽  
Stratospheric Warming ◽  
Chemical Transport Model ◽  
Ozone Destruction ◽  
Stratospheric Clouds ◽  
Lidar Observations

Abstract. A Polar Stratospheric Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major stratospheric warming. Very cold stratospheric temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a stratospheric warming that results into a weakening and warming of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.

scholarly journals Observation of Polar Stratospheric Clouds down to the Mediterranean coast

2007 ◽  
Vol 7 (3) ◽  
pp. 6557-6572
Author(s):  
P. Keckhut ◽  
Ch. David ◽  
M. Marchand ◽  
S. Bekki ◽  
J. Jumelet ◽  
...  
Keyword(s):  
Initial Phase ◽  
Western Europe ◽  
Transport Model ◽  
Polar Vortex ◽  
Mediterranean Coast ◽  
Stratospheric Warming ◽  
Chemical Transport Model ◽  
Ozone Destruction ◽  
Stratospheric Clouds ◽  
Lidar Observations

Abstract. A Polar Stratospheric Cloud (PSC) was detected for the first time in January 2006 over Southern Europe after 25 years of systematic lidar observations. This cloud was observed while the polar vortex was highly distorted during the initial phase of a major stratospheric warming. Very cold stratospheric temperatures (<190 K) centred over the Northern-Western Europe were reported, extending down to the South of France where lidar observations were performed. CTM (Chemical Transport Model) investigations show that this event led to a significant direct ozone destruction (35 ppb/day), within and outside the vortex as chlorine activated air masses were moved to sunlight regions allowing ozone destruction. If such exceptional events of mid-latitudes PSCs were to become frequent in the future, they should not compromise the ozone recovery because their effect appears to be limited temporally and spatially. More importantly, these events might tend to be associated with the initial phase of a stratospheric warming that results into a weakening and warming of the polar vortex and hence into a reduced probability occurrence of PSC temperatures during the rest of the winter.

Lidar observations of the Eyjafjallajokull volcanic ash plume at Leipzig, Germany

2010 ◽  
Author(s):  
Matthias Tesche ◽  
Albert Ansmann ◽  
Anja Hiebsch ◽  
Ina Mattis ◽  
Jörg Schmidt ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Ash Plume ◽  
Lidar Observations

Some changes during the initial phase of the unit system in a large mental hospital

1966 ◽  
Author(s):  
Robert P. Barrell ◽  
Alan S. DeWolfe ◽  
Fred E. Spaner
Keyword(s):  
Initial Phase ◽  
Mental Hospital ◽  
Unit System

Entrainment and Annihilation of Reentrant Excitation in a Periodically Stimulated Ring of Excitable Media

1997 ◽  
Vol 36 (04/05) ◽  
pp. 290-293
Author(s):  
L. Glass ◽  
T. Nomura
Keyword(s):  
Cardiac Arrhythmias ◽  
Initial Phase ◽  
Human Heart ◽  
Periodic Wave ◽  
Excitable Media ◽  
One Dimensional ◽  
Clinical Observations ◽  
Periodic Stimulation ◽  
Reentrant Excitation ◽  
Stimulation Of

Abstract:Excitable media, such as nerve, heart and the Belousov-Zhabo- tinsky reaction, exhibit a large excursion from equilibrium in response to a small but finite perturbation. Assuming a one-dimensional ring geometry of sufficient length, excitable media support a periodic wave of circulation. As in the periodic stimulation of oscillations in ordinary differential equations, the effects of periodic stimuli of the periodically circulating wave can be described by a one-dimensional Poincaré map. Depending on the period and intensity of the stimulus as well as its initial phase, either entrainment or termination of the original circulating wave is observed. These phenomena are directly related to clinical observations concerning periodic stimulation of a class of cardiac arrhythmias caused by reentrant wave propagation in the human heart.

Characterization of dissolved material during the initial phase of softwood kraft pulping

TAPPI Journal ◽  
2013 ◽  
Vol 12 (1) ◽  
pp. 37-43 ◽  
Author(s):  
HANNU PAKKANEN ◽  
TEEMU PALOHEIMO ◽  
RAIMO ALÉN
Keyword(s):  
Mass Transfer ◽  
Molecular Mass ◽  
Initial Phase ◽  
Degradation Products ◽  
Kraft Pulping ◽  
Reaction Products ◽  
Cooking Temperature ◽  
Molecular Masses ◽  
Aliphatic Carboxylic Acids

The influence of various cooking parameters, such as effective alkali, cooking temperature, and cooking time on the formation of high molecular mass lignin-derived and low molecular mass carbohydrates-derived (aliphatic carboxylic acids) degradation products, mainly during the initial phase of softwood kraft pulping was studied. In addition, the mass transfer of all of these degradation products was clarified based on their concentrations in the cooking liquor inside and outside of the chips. The results indicated that the degradation of the major hemicellulose component, galactoglucomannan, typically was dependent on temperature, and the maximum degradation amount was about 60%. In addition, about 60 min at 284°F (140°C) was needed for leveling off the concentrations of the characteristic reaction products (3,4-dideoxy-pentonic and glucoisosaccharinic acids) between these cooking liquors. Compared with low molecular mass aliphatic acids, the mass transfer of soluble lignin fragments with much higher molecular masses was clearly slower.

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