Circulation patterns in the Late Pennsylvanian North American Midcontinent Sea inferred from spatial gradients in sediment chemistry and mineralogy

2019 ◽  
Vol 531 ◽  
pp. 109023 ◽  
Author(s):  
Adam C.E. Turner ◽  
Thomas J. Algeo ◽  
Yongbo Peng ◽  
Achim D. Herrmann
Keyword(s):  
North American ◽  
Sediment Chemistry ◽  
Spatial Gradients ◽  
Circulation Patterns

scholarly journals Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES

2009 ◽  
Vol 9 (11) ◽  
pp. 3755-3776 ◽  
Author(s):  
J. Hegarty ◽  
H. Mao ◽  
R. Talbot
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North American ◽  
East Coast ◽  
North Atlantic Ocean ◽  
Free Troposphere ◽  
The North ◽  
Circulation Patterns ◽  
The Us ◽  
Us East Coast

Abstract. The relationship between synoptic circulation patterns over the western North Atlantic Ocean in spring (March, April, and May) and tropospheric O3 and CO was investigated using retrievals from the Tropospheric Emission Spectrometer (TES) for 2005 and 2006. Seasonal composites of TES retrievals reprocessed to remove the artificial geographic structure added from the a priori revealed a channel of slightly elevated O3 (>55 ppbv) and CO (>115 ppbv) at the 681 hPa retrieval level between 30° N and 45° N extending from North America out over the Atlantic Ocean. Ozone and CO in this region were correlated at r=0.22 with a slope value of 0.13 mol mol−1 indicative of the overall impact of photochemical chemical processes in North American continental export. Composites of TES retrievals for the six predominant circulation patterns identified as map types from sea level pressure fields of the NCEP FNL analyses showed large variability in the distribution of tropospheric O3. Map types MAM2 and MAM3 featuring cyclones near the US east coast produced the greatest export to the lower free troposphere with O3>65 ppbv and a relatively well-defined O3-CO correlation (slope values near 0.20 mol mol−1). The ensembles of HYSPLIT backward trajectories indicated that the high O3 levels were possibly a result of pollutants lofted to the free troposphere by the warm conveyor belt (WCB) of a cyclone. An important finding was that pollutant export occurred in the main WCB branch to the east of the cyclone and in a secondary branch circling to the back of the cyclone center. Conversely, a map type featuring a large anticyclone dominating the flow over the US east coast (MAM6) restricted export with O3 levels generally <55 ppbv and CO levels generally <110 ppbv. There was also evidence of stratospheric intrusions particularly to the north of 45° N in the 316 hPa composites predominately for MAM1 which featured a large cyclone near Newfoundland. However, the concurrence of these intrusions with pollutant export, specifically in the southwestern North Atlantic Ocean, made it difficult to delineate their respective contributions to the 681 hPa O3 composites.

scholarly journals Synoptic influences on springtime tropospheric O<sub>3</sub> and CO over the North American export region observed by TES

2008 ◽  
Vol 8 (6) ◽  
pp. 19743-19789
Author(s):  
J. Hegarty ◽  
H. Mao ◽  
R. Talbot
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North American ◽  
East Coast ◽  
North Atlantic Ocean ◽  
Free Troposphere ◽  
The North ◽  
Circulation Patterns ◽  
The Us ◽  
Us East Coast

Abstract. The relationship between synoptic circulation patterns over the western North Atlantic Ocean in spring (March, April, and May) and tropospheric O3 and CO was investigated using retrievals from the Tropospheric Emission Spectrometer (TES) for 2005 and 2006. Seasonal composites of TES retrievals reprocessed to remove the artificial geographic structure added from the a priori revealed a channel of slightly elevated O3 (>55 ppbv) and CO (>115 ppbv) at the 681 hPa retrieval level between 30° N and 45° N extending from North America out over the Atlantic Ocean. Ozone and CO in this region were correlated at r=0.32 with a slope value of 0.16 indicative of the overall impact of photochemical chemical processes in North American continental export. Composites of TES retrievals for the six predominant circulation patterns identified as map types from sea level pressure fields of the NCEP FNL analyses showed large variability in the distribution of tropospheric O3. Map types featuring cyclones near the US east coast (MAM2–MAM5) produced the greatest export to the lower free troposphere with O3>65 ppbv and O3-CO slopes ranging 0.25–0.36. HYSPLIT backward trajectories indicated that the high O3 levels were possibly a result of pollutants lofted to the free troposphere by the warm conveyor belt (WCB) of a cyclone. An important finding was that pollutant export occurred in the main WCB branch to the east of the cyclone and in a secondary branch circling to the back of the cyclone center. Conversely, a map type featuring a large anticyclone dominating the flow over the US east coast (MAM6) restricted export with O3 levels generally <45 ppbv and an O3-CO slope near zero. There was also evidence of stratospheric intrusions particularly to the north of 45° N in the 316 hPa composites predominately for MAM1 which featured a large cyclone near Newfoundland. However, it was not clear from the available data that these intrusions had a strong impact on the 681 hPa O3 composites in the western North Atlantic Ocean further south where the data showed clear evidence of the influence of pollutant export.

scholarly journals Arctic sea ice melt onset favored by an atmospheric pressure pattern reminiscent of the North American-Eurasian Arctic pattern

2021 ◽  
Author(s):  
Sean Horvath ◽  
Julienne Stroeve ◽  
Balaji Rajagopalan ◽  
Alexandra Jahn
Keyword(s):  
North America ◽  
Sea Ice ◽  
North American ◽  
Longwave Radiation ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Melt ◽  
The North ◽  
Circulation Patterns ◽  
Downwelling Longwave Radiation

AbstractThe timing of melt onset in the Arctic plays a key role in the evolution of sea ice throughout Spring, Summer and Autumn. A major catalyst of early melt onset is increased downwelling longwave radiation, associated with increased levels of moisture in the atmosphere. Determining the atmospheric moisture pathways that are tied to increased downwelling longwave radiation and melt onset is therefore of keen interest. We employed Self Organizing Maps (SOM) on the daily sea level pressure for the period 1979–2018 over the Arctic during the melt season (April–July) and identified distinct circulation patterns. Melt onset dates were mapped on to these SOM patterns. The dominant moisture transport to much of the Arctic is enabled by a broad low pressure region stretching over Siberia and a high pressure over northern North America and Greenland. This configuration, which is reminiscent of the North American-Eurasian Arctic dipole pattern, funnels moisture from lower latitudes and through the Bering and Chukchi Seas. Other leading patterns are variations of this which transport moisture from North America and the Atlantic to the Central Arctic and Canadian Arctic Archipelago. Our analysis further indicates that most of the early and late melt onset timings in the Arctic are strongly related to the strong and weak emergence of these preferred circulation patterns, respectively.

The Changes in North American atmospheric circulation patterns indicated by wood cellulose

Geology ◽  
2007 ◽  
Vol 35 (2) ◽  
pp. 163 ◽  
Author(s):  
Xiahong Feng ◽  
Allison L. Reddington ◽  
Anthony M. Faiia ◽  
Eric S. Posmentier ◽  
Yong Shu ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
North American ◽  
Wood Cellulose ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns

Adaptation of the Connected Speech Test: Rerecording and Passage Equivalency

2020 ◽  
Vol 29 (2) ◽  
pp. 259-264 ◽  
Author(s):  
Hasan K. Saleh ◽  
Paula Folkeard ◽  
Ewan Macpherson ◽  
Susan Scollie
Keyword(s):  
Speech Perception ◽  
North American ◽  
First Language ◽  
Intraclass Correlation ◽  
Normal Hearing ◽  
Connected Speech ◽  
Internal Reliability ◽  
Speech Test ◽  
The Mean ◽  
Unit Standard

Purpose The original Connected Speech Test (CST; Cox et al., 1987) is a well-regarded and often utilized speech perception test. The aim of this study was to develop a new version of the CST using a neutral North American accent and to assess the use of this updated CST on participants with normal hearing. Method A female English speaker was recruited to read the original CST passages, which were recorded as the new CST stimuli. A study was designed to assess the newly recorded CST passages' equivalence and conduct normalization. The study included 19 Western University students (11 females and eight males) with normal hearing and with English as a first language. Results Raw scores for the 48 tested passages were converted to rationalized arcsine units, and average passage scores more than 1 rationalized arcsine unit standard deviation from the mean were excluded. The internal reliability of the 32 remaining passages was assessed, and the two-way random effects intraclass correlation was .944. Conclusion The aim of our study was to create new CST stimuli with a more general North American accent in order to minimize accent effects on the speech perception scores. The study resulted in 32 passages of equivalent difficulty for listeners with normal hearing.

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