نتایج جستجو برای: contaminant plumes

تعداد نتایج: 12358  

2016
Sebastian D. Eastham Daniel J. Jacob

Quasi-horizontal chemical plumes in the free troposphere can preserve their concentrated structure for over a week, enabling transport on intercontinental scales with important environmental impacts. Global Eulerian chemical transport models (CTMs) fail to preserve these plumes due to fast numerical dissipation. This work examines the causes of this dissipation and how it can be cured. GEOS-5 m...

2003
Katja U. Heeschen Anne M. Tréhu Robert W. Collier Erwin Suess Gregor Rehder

[1] Submersible investigations of the Cascadia accretionary complex have identified localized venting of methane gas bubbles in association with gas hydrate occurrence. Acoustic profiles of these bubble plumes in the water column in the vicinity of Hydrate Ridge offshore Oregon provide new constraints on the spatial distribution of these gas vents and the fate of the gas in the water column. Th...

2007
Ricardo Cisneros Andrzej Bytnerowicz Brad Quayle Trent Procter

Remote sensing and GIS techniques were developed and evaluated to retrospectively analyze the impacts of the McNally Fire on air quality. The McNally Fire was a large wildfire over 54,700 ha (150,000 acres) in size that occurred in the Sequoia National Forest, California, 21 July through 26 August 2002. MODIS satellite images and NOAA pictures were used to digitize smoke plumes. Smoke plumes we...

2003
B. P. Wert M. Trainer A. Fried T. B. Ryerson B. Henry W. Potter W. M. Angevine E. Atlas S. G. Donnelly F. C. Fehsenfeld G. J. Frost P. D. Goldan A. Hansel J. S. Holloway G. Hubler W. C. Kuster D. K. Nicks J. A. Neuman D. D. Parrish S. Schauffler J. Stutz D. T. Sueper C. Wiedinmyer A. Wisthaler

[1] Airborne formaldehyde (CH2O) measurements were made by tunable diode laser absorption spectroscopy (TDLAS) at high time resolution (1 and 10 s) and precision (±400 and ±120 parts per trillion by volume (pptv) (2s), respectively) during the Texas Air Quality Study (TexAQS) 2000. Measurement accuracy was corroborated by in-flight calibrations and zeros and by overflight comparison with a grou...

2002
S. Gangadhara B. LaBombard

Accurate measurements of plasma flows in the scrape-off layer (SOL) are a necessary requirement for understanding the physics of tokamak edge plasmas. A system is being developed on Alcator C-Mod for inferring flows parallel (v‖) and perpendicular (vE×B) to local magnetic field lines from impurity emission patterns (“plumes”) generated by local gas injection. Carbon plumes are generated at vari...

2007
Paul R. Holland Daniel L. Feltham Adrian Jenkins

[1] A two-dimensional plume model is used to study the interaction between FilchnerRonne Ice Shelf, Antarctica and its underlying ocean cavity. Ice Shelf Water (ISW) plumes are initiated by the freshwater released from a melting ice shelf and, if they rise, may become supercooled and deposit marine ice due to the pressure increase in the in situ freezing temperature. The aim of this modeling st...

Journal: :Remote Sensing 2015
Michelle J. Devlin Caroline Petus Eduardo Teixeira da Silva Dieter Tracey Nicholas H. Wolff Jane Waterhouse Jon Brodie

A strong driver of water quality change in the Great Barrier Reef (GBR) is the pulsed or intermittent nature of terrestrial inputs into the GBR lagoon, including delivery of increased loads of sediments, nutrients, and toxicants via flood river plumes (hereafter river plumes) during the wet season. Cumulative pressures from extreme weather with a high frequency of large scale flooding in recent...

Journal: :Science 1998
Moore Schubert Tackley

Rapid lithospheric thinning by mantle plumes has not been achieved in numerical experiments performed to date. Efficient thinning depends on small-scale instabilities that convectively remove lithospheric material. These instabilities are favored by hotter plumes or stronger temperature dependence of viscosity, and a simple scaling independent of rheology controls their onset. This scaling allo...

2014
N. Farid J. R. Freeman P. K. Diwakar N. L. LaHaye A. Hassanein

The collisional effects of a background gas on expanding ultrafast and short pulse laser ablation plumes were investigated by varying background pressure from vacuum to atmospheric pressure levels. For producing Cu ablation plumes, either 40 fs, 800 nm pulses from a Ti: Sapphire laser or 6 ns, 1,064 nm pulses from a Nd:YAG laser were used. The role of background pressure on plume hydrodynamics,...

Journal: :Indoor air 2007
T Zhang Q Chen

UNLABELLED To protect occupants from infectious diseases or possible chemical/biological agents released by a terrorist in an enclosed space, such as an airliner cabin, it is critical to identify gaseous contaminant source locations and strengths. This paper identified the source locations and strengths by solving inverse contaminant transport with the quasi-reversibility (QR) and pseudo-revers...

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