scholarly journals A three-dimensional residence-time analysis of potential summertime atmospheric transport to Summit, Greenland

2002 ◽  
Vol 35 ◽  
pp. 403-408 ◽  
Author(s):  
Jessica E. Miller ◽  
Jonathan D. W. Kahl ◽  
Fred Heller ◽  
Joyce M. Harris
Keyword(s):  
Residence Time ◽  
Atmospheric Transport ◽  
Three Dimensional ◽  
Regions Of Interest ◽  
Interannual Variations ◽  
Trajectory Data ◽  
Time Analysis ◽  
Remote Locations ◽  
Transport Component ◽  
Transport Patterns

AbstractThe interannual variations in atmospheric transport patterns to Summit, Greenland, are studied using twice-daily, three-dimensional, 10 day backward trajectory data corresponding to the summers (1 June–31 August) of 1989–98. While previous trajectory climatology studies have been prepared for Summit, the present work considers both the horizontal and vertical components of transport. A three-dimensional residence-time methodology is employed to account for both horizontal and vertical components of transport. the vertical transport component is quantified by passing all trajectories through a three-dimensional grid and tracking the time spent (i.e. the residence time) in each gridcell. This method also allows inspection of trajectory altitude distributions corresponding to transport from upwind regions of interest. the three-dimensional residence-time methodology is shown to be a valuable tool for diagnosing the details of long-range atmospheric transport to remote locations. for Summit, we find that the frequent transport from North America tends to occur at low altitudes, whereas transport from Europe is highly variable. Mean summertime flow patterns are described, as are anomalous patterns during 1990,1996 and 1998.

scholarly journals Transpacific transport of benzo[a]pyrene emitted from Asia

2011 ◽  
Vol 11 (23) ◽  
pp. 11993-12006 ◽  
Author(s):  
Y. Zhang ◽  
S. Tao ◽  
J. Ma ◽  
S. Simonich
Keyword(s):  
North America ◽  
Atmospheric Transport ◽  
Southern Oscillation ◽  
Three Dimensional ◽  
Conveyor Belt ◽  
Global Scale ◽  
Lower Atmosphere ◽  
Transpacific Transport ◽  
Transport Patterns ◽  
Transport Flux

Abstract. A global-scale three dimensional atmospheric transport and chemistry model was applied to simulate transpacific transport of Benzo[a]pyrene (BaP) emitted from Asia. The model results were compared with observations at six monitoring sites. The annual mean and seasonal variation of transport patterns and the contributions of different Asian source regions to transpacific transport flux were investigated. The episodic nature of transpacific transport was also systematically explored. Interannual variability of transpacific transport of BaP was also assessed during the period of 1948–2007. Results showed that strong enhancements of modeled BaP occurred in an area bounded by 70–80° E and 100–120° E. Air containing these elevated BaP concentrations was then delivered eastward by westerly winds. When approaching the West Coast of North America, the descending atmospheric motion carried BaP-laden air into the lower atmosphere. The transpacific transport flux was 1.6 times higher in the winter than in the summer. East Asian emission dominates the transpacific transport flux with a contribution of about 97%. Near ground concentration of BaP induced by Asian sources in North America varied between 1–20 pg m−3. A case study for observation at Cheeka Peak Observatory during March 2002–May 2002 reveals the importance of warm conveyor belt for transpacific transport. The number of days with transpacific transport flux with a factor of 0.5, 1.0, 1.5, and 2.0 larger than the running mean were 9.4%, 0.72%, 0.06% and 0.01%, respectively, implying a mild contribution of episodic transport to the long-term mean transport flux. Significant interannual fluctuation of transpacific transport of BaP was found, including a general decreasing trend during 1948–2007, and especially after the 1970s. The transpacific transport was found to be positively correlated with the Southern Oscillation Index.

scholarly journals Transpacific transport of Benzo[a]pyrene emitted from Asia: importance of warm conveyor belt and interannual variations

2011 ◽  
Vol 11 (7) ◽  
pp. 18979-19009 ◽  
Author(s):  
Y. Zhang ◽  
S. Tao ◽  
J. Ma ◽  
S. Simonich
Keyword(s):  
North America ◽  
Atmospheric Transport ◽  
Southern Oscillation ◽  
Three Dimensional ◽  
Conveyor Belt ◽  
Global Scale ◽  
Lower Atmosphere ◽  
Transpacific Transport ◽  
Transport Patterns ◽  
Transport Flux

Abstract. A global-scale three dimensional atmospheric transport and chemistry model was applied to simulate transpacific transport of Benzo[a]pyrene (BaP) emitted from Asia. The model results were compared with observations at six monitoring sites. The annual mean and seasonal variation of transport patterns and the contributions of different Asian source regions to transpacific transport flux were investigated. The episodic nature of transpacific transport was also systematically explored. Interannual variability of transpacific transport of BaP was also assessed during the period of 1948–2007. Results showed that strong enhancements of modeled BaP concentrations at 3000 m occurred in an area bounded by 70–80° E and 100–120° E. Air containing these elevated BaP concentrations was then delivered eastward by westerly winds. When approaching the West Coast of North America, the descending atmospheric motion carried BaP-laden air into the lower atmosphere. The transpacific transport flux was 1.6 times higher in the winter than in the summer. East Asian emission dominates the transpacific transport flux with a contribution of about 97 %. Near ground concentration of BaP induced by Asian sources in North America varied between 1–20 pg m−3. The number of days with transpacific transport flux with a factor of 0.5, 1.0, 1.5, and 2.0 larger than the running mean were 9.4 %, 0.72 %, 0.06 % and 0.01 %, respectively, implying a mild contribution of episodic transport to the long-term mean transport flux. Significant interannual fluctuation of transpacific transport of BaP was found, including a general decreasing trend during 1948–2007, and especially after the 1970s. The transpacific transport was found to be positively correlated with the Southern Oscillation Index.

scholarly journals Origin and transport of Mediterranean moisture and air

2010 ◽  
Vol 10 (11) ◽  
pp. 5089-5105 ◽  
Author(s):  
I. Schicker ◽  
S. Radanovics ◽  
P. Seibert
Keyword(s):  
Residence Time ◽  
Mediterranean Basin ◽  
Trade Wind ◽  
Trajectory Data ◽  
Data Set ◽  
Mediterranean Regions ◽  
Diagnosis Method ◽  
Seasonal Basis ◽  
The Mediterranean ◽  
The Mediterranean Basin

Abstract. Considering the Mediterranean as a region of high evaporation and low precipitation, evaluations of sinks and sources of moisture and precipitation in the Mediterranean basin have been carried out within the frame of the CIRCE (Climate Change and Impact Research: the Mediterranean Environment) project. Besides these evaluations, residence time and stagnation/ventilation analyses have been carried out to investigate transport to and from the Mediterranean basin and in the basin itself. A Lagrangian moisture diagnosis method calculating budgets of evaporation minus precipitation was applied to a 5.5 year (October 1999–April 2005) trajectory data set and evaluated for eight representative Mediterranean Regions Of Interest (ROI). The Mediterranean basin has been identified as a major source of moisture and precipitation to the surrounding land area and to the basin itself. Main regions of stagnation, i.e. the Po basin, have been defined on a seasonal basis through residence time analysis. Evaluation of the transport to and from the basin shows that the Mediterranean is a crossroad of airstreams where air enters mainly from the northwest and continues in two separate streams, one going southwest over North Africa into the trade wind zone and the other one to the northeast through Central Asia.

Modeling residence time with a three-dimensional hydrodynamic model: Linkage with chlorophyll a in a subtropical estuary

2013 ◽  
Vol 268 ◽  
pp. 93-102 ◽  
Author(s):  
Yongshan Wan ◽  
Chelsea Qiu ◽  
Peter Doering ◽  
Mayra Ashton ◽  
Detong Sun ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Residence Time ◽  
Hydrodynamic Model ◽  
Three Dimensional ◽  
Subtropical Estuary

A Low-Dimensional Dissimilarity Analysis of Unilateral and Bilateral Stroke-Impacted Hand Trajectories

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Jay Ryan U. Roldan ◽  
Dejan Milutinović ◽  
Zhi Li ◽  
Jacob Rosen
Keyword(s):  
Multidimensional Scaling ◽  
Healthy Subject ◽  
Motion Capture ◽  
Early Phase ◽  
Three Dimensional ◽  
High Rate ◽  
Motion Capture System ◽  
Trajectory Data ◽  
The Difference ◽  
Low Dimensional

In this paper, we propose a quantitative approach based on identifying hand trajectory dissimilarities through the use of a multidimensional scaling (MDS) analysis. A high-rate motion capture system is used to gather three-dimensional (3D) trajectory data of healthy and stroke-impacted hemiparetic subjects. The mutual dissimilarity between any two trajectories is measured by the area between them. This area is used as a dissimilarity variable to create an MDS map. The map reveals a structure for measuring the difference and variability of individual trajectories and their groups. The results suggest that the recovery of hemiparetic subjects can be quantified by comparing the difference and variability of their individual MDS map points to the points from the cluster of healthy subject trajectories. Within the MDS map, we can identify fully recovered patients, those who are only functionally recovered, and those who are either in an early phase of, or are nonresponsive to the therapy.

scholarly journals A three-dimensional thalamocortical dataset for characterizing brain heterogeneity

2020 ◽  
Author(s):  
Judy A. Prasad ◽  
Aishwarya H. Balwani ◽  
Erik C. Johnson ◽  
Joseph D. Miano ◽  
Vandana Sampathkumar ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Brain Regions ◽  
Regions Of Interest ◽  
Subcortical Structures ◽  
Neural Structure ◽  
Brain Areas ◽  
X Ray ◽  
Anatomical Imaging ◽  
Brain Pathways ◽  
Critical Aspects

AbstractNeural cytoarchitecture is heterogeneous, varying both across and within brain regions. The consistent identification of regions of interest is one of the most critical aspects in examining neurocircuitry, as these structures serve as the vital landmarks with which to map brain pathways. Access to continuous, three-dimensional volumes that span multiple brain areas not only provides richer context for identifying such landmarks, but also enables a deeper probing of the microstructures within. Here, we describe a three-dimensional X-ray microtomography imaging dataset of a well-known and validated thalamocortical sample, encompassing a range of cortical and subcortical structures. In doing so, we provide the field with access to a micron-scale anatomical imaging dataset ideal for studying heterogeneity of neural structure.

scholarly journals A computationally efficient approach to segmentation of the aorta and coronary arteries using deep learning

2021 ◽  
Author(s):  
Wing Keung Cheung ◽  
Robert Bell ◽  
Arjun Nair ◽  
Leon Menezies ◽  
Riyaz Patel ◽  
...  
Keyword(s):  
Deep Learning ◽  
Coronary Arteries ◽  
Automatic Segmentation ◽  
Three Dimensional ◽  
Regions Of Interest ◽  
Dice Similarity Coefficient ◽  
Processing Unit ◽  
Two Dimensional ◽  
Computed Tomography Images ◽  
Graphical Processing

AbstractA fully automatic two-dimensional Unet model is proposed to segment aorta and coronary arteries in computed tomography images. Two models are trained to segment two regions of interest, (1) the aorta and the coronary arteries or (2) the coronary arteries alone. Our method achieves 91.20% and 88.80% dice similarity coefficient accuracy on regions of interest 1 and 2 respectively. Compared with a semi-automatic segmentation method, our model performs better when segmenting the coronary arteries alone. The performance of the proposed method is comparable to existing published two-dimensional or three-dimensional deep learning models. Furthermore, the algorithmic and graphical processing unit memory efficiencies are maintained such that the model can be deployed within hospital computer networks where graphical processing units are typically not available.

scholarly journals Variability in air-sea O<sub>2</sub> and CO<sub>2</sub> fluxes and its impact on atmospheric potential oxygen (APO) and the partitioning of land and ocean carbon sinks

2007 ◽  
Vol 4 (4) ◽  
pp. 2877-2914 ◽  
Author(s):  
C. D. Nevison ◽  
N. M. Mahowald ◽  
S. C. Doney ◽  
I. D. Lima
Keyword(s):  
Transport Model ◽  
Atmospheric Transport ◽  
Three Dimensional ◽  
Ecosystem Model ◽  
Large Error ◽  
Accurate Estimate ◽  
Carbon Sinks ◽  
Fossil Carbon ◽  
Ocean Carbon ◽  
Potential Oxygen

Abstract. A three dimensional, time-evolving field of atmospheric potential oxygen (APO ~ O2/N2 + CO2) is estimated using surface O2, N2 and CO2 fluxes from the WHOI ocean ecosystem model to force the MATCH atmospheric transport model. Land and fossil carbon fluxes are also run in MATCH and translated into O2 tracers using assumed O2:CO2 stoichiometries. The model seasonal cycles in APO agree well with the observed cycles at 13 global monitoring stations, with agreement helped by the inclusion of oceanic CO2 in the APO calculation. The model latitudinal gradient in APO is strongly influenced by seasonal rectifier effects in atmospheric transport, which appear at least partly unrealistic based on comparison to observations. An analysis of the APO vs.~CO2 method for partitioning land and ocean carbon sinks is performed in the controlled context of the MATCH simulation, in which the true surface carbon and oxygen fluxes are known exactly. This analysis suggests uncertainty ranging up to ±0.2 PgC in the inferred sinks due to transport-induced variability. It also shows that interannual variability in oceanic O2 fluxes can cause increasingly large error in the sink partitioning when the method is applied over increasingly short timescales. However, when decadal or longer averages are used, the variability in the oceanic O2 flux is relatively small, allowing carbon sinks to be partitioned to within a standard deviation of 0.1 Pg C/yr of the true values, provided one has an accurate estimate of long-term mean O2 outgassing.

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