scholarly journals The effect of using local mean versus constant reference salinity to estimate Arctic Ocean freshwater content changes

2021 ◽  
Vol 67 (3) ◽  
pp. 230-235
Author(s):  
I. V. Polyakov
Keyword(s):  
Arctic Ocean ◽  
High Latitude ◽  
Substantial Fraction ◽  
Choice Analysis ◽  
Spatiotemporal Changes ◽  
Local Mean ◽  
Polar Oceans ◽  
The Difference ◽  
Climate Studies

Changes of high-latitude freshwater content (FWC) play an important role in shaping the variability of polar oceans. FWC is defined as depth-integrated departure of salinity from a reference salinity Sref divided by this Sref . A constant Sref is often used for high-latitude FWC estimates. Here it is argued that for analyzing FWC spatiotemporal changes the use of local mean Sref is a better choice. Analysis of 2007 FWC anomalies in the 25–75 m layer demonstrated, for example, that the choice of Sref = 34.8 (which is often used in climate studies) leads to FWC spatial anomalies exaggerated, on average, by ~0.6 m, which is a substantial fraction of total spatial FWC changes. The problem is aggravated in areas where the difference between the local Sref and Sref = 34.8 is greater. Thus, it is concluded that using climatological mean salinities as Sref provides superior estimates of spatiotemporal Arctic Ocean FWC changes.

Total ozone dependence of the difference between the empirically corrected EP-TOMS and high-latitude station datasets

2009 ◽  
Vol 30 (15-16) ◽  
pp. 4283-4294 ◽  
Author(s):  
V. Kravchenko ◽  
A. Evtushevsky ◽  
A. Grytsai ◽  
G. Milinevsky ◽  
J. Shanklin
Keyword(s):  
High Latitude ◽  
Total Ozone ◽  
Latitude Station ◽  
The Difference

The High Latitude Seas and Arctic Ocean

2017 ◽  
pp. 271-296
Author(s):  
Johnny A. Johannessen ◽  
Ole B. Andersen
Keyword(s):  
Arctic Ocean ◽  
High Latitude

scholarly journals Metal coverage ratio of pipeline embolization device for treatment of unruptured aneurysms: Reality check

2015 ◽  
Vol 22 (1) ◽  
pp. 42-48 ◽  
Author(s):  
Liang-Der Jou ◽  
Gouthami Chintalapani ◽  
Michel E Mawad
Keyword(s):  
Flow Diverter ◽  
Pipeline Embolization Device ◽  
Unruptured Aneurysms ◽  
Coverage Ratio ◽  
Reality Check ◽  
Local Mean ◽  
Aneurysm Occlusion ◽  
Occlusion Rate ◽  
The Mean ◽  
The Difference

Background and purpose The metal coverage ratio (MCR) of a flow diverter influences the intra-aneurysmal hemodynamics; a high MCR will occlude an aneurysm early, while a low MCR may delay aneurysm occlusion. The true MCR of a pipeline embolization device (PED) could be lower due to oversize, device deformation, or aneurysm location. In this study deviation of the true MCR from the nominal MCR is assessed and whether their difference affects aneurysm occlusion rate is determined. Methods A total of 40 consecutive patients, each of them treated by one PED for their aneurysms at the internal carotid artery (ICA), were retrospectively analyzed. The DynaCT images of these deployed PEDs were used to determine their true dimensions and estimate three MCRs (local, mean, and nominal). These data were compared in two groups of patients who had different aneurysm outcomes at six months. Results The difference in the local MCR between two groups is small, but statistically significant (24.5% vs 21.6%, p = 05). The local MCR is consistently lower than the nominal MCRs (23.2% vs 30.2%, p < 0.001); however, the difference between the mean and local MCRs is small (23.9% vs 23.2%). Conclusions An expectation that a PED can achieve a MCR of 30% may not be reasonable. Device oversize and deformation during deployment lower the local MCR by 5–7%. A lowered MCR affects the aneurysm occlusion rate at six months.

Separating the influences of low-latitude warming and sea-ice loss on Northern Hemisphere climate change

2022 ◽  
pp. 1-59
Author(s):  
Paul J. Kushner ◽  
Russell Blackport ◽  
Kelly E. McCusker ◽  
Thomas Oudar ◽  
Lantao Sun ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
High Latitude ◽  
North Pacific ◽  
Heat Fluxes ◽  
The Arctic ◽  
Low Latitude ◽  
The Arctic Ocean

Abstract Analyzing a multi-model ensemble of coupled climate model simulations forced with Arctic sea-ice loss using a two-parameter pattern-scaling technique to remove the cross-coupling between low- and high-latitude responses, the sensitivity to high-latitude sea-ice loss is isolated and contrasted to the sensitivity to low-latitude warming. In spite of some differences in experimental design, the Northern Hemisphere near-surface atmospheric sensitivity to sea-ice loss is found to be robust across models in the cold season; however, a larger inter-model spread is found at the surface in boreal summer, and in the free tropospheric circulation. In contrast, the sensitivity to low-latitude warming is most robust in the free troposphere and in the warm season, with more inter-model spread in the surface ocean and surface heat flux over the Northern Hemisphere. The robust signals associated with sea-ice loss include upward turbulent and longwave heat fluxes where sea-ice is lost, warming and freshening of the Arctic ocean, warming of the eastern North Pacific relative to the western North Pacific with upward turbulent heat fluxes in the Kuroshio extension, and salinification of the shallow shelf seas of the Arctic Ocean alongside freshening in the subpolar North Atlantic. In contrast, the robust signals associated with low-latitude warming include intensified ocean warming and upward latent heat fluxes near the western boundary currents, freshening of the Pacific Ocean, salinification of the North Atlantic, and downward sensible and longwave fluxes over the ocean.

scholarly journals Model constraints on the anthropogenic carbon budget of the Arctic Ocean

2019 ◽  
Vol 16 (11) ◽  
pp. 2343-2367 ◽  
Author(s):  
Jens Terhaar ◽  
James C. Orr ◽  
Marion Gehlen ◽  
Christian Ethé ◽  
Laurent Bopp
Keyword(s):  
Ocean Acidification ◽  
Arctic Ocean ◽  
Lower Limit ◽  
Ocean Circulation ◽  
The Arctic ◽  
Model Resolution ◽  
Lateral Transport ◽  
The Arctic Ocean ◽  
Anthropogenic Carbon ◽  
The Difference

Abstract. The Arctic Ocean is projected to experience not only amplified climate change but also amplified ocean acidification. Modeling future acidification depends on our ability to simulate baseline conditions and changes over the industrial era. Such centennial-scale changes require a global model to account for exchange between the Arctic and surrounding regions. Yet the coarse resolution of typical global models may poorly resolve that exchange as well as critical features of Arctic Ocean circulation. Here we assess how simulations of Arctic Ocean storage of anthropogenic carbon (Cant), the main driver of open-ocean acidification, differ when moving from coarse to eddy-admitting resolution in a global ocean-circulation–biogeochemistry model (Nucleus for European Modeling of the Ocean, NEMO; Pelagic Interactions Scheme for Carbon and Ecosystem Studies, PISCES). The Arctic's regional storage of Cant is enhanced as model resolution increases. While the coarse-resolution model configuration ORCA2 (2∘) stores 2.0 Pg C in the Arctic Ocean between 1765 and 2005, the eddy-admitting versions ORCA05 and ORCA025 (1∕2∘ and 1∕4∘) store 2.4 and 2.6 Pg C. The difference in inventory between model resolutions that is accounted for is only from their divergence after 1958, when ORCA2 and ORCA025 were initialized with output from the intermediate-resolution configuration (ORCA05). The difference would have been larger had all model resolutions been initialized in 1765 as was ORCA05. The ORCA025 Arctic Cant storage estimate of 2.6 Pg C should be considered a lower limit because that model generally underestimates observed CFC-12 concentrations. It reinforces the lower limit from a previous data-based approach (2.5 to 3.3 Pg C). Independent of model resolution, there was roughly 3 times as much Cant that entered the Arctic Ocean through lateral transport than via the flux of CO2 across the air–sea interface. Wider comparison to nine earth system models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) reveals much larger diversity of stored Cant and lateral transport. Only the CMIP5 models with higher lateral transport obtain Cant inventories that are close to the data-based estimates. Increasing resolution also enhances acidification, e.g., with greater shoaling of the Arctic's average depth of the aragonite saturation horizon during 1960–2012, from 50 m in ORCA2 to 210 m in ORCA025. Even higher model resolution would likely further improve such estimates, but its prohibitive costs also call for other more practical avenues for improvement, e.g., through model nesting, addition of coastal processes, and refinement of subgrid-scale parameterizations.

Does Rotation Influence Double-Diffusive Fluxes in Polar Oceans?

2014 ◽  
Vol 44 (1) ◽  
pp. 289-296 ◽  
Author(s):  
J. R. Carpenter ◽  
M.-L. Timmermans
Keyword(s):  
Arctic Ocean ◽  
Heat Fluxes ◽  
Small Scale ◽  
Previous Theory ◽  
Thermal Interface ◽  
Diffusive Convection ◽  
Polar Oceans ◽  
Diffusive Fluxes ◽  
Mixed Layers ◽  
Double Diffusive

Abstract The diffusive (or semiconvection) regime of double-diffusive convection (DDC) is widespread in the polar oceans, generating “staircases” consisting of high-gradient interfaces of temperature and salinity separated by convectively mixed layers. Using two-dimensional direct numerical simulations, support is provided for a previous theory that rotation can influence DDC heat fluxes when the thickness of the thermal interface sufficiently exceeds that of the Ekman layer. This study finds, therefore, that the earth’s rotation places constraints on small-scale vertical heat fluxes through double-diffusive layers. This leads to departures from laboratory-based parameterizations that can significantly change estimates of Arctic Ocean heat fluxes in certain regions, although most of the upper Arctic Ocean thermocline is not expected to be dominated by rotation.

scholarly journals Spatial Distribution and Chemical Composition of Road Dust in Two High-Altitude Latin American Cities

Atmosphere ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1109
Author(s):  
Sebastián Vanegas ◽  
Erika M. Trejos ◽  
Beatriz H. Aristizábal ◽  
Guilherme M. Pereira ◽  
Julio M. Hernández ◽  
...  
Keyword(s):  
Latin American ◽  
Principal Component ◽  
Road Dust ◽  
Abundant Species ◽  
Enrichment Factors ◽  
Quality Health ◽  
The Difference ◽  
Potential Factors ◽  
American Cities ◽  
Climate Studies

Road dust (RD) resuspension is one of the main sources of particulate matter in cities with adverse impacts on air quality, health, and climate. Studies on the variability of the deposited PM10 fraction of RD (RD10) have been limited in Latin America, whereby our understanding of the central factors that control this pollutant remains incomplete. In this study, forty-one RD10 samples were collected in two Andean cities (Bogotá and Manizales) and analyzed for ions, minerals, and trace elements. RD10 levels varied between 1.8–45.7 mg/m2, with an average of 11.8 mg/m2, in Bogotá and between 0.8–26.7 mg/m2, with an average of 5.7 mg/m2, in Manizales. Minerals were the most abundant species in both cities, with a fraction significantly larger in Manizales (38%) than Bogotá (9%). The difference could be explained mainly by the complex topography and the composition of soil derived from volcanic ash in Manizales. The volcanic activity was also associated with SO4⁻2 and Clˉ. Enrichment factors and principal component analysis were conducted to explore potential factors associated to sources of RD10. Elements such as Cu, Pb, Cr, Ni, V, Sb, and Mo were mainly associated with exhaust and non-exhaust traffic emissions.

Some Records About The Arctic in Early Chinese Books

1991 ◽  
Vol 10 (2) ◽  
pp. 219-222
Author(s):  
Li Di
Keyword(s):  
Arctic Ocean ◽  
High Latitude ◽  
Cold Climate ◽  
Second Century ◽  
Seventh Century ◽  
The Arctic

A review of early Chinese writings has revealed several references to the Arctic. The oldest of these is Zhou bi suan jing from the second century B.C. The latest reference considered is from the early seventh century A.D. Among the characteristics of the Arctic known to the early Chinese were its high latitude with respect to the pole star, its cold climate and consequent dearth of vegetation, and its lengthy period of winter darkness. The existence of an Arctic Ocean was also recognized.

scholarly journals On the Accuracy of Deriving Climate Feedback Parameters from Correlations between Surface Temperature and Outgoing Radiation

2010 ◽  
Vol 23 (18) ◽  
pp. 4983-4988 ◽  
Author(s):  
D. M. Murphy ◽  
P. M. Forster
Keyword(s):  
Surface Temperature ◽  
Climate Model ◽  
Mixed Layer Depth ◽  
Box Model ◽  
Climate Feedback ◽  
Time Interval ◽  
Feedback Parameter ◽  
Outgoing Radiation ◽  
The Difference ◽  
Climate Studies

Abstract Changes in outgoing radiation are both a consequence and a cause of changes in the earth’s temperature. Spencer and Braswell recently showed that in a simple box model for the earth the regression of outgoing radiation against surface temperature gave a slope that differed from the model’s true feedback parameter. They went on to select input parameters for the box model based on observations, computed the difference for those conditions, and asserted that there is a significant bias for climate studies. This paper shows that Spencer and Braswell overestimated the difference. Differences between the regression slope and the true feedback parameter are significantly reduced when 1) a more realistic value for the ocean mixed layer depth is used, 2) a corrected standard deviation of outgoing radiation is used, and 3) the model temperature variability is computed over the same time interval as the observations. When all three changes are made, the difference between the slope and feedback parameter is less than one-tenth of that estimated by Spencer and Braswell. Absolute values of the difference for realistic cases are less than 0.05 W m−2 K−1, which is not significant for climate studies that employ regressions of outgoing radiation against temperature. Previously published results show that the difference is negligible in the Hadley Centre Slab Climate Model, version 3 (HadSM3).

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