scholarly journals Free-troposphere ozone and carbon monoxide over the North Atlantic for 2001–2011

2013 ◽  
Vol 13 (24) ◽  
pp. 12537-12547 ◽  
Author(s):  
A. Kumar ◽  
S. Wu ◽  
M. F. Weise ◽  
R. Honrath ◽  
R. C. Owen ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
North Atlantic ◽  
Transport Model ◽  
Measurement Data ◽  
Free Troposphere ◽  
Chemical Transport Model ◽  
Significance Level ◽  
The Past ◽  
The North ◽  
The North Atlantic

Abstract. In situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal, are analyzed together with results from an atmospheric chemical transport model (GEOS-Chem) and satellite remote sensing data (AIRS (Atmospheric Infrared Sounder) for CO, and TES (Tropospheric Emission Spectrometer) for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001–2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the possible trends for CO and O3 measurements are −0.31 ± 0.30 (2-σ) ppbv yr−1 and −0.21 ± 0.11 (2-σ) ppbv yr−1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The most important factor contributing to the decreases in CO and O3 at PMO over the past decade is the decline in anthropogenic emissions from North America, which more than compensate for the impacts from increasing Asian emissions. It is likely that climate change in the past decade has also affected the intercontinental transport of O3.

scholarly journals Free troposphere ozone and carbon monoxide over the North Atlantic for 2001–2011

2013 ◽  
Vol 13 (6) ◽  
pp. 15377-15407 ◽  
Author(s):  
A. Kumar ◽  
S. Wu ◽  
M. F. Weise ◽  
R. Honrath ◽  
R. C. Owen ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
North Atlantic ◽  
Measurement Data ◽  
Free Troposphere ◽  
Significance Level ◽  
Mixing Ratios ◽  
The North ◽  
Source Regions ◽  
The North Atlantic ◽  
The Impact

Abstract. In-situ measurements of carbon monoxide (CO) and ozone (O3) at the Pico Mountain Observatory (PMO) located in the Azores, Portugal are analyzed together with results from atmospheric chemical transport modeling (GEOS-Chem) and satellite remote sensing (AIRS for CO and TES for O3) to examine the evolution of free-troposphere CO and O3 over the North Atlantic for 2001–2011. GEOS-Chem captured the seasonal cycles for CO and O3 well but significantly underestimated the mixing ratios of CO, particularly in spring. Statistically significant (using a significance level of 0.05) decreasing trends were found for both CO and O3 based on harmonic regression analysis of the measurement data. The best estimates of the trend for CO and O3 measurements are −0.31 ± 0.30 (2-σ) ppbv yr−1 and −0.21 ± 0.11 (2-σ) ppbv yr−1, respectively. Similar decreasing trends for both species were obtained with GEOS-Chem simulation results. The major factor contributing to the reported decrease in CO and O3 mixing ratios at PMO over the past decade is the decline in anthropogenic CO and O3-precursor emissions in regions such as North America and Europe. The increase in Asian emissions does not seem to outweigh the impact of these declines resulting in overall decreasing trends for both CO and O3. For O3, however, increase in atmospheric water vapor content associated with climate change also appears to be a contributing factor causing enhanced destruction of the O3 during transport from source regions. These hypotheses are supported by results from the GEOS-Chem tagged CO and tagged O3 simulations.

scholarly journals Influence of the North Atlantic oscillation on the atmospheric levels of benzo[a]pyrene over Europe

2021 ◽  
Author(s):  
Pedro Jiménez-Guerrero ◽  
Nuno Ratola
Keyword(s):  
Spatial Pattern ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Transport Model ◽  
Regional Scale ◽  
The South ◽  
Climatic Fluctuations ◽  
The North ◽  
The North Atlantic ◽  
The North Atlantic Oscillation

AbstractThe atmospheric concentration of persistent organic pollutants (and of polycyclic aromatic hydrocarbons, PAHs, in particular) is closely related to climate change and climatic fluctuations, which are likely to influence contaminant’s transport pathways and transfer processes. Predicting how climate variability alters PAHs concentrations in the atmosphere still poses an exceptional challenge. In this sense, the main objective of this contribution is to assess the relationship between the North Atlantic Oscillation (NAO) index and the mean concentration of benzo[a]pyrene (BaP, the most studied PAH congener) in a domain covering Europe, with an emphasis on the effect of regional-scale processes. A numerical simulation for a present climate period of 30 years was performed using a regional chemistry transport model with a 25 km spatial resolution (horizontal), higher than those commonly applied. The results show an important seasonal behaviour, with a remarkable spatial pattern of difference between the north and the south of the domain. In winter, higher BaP ground levels are found during the NAO+ phase for the Mediterranean basin, while the spatial pattern of this feature (higher BaP levels during NAO+ phases) moves northwards in summer. These results show deviations up to and sometimes over 100% in the BaP mean concentrations, but statistically significant signals (p<0.1) of lower changes (20–40% variations in the signal) are found for the north of the domain in winter and for the south in summer.

scholarly journals The Meridional Shift of the Midlatitude Westerlies over Arid Central Asia during the Past 21 000 Years Based on the TraCE-21ka Simulations

2020 ◽  
Vol 33 (17) ◽  
pp. 7455-7478
Author(s):  
Nanxuan Jiang ◽  
Qing Yan ◽  
Zhiqing Xu ◽  
Jian Shi ◽  
Ran Zhang
Keyword(s):  
Indian Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Last Deglaciation ◽  
The Past ◽  
The North ◽  
External Forcings ◽  
The Indian Ocean ◽  
The Last Deglaciation ◽  
The North Atlantic

AbstractTo advance our knowledge of the response of midlatitude westerlies to various external forcings, we investigate the meridional shift of midlatitude westerlies over arid central Asia (ACA) during the past 21 000 years, which experienced more varied forcings than the present day based on a set of transient simulations. Our results suggest that the evolution of midlatitude westerlies over ACA and driving factors vary with time and across seasons. In spring, the location of midlatitude westerlies over ACA oscillates largely during the last deglaciation, driven by meltwater fluxes and continental ice sheets, and then shows a long-term equatorward shift during the Holocene controlled by orbital insolation. In summer, orbital insolation dominates the meridional shift of midlatitude westerlies, with poleward and equatorward migration during the last deglaciation and the Holocene, respectively. From a thermodynamic perspective, variations in zonal winds are linked with the meridional temperature gradient based on the thermal wind relationship. From a dynamic perspective, variations in midlatitude westerlies are mainly induced by anomalous sea surface temperatures over the Indian Ocean through the Matsuno–Gill response and over the North Atlantic Ocean by the propagation of Rossby waves, or both, but their relative importance varies across forcings. Additionally, the modeled meridional shift of midlatitude westerlies is broadly consistent with geological evidence, although model–data discrepancies still exist. Overall, our study provides a possible scenario for a meridional shift of midlatitude westerlies over ACA in response to various external forcings during the past 21 000 years and highlights important roles of both the Indian Ocean and the North Atlantic Ocean in regulating Asian westerlies, which may shed light on the behavior of westerlies in the future.

scholarly journals Modeling the climatic implications of the Guliya δ<sup>18</sup>O record during the past 130 ka

2012 ◽  
Vol 8 (3) ◽  
pp. 1885-1914
Author(s):  
D. Xiao ◽  
P. Zhao ◽  
Y. Wang ◽  
X. Zhou
Keyword(s):  
North Atlantic ◽  
Climate Model ◽  
Surface Air Temperature ◽  
Late Summer ◽  
The Arctic ◽  
The Past ◽  
The North ◽  
Precession Cycle ◽  
The North Atlantic ◽  
Anomalous Pattern

Abstract. Using an intermediate-complexity UVic Earth System Climate Model (UVic Model), the geographical and seasonal implications and an indicative sense of the historical climate found in the δ18O record of the Guliya ice core (hereinafter, the Guliya δ18O) are investigated under time-dependent orbital forcing with an acceleration factor of 100 over the past 130 ka. The results reveal that the simulated late-summer (August–September) Guliya surface air temperature (SAT) reproduces the 23-ka precession and 43-ka obliquity cycles in the Guliya δ18O. Furthermore, the Guliya δ18O is significantly correlated with the SAT over the Northern Hemisphere (NH), which suggests the Guliya δ18O is an indicator of the late-summer SAT in the NH. Corresponding to the warm and cold phases of the precession cycle in the Guliya temperature, there are two anomalous patterns in the SAT and sea surface temperature (SST) fields. The first anomalous pattern shows an increase in the SAT (SST) toward the Arctic, possibly associated with the joint effect of the precession and obliquity cycles, and the second anomalous pattern shows an increase in the SAT (SST) toward the equator, possibly due to the influence of the precession cycle. Additionally, the summer (winter) Guliya and NH temperatures are higher (lower) in the warm phases of Guliya late-summer SAT than in the cold phases. Furthermore, the Guliya SAT is closely related to the North Atlantic SST, in which the Guliya precipitation may act as a "bridge" linking the Guliya SAT and the North Atlantic SST.

Impact of Seasonality in the North Atlantic Jet Stream and Storm Migration on the Seasonality of Hurricane Translation Speed Changes

2021 ◽  
pp. 1-38
Author(s):  
Xi Guo ◽  
James P. Kossin ◽  
Zhe-Min Tan
Keyword(s):  
North Atlantic ◽  
Atlantic Coast ◽  
Jet Stream ◽  
Translation Speed ◽  
Multidecadal Variability ◽  
The Past ◽  
The North ◽  
Term Variation ◽  
The North Atlantic

AbstractTropical cyclone (TC) translation speed (TCTS) can affect the duration of TC-related disasters, which is critical to coastal and inland areas. The long-term variation of TCTS and their relationship to the variability of the mid-latitude jet stream and storm migration are discussed here for storms near the North Atlantic coast during 1948-2019. Our results reveal the prominent seasonality in the long-term variation of TCTS, which can be largely explained by the seasonality in the covariations of the mid-latitude jet stream and storm locations. Specifically, significant increases of TCTS occur in June and October during the past decades, which may result from the equatorward displacement of the jet stream and poleward migration of storm locations. Prominent slowdown of TCTS is found in August, which is related to the weakened jet strength and equatorward storm migration. In September, the effects of poleward displacement and weakening of the jet stream on TCTS are largely compensated by the poleward storm migration, therefore, no significant change in TCTS is observed. Meanwhile, the multidecadal variability of the Atlantic may contribute to the multidecadal variability of TCTS. Our findings emphasize the significance in taking a seasonality view in discussing the variability and trends of near-coast Atlantic TCTS under climate change.

Aeronautical Satellite Systems for Air Traffic Control and Communications in the European Environment

1969 ◽  
Vol 73 (700) ◽  
pp. 283-288
Author(s):  
H. G. Leysieffer
Keyword(s):  
North Atlantic ◽  
Traffic Control ◽  
Air Traffic ◽  
Traffic Surveillance ◽  
Satellite Systems ◽  
The Past ◽  
The North ◽  
The North Atlantic ◽  
Trade Route ◽  
North Atlantic Area

The North Atlantic is increasingly developing into the main trade route of the age. Shipping, the pioneer along this highway of commerce, in the past decade has been joined by air traffic displaying a striking growth rate. Not only is the number of aircraft simultaneously plying the Atlantic routes constantly on the increase, but also the volume of passengers and freight transported on each flight. The question, whether such flow of traffic in the air and on water could be dealt with in future with the safety to which it is entitled, has led to world-wide discussions over the past few years concerning the necessity for an air traffic surveillance system for the North Atlantic area. A further question, whether one should not include also sea traffic in such a system suggested itself. The initiative for holding such discussions naturally proceeded less from air and shipping undertakings, but rather from those committees who are entrusted in supervising the safety in the conduct of man and merchandise.

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