scholarly journals Impact of North America on the aerosol composition in the North Atlantic free troposphere

2017 ◽  
Author(s):  
M. Isabel García ◽  
Sergio Rodríguez ◽  
Andrés Alastuey
Keyword(s):  
Organic Matter ◽  
North America ◽  
North Atlantic ◽  
North American ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic

Abstract. In the AEROATLAN project we study the composition of aerosols collected over ~ 5 years at Izaña Observatory (located at ~ 2400 m a.s.l. in Tenerife, the Canary Islands) under the prevailing westerly airflows typical of the North Atlantic free troposphere at subtropical and mid-latitudes. Mass concentrations of sub10-µm aerosols (PM10) carried by westerly winds to Izaña, after transatlantic transport, are typically within the range 1.2 and 4.2 µg m−3 (20th and 80th percentiles). The main contributors to background levels of aerosols (PM10 within the 1st–50th percentiles = 0.15–2.54 µg m−3) are North American dust (53 %), non-sea-salt-SO4= (14 %) and organic matter (18 %). High PM10 events (75th–95th percentiles ≈ 4.0–9.0 µg m−3) and are prompted by dust (56 %), organic matter (24 %) and nss-SO4= (9 %). These aerosol components experience a seasonal evolution explained by (i) their spatial distribution in North America and (ii) the seasonal shift of the North American outflow, which migrates from low latitudes in winter (~ 32º N, January–March) to high latitudes in summer (~ 52º N, August–September). The westerlies carry maximum loads of nss-sulphate, ammonium and organic matter in spring (March–May), of North American dust from mid-winter to mid-spring (February–May) and of elemental carbon in summer (August–September). Our results suggest that a significant fraction of organic aerosols may be linked to sources other than combustion (e.g. biogenic); further studies are necessary for this topic. The present study evidences how long-term evolution of the aerosol composition in the North Atlantic free troposphere will be influenced by air quality policies and the use of soils (potential dust emitter) in North America.

scholarly journals Impact of North America on the aerosol composition in the North Atlantic free troposphere

2017 ◽  
Vol 17 (12) ◽  
pp. 7387-7404 ◽  
Author(s):  
M. Isabel García ◽  
Sergio Rodríguez ◽  
Andrés Alastuey
Keyword(s):  
Organic Matter ◽  
North America ◽  
North Atlantic ◽  
North American ◽  
Sea Salt ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
The North ◽  
The North Atlantic

Abstract. In the AEROATLAN project we study the composition of aerosols collected over  ∼  5 years at Izaña Observatory (located at  ∼  2400 m a.s.l. in Tenerife, the Canary Islands) under the prevailing westerly airflows typical of the North Atlantic free troposphere at subtropical latitudes and midlatitudes. Mass concentrations of sub-10 µm aerosols (PM10) carried by westerly winds to Izaña, after transatlantic transport, are typically within the range 1.2 and 4.2 µg m−3 (20th and 80th percentiles). The main contributors to background levels of aerosols (PM10 within the 1st–50th percentiles  =  0.15–2.54 µg m−3) are North American dust (53 %), non-sea-salt sulfate (14 %) and organic matter (18 %). High PM10 events (75th–95th percentiles  ≈  4.0–9.0 µg m−3) are prompted by dust (56 %), organic matter (24 %) and non-sea-salt sulfate (9 %). These aerosol components experience a seasonal evolution explained by (i) their spatial distribution in North America and (ii) the seasonal shift of the North American outflow, which migrates from low latitudes in winter (∼  32° N, January–March) to high latitudes in summer (∼  52° N, August–September). The westerlies carry maximum loads of non-sea-salt sulfate, ammonium and organic matter in spring (March–May), of North American dust from midwinter to mid-spring (February–May) and of elemental carbon in summer (August–September). Our results suggest that a significant fraction of organic aerosols may be linked to sources other than combustion (e.g. biogenic); further studies are necessary for this topic. The present study suggests that long-term evolution of the aerosol composition in the North Atlantic free troposphere will be influenced by air quality policies and the use of soils (potential dust emitter) in North America.

scholarly journals Atmospheric Responses to North Atlantic SST Anomalies in Idealized Experiments. Part II: North American Precipitation

2016 ◽  
Vol 29 (2) ◽  
pp. 659-671 ◽  
Author(s):  
Qi Hu ◽  
Michael C. Veres
Keyword(s):  
North America ◽  
North Atlantic ◽  
North American ◽  
North Atlantic Ocean ◽  
Warm Season ◽  
The North ◽  
Precipitation Anomalies ◽  
Sst Anomaly ◽  
The North Atlantic ◽  
Sst Anomalies

Abstract This is the second part of a two-part paper that addresses deterministic roles of the sea surface temperature (SST) anomalies associated with the Atlantic multidecadal oscillation (AMO) in variations of atmospheric circulation and precipitation in the Northern Hemisphere, using a sequence of idealized model runs at the spring equinox conditions. This part focuses on the effect of the SST anomalies on North American precipitation. Major results show that, in the model setting closest to the real-world situation, a warm SST anomaly in the North Atlantic Ocean causes suppressed precipitation in central, western, and northern North America but more precipitation in the southeast. A nearly reversed pattern of precipitation anomalies develops in response to the cold SST anomaly. Further examinations of these solutions reveal that the response to the cold SST anomaly is less stable than that to the warm SST anomaly. The former is “dynamically charged” in the sense that positive eddy kinetic energy (EKE) exists over the continent. The lack of precipitation in its southeast is because of an insufficient moisture supply. In addition, the results show that the EKE of the short- (2–6 day) and medium-range (7–10 day) weather-producing processes in North America have nearly opposite signs in response to the same cold SST anomaly. These competing effects of eddies in the dynamically charged environment (elevated sensitivity to moisture) complicate the circulation and precipitation responses to the cold SST anomaly in the North Atlantic and may explain why the model results show more varying precipitation anomalies (also confirmed by statistical test results) during the cold than the warm SST anomaly, as also shown in simulations with more realistic models. Results of this study indicate a need to include the AMO in the right context with other forcings in an effort to improve understanding of interannual-to-multidecadal variations in warm season precipitation in North America.

ORIGINS OF THE NORTH AMERICAN EPHEMEROPTERA FAUNA, ESPECIALLY THE LEPTOPHLEBIIDAE

1988 ◽  
Vol 120 (S144) ◽  
pp. 13-24 ◽  
Author(s):  
William L. Peters
Keyword(s):  
North America ◽  
Transition Zone ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
North American ◽  
West Indies ◽  
The West ◽  
The North ◽  
The North Atlantic ◽  
Mexican Transition Zone

AbstractThe complex origins of the North American Ephemeroptera fauna extended from the Lower Permian to the Recent. This paper discusses origins of North American genera of the cosmopolitan family Leptophlebiidae with a few examples from other mayfly families. The two extant subfamilies, Leptophlebiinae and Atalophlebiinae, probably evolved at least by the mid-Cretaceous, or about 100 million years before present. The primitive Leptophlebiinae are distributed throughout most of the Northern Hemisphere and the ancestors of the Leptophlebia–Paraleptophlebia complex within this subfamily dispersed widely by the North Atlantic route as early as the mid-Cretaceous and later probably by northern trans-Pacific dispersals through Beringia. The ancestors of Habrophlebia dispersed through the North Atlantic route at an early time, but the vicariant distribution of Habrophlebiodes in several areas of the Oriental Region and eastern North America correlates with the Arcto-Tertiary forest that covered most of the Northern Hemisphere including Beringia from the Early Tertiary into the Pleistocene. Within the nearly cosmopolitan Atalophlebiinae, Traverella is austral in origin and probably dispersed north through the Mexican Transition Zone during the mid-Tertiary as an ancient dispersal and then dispersed to its northern and eastern limits following the last Pleistocene deglaciation by way of the Missouri River tributaries. Thraulodes and Farrodes are both austral in origin and probably dispersed north through the Mexican Transition Zone during the Early Pleistocene as a relatively recent dispersal. The origins of Choroterpes sensu stricto and Neochoroterpes in North America are unknown. The mayfly fauna of the West Indies is Neotropical in origins, and no affinities between the West Indies and North America through Florida have ever been confirmed.

scholarly journals The influence of boreal biomass burning emissions on the distribution of tropospheric ozone over North America and the North Atlantic during 2010

2012 ◽  
Vol 12 (4) ◽  
pp. 2077-2098 ◽  
Author(s):  
M. Parrington ◽  
P. I. Palmer ◽  
D. K. Henze ◽  
D. W. Tarasick ◽  
E. J. Hyer ◽  
...  
Keyword(s):  
North America ◽  
Biomass Burning ◽  
North Atlantic ◽  
Tropospheric Ozone ◽  
Free Troposphere ◽  
Scaling Factors ◽  
The North ◽  
Ozone Distribution ◽  
The North Atlantic ◽  
Satellite Instruments

Abstract. We have analysed the sensitivity of the tropospheric ozone distribution over North America and the North Atlantic to boreal biomass burning emissions during the summer of 2010 using the GEOS-Chem 3-D global tropospheric chemical transport model and observations from in situ and satellite instruments. We show that the model ozone distribution is consistent with observations from the Pico Mountain Observatory in the Azores, ozonesondes across Canada, and the Tropospheric Emission Spectrometer (TES) and Infrared Atmospheric Sounding Instrument (IASI) satellite instruments. Mean biases between the model and observed ozone mixing ratio in the free troposphere were less than 10 ppbv. We used the adjoint of GEOS-Chem to show the model ozone distribution in the free troposphere over Maritime Canada is largely sensitive to NOx emissions from biomass burning sources in Central Canada, lightning sources in the central US, and anthropogenic sources in the eastern US and south-eastern Canada. We also used the adjoint of GEOS-Chem to evaluate the Fire Locating And Monitoring of Burning Emissions (FLAMBE) inventory through assimilation of CO observations from the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument. The CO inversion showed that, on average, the FLAMBE emissions needed to be reduced to 89% of their original values, with scaling factors ranging from 12% to 102%, to fit the MOPITT observations in the boreal regions. Applying the CO scaling factors to all species emitted from boreal biomass burning sources led to a decrease of the model tropospheric distributions of CO, PAN, and NOx by as much as −20 ppbv, −50 pptv, and −20 pptv respectively. The modification of the biomass burning emission estimates reduced the model ozone distribution by approximately −3 ppbv (−8%) and on average improved the agreement of the model ozone distribution compared to the observations throughout the free troposphere, reducing the mean model bias from 5.5 to 4.0 ppbv for the Pico Mountain Observatory, 3.0 to 0.9 ppbv for ozonesondes, 2.0 to 0.9 ppbv for TES, and 2.8 to 1.4 ppbv for IASI.

scholarly journals The Global Repercussions of the 1947 Symposium on Fish Populations in Toronto: Scientific Networks and the Over-fishing Question

2018 ◽  
Vol 40 (1) ◽  
pp. 76-97 ◽  
Author(s):  
Jennifer Hubbard
Keyword(s):  
North America ◽  
North Atlantic ◽  
North American ◽  
Fish Populations ◽  
Biological Station ◽  
The North ◽  
The North Atlantic ◽  
Scientific Networks

A relatively small, contentious, and long-forgotten meeting, the 1947 Symposium on Fish Populations, had enormous and decades-long repercussions for global fisheries policies. Convened in Toronto by Archibald Gowanlock Huntsman, former director of the Atlantic Biological Station, it drew together leading North American fisheries biologists and professional fishermen. By exposing the lack of agreement on, or understanding of, the nature of overfishing, this meeting made it difficult for later scientists to challenge pro-industry fisheries policies. The published proceedings, in-demand by a tight network of fisheries scientists across North America and the North Atlantic, guaranteed this meeting’s disproportionate and unfortunate impact.

scholarly journals Combined Influences on North American Winter Air Temperature Variability from North Pacific Blocking and the North Atlantic Oscillation: Subseasonal and Interannual Time Scales

2020 ◽  
Vol 33 (16) ◽  
pp. 7101-7123 ◽  
Author(s):  
Binhe Luo ◽  
Dehai Luo ◽  
Aiguo Dai ◽  
I. Simmonds ◽  
Lixin Wu
Keyword(s):  
North America ◽  
Air Temperature ◽  
North Atlantic ◽  
North American ◽  
North Pacific ◽  
Eastern North America ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation ◽  
The North Pacific

AbstractWinter surface air temperature (SAT) over North America exhibits pronounced variability on subseasonal, interannual, decadal, and interdecadal time scales. Here, reanalysis data from 1950–2017 are analyzed to investigate the atmospheric and surface ocean conditions associated with its subseasonal to interannual variability. Detrended daily SAT data reveal a known warm west/cold east (WWCE) dipole over midlatitude North America and a cold north/warm south (CNWS) dipole over eastern North America. It is found that while the North Pacific blocking (PB) is important for the WWCE and CNWS dipoles, they also depend on the phase of the North Atlantic Oscillation (NAO). When a negative-phase NAO (NAO−) coincides with PB, the WWCE dipole is enhanced (compared with the PB alone case) and it also leads to a warm north/cold south dipole anomaly in eastern North America; but when PB occurs with a positive-phase NAO (NAO+), the WWCE dipole weakens and the CNWS dipole is enhanced. The PB events concurrent with the NAO− (NAO+) and SAT WWCE (CNWS) dipole are favored by the Pacific El Niño–like (La Niña–like) sea surface temperature mode and the positive (negative) North Pacific mode. The PB-NAO+ has a larger component projecting onto the SAT WWCE dipole during the La Niña winter than during the El Niño winter because a more zonal wave train is formed. Strong North American SAT WWCE dipoles and enhanced projections of PB-NAO+ events onto the SAT WWCE dipole component are also readily seen for the positive North Pacific mode. The North Pacific mode seems to play a bigger role in the North American SAT variability than ENSO.

THE POST-GLACIAL COLONIZATION OF THE NORTH ATLANTIC ISLANDS

1988 ◽  
Vol 120 (S144) ◽  
pp. 55-92 ◽  
Author(s):  
J.A. Downes
Keyword(s):  
North America ◽  
North Atlantic ◽  
North American ◽  
High Arctic ◽  
The Arctic ◽  
Land Bridge ◽  
The North ◽  
The North Atlantic ◽  
North Greenland ◽  
Arctic Fauna

AbstractThe paper discusses the nature and origins of the present-day insect faunas of Greenland, Iceland, and the Faeroes in relation to those of North America and Europe. The markedly warm-adapted faunas of the Early Tertiary were modified or eliminated as the climate cooled from the Oligocene onward to the Pleistocene glaciations. The Wisconsinan glaciation peaked about 20 000 years ago, and then gave way rapidly to the arctic and cool temperate climates of the present, and the North Atlantic islands thus became habitable again but separated by wide expanses of northern seas. At most only a few strongly arctic-adapted species could have persisted through the Pleistocene and no land bridges from the continents have existed since the Early Miocene, 20 million years ago.Southern Greenland, Iceland, and the Faeroes have been colonized across sea passages from the adjacent continents, mainly by air but partly by sea, during the postglacial period (ca. 10 000 years). The faunas are all young, with no endemic species among about 2000 in all; the faunas are not arctic but distinctly subarctic, mainly of the High and Low Boreal life zones, and derived from these life zones of North America or Europe. The naturally established faunas are small or very small, less than 14% of the corresponding continental faunas, and are obviously disharmonic, with some groups absent across the North Atlantic, e.g. Culicidae, Tabanidae, Tachinidae, Papilionoidea, aculeate Hymenoptera (except Bombus sp.). This indicates a severe "sweepstakes" route. The lack of Tachinidae is noteworthy because their hosts are plentiful, and indicates dispersal by air, with adult Tachinidae, unlike adult Lepidoptera, unable to make the journey; dispersal by a land bridge would offer parasites and hosts an equal opportunity. Aerial transport is indicated also by the high proportion of migrant species (of Lepidoptera) in the island faunas, and the arrival in Surtsey (a new volcanic island) of almost 25% of the Icelandic fauna in 12 years. The Surtsey observations suggest that the Icelandic fauna is preadapted to aerial dispersal, by selection during its journey from Europe.The fauna of southern Greenland is derived partly from boreal America and partly from boreal Europe. The North American moiety becomes vestigial in Iceland and the Faeroes and does not reach Europe. Iceland and the Faeroes have been populated from northwestern Europe, especially Britain and Scandinavia. A few species extend to southern Greenland and thence, or even directly, reach North America, and have thus completed a post-glacial traverse of the North Atlantic.The fauna of North Greenland differs fundamentally from all the above. It is a high arctic fauna, nearly identical with the high arctic fauna in Canada, and thus complete, not disharmonie, though very small by virtue of its high arctic nature. It has encountered no "sweepstakes" dispersal. North Greenland is separated from High Arctic Canada only by a narrow channel which permits winter dispersal by wind across unbroken sea ice. Biologically, North Greenland is part of the North American High Arctic, and although certain species (e.g. mosquitoes and butterflies) may extend somewhat into southern Greenland, it has not contributed to the basic faunas of the North Atlantic islands.Among other problems, the extreme variability in wing pattern of many Lepidoptera in Iceland, the Faeroes, and Shetland is also commented on.

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